Document text
FM 24-12 Table of Contents
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Homepage Information Instructions
Field Manual
No 24-12
*FM 24-12
HEADQUARTERS
DEPARTMENT OF THE ARMY
Washington, DC, 17 July 1990
FM 24-12
COMMUNICATIONS IN A "COME-
AS- YOU-ARE" WAR
Table of Contents
Preface
Chapter 1 - Planning Considerations
1-1. General
1-2. Reduced Equipment Planning
1-3. NBC Environment
1-4. NBC Communications
Chapter 2 - FM Radio Operations
2-1. General
2-2. Frequency Planning
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FM 24-12 Table of Contents
2-3. Planning Range
2-4. FM Radio Security
2-5. Squelch Capabilities
2-6. Net Radio Interface
2-7. FM Radio Operations Example
2-8. Technical Characteristics
2-9. Typical Configurations
Chapter 3 - AM Radio Operations
3-1. General
3-2. Reduced Assets
3-3. Equipment Considerations
3-4. AM Radio Security
3-5. Netting Old and New Equipment
3-6. Interoperability Procedures
Chapter 4 - Telecommunications Center, Switching, and Patch Panel
Operations
4-1. General
4-2. Telecommunications Center Operations
4-3. Telecommunications Center Operations Example
4-4. Tactical Facsimile Operations
4-5. Switching Operations
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FM 24-12 Table of Contents
4-6. Patch Panel Operations
4-7. Patch Panel Replacement Example
Chapter 5 - Wire and Cable Operations
5-1. General
5-2. Installation Considerations
5-3. Equipment Utilization
5-4. Installation Methods
5-5. Existing Wire/Cable Systems
Chapter 6 - Alternate Means of Communications
6-1. General
6-2. Messenger Service
6-3. Visual Signaling
6-4. Panel Signaling
6-5. Pyrotechnic Signaling
Chapter 7 - Communications Security Operations
7-1. General
7-2. Authentication Systems
7-3. Transmission Security
7-4. Codes
7-5. Ciphers
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FM 24-12 Table of Contents
7-6. Brevity Lists
7-7. COMSEC Operations Support
Chapter 8 - Tactical Satellite Communications Operations
8-1. General
8-2. Advantages
8-3. Deployment
Appendix - MSE Interoperability
Glossary
References
Authorization Letter
DISTRIBUTION RESTRICTION: Approved for public release; distribution is unlimited.
*This publication supersedes TC 24-18, 15 March 1985.
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FM 24-12 Preface
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Preface
Purpose and Scope
This publication is designed as a handbook oi helpful information and
methods for providing essential, coflimun I cations support in the face of
cofluuuni cations equipm tut shortages in AC and EC unit*. It alao addresses
nifitf toils far achieving Lntflra-pfirabLli.Ly between diff(?rtfrit generations of
tactic^] communications equipment.
This publication can be used by the planner h the supervisor 7 and the
operator. It suggests field expedient solutions, most of which are found in
current tlae Urinal literature, Somti of thtK4i suggestions use field expedient
techniques — methods not normally considered thst may require additional items.
Thfi employment techniques are described in general terms. Specifics will
he dictate-d hy the situation and by the appropriate equipment Jtianuals, These
techniques are proven and may even provide increased Eligibility in
cojnoincii cations systems. The rtzcajnme cided methods are not intended to be contrary
to r ngf u la t.i o rts or po.l i r.\ e a on ma in t a i Eiing 1 US Iiig t (taodl f V ing. N or C ro SS level ing
equipment. They do p however ± provide Innovation and flexibility in getting the
message through on the modern battlefield.
A chapter addressing TRI-TAC equipment, especially OfiM and the basis of
how it: LiiLcrfacts with USE will be added to this manual in the next revision-
The Appendix acid^sse^ initial lessons learned about. hl£E to TRI-TAC
Inte r op e r ab i 1 i ty -
User Information
The proponent of this publication is IEQ TEADOC, Your comments on this
publication are encouraged P Submit change^ for improving this publication on DA
Forra 202S (Recommended Changes to Publications and Blank Forms) and key thtfti La
pages ami H.nes of te^t tn which they ap^ly. If 1>A F^nn 2U2S is not available,
a letter is acceptable. Provide reasons for your comments to ensure complete
understanding and proper evaluation, FoKV^rd your LonnneiLts to CoirufiaiideE, United
States Army Signal tenter and Fort Gordon, ATTtf; ATZH-DTL, Port Gordon,
Georgia 30^05-5075-
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FM 24-12 Planning Considerations
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Chapter 1
Planning Considerations
1-1. General
a. The RC makes up nearly half of the military capability of today's US Army. RC units, in many
instances, do not have a complete fill of authorized communications equipment; what they have may
consist of different generations of equipment. Current economic realities limit how much additional
communications equipment RC units can expect to receive. Thus, RC units must be prepared to
mobilize with the equipment on hand in a "come-as-you-are" war.
b. AC units are also affected by this dilemma. Many RC units are related to an AC unit under an
affiliation or roundout program. More specifically, they train and operate with their active
counterparts. If old and new equipment must be interfaced, both AC and RC units must know the
proper equipment interface procedures.
c. A similar problem could exist between allied units using different types of communications
equipment, and US units using standardized, modernized, or upgraded communications equipment.
Any military unit faces the possibility of operating with a shortage of equipment. Combat losses,
excessive usage, maintenance problems, normal wear and tear, and delayed receipt of new equipment
reduce equipment availability.
d. OPSEC principles must be inherent in all phases of a "come-as-you-are" war. The principal
OPSEC elements of physical security, information security, signal security, and military deception
must be continually applied, not only during combat operations, but also during peacetime planning.
This ensures the protection of military operations and activities and prevents hostile exploitation of
identified weaknesses. Shortages of equipment and personnel, equipment interface problems, training
deficiencies, and other such problems are exploitable weaknesses that must be properly protected.
Remember, the way we practice is the way we fight.
e. The NBC environment must be included in planning considerations. Communications in NBC
conditions must be realistically anticipated and discussed with candor.
1-2. Reduced Equipment Planning
a. The key to operating with reduced equipment quantities is advance planning and action. Viable
alternatives must be devised and supporting equipment and personnel must be requisitioned,
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FM 24-12 Planning Considerations
obtained, and readied. Critical questions must be answered. For example, what communications
support can the first brigade expect based on the division's present capabilities? What is the tactical
situation and what actions are planned next? What signal assets are available for supporting these
actions? What are the minimum necessary communications support requirements for DTAC to the
brigade TOC, DTOC, DISCOM, or others? What are the priorities?
b. There are no pat answers. We do know that the following types of traffic are essential:
q Command.
q Operations.
q Intelligence.
q Fire support.
q Logistics.
c. The next question is which means will be allocated to the respective critical needs? FM radio is
used for the immediate command, operations, and fire support traffic. Some of this traffic will have to
be passed over AM radio and multichannel radio systems, supplemented by alternate means. Lesser
priority traffic should be passed over alternate means such as motor and air messenger service to the
maximum extent possible.
1-3. NBC Environment
a. In the past, combat communications have been installed under difficult yet understandable
conditions such as bad weather, limited equipment, and even hostile fire. These conditions are
understandable because they have been experienced. We have grown up in good and bad weather.
We have read combat histories, watched combat films, and even listened to soldiers who have
participated in combat. The future battlefield will include an NBC environment not yet experienced.
(See FM 3-100 for the fundamentals of NBC defense. )
b. The equipment may be contaminated by biological and chemical agents. Decontamination of
internal electronic components may be difficult if not impossible. (See FM 3-5 for NBC
decontamination and FM 3-3 for NBC contamination avoidance.) Thus, continuous operations in
MOPP and its effect on personnel and installations must be included in planning estimates. Forward
communications teams, PCM relays, and FM retransmission stations need to become familiar with
displacement under limited visibility while in MOPP.
c. Operators are not as effective while in MOPP. Handling knobs while wearing bulky gloves can
frustrate operators. Voice communications are difficult, not only with FM and AM/SSB radios, but
also with orderwires, switchboards, and patch facilities. The problems in understanding verbal
instructions can slow system installation and subscriber use. The MOPP equipment can generate heat
and cause operator sweating which irritates the soldier causing anxiety and inattention to details. (See
FM 3-4 for individual and collective NBC protection.)
d. Leaders, especially NCOs and first line supervisors, must understand that direct involvement in
this situation may not solve the problem. The universality of MOPP appearance and the distortion of
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FM 24-12 Planning Considerations
voice quality make familiar leaders appear unrecognizable. Only through proper supervisor training
can soldiers' natural apprehension be translated into confidence.
1-4. NBC Communications
a. Communications will be affected in at least two ways during nuclear warfare: communications
blackout and physical damage to equipment.
(1) Communications blackout is caused by intense ionization of the atmosphere in the vicinity
of the blast. The blackout may last for a few seconds or several hours. It may be more severe
on some frequencies than on others. During this period, communications is impossible.
(2) Physical damage depends on the nearness of the blast to the equipment. It can range from
total disintegration (at ground zero) to thermal (heat) damage (several miles away) to electrical
breakdown caused by the EMP radiated from the burst (several miles away). The EMP is
perhaps the most subtle cause of physical damage. It is a very intense radio wave of extremely
short duration produced at the instant a nuclear weapon is detonated. It usually lasts a fraction
of a second. But the power it may deliver to a radio receiver can be a billion times greater than
what is normally received from a transmitter. This extremely high power density can damage
some signal equipment. EMP is silent and invisible.
b. The ability of a unit to continue to communicate during a tactical nuclear war will depend on
planning, training, and equipment hardness. These actions must begin long before the war begins.
System planning must use minimal resources to perform the mission allowing a portion to standby.
Training must incorporate the use of hardened CPs and EMP prevention steps, such as shielding by
natural terrain, burying of cables, and disconnecting equipment when not in use. Equipment
hardening and buffering devices are included in new equipment development. However, these steps
are based on mission accomplishment in a nuclear environment. All soldiers must train the way we
expect to fight and communicate.
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FM 24-12 Chptr 2 FM Radio Operations
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Chapter 2
FM Radio Operations
2-1. General
a. Single-channel FM voice radios are the primary communications means used in almost all tactical
Army units below brigade level. FM radios give the tactical commander quick, reliable, and flexible
communications needed to control the battle. The AN/VRC-12 series used by active and reserve units
is the only family of FM radios currently used by the Army. With the fielding of SINCGARS, the
Army may use two families of FM radios. The signal personnel of both AC and RC must prepare to
operate tactical FM radio nets containing both families of radios.
b. FM radios must take some of the additional burden when shortages of multichannel equipment
force reliance on other means of communications. FM radios add a great deal of flexibility to our
communications system. This section addresses techniques useful in providing essential command
and control communications in the face of equipment shortages.
2-2. Frequency Planning
a. Figure 2-1 shows a comparison of frequency ranges between the AN/VRC-12 series and the
SINCGARS radio sets. In addition to the extended range of SINCGARS, channel- spacing problems
must be anticipated when interfacing AN/VRC-12 and SINCGARS. The channel spacing for AN/
VRC-12 is 50 kHz. The channel spacing for SINCGARS is 25 kHz. When interfacing, frequencies
must end in 00 or 50.
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FM 24-12 Chptr 2 FM Radio Operations
SINCGARS
30.000
30.025
30050
30 075
30.100
30.125
30.150
30.1 75
30.200
AN/VRC-12
30,000
30.0EO
30.100
30.1 50
30.200
|_30
[7&.95
MHZ
l
MHZ
MHZ
VRC-12
SIMCGAFfl
l
Figure 2^1, Frequency comparison chart.
b. Obviously, all radios for a particular net must be capable of operating on the same frequency. Net
frequencies must be assigned with primary consideration given to the old radio's frequency tuning
capabilities. This applies also to channel spacing. The AN/VRC-12 series has a channel every 50 kHz
and the SINCGARS equipment every 25 kHz. Nets involving both series radios must consider these
differences and plan for proper channel separation.
2-3. Planning Range
a. Older radios have less range than the newer radios, so the maximum planning range must not
exceed that of the older radios. Antennas on vehicles are vertically polarized; therefore, polarization
usually presents no problem. The distance problem may be eased by the careful placement of
retransmission stations in the unit's area of operations. Retransmission is effective but must be
carefully controlled and properly employed using electronic warfare considerations.
b. The range of the FM radio sets can be extended by the proper location and orientation of the
antenna system in regard to the vehicle and terrain. Additional distance can be obtained using
elevated ground plane antennas such as the RC-292 or OE-254. Field expedient antennas may also be
used not only to increase range but also to provide more directivity while reducing interference and
detection. The SINCGARS may use the RC-292 in the single-channel mode. The OE-254 may be
used in single-channel and frequency-hopping modes. Field expedient antennas may be used with
SINCGARS in single-channel mode.
c. The planning range can be further extended with retransmission operations.
(1) Retransmission, or retrans for short, offers the commander a valuable alternative when
multichannel equipment is in short supply or absent. As with NRI, retransmission is often not
used to maximum advantage because of lack of knowledge or lack of confidence in its
effectiveness. A shortage of multichannel equipment requires better planning and use of all
other communications assets; retransmission is no exception.
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FM 24-12 Chptr 2 FM Radio Operations
(2) A primary application of retransmission is the extension of a particular communications
link such as an FM command net or a fire direction net. Another application might be a
logistical link from brigade trains to the DISCOM area in the absence of multichannel. Traffic
on this link would be for urgent requests for resupply of critical items only such as
ammunition or POL, or for a contact team for the maintenance of critical items. Routine traffic
should be sent by other means.
(3) Retransmission should also be used to support anticipated operations or planned moves of
important elements. For example, if a brigade CP is moving to a certain location at 1600
hours, a retransmission station could provide a communications link back to the DTOC.
Retransmission may also allow the brigade CP to locate in a position that provides better
physical security while still maintaining its essential FM radio communications.
(4) Retransmission sites must be carefully chosen to maximize retransmission distance while
at the same time minimizing enemy interception. Several alternate sites should be chosen for
each retransmission facility to allow for periodic displacement.
d. HF radios, such as the AN/GRC-106 or the AN/PRC-104, are used for long-range
communications.
2-4. FM Radio Security
a. The AN/PRC-25 is not capable of operations using secure equipment. The AN/PRC-77 and AN/
VRC-12 series radios can be secured with VINSON. SINCGARS can also be secured with VINSON.
Planners should attempt to exchange equipment if certain nets must be on-line secured, and leave
other nets to use low-level encryption and authentication procedures. Regardless of which security
system is used, all nets must use proper radio procedures.
b. Chapter 7 discusses COMSEC. It covers the use of proper procedures and encryption systems in
voice and record communications. Part of our security effort must be directed at operations that
prevent the enemy from locating our emitters or analyzing our traffic. This is essential to survival on
the modern battlefield. Every operator and user of signal systems should read and practice the
techniques described in FM 24-33 and ACP 125(D) . All communicators should practice daily the
basic ECCM techniques described below .
(1) Use the lowest power possible for the required communications when power settings are
adjustable. This is especially important the closer the transmitter is to the FLOT.
(2) Reduce on-the-air communications time. Both the quantity and length of transmissions
must be kept to a minimum to deny the enemy the opportunity to detect and exploit friendly
communications. Minimal transmissions should be coupled with frequent moves for greater
security against enemy direction finding efforts.
(3) Change call signs and frequencies and use the proper authentication and COMSEC
practices as specified in the unit SOI.
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FM 24-12 Chptr 2 FM Radio Operations
(4) Train all radio operators to practice sound radiotelephone procedures and use them in all
training and operations.
(5) Emplace antennas and all noncommunications emitters properly. Terrain masking is an
invaluable technique for denying the enemy knowledge of your location and unit.
(6) Use digital communications terminals such as the AN/PSC-2 or TACFIRE digital message
device when possible to take advantage of burst and error corrected transmission.
c. Many RC units are equipped with the AN/VRC-47 radio, enabling them (doctrinally) to operate in
two separate radio nets at the same time. When the AN/VRC-47 is equipped with a KY-38 FM
security device (or similar secure equipment), the RT-524 receiver-transmitter continues to function.
But the R-442 auxiliary receiver will be inoperative since the KY-38 accommodates only the RT-524.
The result is one AN/VRC-47 that was formerly engaged in a two-net function is now capable of only
single-net operations. This shortfall must be considered in the planning. Similar problems occur when
installing the KY-38 on the AN/VRC-44 and AN/VRC-48. If using the VINSON KY-57 security
device, both the R-442 and RT-524 will operate in the secure mode.
2-5. Squelch Capabilities
a. The AN/VRC-12 series radios have the ON and OFF positions in both new squelch and old
squelch. The old squelch was used with the AN/GRC-3 through -8 series radios which are no longer
in the inventory. The AN/PRC-77, AN/PRC-25, and SINCGARS can be operated in new squelch or
without squelch. The AN/VRC-12 series radios should be used in new squelch on or new squelch off
mode only.
b. Squelch is particularly important when netting (interoperability) with allied forces whose tactical
FM radios operate in the old squelch and have limited frequency range. Close coordination is
required when netting with allied forces.
2-6. Net Radio Interface
a. NRI is a highly effective method for bridging the commander's two primary means of command
and control: tactical radio and telephone networks. It is normally used only by commanders and key
staff members, but in a "come-as-you-are" war more people may need to use NRI. This is because
shortages of multi-channel equipment force the commander to find alternate communications routes,
and NRI is one of the most flexible.
b. Commanders have not made full use of their NRI capabilities in the past because-
q Some commanders and communications personnel do not know enough about NRI.
q Some units lack technical expertise, resulting in lack of confidence by the commander in the
NRI system.
q Some commanders do not trust vital communications traffic to NRI systems because of lack of
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FM 24-12 Chptr 2 FM Radio Operations
confidence in NRI.
q NRI, at this point in time, is not capable of end-to-end encryption.
c. NRI extends communications distance because it connects the tactical radio into the division/corps
wire system. Some NRI stations can also be used as retransmission stations, not simultaneously, but
alternately in either mode. For example, the commander in his vehicle calls the NRI station to place a
call back to the DTOC. The NRI operator attempts to call through, but the circuits are busy. As a
result of thorough training and by knowing the SOI retransmission frequency, the operator switches
over to the retransmission frequency and puts the call through to the NRI station serving the DTOC.
d. NRI stations, like other FM radio installations, must be moved periodically to various alternate
sites, both to adequately serve the headquarters or elements it supports and to enhance security and
survival. The move may be necessary to support a new tactical CP or to support fast-moving
operations. These moves are supported by-
q Planning acceptable communications sites.
q Considering the mission and security requirements.
q Planning and installing wire/cable to tie in to the division or corps wire/cable system.
q Establishing a "jump" facility that moves into position to support operators before shutting
down and moving to another facility.
Pre-positioning of wire/cable system terminations is absolutely necessary on the fast-moving
battlefield.
e. NRI systems must connect to switchboards to have access to the telephone network. The
switchboards can be manual or automatic boards and either can process NRI calls— but not without
prior identification of the NRI circuits and adequate training of operators (both switchboard and
radio). Switchboard operators must know telephone traffic diagrams well to react adequately and
quickly. SOPs must identify those individuals who are authorized to use NRI circuits. All users of
NRI systems must use low-level security procedures since NRI is not secure. NRI frequencies are
found in the unit SOI. NRI procedures for both radio and telephone are found in the supplemental
instructions in the unit SOI. All NRI users must use proper procedures when communicating.
f. The AN/GSA-7, AN/GRA-39, AN/GRA-6, and C-6709/G are associated items of NRI operation.
More complete explanations are covered in FM 24-18 .
(1) Radio set control AN/GSA-7 provides an interface between a radio set and a switchboard
which can be located for planning purposes up to 16 km (10 miles) from the radio set. There
are four methods of providing NRI ( Figure 2-2 ), depending on the number of AN/GSA-7s in
the system. The four methods are described in FM 24-18 . These variations provide for both
attended and unattended operation of the AN/GSA-7.
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FM 24-12 Chptr 2 FM Radio Operations
(10 Miles. MaxJ CJt-7474/U
Field
_f m\ AN/ l/r ftecif i ver- '
_ Swiichboard *1 ~ fr . _ IT Transmits
i r GSA,? 1 1 to
-ill nLi^rnii-.tJr
fltzJ 2 - 1
Tr^nsmttar
I P
AN/
GSA-7t
SwilCh^b&rc 1
TflJep^Uriu
1. *h/GSA-7at Bolh ^nians; Rarfio Operas not Reared ac AJY/GSA-7.
h«ld
Telephone-
H ~~
S^ic^hbnartf.
— i
AN/
15A-V
Trans pM^ur H
D-
"l I rans
MS
Tran&mntpr
3
H-M/PT —
Rad:o
Gpdr&tnr
?. AN/GSA-7 4 t On? SiAUcn: fladk. Oparaior Haired ar AN/G5A-7.
CK-l0177/Uf2W:)
P3r[ of
0^574/QRA ^
I Fi*lii j — :
"ctephoii* r—
Switcboa/d
AN/
MG5A-7I
Transmiiiflrl- 1
— I I ransn
3 AN/GSA-7 &; Ow Station, 0-B74/GRA a-. Ochcr;
No fifrdipOraralor fteq^riredal AN/GSA-7.
j Hands*: ■
j (Connec-^io
Audio
Receptacle
when RT
ia RT-S05/
pac-zsor
RT-041/NIC-
Fi^ld
; Te^ephDne
_Swi(chfiDErrt r-
fanned ?dn>
Radio LirJc for
Switchiici^fd
Operator
^onildrCan-a.
Monitor
leiepron*
AN/
JBSA-7I
Rtdcpivar-
Transmitter
m
Transmittal
4. AN/GSA.? al OneSution, Radio Monitor Ti^phsna. No Radio OjwraT&r Requir"^.
Figure 2-2, Four methods of NRI.
(2) Radio set control group AN/GRA-39 can provide remote control of receiver-transmitters
up to approximately 3.2 km (2 miles). It can also provide NRI among SB-22, SB-86, SB-3082,
and SB-3614 switchboards and receiver-transmitters such as the AN/PRC-25, AN/PRC-77,
and AN/VRC-12 series radios. NRI operation with the AN/GRA-39 can be remoted up to 1.6
km (1 mile) between the switchboard and the receiver- transmitter. Specific procedures for
remote operation and NRI operation are described in the operator's technical manuals for the
radios and for the AN/GRA-39.
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FM 24-12 Chptr 2 FM Radio Operations
(3) Radio set control AN/GRA-6 can provide remote radio control of a radio set up to 3.2 km
(2 miles). It can also be used to provide NRI between an SB -22 switchboard and the radio set.
(4) Radio set control C-6709/G provides the capability for manned integration between 4- wire
tone signaling telephone communications systems and push-to-talk radio systems. The C-6709/
G is compatible with both current and future wideband transmission requirements. The 300 Hz
to 70 kHz baseband allows the unit to accommodate a wide variety of interfaces for data
communications and other needs. Radio keying can be accomplished with manual control by
the NRI operator, by DTMF procedures, and/or by automatic voice actuation. It contains an H-
250 handset, an H-325 headset microphone, and connecting cables with a basic unit. The C-
6709/G provides facilities for controlling transmitter/receiver circuits of a variety of tactical
radios in a 4-wire switched system comprised of AN/TTC-38s, AN/TTC-39s, SB-3614(V),
CNCEs, and radios with COMSEC, such as PARKHILL and VINSON.
2-7. FM Radio Operations Example
a. You are the S3 of the 52d Division (Mechanized) Signal Battalion. The DTAC is presently in the
vicinity of the 1st Brigade. The G3 has notified you that the tactical CP is moving to the vicinity of
the 3d Brigade and will be on site in four hours. No multichannel equipment is available to support
the tactical CP or the 3d Brigade Headquarters. The commanding general's M577 has two FM radio
sets, but only one RATT set is available for support at the new site.
b. How can you provide for minimum essential support for the tactical CP at the displacement
location within four hours?
c. Obviously you cannot provide the tactical CP with the full doctrinal communications system at the
displacement location. First, examine how the two FM sets could be employed. One set will be
operating in the division command net. The other FM set must be used for an NRI circuit back to the
extension node serving the 3d Brigade. In this situation, at least two priority circuits must be
engineered from the extension node to the DTOC. These circuits would go to the G2/G3 and FSE in
the DTOC. This configuration allows the CG to use his priority NRI to establish calls to the
appropriate element in the DTOC. As a minimum-
q Extension node NRI stations supporting the 3d Brigade must be reassigned and must be
prepared to support the CG's high priority calls.
q Dedicated circuits must be engineered from the extension node switchboard through the
division communications system to the DTOC.
q NRI and switchboard operators must be well briefed for this type of system.
q DTOC personnel must be prepared to share the two priority lines from the extension node.
d. A retransmission station (if available) is needed to support the NRI system back to the extension
node when actions to accomplish the above begin. Also, field wire lines must be installed (terrain and
tactical situation permitting) to provide additional circuits to the new tactical CP location from the
extension node. These wire circuits need a way that permits the NRI system to leave the air. This
reduces the electronic signature of the tactical CP and improves its survivability. Also, the one RATT
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FM 24-12 Chptr 2 FM Radio Operations
set at the tactical CP must be used for both command and operations traffic.
2-8. Technical Characteristics
FM operations are the backbone of combat communications. To plan communications networks
effectively, the planner must know the technical characteristics of the radio equipment. Table 2-1
compares the important characteristics of the receiver-transmitter units that are the chief components
of both the AN/VRC-16 series and the SINCGARS FM radios. Especially important are frequency,
channel spacing, squelch, and secure equipment capability.
Table 2-1. Characteristics of both old aid new generation
FM radio equipment >
FREQUENCY (WSHz|.
TUNING
! CHANNEL SPACING
POWEfl OUTPUT
at uwrr
COVERAGE
1WATT8]
' RT-524
30-75.95
DeitETU
.05 MU*
3E-6EiHiflh| 0.5-10 (Lcw|
KT-24G
30-7&.9G
tJet&nc
.05 MHz
35 A5 I Hig.h | Q.5-10 (Lpw|
RT-sn*
30-75.95
DctfcrtC
EOkhU
1.1-2
IPRC-25J
RT-0i1
30-75.95
Dotan(
.OEM Hz
1 .5-4
IPRC-77J
SiNCDAHa"
^O-SV.SJS
SyrUhflaiisd
25 kHz
(Lcw| 500 mi«avtfa".Ei
(Mfldiutfi) IN nicrDwlCtS
<High|4wfltts
flared Jmi] fkn - !
Squalch
Ualrifl Unli
Sflcurhy Equipment
PT-534
25 mi (40 k m > High-
5 rnf (EknlLov^
Rfow/Old/grr
All
K-V-a/KY-3B/Or-57
*r-2*G
2Gnii(40kmJH.flH-
5 m't f5 kpl Low
Hew/Old/Otf
AN
KY-B/KY-SB/^Y-^
ET-SOG
5 mr(akrn|
Wflw/OFf
All
Nona
(Hti£-23|
WT-S41
5 m-i(9 tm|
Mpw/Off
AIJ
KY-36VKY-57
(HKC-77I
SlhCGARS
O-3D0 m (Low!
0,3-4 km |Mflcli-LJm|
^-1fi km (Hiflhl
with p-jwai
NftWOH
All
KY-57
(wwvn^ea,
-90.-91,-93):
6- 35 Km
2-9. Typical Configurations
Current typical configurations of FM radio equipment are listed in Table 2-2 .
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FM 24-12 Chptr 2 FM Radio Operations
Table 2-2, Configurations of AN/VRC-12 series FM radios.
AN/VRC-1Z FAMILY
i Conl : gi;rg!i^ns:
Convener.!
RT-?46"vRC
R-M2-VHC
RT-524"JHC
12
1
1
43 44 4S
1 i 2
Q 2
DOC
46
D
D
1
*7
C
1
1
48
1
C
D
£
AT-SU'VRS
0-' AS -1725
1
1 1 2
1
1
2
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FM 24-12 Chptr 3 AM Radio Operations
RPL
GE3H
iJBD
RDL Table of Document Download
Homepage Contents Information Instructions
Chapter 3
AM Radio Operations
3-1. General
Equipment shortages or differences may cause serious problems. The problems could result in having
only one or two radio sets to pass all the traffic normally passed by six or more sets. AM radios,
combined with ancillary equipment, can pass traffic in either of three modes: voice, RATT, or CW. This
chapter addresses solutions to the problems caused by equipment shortages or differences.
3-2. Reduced Assets
Following are alternatives for operating with reduced assets:
a. Operate one AM radio in several nets using an established time schedule. Select the most important
net to monitor and operate in. Enter the other nets only when necessary to pass traffic. Enter the other
nets at preplanned times or notify the other stations by telephone or FM radio at unscheduled times. The
schedule should change every day and be randomly generated to preclude the enemy from analyzing
your traffic pattern.
b. Preplan all messages by using brevity lists and codes to shorten the time spent on the air.
c. Use the TCC's off-line teletypewriters to prepare teletypewriter tapes prior to submitting traffic to the
RATT operator for transmission. This reduces the RATT operator's burden and saves transmission time.
d. Use FDX operation on equipment which has FDX capability. Much more traffic can be passed over
FDX circuits than over half-duplex circuits, thereby reducing time required for passing traffic.
e. Transmit low priority traffic over alternate means, such as messenger or multichannel radio, if they
are available.
f. Use one radio, if possible, for several individuals, staff sections, or units.
g. Establish a wire link with a distant station using the existing teletypewriter and secure device along
with a telegraph terminal TH-5/TG or TH-22/TG when the radio or modem of a RATT system is
defective. Speech-plus can also be provided using this technique by using telegraph-telephone terminal
AN/TCC-14 or AN/TCC-29.
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FM 24-12 Chptr 3 AM Radio Operations
h. Use error correcting burst communication devices, such as the AN/PSC-2, if available, to cut down
on air time and errors.
3-3. Equipment Considerations
a. When different types of AM radios must work together in the same net, the SOI must include proper
frequency assignments compatible to each type of radio equipment. All nets using two or more different
AM radios are restricted to certain frequency ranges or modes of operation. (The various technical
characteristics of all the AM radios currently in the Army inventory will be covered later in this
chapter.) Frequency and mode assignments must be coordinated prior to joint operations when units
with different AM radios may be involved together.
b. When planning nets, radio planning ranges must be considered. Certain AM radios have much more
power than others, so planning ranges must be based on the least powerful radio's capabilities. Related
to the distance factor is the type and polarization of antennas. Antennas must be properly polarized and
correctly oriented. For extended ranges, a half-wave doublet antenna, such as the AN/GRA-50, should
be used whenever time and terrain permit.
c. By obtaining prior approval, various civilian radios with AM, CW, and SSB capabilities can be used.
When using civilian radio equipment, proper military procedures will be used. For operation of ranges
between and 450 km, the near vertical incidence skyware technique described in FM 24-18 , Appendix
N, should be used. This will allow skip zone free omnidirectional communications at low power under
all conditions.
NOTE: Under no circumstances will citizen's band procedures be used.
3-4. AM Radio Security
Some military AM radios may be secured in the voice mode using the KY-65. Most AM radios can be
secured for RATT operation using TSEC/KW-7 or TSEC/KG-84A security devices. Some of the older
radios have not been modified to accept the KW-7 at this time but can be altered to accept it as required.
If time and situation permit, ensure that all your radios have been modified to accept security devices.
When operating a nonsecured radio in voice or CW modes, codes or off-line encryption methods must
be used.
NOTE: The KG-84A will only operate with AN/GRC- 142/122 RATT sets equipped with
MK-2488 installation kits.
3-5. Netting Old and New Equipment
Most AC use the newer families of SSB radios, whereas RC have a combination of the older AM and
the newer SSB equipment. The new equipment can work with the older equipment, but it takes just a
little extra care to make it work correctly. The planner needs to know the technical characteristics of all
the radio sets involved to plan the communications network properly. Table 3-1 is a comparison of
technical characteristics of the AM radios in the Army inventory.
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FM 24-12 Chptr 3 AM Radio Operations
Table 3-1, AM radio technical characteristics.
' H
t
Nomenclature
Configurations
Typ« of
St>rvlta
Tuning
Power Output
Planning Range
AK/ciHr: -ia
GRC-4&.VRC-2&
VSC-1
D33 Voice. CW,
RATT
CtncinuGuK
icttw
HQfcM 150 mi|
ak/^r: *i
DS9 Voioe. C^V
Continuous
CW/RATT4&0W
l&TO KM I'OCOm.i
AH/GFlC-^D
D^S Vni--u. CUV,
HA11
CcndnuojE
CW/:RATT45QU
16£0 KM MOtXJjnl .
Afc/GRC-i&9
Dii3 VuiCfc, CW
Cuntinuc-.J!;
10W J 5W
121 KM 1 7b' mi|
■a
5
AN/GR" fl"?
VRC-34
DS3 Vobe. CA J
Ctmru-ous
Vine 7W
CVu 1 &'A"
■ e to ?o km
nO co 31 niii
i
! A^/mr r^
SSS voice CU
CtnTiHucMJft
£fl KM ffiO ni|.
AN/rvim?-£
I native cnlyi
059 Voice. CW
RAIT
C^ntfnu-puE
NA
160 KM n 00 mil
Ah/MRM-
Continue js
Voice 4G0W
CVU/RATT4bCW
ISO KM (100 mil
z.
an/gr:-106
GRC-122, GKC-K2
VSC-2, VSC-3
A^/fi^R Voice. CW
RAH FSK/NSK
DeCenl
Voice 400W
CW-RATT2Q0W
tiO <M |b0 1i JWi !
16Qle24CO<M
|1DQ |c> E491 rnij
AN/FPC-47
SSBI'ustk. c.w
: Dr;tr:n1
H^hlOOW
_juw 20W
AN/PRC-&*A
D5I3 Vpicp. CW
Jetem
V-Sii^ I.5W
CW 5'A'
2* KM Hz \r\)
AN.-^RC-^O
SEd Vo cc. C'/V
Deten:
Vmsd ?.bW
121 KM I7B .nil
4300 KM
.;2*nO nil
AN/PRC-7A
PRC 74 A. PRC-
74B,F^C-74C
SSB Vq ce C'^
1
Detem
1 bW
JO KM |26miji
^/G=:C-?13A
w/GRC-i&aa
DATA.-flAfT F5K,
* CW
C«tenL
4f\/PRC IQ4 ™\ 23SEKM
AN/GRC-?1? 20 W \(14S1 mi)
4N/ GKC- 1 B2 1 LXJ- 40O'iV ^v
NOTE - IHFR ONLY OPERATES
NOTE - AN/PHC-10* IS USER
CW IN NON-STAJ MODE.
OWNED AND OPERATED EQUIPMENT.
a. The most important technical characteristics to consider when netting two different radios are the type
of tuning and type of emission.
(1) Table 3-1 shows that the older radios have continuous tuning whereas the newer radios have
detent tuning. The difference between these two is that detent-tuned radios can tune only to
certain frequencies and cannot tune to the in-between frequencies to which the continuous-tuned
radios can tune. The continuous-tuned radios must tune to the detent- tuned radios. This includes
the radio systems used by other military services (such as Marines, Navy, Air Force) .
Continuous-tuned radios operate approximately 1.5 kHz below the detent-tuned radio's
frequency. The NCS should have a new series radio set to which all radios can tune. If the NCS
does not have a new series radio set, the operator should direct a station with a new series radio
to provide the signal to which all others tune. Check Table 3-2 for compatible frequency ranges.
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FM 24-12 Chptr 3 AM Radio Operations
Table 3-2. AM radio frequency ranges
Nomenclature Frequency Range
Frequency in NtHz
& 10 IB 20 25 30 36
i
VJ/C^ P C- 1 R Tr^r sm r 1 .» to 20.C Mh*
AN/G HC- 1 9 R*rt*i vi 0.6 to 32 M L z |^_^_|^_^^J^^
7r a iik riFt^r T-3GS ' 1 . 5 to 20.0 tf-H z
Ken« ¥<:r R 3&0 ** Cl.R To 32 tf Hi
Afo/GRC- 1 Ofl r ■ arismit 3. 3 l^ 22.0 tf H?
A N .-'GRC- 1 03 Recti «: 3.0 l* 24.0 M Hz
AN/GHU-S/ i.OM 12.0 M Hi
A VFHC-M 3.4 -o 5 MH z
6.3w 30.0 MH?
■
■
AN/GPC 1 3B 2 m 2ft 959 MHz
ftN/G P C- 1 06! A| 2 .0 to 2&.9G9* Uhi
AN/P^il 47 2 D M 1 1 999 MHz
AN/PRC-6JA 2 2toG.O\iH/
A N/ P RC- 7C*-* 2 C Lu 7E 9^9 MHz
A.P. / ^nc -74/ 74A 7 C 1 p 1 J OCX) MHz
AN/ =ftC-74S ■- 74 C 2.0 lo 1 7."9&3 MHz
HFP. 2.0 10 29.9999 MW?:
AN/PRC 1C4.AN/GRC-213
andAN/GRC- J 93
l i r
^
" 1 -j6B r* rt cnrrpnnart ol AN /GRC- 26 D, Aft/GflC il , *nd AN/MRT-9.
"R-390 iH * cr.r-K-ncnt o J AN-GKC-itiD, A^/gRC-41 . AN/ VIA H -3.. *;"id AN/MRT-*
" * ' AA /PR T 73 j* i|w Yor 30.00 CO JEi 999 Mt ■ t.
(2) Emission types must match. In the CW mode, the type of emission for both old and new
series radio sets is the same. In the FSK mode, the type of emission is the same, but the way the
carrier shifts is different -a problem that can be overcome. The type of emission for voice,
however, is different. The old series equipment uses DSB while the new series equipment uses
SSB and compatible AM. Only the compatible AM mode of the new series radio can be used
with the older equipment. SSB cannot be used to communicate with the older series equipment.
b. The difference in frequency ranges must also be considered when operating old and new series radio
sets together. The old series radio sets have a transmitting frequency range between 1.5 to 20 MHz, and
a receiving frequency range between 0.5 to 32 MHz. The new series radio sets have a frequency range
for transmitting and receiving from 2.0 to 29.999 MHz. When operating between the old and the new
series radios, the operating frequency must be within 2.0 to 20 MHz.
c. The most commonly used old series RATT sets are the AN/GRC-46 and the AN/GRC-26D. They are
used by RC. The most commonly used new series RATT sets are the AN/GRC-142 and the AN/GRC-
122. They are used by both RC and active Army. Older generation radio sets may be used by other
services, and may be encountered during joint operations. Characteristics of both old and new series
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FM 24-12 Chptr 3 AM Radio Operations
equipment are listed in Table 3-3 .
"3abTe 3-3. Characteristics of old and new generation AM radio nets.
Old Family
New Family
RTUnit
AN/GRC-19
T 19&
AN GRC-106
RT-eea
392
AN/GRC-26 1"}
T-3G8
or
RT -834 | AN/ GBC-1 06A|
AM -3349
R-390 (Zeach)
IHFft
AN/PRC-104/GRC 213
AN/GRC-193
Coverage
Transmit 1-E- 20.0 MHz.
Repceppv«0.G- 32.0 MHz
Tr^ngmrt and Heofiivfr
2 - 29.999 MHz |RT 662/GHC)
2 - 29.9999 MHz JRT-S34/QRC)
Tuning
CanlifiuOUS
Detent
Power
Output
T-195 100 waits
T-3£fi 450 watts
200 watla ftATT/CW
400watlE (PEP] V&l«
Channels
MA
| continuous tuning]
Every 1 kHz(RT-e62|
Every 1QD Hz (RT-S34|
Madft&of
Operation
DSB Volet
cw
FSK4B5C He Shift]
SSB Voice, Compatible
AM Voice
NSKra&HzsbifO
FSKIB50 Hz Shift}
cw
Security
*KW-7 |H ATT only)
'KW-7(R ATT only]
Equipment
* TSEC/KG-84A to replace TSEC/KW-7.
3-6. Interoperability Procedures
The rules for netting old and new series radio sets for voice, CW, and RATT operations are given
below.
a. Voice operations.
(1) For new series radio sets An/GRC- 142/122
q Tune for normal voice operation.
q Change the SERVICE SELECTOR switch on the RT-662 or RT-834 from the AM
position.
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FM 24-12 Chptr 3 AM Radio Operations
q Conduct normal voice operation.
(2) For old series radio sets AN/GRC-46 and AN/GRC-26D-
q Tune equipment as usual for voice operation.
q Rotate the CONTINUOUS TUNING dial for clearest voice reception while receiving
voice signal from a station in the net using a new series radio set.
q Realign transmitter to receiver.
q Conduct normal voice operation.
(3) For voice tuning procedures of old and new radios, see Table 3-4 .
Table 3^4. Voice tuning procedures-
Old Radios
New Radios
Tune equipment aa usual.
1
1 . Turt* -For SSB voice
operations.
2. Change the SERVICE
SELECTOR twitch f ram
SSB. 1 IM$K to the compatible
AM position-
b. CW operations.
(1) For new series radio sets AN/GRC- 142/1 22-
q Tune radio set for normal operation.
q Change the SERVICE SELECTOR switch on the RT-662 or RT-834 to the CW position.
NOTE: In the CW mode, the transmitted RF signal is 2 kHz higher than the frequency
indicated on the receiver- transmitter MC and KC controls.
q Lower the operating frequency by 2 kHz on the RT-834/662. Key radio set with CW
keying device and adjust BFO control left or right for comfortable listening tone.
q Conduct normal CW operation..
(2) For old series radio sets AN/GRC-46 and AN/GRC-26D-
q Tune radio sets for normal CW operations.
q Rotate the CONTINUOUS TUNING dial on the receiver until a clear CW signal is heard
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FM 24-12 Chptr 3 AM Radio Operations
while receiving a CW signal from a station in the net using a new series radio set.
q Realign transmitter to receiver.
q Conduct normal CW operations.
(3) For CW tuning procedures of old and new radios, see Table 3-5 .
Table 3-5, CW tuning procedures.
Old Radios
New Radios
1, Tunft equipment as usue I
2- Lower the ops-rating
frequency l>Y 1-5 kHz rf
using thfl AN/FHC-9J.
1 . Tuna aquipmom farCW
pper&tian.
2. Lower the Qpsrating
frflquftnty by 2 kHta
c. RATT operations.
NOTE: Other than netting with the continuous tuning dial for voice and CW operations,
the operator of the new series radio set was the only one that had to make changes in the
normal tuning procedures of his radio set. For RATT operations, both the operator of the
old series and the new series radio sets must make changes from the normal tuning
procedures. The primary reason is the position of the mark and space signals in relation to
the carriers of the two types of equipment. Old series radio sets transmit the mark signal
above the carrier and the space signal below the carrier. The new series radio sets transmit
the mark signal below the carrier and the space signal above the carrier.
(1) For new series RATT sets AN/GRC- 142/122, VSC-2, and VSC-3-
q Tune RATT equipment as usual for normal RATT mode of operation ( Table 3-6 ).
q Change the SERVICE SELECTOR switch on the RT-662 or RT-834 to the FSK position.
q Change the RECEIVE switch on modem MD-522 from normal to reverse.
q Change the MODE SELECTOR switch on MD-522 to 850 Hz.
q Adjust the BFO on the MD-522 for reverse scope alignment when receiving a
teletypewriter signal. If necessary, adjust the frequency vernier to assist BFO scope
alignment when tuning the receiver to the receive signal.
q Conduct normal RATT operation.
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FM 24-12 Chptr 3 AM Radio Operations
Table 3-6. RAH tuning procedures, AN/GRC-+6, YSC-1, VRC-29.
AN, GHC-46 r VSC- 1 r VRC-29
AN/GRC 142/122, VSC 2, VSC-3
1. Change th* SERVICE switch cm tha
CV-27B from nwmfll tu r*v*rt#.
2. ActJUBt thfl R 332 to thd tuning
Signal Of the AN/GPC-142'- 1 22, VSOZ,
or V5C-3- Adjust until h marii 40
-^Hin-Ei I io the- right o$ ia recaivwd
en canv«rij» CV-278.
3. Tune the IrarksmiiCfir T-1 9E for
a mari 40 rnading to the right Of
vn Ihft converter.
1. Chang* tha SEflVlCE switch
on, the RT-662 or RT-B34 to
FSK position.
2. Chang* the R ECEIVE switch on
MD-&22 iram normal Io nvefoo.
3. Chang* the MODE 5 E1.ECTDH
uwilcli on 1h& M D-522 to S50
Hz.
4. AdjuaL the BFO control on th«
MD EZ2 lot rsuarae acope alignrmnt.
If necessary, Adjust thn IrtquMicy
vnrnier tci uuildl BFO acopB alignment
whflfi tuning ih& rtHMlvar to the receive
vgn#L.
NOTE: When receiving a teletypewriter signal from like equipment (new series
radio to new series radio), the RECEIVE switch must go back to NORMAL in
order to receive.
(2) For old series RATT set AN/GRC-46, VSC-1, and VRC-29-
q Tune RATT equipment as usual for normal RATT mode of operation ( Table 3-6 ).
q Change the SERVICE switch on converter CV-278 from normal to reverse.
q Adjust receiver R-392 to the tuning signal of the AN/GRC- 142/122, VSC-2, or
VSC-3. Adjust until a mark 40 signal to the right of is received on converter CV-
278.
q Realign transmitter to receiver.
q Conduct normal RATT operation.
(3) For old series RATT set AN/GRC-26D-
q Tune RATT equipment as usual for normal RATT mode of operation ( Table 3-7 ).
q Change the MARK HOLD switch on converter CV-1 16 from XTAL (left)
(NORM) position to the XTAL (right) (REV) position.
q Adjust receiver R-390 to the tuning signal of the AN/GRC- 142/122, VSC-2, or
VSC-3. Adjust until a mark 50 signal to the right of is received.
q Realign transmitter to receiver.
q Conduct normal RATT operation.
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FM 24-12 Chptr 3 AM Radio Operations
Table 2-7, RATT tuning procedures, AN/GRC-26D.
AN/GRC-26D
1- Change tho MARK HOLD milch on
the C V 1 1 6 converter from XT AL flHftJ
(NORM] loXTAL (rightl |REV]_
2- Adjust the fi- 390 to the tuning
signal ol the AN GRC 142 122.
V5C-2„ VSC-3- Adjust until a mark
50 signal to the nyhn ot is
received oh the CV-1 1 6 converter.
3. Tune the T- 3 58 far a mark 50
redding to the right of on the
converter.
AN/GRC 142/1 22, VSC-2,
VSC-3
1. Changa the SERVICE SELECTOR
a witch on the RT-662 or RT-B34
tc the FS-K positron.
2. Change the RECEIVE *witch &n
MD--&22 from normal to reverse.
3. Change the MODE SELECTOR twitch
on the MD-522 10 860 Hi-
4. Adjust the BFO control on the
MD-62t ior reverse stops alignment.
If nace£sary P adjust the frequency
vurnnrlo auist BFO scope alignment
when tuning the receive* to the
rac«VB aional.
NOTE 1: When receiving a teletypewriter signal from Nka
ey moment 4 old seritts radio to oJd series radio], the SERVICE
switch on CV-278 or the MAR K HOLD switch on CV-1 1 &
must go back to the normal apa rating position to receive
NOTE 2: When operating fc*cura WATT and you ana not receiving ,
the t&letype writer* may run open. To itop thsm hum running
opnn, return the SERVICE switch on the converter CV-27S to
the MARK HOLD position. On the CV-116. wtttie MARK HOLD
switch beck to- the MARK HOLD position.
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FM 24-12 Chptr 4 Telecommunications Center, Switching, and Patch Panel Operations
RPL
,CHH
dBD
RDL Table of Document Download
Homepage Contents Information Instructions
Chapter 4
Telecommunications Center, Switching, and Patch Panel
Operations
4-1. General
A signal organization must improvise when it does not have enough TCC equipment. All TCCs and
RATT assemblages that currently provide over-the-counter record traffic support will be phased out
by 1994. They will be replaced by user-owned and -operated LDF AN/UXC-7 and the
microcomputer communications terminal AN/UGC-144. The user-owned and -operated operational
concept/architecture will be phased in at EAC as the TRI-TAC Block III equipment (AN/TTC-39A
and DGM) are fielded. AT ECB, phase in will be synchronized with the MSE fielding schedule.
4-2. Telecommunications Center Operations
When a signal organization is short of TCC equipment, it must use available shelters or properly
secured and guarded tents. However accomplished, the TCC function must be performed.
a. Fabricate a TCC using spare shelters/tents, field tables, and spare teletypewriter equipment from
inoperable RATT or TCC rigs. Be sure to use the appropriate on-line cryptographic equipment. This
practice is subject to the command's policies on use and modification of equipment.
b. Establish a direct wire circuit between the TCC and the RATT rig handling priority traffic.
Remoting the teletypewriter allows page copy to be transmitted and received directly at the TCC
without additional processing or handling by radio operator personnel.
c. Cross train staff section clerical personnel in message preparation so that message traffic can be
prepared in proper format for transmission before it is processed at the TCC. This lessens the impact
of a shortage of TCC resources by spreading the workload. It does place an additional training burden
upon the unit by requiring more people to know how to prepare messages. Messages must be short to
optimize the use of available traffic channels. (See the discussion of low-level encryption and brevity
codes in Chapter 7 .) TCC personnel are not expected to modify or shorten messages by applying
brevity codes to the messages. TCC personnel transmit message texts exactly as they receive them;
any modification or shortening of messages must be accomplished by originators. (See DA Pam 25-7
for procedures on JINTACCS message text format.)
d. Increase the quantity of air and motor messengers available to make up for lack of TCC processing
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FM 24-12 Chptr 4 Telecommunications Center, Switching, and Patch Panel Operations
and transmission facilities. (See Chapter 6 .)
e. Obtain and use additional quantities of AN/TCC-14 or AN/TCC-29 assemblies (which provide a
speech-plus teletypewriter capability) for better use of available voice channels. Use of off-line
encryption methods increases if TCC equipment is in short supply. (Low-level encryption methods
are discussed in Chapter 7 .)
NOTE: When assembling or fabricating temporary TCC facilities, it is essential to use
proper grounding procedures.
f. Use facsimile equipment or microprocessors to route messages and overlays to their destinations.
These devices can be used over different means of communications, such as FM radio, multichannel,
and other facilities.
4-3. Telecommunications Center Operations Example
a. Your brigade CP area received enemy artillery fire, seriously injuring one operator and destroying
the TCC equipment.
b. What is a temporary solution pending replacements for the TCC equipment?
c. One solution is to use a RATT rig as a temporary TCC. This requires several measures not
normally used.
(1) The RATT rig chosen cannot operate in its normally assigned net full time. Provisions
must be made for the passage of its usual traffic by alternate means or the passage of reduced
amounts of traffic by the RATT rig for limited periods of time.
(2) The RATT equipment operators involved must have appropriate ACPs, other required
publications, and the training to properly process the traffic.
(3) Additional personnel must be tasked and trained ahead of time to augment the message
processing capability of RATT equipment operators.
(4) Maximum use of alternate means must be made during the shortage of the TCC equipment
and personnel.
(5) Other equipment with teletypewriter capabilities can be tasked to perform TCC functions.
This also requires advance cross training of additional personnel in TCC procedures.
(6) Originators must make special efforts to keep messages short during the period of the TCC
shortage. Message brevity is a good practice any time, but is especially valuable during
periods of equipment and personnel shortages.
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FM 24-12 Chptr 4 Telecommunications Center, Switching, and Patch Panel Operations
4-4. Tactical Facsimile Operations
TCCs are rapidly being replaced by facsimile devices that can operate with the current inventory of
communications equipment. These devices are user-operated and user-installed. The user can call up
the addressee, confirm the link, transmit the copy, and verify the quality without interfacing with
over-the-counter TCC service. This system has been fielded in Europe and virtually eliminates record
traffic at brigade and separate battalion levels.
4-5. Switching Operations
Switching equipment is in short supply in many RC units and can also be expected to be in short
supply during combat operations. This presents a serious problem to all commanders and
communicators; however, measures can be taken to reduce the effect of switching equipment
shortages.
a. Reduce the number of local lines to various subscribers. This must be done based on the
commander's established priority system considering the minimum critical needs of the unit.
b. Establish a limited number of common-user telephone points or booths in staff areas. Phone usage
in these activities should be restricted to certain predesignated users.
c. Limit lower priority calls to lesser-traffic hours and limit the call length. Noncritical administrative
and logistics traffic can be passed during these hours or passed over alternate means.
d. Establish hot loops within specific activities and use a ringing code to alert users. This party line
approach eliminates each party being connected directly to a switchboard and reduces the
switchboard load.
e. Reduce manual operator interventions. Patch (or direct wire) priority circuits from the TOC and
certain other priority users directly through the multichannel radio system (or alternate means)
supporting that circuit to the distant subscriber.
f. Enforce telephone discipline during critical periods. Develop a local minimize policy for use over
voice communications facilities.
g. Limit sole-user circuits to two- wire configurations and eliminate sole users in four-wire patterns,
h. Use local commercial telephone systems when possible.
4-6. Patch Panel Operations
The patch panel is literally the heart of a signal center operation. The absence or loss of a patch panel
presents a large obstacle to the communicator but not an impossible one. Patching service can be
provided when short a patch panel.
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FM 24-12 Chptr 4 Telecommunications Center, Switching, and Patch Panel Operations
a. Fabricate a patching facility using distribution boxes J-1077A/U. Additional J- 1077 A/Us are
essential in overcoming the problems of a missing patch panel. A cargo trailer can be used for this
purpose. Mount J- 1077 A/Us on boards on each side of the trailer and fabricate an operator's table at
the front. (See Figure 4-1 .)
Figure 4-1, Cut-a-way view of fabricated patch facility.
(1) Maintain polarity when patching between J- 1077 A/Us using single strands of WF-16 field
wire and labeling each connection.
(2) Develop a detailed patching log to control patching. This log would be substantially
different from the normally used log due to the nature of the homemade patch facility.
(3) Mount a switchboard and phone on the operator's table for local interconnection and for
circuit control and monitoring.
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FM 24-12 Chptr 4 Telecommunications Center, Switching, and Patch Panel Operations
b. Use distribution box J-2317A/U or terminal box TA-125 as an alternative to using J-1077A/Us.
The TA-125 cannot be directly connected to 26-pair cable but does provide a flexible method of
interconnecting circuits. Short runs of WF-16 can be made from the terminals of the signal entrance
boxes of various communications assemblages to the locally constructed patching facilities using
distribution boxes J-1077A/U or J-2317A/U, or terminal box TA-125.
c. Use additional SB-22 switchboards, if available, to patch circuits on a limited basis. Their limited
capacity severely restricts their use as patches; but, when used in conjunction with carefully
controlled direct wiring between assemblages, they provide a measure of flexibility.
d. Have units that support a standard troop structure develop a prepatched board to handle known
requirements. This leaves other limited patching facilities to handle new or changing requirements.
4-7. Patch Panel Replacement Example
a. You are a platoon leader. Enemy action has destroyed the patch panel. There are no casualties
since the operators had time to take cover before the patch panel was hit. Replacements for the
damaged cables are available.
b. How do you get your circuits operational pending receipt of another patch panel?
c. A possible solution is to establish a temporary patching facility using junction boxes such as J-
1077A/UorJ-2317A/U.
(1) Junction Box J-2317A/U is preferred since it terminates four each 26-pair cables and is not
wired normal through as is the J-1077A/U. Consequently, the J-2317A/U is highly useful as a
temporary patch facility.
(2) Patching is accomplished using lengths of field wire. Special patch records must be made
to record these unusual field wire patches.
(3) Special attention must be given to patching the critical circuits first. Your systems control
records will indicate these.
NOTE: Special attention must be given to maintaining proper polarity (in addition to
RECEIVE-SEND pair transposition) when patching using this method.
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FM 24-12 Chptr 5 Wire and Cable Operations
JQQ
RDL Table of Document Download
Homepage Contents Information Instructions
RPL
,CHH
Chapter 5
Wire and Cable Operations
5-1. General
a. Wire and cable are used to interconnect activities within CPs and between radio relay terminals and
switching centers. Long haul wire circuits (trunks) are installed to complement radio systems when
time, personnel, and equipment are available. Wire is especially useful in operations where
movement is limited.
b. Summarized below are some of the advantages and disadvantages of using wire and cable.
(1) Advantages.
(a) Reduces the need for radio and decreases radio interference.
(b) Reduces the electronic signature of CPs.
(c) Reduces the enemy's jamming, interference, and direction-finding capabilities.
(d) Provides backup and increased traffic-passing capabilities for radio systems.
(e) Is not subject to interference or jamming.
(f) Can be secured by VINSON or PARKHILL COMSEC equipment and wire line adapters.
(2) Disadvantages.
(a) Slow to install/recover. Requires additional manpower.
(b) Not a secure means unless encrypted. Wire has some security but is subject to disruption.
(c) Not reactive to fast-moving situations.
(d) Limited by terrain and distance considerations.
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FM 24-12 Chptr 5 Wire and Cable Operations
(e) Susceptible to damage by friendly action; for example, wheeled and tracked vehicle
movement.
(f) Susceptible to damage by indirect fire.
(g) Is a good conductor of EMP which will damage attached telephone and switching
equipment.
5-2. Installation Considerations
One of the first actions when establishing a signal site is the start of intra-site wire/cable installation.
Practically all signal equipment at some point interfaces with wire/cable, especially when there is a
shortage of multichannel equipment. The following actions are essential for successful wire/cable
installation:
a. Plan for and requisition sufficient quantities of wire/cable and installation equipment to provide for
known and recurring requirements. The range of field wire circuits varies with the type of wire and
the terminating equipment. For planning purposes, the range of field wire circuits using battery
operated telephones is 22.5 to 35.4 km (14 to 22 miles); using sound powered telephones, it is 6.4 km
(4 miles).
b. Cross train personnel on wire/cable installation and operations. Personnel associated with
equipment in short supply, and personnel in staff sections, should be cross trained so they will be
capable of installing wire/cable circuits for their element/headquarters. Then each section that
requires a telephone line can lay its own field wire to a centrally located, premarked distribution box
J-1077A/U.
c. Plan for and install pre-positioned wire termination sites to the maximum extent possible. This pre-
positioning should be related to planned or potential operations in order to provide headquarters
elements immediate connection to the division/corps wire system upon displacement. This assumes
that the potential site is in friendly territory and that operations in the area will not destroy the system.
Typical uses of pre-positioned wire systems include quick connection of a brigade or tactical CP
element or of a retransmission/NRI station to the system.
d. Fabricate short runs using WD-1 field wire when multiple-pair cables are in short supply. Use
special caution to tag and identify pairs when using this technique.
e. Plan for additional vehicle, fuel, and maintenance support needed for IOM of wire and cable
systems. Within most signal TOEs, the volume of cable and wire authorized exceeds the unit's
capabilities to transport it in a single movement.
5-3. Equipment Utilization
a. The following wire and cable are used predominantly throughout the tactical arena:
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FM 24-12 Chptr 5 Wire and Cable Operations
(1) WD-l/TT consists of two 23-gauge conductors, individually insulated and twisted
together.
(2) WD-1A/TT has two insulated conductors bonded together.
(3) WD-36/TT is a two-conductor, lightweight assault wire. It is used when rapid installation
and light weight are factors of primary importance. It is designed for one-time use only.
(4) WF-16/TT is a four-conductor (two-pair) field wire that is used with the new 4- wire
telephone system.
(5) WF-8( )/G, spiral-four cable, is a 4-wire transmission line for carrier communications
systems. It is used for long distance VF circuits. A universal connector plug is attached to each
end.
(6) CX-1 1230G is an interarea coaxial cable. It consists of two twisted coax tubes and
provides transmission lines for 12-, 24-, 48-, and 96-channel TDM/PCM systems.
(7) CX-4566 is an intersite, multi-pair cable. It consists of 26-pair and is used for internal site
connections and limited distance extensions to CPs.
b. Additional equipment is available to combat distortion and loss on long cable runs. TD-204
telephone repeaters are used to increase the strength of a signal that has been decreased by line loss. It
consists of amplifiers and associated components (repeating coils, equalizer networks, and hybrid
coils). TD-206B/G pulse form restorers retime and regenerate a pulse train on a PCM cable. The
pulse form restorers are placed at one mile intervals up to a total of 39 restorers on a given cable run,
for a total maximum of 64.4 km (40 miles). The maximum channel capability of the PCM cable run
is 48 channels. The TD-202 in addition to TD-204 and TD-206B/G are used by AN/TRC-1 17, AN/
TRC-1 10, AN/TCC-60/69, AN/TCC-61, and AN/TCC-65.
c. Fiber-optic cable has become an integral part of the Army inventory. It is available for use in the
tactical environment. Fifteen-channel, fiber-optic cable will provide full duplex digital
communications over a maximum range of 6 to 8 km (3.8 to 5 miles) with an average distance
estimated to be 4 km (2.5 miles) (without restorers) at a data rate of 72 kilobits. With restorers, range,
and rate increase up to 19.2 megabits and up to 64.4 km (40 miles).
5-4. Installation Methods
a. Aerial (overhead) wire/cable provides the most satisfactory service and is the easiest to maintain.
However, it is subject to weather, enemy action, EMP, and artillery airbursts, and requires more time
to install.
b. Surface wire/cable requires minimum time and equipment to install. Installed properly, it provides
reliable circuits; installed improperly, it requires immediate and constant maintenance. It is also
vulnerable to damage by troop, vehicular movement, and weather.
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FM 24-12 Chptr 5 Wire and Cable Operations
c. Buried wire/cable is more electrically stable than surface or aerial installation, and is less subject to
weather. It is the preferred installation if time permits. It is difficult to maintain and recover. Buried
cable also provides better protection from the effects of EMP in a nuclear environment.
5-5. Existing Wire/Cable Systems
Evaluation of available commercial cables may be done in peacetime for contingency use in war.
Examples of systems that can offer alternative means are highway telephones, railway systems, and
forestry services.
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FM 24-12 Chptr 6 Alternate Means of Communications
RPL
,CHH
dBD
RDL Table of Document Download
Homepage Contents Information Instructions
Chapter 6
Alternate Means of Communications
6-1. General
Numerous alternate means of communications are available to the field commander. The most
commonly used will be addressed in the following paragraphs .
6-2. Messenger Service
Messenger service is one of the oldest and most effective alternate means of communications but is
no longer a dedicated Signal Corps responsibility. Commanders can greatly enhance their ability to
control their units by effectively using all types of messengers from all battalions and staffs.
a. The need for messengers is inversely related to our desire and/or ability to use radio. There are
many disadvantages in relying too heavily on radio communications. Messenger service is an
important consideration for combat operations. With the EMP effect becoming more of a tactical
probability than a possibility, messenger service may become the only viable communications after
the initial outbreak of wartime hostilities.
(1) Advantages to messenger service are as follows:
(a) Permits delivery of lengthy, bulky items not requiring immediate action; or requiring
lengthy transmission times, such as, operation plans, map overlays, administrative/logistical
matters, and reports.
(b) Reduces the need for using radio.
(c) Reduces mutual radio interference by reducing radio traffic and transmission time.
(d) Reduces the enemy's EW capability by—
q Providing a secure communications means which is not subject to EW.
q Deferring exposure of critical nets until they become urgently needed.
q Making it more difficult for the enemy to identify critical nets.
(2) Disadvantages to messenger service are as follows:
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FM 24-12 Chptr 6 Alternate Means of Communications
(a) Slower than electrical means.
(b) Subject to enemy action, terrain, and weather conditions.
(c) Requires dedicated equipment and trained personnel.
b. The type of messengers employed is determined by the urgency, bulk of messages, the terrain, the
weather, and the availability of transportation.
(1) Foot messengers are used for CP distribution and in small units.
(2) Motor messengers are used between headquarters.
(3) Air messengers are used to speed up delivery over long distances, over difficult terrain,
over enemy controlled territory, or for vital or urgent messages.
c. The types of service available by messengers, usually at EAC, are scheduled, special, and
exchanged.
(1) Scheduled messengers follow prearranged and published time schedules, travel designated
routes, and stop at predesignated points and headquarters. They normally deliver and pick up
message traffic at TCCs or exchange points.
(2) Special messengers are used when scheduled service has not been established or to
augment scheduled service. They are employed when the urgency of a message will not allow
the message to wait for scheduled messenger service or transmission by other communication
means.
NOTE: Couriers transporting COMSEC or classified materials orders IAW AR 66-5.
(3) Exchanged messengers are exchanged between specified headquarters when personnel and
vehicle assets permit. These messengers would know routes back to their parent headquarters
and would deliver high priority messages only.
d. Additional sources of messenger service should be considered.
(1) Personnel should never leave a CP en route to another unit without consulting the TCC for
possible message traffic for that unit. Liaison officers can assist during times of limited
messenger resources.
(2) Certain designated headquarters act as clearing houses and reroute points for messages.
This allows unit messengers to pick up and deliver to these points, freeing dedicated
messengers for more frequent delivery and pickup between relay points.
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FM 24-12 Chptr 6 Alternate Means of Communications
(3) Commanders should identify those organic assets which in an emergency could be used for
messenger purposes. They should provide necessary training and planning so these assets can
be effectively used when needed. All assets should be considered for the role; for example, the
commander's vehicle and driver and the S3 's vehicle and driver.
6-3. Visual Signaling
An alternative to electronic communications is visual signaling. This form of communications has
been used extensively throughout the history of military operations. However, the flexibility, range,
and speed of today's radios have reduced the use of visual signaling. Few units today would be
capable of establishing a working system of visual communications without first conducting
extensive planning and training.
a. Visual signaling systems normally require simple equipment. They provide timely point-to-point
communications over the distances usually associated with company, battalion, and sometimes
brigade and division deployments. They are not normally susceptible to EMC and EMP problems and
are relatively reliable in many combat situations. Training requirements vary with the systems used
and can be taught at unit level.
b. Visual signaling is not a cure-all. Numerous limitations need to be recognized. Visual signaling
sites must be within LOS of each other and the signal means used must be distinguishable at the
desired range. Fog, rain, snow, smoke, and background light conditions can reduce effective ranges.
c. Visual signaling cannot adequately handle the mass of routine communications between echelons,
but it can be used as an alternate means to pass the high priority messages that may affect the tactical
situation. Units should consider their requirements for continuous command communications, then
develop a visual system that will provide an effective backup to their current systems. Realistic
training of personnel and frequent practice during training exercises enhance a commander's ability to
maintain effective control of assigned and attached units.
d. Visual signaling systems employing flashing lights of various types are most effective because
they provide distinguishable signaling at great ranges. Several field expedient visual signaling
devices are readily available to the tactical command.
(1) Any standard flashlight can be pulsed in a controlled manner and can normally be seen
over several hundred meters in daylight and up to two or more kilometers at night. A more
directional beam can be obtained by attaching any sort of cylindrical extension.
(2) Any other light source, including chemical lights, that can be keyed is also usable. An
example is a vehicle headlight used with a keying device and a director to provide long-range
signaling.
e. Reception of visual signals can be enhanced using readily available devices.
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FM 24-12 Chptr 6 Alternate Means of Communications
(1) A pipe or other device pointed directly at the visual source can be used to limit the
receiver's susceptibility to distraction. Such a device should be stabilized to prevent movement
while in use.
(2) Binoculars assist in distinguishing the signals at greater ranges. At night, the use of
ambient light devices such as night vision goggles AN/PVS-5 or night vision sight AN/PVS-4
can greatly extend the system's range. The PVS-5 or PVS-4 is authorized in many divisional
units including infantry/mechanized, infantry battalions, engineer battalions, division artillery
units, cavalry and air cavalry troops, and air defense artillery battalions.
f. A flashing light system can be both an asset and a liability.
(1) Flashing light signaling sites will often be visible from enemy positions and appropriate
safeguards must be planned. Using infrared or near infrared sources and receiving devices will
prevent unaided observation; however, most potential adversaries also use the infrared
spectrum and can observe these signals.
(2) Visual signaling sites should be remoted from CP locations to maintain CP location
security. Remoting may also be required to attain LOS.
(3) Portability and weight of equipment used is an asset. If the equipment can readily be
mounted in trees or on antenna towers, LOS may be more easily attained.
(4) Communications between the signal site and CP is mandatory. Wire is strongly
recommended, but short-range radio or a messenger could be used.
(5) Messages prepared for transmission by visual means should be as short as possible to
facilitate the slower transmission speed and concentration required to copy at long ranges.
Properly encrypted brevity codes should be used.
(6) Flashing light systems can use directional or nondirectional devices. Nondirectional
equipment will generally provide less range, but can be used to transmit to more than one
receiver simultaneously.
(7) All signal sites should be manned by a minimum of two personnel to enable one to focus
attention on the distant sender and the other to record or relay the message over the telephone
as it is received.
(8) Operators must be trained in the transmission and reception of code.
6-4. Panel Signaling
Panel signaling is used primarily between ground troops and aircraft. Its use is very limited and is
covered by instructions in the unit's SOI. Care must be exercised in panel use to ensure that the panels
can easily be seen from aircraft and that the hovering aircraft do not disclose CP or signal site
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FM 24-12 Chptr 6 Alternate Means of Communications
locations when reading the panels.
6-5. Pyrotechnic Signaling
Pyrotechnic signaling uses colored smoke, colored and combinations of star clusters, or parachute
flares. This kind of signaling is limited to prearranged signals. These signals are prescribed at
command-, corps-, division-, brigade-, battalion-, and, under certain conditions, company-level.
Meanings of signals are provided in the SOI or operation orders. Continual reassessment for
completeness and adequacy of this signal system is encouraged.
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FM 24-12 Chptr 7 Communications Security Operations
RPL
,CHH
dBD
RDL Table of Document Download
Homepage Contents Information Instructions
Chapter 7
Communications Security Operations
7-1. General
a. Success on today's battlefield depends on the commander's ability to concentrate superior combat
power at critical times and places. A key to this success is superiority in command and control via
communications. Effective communications is essential to winning.
b. The enemy realizes the importance of our communications systems and will continuously try to
interfere with our ability to communicate. He will try to gather intelligence from our
communications, and then he will try to disrupt them. He will attempt to interfere by breaking into
our nets and trying to deceive us, or he will try to jam us. Failing at these measures, he will try to
destroy communications by fire. Our battlefield success will depend heavily on how well we
minimize his attempts to disrupt our communications systems.
c. Communications security is the protection resulting from the application of crypto security,
transmission security, and emission security. These protective measures are taken to deny
unauthorized persons telecommunications information. This chapter addresses primarily the
cryptographic and transmission security portions of COMSEC.
d. Presently, AC and RC have a substantial shortage of COMSEC equipment. No quick or easy
solutions are in sight. The need for COMSEC is essential; if adequate quantities of COMSEC
equipment are not available, the commander must take other measures to secure his communications.
Additionally, the active Army must also be skilled in the use of manual encryption techniques.
Because most RC units possess little secure voice equipment, the active Army must anticipate
transmitting and receiving traffic with the reserves using manual encryption techniques. Remember,
manual encryption is also the backup for loss or failure of machine crypto systems. Therefore, all
forces must maintain proficiency in the manual encryption area, regardless of interaction with other
forces. Below are alternative methods and systems which can be used in lieu of on-line crypto
systems. They present some difficulty when large volumes of traffic must be processed; however,
these methods are essential to assure success and survivability on future battlefields.
7-2. Authentication Systems
a. An authentication system is designed to protect a communications system against the acceptance of
fraudulent transmissions. Everyone who communicates in a tactical or strategic environment requires
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FM 24-12 Chptr 7 Communications Security Operations
some method of authenticating. Good authentication practices contribute to combat survival and
effectiveness, because they aid in establishing the validity of a transmission, message, or originator.
All commanders must implement their use during training and actual operations.
b. Combat experience in Vietnam proved that IED by the enemy contributed to substantial numbers
of casualties and caused many missions to fall short of desired results. Proper authentication
procedures can prevent an enemy from posing as a friendly station. The enemy is adept at IED and
needs only a moderate degree of skill to seriously affect our communications when we do not
authenticate. A balance has to be struck so that effective communications is maintained without
harassment of friendly communications. Guidance on the use of authentication systems is found in
the unit SOI, ACP 122(D) , AR 380-40 , and TB 380-41 .
c. IED is the easiest EW technique to counter. Authentication is one of the best means available to
stop enemy IED efforts. Operators are required to authenticate when they—
q Suspect a transmission is from an enemy station operating in the net (deception).
q Direct a station to go to radio silence or to break that silence. (Self-authentication can be used
if authorized by the SOI.)
q Are challenged to authenticate.
q Talk about enemy contact, give an early warning report, or issue any follow-up report.
q Transmit directions which affect the tactical situation such as "Move to..." or "Turn off the
radio." (Conversely, they challenge any directives like these with a request to authenticate.)
q Cancel a message.
q Open the net or resume transmitting after a long period of silence.
q Transmit to someone who is under radio listening silence.
q Transmit a classified message in the clear.
q Transmit messages in the blind; that is, neither desiring nor expecting a reply.
d. Challenge if you are not sure that authentication is required. If a station takes more than 5 seconds
to authenticate, rechallenge. Why 5 seconds? Because an enemy operator may try to contact another
station and have it respond to that same challenge, thereby obtaining the appropriate reply to your
challenge.
e. The two most commonly used authentication procedures are challenge-reply and transmission
authentication. The main difference between the two is that challenge-reply requires two-way
communications, whereas transmission authentication does not. Even though transmission
authentication requires only one-way communications, it is neither as simple nor as flexible as
challenge-reply. The challenge-reply procedure most often used has a more flexible application.
(1) Challenge-reply.
C12 THIS IS A06 OVER
A06 THIS IS C12 OVER
C12 THIS IS A06 TURN EAST AT X-RAY OVER
A06 THIS IS C12 AUTHENTICATE HOTEL VICTOR OVER
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FM 24-12 Chptr 7 Communications Security Operations
C12 THIS IS A06 I AUTHENTICATE WHISKEY OVER
A06 THIS IS C12 WILCO OUT
(2) Transmission authentication.
NOTE: Transmission authentication is used only when it is impossible or impractical
to use challenge-reply authentication.
J8C THIS IS B6A DO NOT ANSWER
TURN EAST AT CROSSROAD X-RAY
AUTHENTICATION IS VICTOR PAPA
I SAY AGAIN
J8C THIS IS B6A DO NOT ANSWER
TURN EAST AT CROSSROAD X-RAY
AUTHENTICATION IS VICTOR PAPA
OUT
7-3. Transmission Security
Several categories of tactical information require transmission security protection. These are listed in
FM 34-62 , Appendix C. It is important that you learn these categories.
7-4. Codes
a. A code is a language substitution system that transforms plain language of irregular length, such as
words or phrases, into groups of characters of fixed length. A code has an underlying plaintext of
variable length, whereas a cipher has an underlying plaintext of fixed length (see paragraph 7-5 ). The
codes that you will use are usually found in your unit SOI packet.
b. Two types of codes are normally used in tactical communications: security codes and brevity codes
(only as authorized). A code used to hide meanings from another party is a security code. A code
used to shorten transmissions is a brevity code. A brevity code only shortens transmission; it does
NOT provide security. It is referred to as a brevity list. The international Q and Z signals found in
ACP 131(D) and the police 10-code signals are examples of brevity lists. Brevity lists must be used
in conjunction with an approved code to provide security.
c. Most codes can be placed into one of three categories: numerical, operations, and special purpose.
(1) Numerical codes are among the simplest and most useful types of codes and are used to
encode numbers. They are almost always digraphs (two-letter configurations) and are
designed to protect intelligence bearing QUANTITATIVE portions of tactical
communications, especially voice communications. They provide a short term tactical
advantage when it is impossible or impractical to secure information to any greater degree.
They are intended for use through the lowest operational levels. They can be used to protect
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FM 24-12 Chptr 7 Communications Security Operations
the when, where, and how many in communications that might otherwise be unencrypted. (For
example, they may be mixed with plain language, operating signals, or a brevity list.)
Numerical code examples are given below .
(a) Hours designation:
Plaintext— Meeting time is 1530.
Code value --Meeting time is I set XXBKWG.
(b) Frequency designation:
Plaintext -Change frequency to 14990 kHz at 1600.
Code value -Change frequency to I set XYFXMPE at HITV.
(2) OPCODE, in contrast with numerical codes, can be used to encrypt the what, who, why,
how, and how many— the QUALITATIVE information in messages. They DO NOT, however,
provide adequate protection for information if mixed with plain language. OPCODES have a
vocabulary of usually 1,000 to 3,000 entries and generally use trigraphic (three-letter) code
groups. OPCODES are usually multipurpose or general in that they may be used to encrypt
different sorts of information. OPCODES are intended for use down through the lowest
operational levels. Operations codes examples are given below .
(a) A simulated message of tactical operation assignment:
Plaintext-Continue on assigned mission.
Code value- AAL.
(b) A simulated message of tactical operation report:
Plaintext— Battalion action at crossroad.
Code value -OXW RFM RFX WOX.
(3) Special purpose codes are OPCODE-type items but are generally designed for encrypting
specialized types of messages such as radar reports and fire missions. Their vocabularies are
usually limited in size and scope and may consist of single letter, digraphic, or trigraphic code
groups. Frequently, they are intended for more sensitive application than general codes and are
often used at higher echelons. Many such special purpose codes are of the one-time variety.
Special purpose code examples are given below .
(a) Simulated message —Communications equipment, radar station reports:
Plaintext-TRC capability impaired, jamming suspected hostile.
Code value-OTV JNP. '
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FM 24-12 Chptr 7 Communications Security Operations
(b) Simulated message --Artillery mission report:
Plaintext— Target altitude 2,500 meters.
Code value-XHY OHT.
d. Many codes are custom designed to meet requirements of specific users. They are fabricated in
response to specific COMSEC needs. They can be produced for any commander who requires an
individually tailored item. These codes are not to be produced without NSA approval. Most users,
however, use only a few standardized systems. Standardized systems can be obtained and pre-
positioned at appropriate levels in the distribution. This should be a consideration when requesting
COMSEC support. If not regularly used, codes may not be on hand at the local COMSEC support
agency. If not readily available, codes must be ordered through COMSEC logistic channels. Users
and commanders should consider that custom designed codes require sufficient lead time to produce.
Although a standardized system may not be the best solution to a tactical COMSEC problem, it may
serve as an effective interim system until a more suitable custom designed product can be produced.
You should never try to make up your own brevity codes since experience has shown they are too
easily broken by the enemy. Only use authorized and approved codes.
e. The use of codes to gain advantage over an enemy cannot be overemphasized. Everyone using
codes must be familiar with their capabilities, limitations, and intended usages for codes to be
effective.
(1) Codes intended for tactical application are designed to provide ONLY that amount of
security consistent with operational needs.
(2) Tactical OPCODES usually require that messages be composed prior to being encrypted
and transmitted. Users need a pencil, paper, and a place to write in order to work on
OPCODES.
(3) A tactical OPCODE is of specific but limited usefulness in the operational environment. It
is difficult to use in the midst of hostilities or when riding in a vehicle. It cannot adequately
protect high level communications.
(4) Numerical codes can usually be operated without pencil and paper. Numerical codes can
provide protection to quantitative elements of information that pertain to an immediate tactical
situation. However, they are not as secure as properly used OPCODES or numerical ciphers.
(5) All codes have a cryptoperiod. They also have usage rules that outline restrictions on their
employment. If a code is used in a way for which it is unintended, security can break down
quickly. Total encryption using tactical codes is not always desirable or possible. Encryption
of information the enemy already knows may help assist him in breaking our code system.
(6) One-time codes have special usage characteristics because of their one-time cryptoperiod.
These codes provide a high degree of security and can be used for traffic with long-term
intelligence value.
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FM 24-12 Chptr 7 Communications Security Operations
(7) The commander can request that the local INSCOM counter SIGINT personnel produce a
code that will meet his needs when an emergency arises that does not allow a unit to use
authorized codes (such as, compromise or cut off of distribution). Under no circumstances
should unauthorized codes be used.
(8) Training must emphasize security and resupply procedures for codes to ensure that all
personnel involved in their handling and use are properly trained.
7-5. Ciphers
a. The one-time pad is a language substitution cipher system which transforms plain language
formations of fixed length (numbers and/or letters) into characters or groups of characters of fixed
length. In a cipher system, the underlying plaintext is fixed in length; in a code system the underlying
plaintext is variable in length. A one-time pad has no vocabulary as such, and almost anything can be
said using pads. One-time pads are highly secure and are used mainly for special operations.
b. All one-time pads have variables which are used to transform plaintext into cipher text. These
variables are presented in the form of recognizable characters such as letters and/or numbers. Each
individual key is used only once, from which is derived the name one-time pad.
c. The substitution of cipher text for plaintext and vice versa is performed according to a specified
rule which uses the key variables discussed above. The rule, how to work the pad, is what
distinguishes one type of system from another.
d. The three basic varieties of one-time pads are literal, digital, and literal/digital.
(1) A literal pad can encrypt letters only, so numbers must be spelled out before encryption.
This gives great flexibility in the variety of plaintext that can be encrypted, but also results in a
longer encryption time than would be experienced with a code.
(2) A digital pad encrypts digits only. If information to be protected is strictly numerical,
digital pads can directly encrypt the plaintext. It is not uncommon for it to be used to directly
encrypt narrative text if the text can be taken from a brevity list whose equivalent groups are
numerical. This technique is especially valuable between speakers of different languages, as
operators need no linguistic skills since transmission involves only digits.
(3) Literal/digital pads are used to encrypt both letters and numbers directly. Their
applications are similar to literal-only pads except they can directly encrypt numbers without
spelling them out. They are most useful over good quality circuits which are least likely to
require spelling numbers.
(a) Standardization systems constitute the majority of one-time pads. Standard systems
accommodate most operational systems, but custom designed pads can be ordered through the
local COMSEC support agency by any commander who has a legitimate need for special
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FM 24-12 Chptr 7 Communications Security Operations
material.
(b) Pads can be used to protect highly sensitive traffic since they provide security for an
indefinite time. Pads require a pencil for their operation, and some require that messages be
composed before encryption. Writing space is normally provided for writing directly on the
pad. A pad key is intended for one-time use only. If more than one message is enciphered in
the same stretch of key, it is possible to break both messages.
(c) One-time pads, like one-time codes, are most effective on point-to-point or broadcast nets.
(d) One-time pad example:
Plaintext-14.5. Code value-XKBQ.
Message transmitted -Page 030, set 3, XKBQ.
e. Numerical ciphers, as with a pad, are characterized by the fixed length of the underlying plaintext.
In all cases, this is a one-for-one substitution.
(1) The two types of numerical ciphers are the one-time ciphers and the standard cipher
system. The one-time ciphers are an easy-to-employ, highly secure, numerical enciphering
system. They can be used on basic numerical data or on a fixed format, such as specific data
reports for personnel summaries. The standard numerical cipher system for enciphering
numbers is DRYAD.
(2) A limited transmission authentication capability and a challenge/reply authentication
capability are also provided with this system.
7-6. Brevity Lists
a. There may be instances where the types of information to be exchanged are not sufficiently varied
to warrant the use of an extensive operations code. In such cases, it may be preferable to use a brevity
list ( Figure 7-1 ) in conjunction with a numerical cipher. Security is provided by encrypting numerical
equivalents with an approved cipher system such as the DRYAD system.
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FM 24-12 Chptr 7 Communications Security Operations
EXECUTION
062 Execute aerial recon of \.oc) to (lycl st (time).
063 Execute airborne assault at i'vc). (trme).
064 Execute airmobile assatHt
066 Execute ambusr. at (loch Itime;.
Execute DZ preparation of enrerrjcncy p\a-\
ule deiey tc doc) a[ Ki^ie).
0S5
086 Execute
087 Execuie p. j e
088 Execute Recon
0B9 ExecLte Screen Forw
090 Exectte Screen Fgrw
090 Spare
091 Spare
092 Spare
uve to (icc'i at ittme).
e at liimel.
OPLAM (#) at (time),
ihery {£!■ at (time).
trorvi Hoc) a' ((irrt)
(tinmc-;-
moi.
Figure 7-1- Example of brevity list.
b. Use of a brevity list has certain advantages over use of an operations code. Use of a brevity list
eliminates the need to distribute, account for, and destroy an operations code in which the greatest
part of the vocabulary is never used.
c. Brevity lists may be found in the supplemental instructions in the unit SOI. If there is no list
present, it may be added at the unit level permanently or temporarily for a particular exercise.
d. A brevity list approach is an extremely practical alternative to an operations code—
q When the information exchange requirement is relatively limited.
q When the entries can be held to a minimum number of sentences, phrases, and/or words.
q When the messages are generally short.
q Where the vocabulary entries consist primarily of complete, independent thoughts.
7-7. COMSEC Operations Support
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FM 24-12 Chptr 7 Communications Security Operations
a. A unit must have a COMSEC account or have access to a COMSEC account, before it can conduct
meaningful COMSEC training. Most units either have approved containers or a facility for storing
COMSEC material or can obtain an approved container through supply channels. Command is
responsible for establishing a COMSEC account. The unit must then train and operate using
COMSEC equipment and/or systems. Commanders must use AR 380-40 and the TB 380-41 series in
establishing COMSEC support for their unit. Although it places an additional burden on the
commander to use COMSEC systems, their use is essential to success and survival on the battlefield.
COMSEC IS NOT AN OPTION; IT IS MISSION-ESSENTIAL.
b. Unit SOPs must be clear on the use of COMSEC equipment and systems, both for administrative
operations and tactical operations. All personnel should be familiar with SOP instructions and SOI
instructions on the unit's particular COMSEC systems. Personnel must be familiar with procedures
for resupply of COMSEC material during operations, and the COMSEC custodian must provide for
an adequate supply of COMSEC material to be on hand for both training and/or operations.
c. Training programs must ensure that all necessary personnel receive adequate instructions and
training on COMSEC procedures by both formal and on-the-job training. The INSCOM support
activity can provide invaluable assistance in establishing, maintaining, and evaluating your unit's
COMSEC account, training program, SOP, and storage facilities. Their support must be scheduled
well ahead of time due to the number of units each activity supports. Information on storage and
accounting for COMSEC equipment can be found in AR 380-40 , AR 640-15 , and the TB 380-41
series.
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FM 24-12 Chptr 8 Tactical Satellite Communications Operations
JQQ
RDL Table of Document Download
Homepage Contents Information Instructions
RPL
,CHH
Chapter 8
Tactical Satellite Communications Operations
8-1. General
a. TACSATCOM helps to fulfill the need for command and control communications on the modern
battlefield. TACSATCOM has the following assets and features:
q Extended range.
q High transmission reliability.
q Rapid emplacement.
q Easy siting.
q System flexibility.
q Survivability.
q Burst transmission and low power output capability.
b. These critical requirements are not fully satisfied by terrestrial communications systems. However,
the Army is fielding GMF satellite communications that will complement communications links now
served by LOS radio relay troposcatter and HF SSB radio systems. This satellite communications
capability will greatly improve command and control communications.
8-2. Advantages
TACSATCOM systems are uniquely capable of meeting the above parameters. Their proficiency
lends a broader scope to communications.
a. Range. The number of satellite terminals that can be supported in a theater of operation depends
upon the location of each terminal with respect to the satellite antenna footprint, mode of operation,
number of channels used, and condition/gain setting of the satellite itself.
b. Reliability. The TACSAT links will be equipped with organic antijam circuitry to enable them to
survive certain degrees of intentional and unintentional radio interference. However, severe weather
can cause satellite links to degrade.
c. Rapid emplacement. Set up and tear down of the ground terminal takes about 30 minutes.
d. Easy siting. High ground is not required; rather, natural terrain features, such as valleys, can be
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FM 24-12 Chptr 8 Tactical Satellite Communications Operations
used to shield the terminal from detection or interference from ground-based emitters. However,
masking of the antenna must be avoided. This will require level ground and may require low horizon
and open area.
e. Flexibility. Since all TACSATCOM terminals in a given theater use the same satellite, connectivity
can be quickly reconfigured providing great flexibility in changing battlefield conditions. The
TACS AT link can provide continuous communications between widely dispersed elements of a
highly mobile tactical force.
f. Survivability. The mobility of these terminals, large bandwidths, antijam capability, and siting
advantages greatly reduce the threat to satellite terminals. However, if the satellite becomes
inoperative for any reason, the TACSATCOM system is shut down.
8-3. Deployment
a. The terminals will augment selected HF, LOS, and tropo multichannel systems from brigades to
theater Army. They will satisfy critical command and control multichannel transmission requirements
from the maneuver brigade level through echelons above corps. In most cases, multichannel GMF/
TACSATCOM will reduce the number of terrestrial LOS and tropospheric scatter terminals required
to support a force, but will not eliminate the need for terrestrial multichannel communications. The
terrestrial multichannel terminals will be used to support less critical and/or shorter communications
links.
b. The AN/PSC-3 and AN/VSC-7 will be used by special forces and ranger units for minimum
essential communications. The AN/URC-101 and AN/URC-110 are used for special contingency
units at selected corps and division level. The AN/MSC-64 will be used primarily for emergency
action record traffic in units required to be in the special communications system network.
c. The multichannel SHF system (AN/TSC-85A and AN/TSC-93A) will augment the multichannel
systems at corps, division, and brigade level. For example, a TACSATCOM system will be assigned
to a separate brigade, giving the separate brigade a fast moving, flexible, and reliable
communications capability with its higher headquarters. For doctrinal deployment at division level,
see FM 11-50.
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Appendix A MSE Interoperability
RPL
,CHH
dBD
RDL Table of Document Download
Homepage Contents Information Instructions
Appendix
MSE Interoperability
A-l. Planning for MSE Interface
a. The requirement for establishing and controlling communications remains from higher to lower,
left to right, and supporting to supported. With MSE that doctrine transcends more than just
establishing and maintaining network integrity. The element in the higher, left, or supporting
category also supplies the requisite equipment when augmentation is needed and coordinates and
provides the necessary frequencies, frequency plans, COMSEC keys, codes, software, and control
mechanisms.
b. MSE interface with other systems, such as EAC, TRI-TAC, or NATO, requires detailed planning
and coordination. Signal planners must coordinate signal timing relationships, digital trunk group
numbering and channel assignments, area codes, digit editing, and exchange of TG and AIRK
COMSEC keys to ensure successful switch interface. Normally, the MSE gateway switch will modify
its data base to accommodate the TRI-TAC switch.
A-2. Installation Parameters for MSE Interface
The CX-1 1230 cable used to interconnect the various assemblages is issued in 1/4-mile reels. Tables
A-l through A-7 give cable adjustment settings for lengths of cable from 1/4 to 1 mile (1 to 4 reels).
The "cable reels" line lists the four possible cable lengths as 1/2/3/4 for 1, 2, 3, and 4 reels
respectively. The cable adjustment for each cable length is similarly listed for transmit and receive at
each assemblage. For example, a transmit listing of 4/4/4/4 means that the setting is 4 for each of the
four possible cable lengths. The letters a, b, c, d, and e are used for settings of 0, 1/4, 1/2, 3/4, and 1
mile respectively. NA means no adjustment or not applicable.
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Appendix A MSE Interoperability
Table A-l. NS to EAC via AN/THC-151.
1 -^^
i
NS
TRC-151
TRC-1B1
TTC-39/39A
"Timing
Mfittflr
NA
NA
IHflflflr
Bit rate
E7fl kh/s
BVSkb/fi
576 kb/e
676 kb/a
Modulation
Dipulsa
□ipuli&
Dipulw
Dipulva
Cable i^fll*
1/2/3/4
1/2/3/4
1/2/3/4
1 Z2/3/4
Cable xwn'ft
4/4/4/4
e/e/e/e
a/e/e/a
4/4/4/4
Cable rev
1/2/3/4
b/c/ol/8
b/d/d/B
1/2/3/4
CCS channel
1st
NA
NA
1*t
RSS channel
NA
MA :
MA
NA
Traffic channels
2-32
NA
NA
2-32
Control nnde
Np
No
Yes
Ym
Glare
Accept |
NA
NA
"*■
Table A-2. NS to EAC via AN/TRC-170.
1
1
! NS
TRC-170
TRO170
TT039/3SA
Timing
Master
NA
NA
Matter
Bit rat*
5l2kb/e ,
512fcb/a
512 hb/B
512M>/s
Modulotrdn
Piphate
Biphase
Diphaae
Diphaca-
Cabfe rtiftta
1/2/3/4
NA
NA
1/2/3/4
Cabte am it
4/4/4/4
NA
NA
4/4/4/4
Cpbta i-c^f
1/2/3/4
MA
NA
1/2/3/4
CCSchsrinet
1st
NA
NA j
1st
RSSchannsI
NA
NA
NA
NA
Traffic channels
2-32
NA
NA
2-32
Control nod*
Nq
No
Vea
Yse
GJara
AcrapL
NA
NA
Reject
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Appendix A MSE Interoperability
Table A-3, NS to £AC in* a AH/ISC-85A/93A
(using TD-1337 TRI-TAC port).
NS
TSC-93A
TSC-B5A
TTC-39/39A
"liming
Master
crjce
CNCE
Master
Borate j
576 kb/»
576 kb/s
; 67C kij/B
676 kb/t
ModulHtirpri
Dipha&e
Diptie Be
; Diphaco
Diphe&e
Cable r&eli
1/2/3/4
1 Z2/3/4
1/2/3/4
1/2/3/4
Cable jfmit
4/4/4/4
1 Z2/3/4
1/2/3/4
4/4/4/4
Cable rev
4/4/4/4
1/2/3/4
1/2/3/4
4/4/4/4
CCS channel
1st
NA
NA
lit
FESS chflfinal
NA
NA
NA
NA
Traffic chemists
2-32
2-32
2-32
2-32
Control nQtfe
No
No
Yea
VM
Glare
Accept
NA
NA
Reject
Table A-4, NS to EAC via AN/TSC-85A (using MO- 1025).
IMS
1 1
1
TSC-S5A
TSC65A
TTC-39/39A
Tim(ng
Master
CNCE
CNCE
MeatBr
Bit rate
676 kh/s
676 kfa/a
S7fl kb/a
576 kb/a
Modulation
Diphaae
Dkpha»
Diphaaa
DiptlHBfi
Cable r*els
1/2/3/4
1/2/3/4
1/2/3/4
1/Z/3/4
CahlBXpnit
4/4/4/4
IMA
NA
4/4/4/4
Gab lit rtv
4/4/4/4
NA
NA
1/2/3/4
CCS channel
1st
NA
NA
1st
RSS channal
NA
NA
MA
NA
Traffit chan-itilj
2-32
2-32
2-32
2-32
Gcnirti. node
No
Nd
Y«
Ye*
Glare
Accept
NA
NA
Reject
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Appendix A MSE Interoperability
Table A-5. NS to NS via AN/TSC-85A/93A
(using TD-1337 Tfll-TAC port).
NS
TSC-85A
TR093A
IMS
Timing
NlBStflJ"
CNCE
CNCt
Master
Bit net*
1 1 62 kb/ *
1 1 &2 kb/«
11B2kb/B
1 1 52 kb/*
Modulation
Diphase
Diphaae
Dtphose
Diphaso
Cable meis
W2/3/4
1/2/3/4
1/2/3/4
1/2/3/4
Cable k mit
4/4/4/4
1 Z2/3/4
1/2/3/4
1/2/3/4
Cable rev
4/4/*/4
1/2/3/4
1/2/3/4
4/4/4/4
CCS channel 1
1st
NA
NA
1st
RSS Channel
2d
NA
IMA
2d
Tn/f Ic Channels
3 94
NA
NA
3-64
Control node
Yea
VflE
No
No
Gin re
R&jtict
NA |
NA
Accept
Table A-6. NS
to MS via AN/TSC-35A
(using MD-1026).
NS
T5C-B5A
TROSSA
NS
Timing
Matter
CNCE 1
CNCE
Master
Bit rata
1152 kb/t
1l5Zhb/»
1162kb/a
1152 kb/s
ModulEtPDn
Dip4iBB&
[>i phase
Dlphfl-rt
Diphdte
Cable reels
1 Z2/3/4
1/2/3/-4
1/2/3/4
1/2/3/4
Cable xmJt
4/4/4/4
NA
NA
4/*/4/4
Cable rev
1 Z2/3/4
NA
NA
1 Z2/3/4
CCS chftrtrtftl
1st
NA
NA
let
RSS channel
2d
NA
NA
2d
Traffic ttanrMh
3-64
NA
NA
3-64
Control noda
Ves
Ves
Wo
No
GLare
Hsjact
NA 1
MA 1 Accspt
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Appendix A MSE Interoperability
Table A- 7. MS to LENS via AN/TSC-85A/93A
(using TD-1337 TRI-TAC port).
NS
TSC-S5A
TSC-93A
UEN
Timing
Master
CNCe
GNCE
Master
Bit rate
B7fl kt>/fl
576 kb/l
576 kb/s
57ft kb/a
Modulation
Di phase
Diphase
Oiphs*ft
Di phase
Cablfr rests
i/a/3/4
1 /a/a/a
1/2/3/4
1/2/3/4
Cable nn\\t
4/4/*/4
1/2/3/4
1/2/3/4
, 4/4/4/4
Cnblw rev
4/4/4/4
1/2/3/4
1 Z2/3/4
4/4/4/4
CCS chdnnek
lit
NA
NA
iwt !
RSS channel
2d
NA
NA
2d
Trnff Ic channels
3-32
NA
NA
3-32
Control node
Ye*
Ye*
No
No
Glare
Relecl
NA
NA
Accept
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FM 24-12 Glossary
JQQ
RDL Table of Document Download
Homepage Contents Information Instructions
RPL
,CHH
Glossary
Abbreviations and Acronyms
AC Active Components
ACP Allied Communication Publication
AIRK area inter switch rekey
AM amplitude modulated/amplitude modulation
BFO beat frequency oscillator
CEOI Communications-Electronics Operation Instructions
CG commanding general
CNCE communications nodal control element
COMSEC communications security
CP command post
CW continuous wave
DA Department of the Army
DGM digital group multiplexer
DISCOM division support command
DSB double side band
DTAC division tactical command post
DTMF dual-tone multifrequency
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FM 24-12 Glossary
DTOC division tactical operations center
DZ drop zone
EAC echelon above corps
ECB echelons corps and below
ECCM electronic counter-countermeasures
EMC electromagnetic compatibility
EMP electromagnetic pulse
EW electronic warfare
FASC forward area signal center
FDX full-duplex
FLOT forward line of own troops
FM frequency modulated/frequency modulation
FSE fire support element
FSK frequency shift keying
Gl Assistant Chief of Staff, Gl (Personnel)
G2 Assistant Chief of Staff, G2 (Intelligence)
G3 Assistant Chief of Staff, G3 (Operations and Plans)
G4 Assistant Chief of Staff, G4 (Logistics)
GMF ground mobile forces
GW ground wire
HF high frequency
HQ headquarters
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FM 24-12 Glossary
Hz Hertz
IAW in accordance with
IED imitative electronics deception
IHFR improved high frequency radio
INSCOM United States Army Intelligence and Security Command
IOM installation, operation and maintenance
JINTACCS Joint Interoperability of Tactical Command and Control Systems
JUH-MTF joint user handbook for message text format
kb/s kilobits per second
KC kilocycles (kilohertz)
kHz kilohertz
km kilometer
LDF lightweight digital facsimile
loc location
LOS line of sight
MC megacycles (megahertz)
MHz megahertz
mi miles
MODEM modulation/demodulation equipment
MOPP mission-oriented protection posture
MSE mobile subscriber equipment
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FM 24-12 Glossary
NA not applicable
NATO North Atlantic Treaty Organization
NBC nuclear, biological, chemical
NCO noncommissioned officer
NCS net control station
norm normal
NRI net radio interface (see RWI)
NS node switch
NSA National Security Agency
NSK narrowband shift keying
OPCODE operations code
OPLAN operations plan
OPORD operation order
OPSEC operations security
PCM pulse code modulation
PEP peak envelope power
RATT radio teletypewriter
RC Reserve Components
rev receiver
rec receive
recon reconnaissance
retrans retransmission
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FM 24-12 Glossary
rev reverse
RF radio frequency
RT receiver-transmitter
RWI radio wire integration (changed to NRI-net radio interface)
51 Adjutant (US Army)
52 Intelligence Officer (US Army)
53 Operations and Training Officer (US Army)
54 Supply Officer (US Army)
SCCS satellite communications control system
SHF super high frequency
SIGCEN signal center
SIGINT signals intelligence
SINCGARS Single-Channel Ground/Airborne Radio System
SOI signal operation instructions
SOP standing operating procedure
SSB single side band
STAJ short term anti-jam
suppl supplement
tac tactical
TACFIRE tactical fire direction system
TACSAT tactical satellite
TACSATCOM tactical satellite communications
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FM 24-12 Glossary
TCC telecommunications center
TOC tactical operations center
TOE table(s) of organization and equipment
TRADOC United States Army Training and Doctrine Command
TRI-TAC Joint Tactical Communications
VF voice frequency
VHF very high frequency
VRC vehicular radio configuration
w watt
xmit transmit
XTAL crystal
Terms
BREVITY LIST.
A list used to shorten transmissions. It does not provide security.
DETENT TUNING.
A method of tuning a radio to an operating frequency where the dial clicks into place at each
frequency.
FIBER-OPTIC CABLE.
A small, lightweight cable using pulses of light for transmission. Very low error rates but
extremely susceptible to damage.
JAMMING.
The intentional transmission of radio signals in order to interfere with the reception of signals
from another station.
KEY LIST.
A publication containing the key for a particular cryptosystem in a given cryptosystem.
MODULATE.
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FM 24-12 Glossary
To vary the amplitude, frequency or phase of a wave by impressing one wave on another wave
of constant properties.
NESTOR.
A communications security device.
NET.
Organization of stations capable of direct communications on a common channel, often on a
definite schedule.
NET AUTHENTICATION.
Identification used on a communications network to establish the authenticity of several
stations.
PARKHILL.
COMSEC device for HF radios.
PATCH PANEL.
A panel that contains means for changing circuit configurations; usually, it consists of
receptacles/jacks into which jumpers/plugs can be inserted.
PATCHING.
Connecting two lines or circuits together temporarily by means of a patch cord.
POLARITY.
A condition by which the direction of the flow of current can be determined in an electrical
circuit. Having two opposite conditions; one positive and one negative.
SECURITY CODE.
A code used to hide meanings from another party.
SIDEBANDS.
The frequency bands on both sides of the carrier frequency.
SQUELCH.
To shut off the audio output of a radio when a signal is not being received.
TRAINS.
A service force or group of service elements which provide logistics support.
TROPOSPHERIC SCATTER (TROPOSCATTER).
The propagation of radio waves by scattering, as a result of irregularities or discontinuities in
the physical properties of the troposphere.
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FM 24-12 Glossary
VINSON.
COMSEC device for combat net radios.
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FM 24-12 References
RDL Table of Document Download
Homepage Contents Information Instructions
RPL
,CHH
References
Required Publications
Required publications are sources which users must read in order to understand or to comply with
this publication.
Army Regulations (AR)
AR 530-2 Communications Security
AR 530-3 (C) Electronic Security (U)
Field Manuals (FM)
FM 11-50 (HTF) Combat Communications Within the Division (How to Fight)
FM 24-1 Combat Communications
Related Publications
Related publications are sources of additional information. Users do not have to read them to
understand this publication.
Allied Communication Publications (ACP)
ACP 122 (D) (C) Communications Instructions-Security (U)
ACP 125 (D) Communications Instructions—Radiotelephone Procedures
ACP 131 (D) Communications Instructions— Operating Signals
Army Regulations (AR)
AR 66-5 Armed Forces Courier Service
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FM 24-12 References
AR 105-64 US Army Communications- Electronics Operation Instructions Program
AR 310-25 Dictionary of United States Army Terms (Short Title: AD)
AR 310-50 Authorized Abbreviations and Brevity Codes
AR 380-5 Department of the Army Information Security Program
AR 380-40 (C) Policy for Safeguarding and Controlling COMSEC Information (U)
AR 530-1 Operations Security (OPSEC)
AR 530-4 (C) Control of Compromising Emanations (U)
AR 640-15 Criteria for Insuring the Competency of Personnel to Install, Maintain and Repair
Communications Security Equipment
Department of the Army Form (DA Form)
DA Form 2028 Recommended Changes to Publications and Blank Forms
Department of the Army Pamphlets (DA PAM)
DA PAM 25-7 Joint User Handbook for Message Text Formats (JUH-MTF)
DA PAM 25-30 Consolidated Index of Army Publications and Blank Forms
Field Manuals (FM)
FM 3-3 NBC Contamination Avoidance
FM3-4 NBC Protection
FM3-5 NBC Decontamination
FM 3-100 NBC Operations
FM 24-2 Radio Frequency Management
FM 24-16 Communications- Electronics: Operations, Orders, Records and Reports
FM 24-17 Tactical Telecommunications Center Operations
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FM 24-12 References
FM 24-18 Tactical Single-Channel Radio Communications Techniques
FM 24-33 Communications Techniques: Electronic Counter-Countermeasures
FM 24-35 (0) Communications-Electronics Operations Instructions (The CEOI)
FM 24-35-1 Signal Supplemental Instructions
FM 34-62 Counter- Signals Intelligence (C-SIGNT) Operations
Technical Bulletins (TB)
TB 380-41 (0) Procedures for Safeguarding, Accounting, and Supply Control of COMSEC Material
Technical Manuals (TM)
TM 11-5135-15 Radio Set Control AN/GSA-7
TM 11-5820-398-12 Operator's and Organizational Maintenance Manual (Including Repair Parts and
Special Tool Lists): Radio Set, AN/PRC-25 (Including Receiver Transmitter, Radio, RT-505/ PRC-
25)
TM 11-5820-401-10-1 Operator's Manual for Radio Sets AN/VRC-12, AN/VRC-43, AN/VRC-44,
AN/VRC-45, AN/VRC-46, AN/VRC-47, AN/VRC-48, and AN/VRC-49 (Used Without Intercom
Systems)
TM 11-5820-401-10-2 Operator's Manual: Radio Sets, AN/VRC-12, AN/VRC-43, AN/VRC-44, AN/
VRC-45, AN/VRC-46, AN/VRC-47, AN/VRC-48 and AN/VRC-49 (Used With an Intercom System)
TM 11-5820-401-20-1 Organizational Maintenance for Radio Sets, AN/VRC-12, AN/VRC-43, AN/
VRC-44, AN/VRC-45, AN/VRC-46, AN/VRC-47, AN/VRC-48 and AN/VRC-49 (Used Without
Intercom Set)
TM 11-5820-401-20-2 Organizational Maintenance for Radio Sets, AN/VRC-12, AN/VRC-43, AN/
VRC-44, AN/VRC-45, AN/VRC-46, AN/VRC-47, AN/VRC-48 and AN/VRC-49 (Used With
Intercom System, AN/VIC- 1(V))
TM 11-5820-498-12 Operator's and Organizational Maintenance Manual: Radio Sets, AN/VRC-53,
AN/VRC-64, AN/GRC-125 and AN/GRC-160 and Amplifier-Power Supply Groups OA-3633/GRC
and OA- 3633A/GRC
TM 11-5820-667-12 Operator's and Organizational Maintenance Manual: Radio Set, AN/PRC-77
(Including Receiver Transmitter, Radio RT-841/PRC-77)
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FM 24-12 References
Training Circulars (TC)
TC 24-20 Tactical Wire and Cable Techniques
TC 24-21 Tactical Multichannel Radio Communications Techniques
TC 24-24 Signal Data References: Communications-Electronics Equipment
Projected Publications
Projected publications are sources of additional information that are scheduled for printing but are not
yet available. Upon print, they will be distributed automatically via pinpoint distribution. They may
not be obtained from the USA AG Publications Center until indexed in DA Pamphlet 25-30.
Field Manuals (FM)
FM 11-50 Combat Communications Within the Division (Heavy and Light)
FM 24-35 Signal Operation Instructions: The "SOI"
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FM 24-12 Authorization Letter
RPL
,CHH
dBD
RDL Table of Document Download
Homepage Contents Information Instructions
FM 24-1 2
Hy Order of the Secretary of the Arrtiy;
CARL E. VUONO
General ^ United States Army
Chief of StalT
Official;
WILLIAM J, MEEHAN, IT
Brigadier General, United Slates Army
The Adjutant General
DISTRIBUTION:
Aftivt Arfriyj ARJfG^ and QSAK: to be distributed in accordance wi Lb
DA Form 12-1I-E, requirements far FM 24-12, Communics Lions in n
"Cotnt-Aji-YuEi-Ajrfi 11 War (Qty rqr block no. 0092") r
■■::.■. IS.ivm nr.- ■ r i - . i 1.|, Off .-_■; i ?m- ■ - ■' l=- ■' -"CO H
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