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Theses and Dissertations 1. Thesis and Dissertation Collection, all items
1973-06
A cable carrier FM telephone system.
Heath, Charles Maples Jr.
Monterey, California. Naval Postgraduate School
http://ndl.handle.net/10945/16513
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A CABLE CARRIER FM TELEPHONE SYSTEM
Charles Maples Heath
NAVAL POSTGRADUATE SCHOOD
JONTEREY, CALLF. 93940
A CABLE CARRIER FM TELEPHONE SYSTEM
by
Charles Maples Heath, Jr.
Thesis Advisor: Gerald D. Ewing |
June 1973 ‘TT 7
Approved for public release; distribution unlimited.
Pee pra CARR Pere) TELEPHONE SYSTEM
by
Ghiamles Maples Heath, Jr.
Lieutenant Commander, United States Navy
B.S., United States Naval Academy, 1964
Submitted in partial fulfillment of the
requirements for the degree of
MoomERVOF SCIENCE IN ELECTRICAL ENGINEERING
from the
NAVAL POSTGRADUATE SCHOOL
June 1973
LIBRARY
NAVAL POSTGRADUATE SCHOOD
MONTEREY, CALIF. 93940
Pol RNeL
A multichannel frequency division multiplexed FM tele-
phone system is presented. The system is intended for use
in organizations where large numbers of telephones are normally
installed and is compatible with conventional switchboards.
Advantages provided by the system are: reductions in installed
wiring, the ability to relocate telephone sets by the sub-
Scriber, and compatibility with other coaxial cable systems.
or.
ie .
IV.
Ne
TABLE OF CONTENTS
INTRODUCTION
Meri te ie oo fe PePHONY IN THE UNITED STATES
DESIGN CONST DERATIONS AND SPECIFICATIONS
Pee oN “GONS FEDERATIONS.
Eee OUBPN@GYmALTLOCATION ... . «2 , os
Gre ov Slav SPECIFICATIONS .
GimeOokyY OF OPERATION. .. .
Poe Nei ASPECES OF SYSTEM OPERATION.
B. PBX MULTIPLEX UNIT CIRCUIT OPERATION
Po webeansmit ter Operation. |
2. Receiver Operation
Coy eX tENSION MULTIPLEX UNIT CIRCUIT OPERATION
1. Transmitter Operation.
2. Receiver Operation
_RESULTS AND CONCLUSIONS. ......
APPENDIX A CHANNEL FREQUENCY ASSIGNMENT.
APPENDIX B ILLUSTRATIONS ...
BIBLIOGRAPHY
Mitt AL piStRIBUTION List.
FORM DD 1473
19
19
21
24
25
25
28
28
3h
34
34
35
36
Bo
39
56
59
60
TABLE
I @
Eist OmeaseLES
Channel Frequency Assignment
B16)
FIGURE
le
2
IO
aL
2
Tee
14.
les
On
17.
ee
19.
20.
PIS tT Ones ERATIONS
Frequency Allocation
Pushbutton Dial Keyboard
System Block Diagram
PMU and EMU Block Diagrams
PMU Transmitter Schematic Diagram.
PMU Transmitter Component Values
PMU Receiver Schematic Diagram
PMU Receiver Component Values.
CA-3089 Block Diagram.
CA-3089 Schematic Diagram.
CA-3089 AM Rejection
CA-3089 AGC and Meter Outputs.
CA-3089 S/N Characteristic
CA-3089 S/N with Squelch
CA-3089 AFC Output
Gre oUc9 Duning Characteristic.
EMU Transmitter Schematic Diagram.
EMU Transmitter Component Values
EMU Receiver Schematic Diagram
EMU Receiver Component Values.
39
40
41
42
43
4 4,
45
46
4.7
49
49
50
50
Sel
Sil
BZ
oe)
54
55
ACKNOWLEDGEMENTS
The assistance and advice received from Dr. Gerald D.
Ewing, thesis advisor, was invaluable in this project. The
counsel provided by Mr. Herb Borchers and Mr. Jerry Olmsted
of Coastcom Inc. is gratefully acknowledged.
ieee DKODUC TION
Organizations such as hospitals, hotels, and governmental
offices require large numbers of internal telephone exten-
ffens, Existing systems require installed wire pairs dedicated
memeach extension. Initial installation costs are high and
changes in extension locations must be made by telephone
company technicians. In addition, users such as hospitals
and hotels normally have coaxial cables for television in-
Stalled which have a surplus of bandwidth when used only for
entertainment television.
The system proposed would allow the installation of a
multiplex telephone network that is compatible with cable TV.
Considerable savings can be realized in the short term by
Miemreduction of wiring costs in new ee and in the
long term by the capability to add additional extensions
Peehowteadaing additional cables. Over the life of the
System more savings would occur because of the portability
of the telephone sets. Relocation of an individual subscriber's
telephone set would eae ee emily the connection ot a CoOaxtal
plug. The subscriber would retain his number and hence not
Beata ne Switchboard Or directory changes. In addition, a
relocation would be made by the user without telephone
company assistance.
Developments in multiplex telephone and cable TV are in-
cluded in the following pages. Recent developments in cable
Systems were particularly important in the design and
feasibility considerations for this system.
Solid state and integrated circuit technologies were
utilized in designing the system. Existing integrated cir-
cuits were used when they permitted more economical circuits
than were possible with discrete components. Unfortunately
several initially promising components such as phase locked
loops could not be used because of bandwidth limitations.
II. MULTIPLEX TELEPHONY IN THE UNITED STATES
ive hastory of multiplex telephony is in effect the
development of this communications method by the American
Telephone and Telegraph Company. The Bell System, as it is
more commonly referred to, dominates the one industry
and has a great influence in international telephony pro-
gress’ and policy. pete ene of the development of ieee mee
plex Mente ony by the Bell System is therefore typical of
international progress and is virtually a complete chronicle
of American progress.
The principle of multiplexed, wire carried communica-
tions predates, and was instrumental in, the development
of the telephone. Alexander Graham Bell's initial research
feendirectecd toward the perfection of a "harmonic telegraph".
His concept was that of mechanically producing audio freq-
Wency vibrations and then transmitting several of these
frequencies over a common transmission line. (Ref. 1) A
more efficient telegraph network could then be had. At the
receiving station another mechanical device, usually a tuned
metal reed, would vibrate when the appropriate harmonic was
received. Quite by accident during his harmonic telegraph
research Bell and his assistant, Thomas A. Watson, discov-
ered that not only could invariant frequencies be trans-
mitted and detected, but also the modulations of the human
voice. Bell soon abandoned his primitive frequency multi-
plexing research for work on the equally primitive voice
communications system. As a result of his work he received
his historic patent, number 174,465, in 1896 for 'tAn Improve-
ment in Telegraphy," i.e. the telephone.
The combination of frequency multiplexing from the
harmonic telegraph and voice modulation from the telephone
had to wait until the telephone was further perfected and the
demand for circuits was high enough to justify the complex-
ities of multiplex telephony.
The telephone was limited to local intracity use when
first developed due to the lack of a suitable wire for inter-
Seay eeOumnectlone. (ket.2) Wath the application of hard
drawn copper wire to open wire construction by Thomas B.
Doolittle ‘long distance"! connections became possible. In
1884 a line was strung between Boston and New oe Further
@eeeress In an intercity telephone network awaited the in-
vention of the electronic vacuum tube by Lee DeForest.
eee. PD. Arnold proposed in 1915 that the vacuum tube be
used to create practically perfect telephone transmission
over long distances.
In 1892 John Stone in the United States and Pupin,
Hutin, and LeBlanc in Europe devised schemes for telephone
multiplexing. Spark gap generators were used to produce the
@eerier frequency. Signal amplification was at that time
impossible. Experiments by Major G. O. Squier, head of
the United States Army Corps at Fort Monmouth, New Jersey,
with multiplex transmission over a short cable in 1910
further laid the foundation for future practical systems.
(Ref.3) It might be noted that the term rae implies
frequency multiplex, versus time multiplex. Until the
development of solid state electronics the promise of time
division multiplex was out of practical reach for telephony.
Time division multiplexed telegraphy could be accomplished
through the use of mechanical commutators however.
In 1918 the Bell System installed a carrier current
telephone circuit using open wire construction between Pitts-
burg and Baltimore.(Ref.4) It provided four taiking channels
for each wire pair and was designated the A system. This
10
Meeweto be the first of a Jong series of alphabetically
designated intercity systems. In this system a connection
was duplexed with both directions of transmission on the
same frequency. Hybrid coils were used to separate the send
and receive signals. The hybrid coil system gradually fell
into disfavor because of maintenance difficulties. By
1923 the Bell System boasted of a carrier system "That if
feedeend to end would stretch half way around the globe."
To be exact they had a 29 channel capability over 3,941
miles or a total of 14,676 channel miles. The longest
link was from Harrisburg to Chicago, a distance of 742 miles.
In 1920 the three channel Type B system was introduced.
It used separate frequencies for send and receive and
thereby did away with the troublesome hybrid coils. As with
the type A system amplitude modulation was utilized. By
1923 the advantages of multiple wire cables over open wire
lines had been recognized and installation of aerial cables
was under way. In addition to telephone circuits these
Systems also carried telegraph circuits. A typical network
installed between Denver and Los Angeles in 1924 had three
telephone and 14 telegraph circuits operating on four wires.
In the type A system single sideband (SSB), supressed carrier
was used, but the type B system was SSB, with carrier.
Paralleling the development of the multiplexing systems
were improvements in the transmission medium. The advantages
as
precable use were recognized, but the state of the art in
cable construction did not yet give cables an unqualified
advantage over the older open wire scheme. Cable trans-
mission became the dominant mode when circuit requirements
became too large for practical open wire construction and
when telephone repeaters were perfected that could compen-
sate for the cables' large losses. The Bell System then
gradually changed from an exclusively open wire network to
a mixed medium network when first multiwire cables, then
coaxial cables, and finally microwave links were added.
Mie first long distance toll cable in the United States
was placed in service between New York and Philadelphia in
1906. The cable installed between Chicago and New York in
1918 was typical of those in use and contained 300 circuits
toma 2 5/8" diameter lead sheathing. (Ref. 5)
Further research led to the introduction of the type C
System in 1925. It was a three channel system that used
Euugle sideband, suppressed carrier transmission. In this
improved system equal spacing of channel frequencies had
been abandoned in favor of variable spacing. This technique
increased the efficiency of bandwidth usage. As with the
type B system different frequencies were used for trans-
mitting the send and receive components of each circuit.
Frequencies no higher than 30 KHz were used because of
12
open wire construction predominance in the existing Bell
System network and the limited bandwidth it Penn rocmqr ene)
The next system developed was the type D which pro-
wagiedea Single channel carrier circuit for short haul use.
It again was a single sideband, suppressed carrier, ampli-
tude modulated scheme.(Ref.7)
Multiple channel systems previously discussed were all
femeetoll (long haul) circuits. By 1933 the Bell System
could see the need for multiplex systems that could increase
the capacity of shorter trunks. However the depression
Bamleowed only research on and not installation of such
systems.(Ref .8)
The need for broadband communications capabilities aiso
began to be apparent in the 1930's. An electronic curiosity,
the television, was one system that would require broader
bandwidths than were currently available. Therefore COaxta!
cables, whose characteristics were predicted by electro-
magnetic theory, came under scrutiny. In 1934 the Bell
System was constructing and testing various types of coaxial
cable with an eye toward improving toll circuit capabilities
as well as opening up a new communications medium. (Ref .9)
The first coaxial cable system was installed between New
York and Philadelphia in 1935. It was 95 miles long, had
repeaters every 10 miles, and had a bandwidth of 1 MHZ.
It could carry 240 simultaneous two way conversations.
12
These channels were collected in 12 channel "groups."
Conversion to subcarrier frequencies was done in two stages
of modulation.
The type K systen, introduced in 1937, used the group
modulation principle with transmission over a multiple wire
cable.(Ref.10) Other important features of the system were
repeaters at 17 mile intervals and 4 KHz channel spacing.
It was predicted at the time that the end of open wire toll
construction was in sight and that the economies of the
new system would make short haul multiplexing a strong
Mecsitbality.
In 1938 the first long distance transmission of tele-
vision over a coaxial cable had been carried out on the
Philadelphia to New York, 1 MHz cable.(Ref.11) The results
were not satisfactory for commercial use, but they pointed
the way toward wider bandwidth coaxial cable and the simul-
taneous multiplexing of television and telephone on the same
cable. Three additional carrier systems were introduced
in the late 1930's. The type H system was developed as
an improvement on the existing type D system.(Ref.12) One
of its features was the capability to include repeaters for
improved performance. The 12 channel type J system included
many features of the type K, but was intended for open wire
installations. As such it was used to supplement the exist-
ing type C system. The type M system used high voltage lines
14
as its transmission medium and found only limited use.
Peyetical toll coaxial cable transmission was introduced by
m@meetype Ll system.(Ref.13) It had the capability of carry-
mem 430 long haul channels. In addition 120 short haul
channels could be utilized if necessary. The cable's band-
width was 2 MHz.
With the type Nl system the Bell System improved multi-
oe cable capacities in 1950.(Ref.14) It was designed to
carry as many as 1800 channels on a 300 pair cable from 15
to 20 miles. Increased distances could be achieved if
necessary. A new technique used was compression and expan-
Sion of speech volume which permitted reductions in crosstalk
and noise. Out of band signaling was added to give an
associated signal channel just above each voice channel. As
with other large capacity systems the 12 channel grouping
Scheme was used.
As a result of extensive research in microwave devices
the Bell System was able to open the TD2 microwave multiplex
system in 1950. Frequency modulation was used in the TD2
to provide 6000 low noise channels. A prime reason for the
microwave system's installation was the desire to establish
a nationwide television transmission network. The system
supplemented the existing telephone cables which were unable
to meet an unprecedented postwar demand for circuits.
Creating the microwave network was a major undertaking by
Des,
any standard. Not only did new types of terminal equipment
have to be developed, but a nationwide net of transmission
stations and repeaters with their associated equipments had
to be both designed and manufactured. The requirement for
even more circuits in later years resulted in the later de-
velopment of the TD3, TH, TJ, TL, and TH3 systems.
As a further step to improve the utilization of exist-
ing open wire installations, the type O system was put in
commercial service in 1952. It was intended for circuits
ranging from 15 to 150 miles long and was the open wire
Counterpart of the type N cable system.(Ref.16) This new
system used the Signaling and noise reduction schemes intro-
duced in the type N, but used single sideband instead of
the N's simpler double sideband method. Full capacity of
the type O was 16 channels, arranged in groups of four.
The L3 coaxial system was placed in operation in 1953.
It had a capacity .of 1860 telephone channels or in a second
version 600 channels. The L3 was designed as an improvement
on the Ll and as such had as a prime design consideration
the reuse of Ll facilities, equipment, and cables.(Ref.17)
The L3's parameters were bawed on long haul usage of 4000
miles.
Solid state devices came into use in the type Pl. De-
Signed in 1956 for rural use it provided up to four stackable
channels for either open wire or cable installations. As
16
with other wire carrier systems amplitude modulation was
used for simplicity.(Ref.18) Rural usage was also envisioned
for the type Tl system in 1962.(Ref.19) Because of further
improvements in solid state devices and coding procedures
memes able to utilize time division multiplexing in con-
Beet aon with pulse code modulation (PCM) and had a capacity
of 24 channels. In a move to standardize interfaces the
Bell System catagorized their multiplex terminals as "L
Systems.'"*(Ref.20) The L multiplex terminals were then
subdivided into systems of different capacities and capa-
bilities. These terminals were designed to operate with the
Mil Ss, and L4 coaxial cable lines and with the TD2, TD3,
TH, TJ, and TL microwave links. Single sideband with 4KHz
Channel widths was used. Continued improvement of older
systems resulted in the combination of the type O terminals
with the Nl carrier lines to produce the ON1].(Ref.21)
Further improvements upped the ONl's 16 channel capacity
to 24 channels in the ON2. A solid state, 12 channel,
double sideband, amplitude modulation scheme was used in
the advanced N2 system. Again the upgrading process came
into play and the N3 with 24 channels was produced, but with
Single sideband vice double.
The latest systems in use with the Bell System are the
TH3 microwave system (Ref.22), the L4 coaxial cable system
(Ref.23), and the Tl time multiplex system. The first two
7
are for use between switching centers, while the third is
used to increase capabilities in rural and other low density
areas. None of these systems are suitable for use within
a large suscriber's organization, such as a hotel or office
building. Nor are plans to introduce systems for such use
in the near future apparent. Research is being carried out
in new methods of transmission such as laser beams and milli-
meter waveguides. The future will probably mirror the past.
There will be periodic changes in transmission media as
technology permits, followed by continued updating of equip-
ment. Each new system will share some of the equipment of
older systems and the basic channel parameters will remain
unchanged. A trend toward systems with shorter economical
ranges seems inevitable because of the continued increase in
demand for telephone circuits and broadband data links.
iis
fei DiESiGN CONSIDERATIONS AND SPECIFLCATIONS
a en oes
fee DESIGN CONSIDERATIONS
In order to achieve economies over existing telephone
systems the proposed system must meet two basic requirements:
it must be compatible with standard PBX switchboards and it
must be capable of sharing coaxial cables with cable TV
systems. The compatibility with existing telephone equip-
ment and transmission parameters allows installation of
this system with a minimum of interface problems. There is
no requirement for additional equipment to match this system
to standard telephone company equipment. A bonus derived
from Rpeiowompatibility ti hesomAet CAlity OL anetall ing
meer system in existing installations in order to boost the
Sapacity of installed wiring. Older Beata EOiwlnS Lance.
might be made suitable for occupancy by tenants who require
more telephone extensions than any existing wiring could
normally carry. If the installation of additional wiring
was not economically feasible this multiplex system would
fietevan Obvious need.
PiWewinctallation of cable TV systems in buildings is
becoming more common every day and is universal in newly
constructed hotels, motels, and hospitals. New cable TV
oy ell-wate LTrequired by law to be suitable for the future
19
BmcOrporation of a two-way communications capability. Since
mie resultant installation of coaxial cables is becoming so
Meevalent, any additional capability that can be given them
mic reduces other ieee requirements results in an immedi-
ate savings. Studies have shown that to avoid the possibility
of mutual interference additional communications signals
should be well below the lowest standard TV broadcast band
fememme! 2 at 54 MHz). An upper limit of 30 MHz on addition-
al signals is generally considered sufficient(Ref.24) .
ireaddition to the limiting design considerations above,
other features were deemed worthy of inclusion. In antici-
pation of future nationwide use of tone generation dialing,
the system was designed to use this method signaling.
With modifications the older make and break dialing method
could be used. A parts' cost of $35 per extension was set.
as a goal. The cost of the system manufactured in quantity
would be about three times that figure. The individual
telephone set, which would contain a conventional handset
enaedial tone generator, in addition to the multiplexing
Seircuatry, would have to be ES portable in Set erreak
manufactured form. The power for each extension would come
from a central supply. The extension would therefore not
have to be located near a conventional AC outlet.
To free the system from high ringing voltages, ringing
as accomplished with an amplified audio tone. Individual
20
extensions could be given unique ring tones. Such a feature
is convenient in crowded offices which contain several
extensions. Send and receive bands would be frequency
Meparated to reduce crosstalk and to avoid the complexity
mieedirectional signal separation circuits. FM was chosen
over AM in order to take advantage of the noise rejection
meatures of the former. Standard 10.7 MHz IF was used,
allowing use of available integrated circuits and filters.
To as great a degree as possible circuits such as
oscillators were designed to be suitable for use in several
components of the system. This minimizes the number of
unique circuits in the system and increases standardization.
Mem transmitter/receiver unit is suitable for use over
the entire 5-30 MHz system frequency range with a minimum
@eechanges. Shifting a unit from one band to another re-
aurres Only substitutions or tuning of tuned circuits. In
the system's final manufactured form that might be accom-
plished by small plugin modules.
B. FREQUENCY ALLOCATION
The cornerstone of any frequency division multiplex
System is the frequency allocation plan. Design considera-
tions and tradeoffs hinge on the available frequency spec-
trum and the number of channels desired. As previously
mentioned this system is limited to a band of about 25 MHz
eu
between 5 MHz and 30 MHz. Since the system is intended for
use with conventional telephone networks, the standard 4
KHz audio channel was adopted. Figure 1 illustrates the
audio channel, the voice bandpass within that channel, and
the 20 Hz out-of-band ring frequency. It might be noted
that additional out-of-band signaling 1s possible in the
Meeer section of the channel between the voice bandpass and
@m@erchannel boundry. Figure 2 contains a diagram of a
pushbutton dialing keyboard that would be suitable for use
with the proposed system. In this case the dial Signal is
in-band and each digit or character has a pair of correspond-
ing frequencies, one from the low-band and one from the
high-band. Although only 12 buttons are presently used in
commercial installations, 16 buttons are possible if the
Spare frequency combinations are used.
Because a key component of the proposed system is an
iipegrated circuit originally intended for use in FM broad-
cast receivers, the standard maximum frequency deviation of
* 75 KHz about the carrier is used. Asa precaution against
adjacent channel interference £ 100 KHz is allowed for each
Sideband. The proposed system therefore requires 200 KHz
for each one-way channel and hence 400 KHz for each ex-
tension, as.shown in Figure 1.
Of the original 25 MHz available a portion around the
10.7 MHz intermediate frequency (IF) of the receiver circuit
ee
is unusable. The remaining spectrum has been broken up
mato 6O channels in Table 1. Channels 1 thru 12 are below
Seemeedegap and 13 °thru 60 above. The lower l2 channels are
less desirable for use than the 48 upper channels. Because
mlecarriers are on odd hundreds of kilohertz, second
harmonic interference 1S avoided. However third harmonic
interference between the upper and lower channels is possible.
Therefore if an installation required 48 or fewer extenSions,
the lower group would be left vacant. If an installation
Called for more than 60 extensions two or more coaxial
Cable trunks would be necesSary. For instance if a building
required from 30 to 60 extensions per floor a trunk could
be run to Sen floor. The desired flexibility in extension
relocation would be somewhat limited in such an installation.
An extension could not be relocated from a plug supplied by
one trunk to a plug supplied by another trunk without a cross-
patch being made at the PBX switchboard.
In installations which do not require the simultaneous
transmission of both telephone circuits and broadcast tele-
vision, the systems spectrum could be extended above 30 MHz,
Waking additional channels available. Limiting factors on
Enesnumber of channels that might be added could be the
eepapilaty Of the coaxial cables to carry the total DC power
requirements for the extension multiplex units and the
possible occurrence of harmonic interference problems.
ZS
meee oYolEM SPECIFICATIONS
Method of modulation:
Maximum carrier deviation:
Bandwidth per oneway channel:
Total bandwidth per channel:
Audio bandwidth:
Carrier frequency range:
Receiver IF frequency:
Maximum number of extensions:
Signal to noise ratio:
mermonic distortion:
Power supply voltage:
Power usage per extension:
Impedance at PBX terminals:
fee Signal:
Dial signal:
Crosstalk between adjacent
channels: |
.24
Frequency modulation, double
Sideband, with carrier
~ 75 KHz
200° KHz
400 KHz
4 KHz
5-30 MHz
1077 Wiz
60
-45 db
-40 db
10-12 VDC
1 W
600 Ohms
In-band audio tone
In-band audio dual-tone
-60 db
[MeeeetimbORyY OF “ORE RAT TON
Pee NeRAL ASPECTS OF SYSTEM OPERATION
The multiplex system's configuration is illustrated in
Figure 3. Each extension multiplex unit (EMU) is an FM
mmemsceiver. The PBX multiplex unit (PMU) contains trans-
ceivers that closely resemble the extension units, but with
additional features. Figure 4 breaks these units down
into functional blocks. The system has two general oper-
ating modes that correspond to the two operating modes of
conventional telephones. These are the hook-on and hook-off
states and they refer to the status of the Bevo nne hand-
Peet the handset 1S in its cradle the extension is in
the hook-on state and conversely if the handset has been
removed from its cradle to send or receive a call the hook-
off state exists. |
The most common state for an extension is the hook-on.
ii this case the extension is idle and is ready to receive a
call. The PMU's individual transmitter and receiver sets
are energized. The transmitters are sending out unmodulated
carrier Signals to which the corresponding EMU receivers are
fumed. the-.ring detector is also energized. The PMU audio
somal switch is open, preventing 20 Hz ring signals from
the PBX from reaching the PMU transmitter. At the EMU
25
mpeeieeceiver 1S active, but not the transmitter which is
turned off to conserve power and to reduce the number of
active frequency bands.
If a call is received by the PBX for an extension the
PBX selects the proper connection for the corresponding PMU
set. The PBX would detect that a hook-on state existed using
a DC resistance detector and would commence standard 20Hz
rings. The ring detector would detect the rings and acti-
vate the ring tone generator. These ring tones would modulate
the PMU transmitter. At the EMU the carrier would be de-
modulated and the audio ring tones amplified. The subscriber
would then hear the extension'sSunique ring tone coming from
the small ring tone speaker just as he would hear the bell
in a conventional extension. When the call is answered by
picking up the handset the extension's state would be changed
to hook-off. The ring tone speaker would be disconnected
sma the handset connected to the EMU's circuits. In addition
the EMU transmitter would be energized. The EMU trans-
Mitter's carrier would go over the coaxial cable to the PMU.
The PMU receiver would sense the presence of the carrier and
activate the audio signal switch which would in turn connect
ume PMU receiver to the PBX. The ring detector would be
Hert som because only 20Hz ring signals are of sufficient
magnitude to be detected by the ring detector so there is no
possibility of speech signals keying the ring tone generator.
26
The PMU would now present the standard 600 ohm hook-off re-
sistance to the PBX. The system would now be ready to
Garry a two way conversation over the activated extension.
If the system is in the hook-on state and a subscriber
desires to make a call an abreviation of the previous se-
@@enee takes place. When the handset is removed from its
cradle the ring tone speaker is disconnected and the handset,
transmitter, and audio signal tone generator are placed in
operation. The subscriber can then dial the desired number
by keying the audio signal tone generator. The Signal tones
are within the bandpass of the telephone and are transmitted
in the same manner as speech. Switching processes are
carried out at the telephone company's switchboard. Busy
and out of order signals from the PBX would also be handled
in-the same manner as speech. At the PMU the extension's
carrier would be detected and the audio signal een would
oe aetivated aS before.
When the system is in a hook-off state the system is
in the operating setup as described in the above paragraph.
Both sets of receivers and transmitters are energized and
the PMU presents the proper 600 ohm resistance to the PBX.
Micering detector is activated but is not subject to signals
that would cause it to key the ring tone generator.
ae
pero MULTIPLEX UNIT CIRCUIT OPERATION
eetranomitter Operation
Figure 5 presents the schematic diagram of the PMU
transmitter and Figure 6 tabulates the values of the compo-
ments.
Mimew transmitter is linked to the PBX at the terminals
labeled '*FROM PBX.'! When the extension is in the hook-on
Mede, 1.e., the extension is not in use, relay/switch X1
is open. A ring signal would be transmitted to the ring
detector circuit by the transformer T2. The full-wave
Geewer ler consisting of diodes: D5, D6, D7, and D8, dropping
resistor R11 and smoothing font C10, would convert
meen 2O0HZ2 ring signal to the JOVDC supply voltage for the
mae, tone generator. Since ring signals from the PBX are
methe order of 9OV, ordinary audio conversation signals
which are in the order of 2V are too small a activate the
ring tone generator.
The ring tone generator is a phase-shift oscillator
which generates an audio tone. C14 provides the feedback
necessary for oscillation and a portion of the required
phase-shift. Cll and Cie conpiere the required phase-shift.
By varying the values of Cll and Cl2 the frequency of the
Seeitlator can be changed. In this manner each extension
Gammoe Given a uUhique ring tone. Q5 is included as an
Zo
emitter-follower to prevent the loading down of the oscilla-
tor. C15 couples the ring tone generator to the transmitter
emer blocks DC.
If the extension 1s in the hook-up mode the EMU
transmitter is activated and sends a carrier signal to the
PMU receiver. The presence of this carrier is indicated
by an increase of the voltage at the "*METER'® terminal of the
PMU receiver and the corresponding terminal of the PMU trans-
mitter. For typical operating conditions the voltage would
m@emerom LVDC to 2+VDC. D2 and D3 bias Ql so that a voltage
mammepoeut |. .,SVDC will turn Ql on, this would in turn activate
mm@geciose Xl. Dl and Cl allow the circulation of currents
through X1] and prevent voltage spikes that could damage Q]l
Or cause Xl to chatter. Rl serves tc seize the switchboard
for outgoing calls by presenting the proper DC resistance of
600 ohms to the PBX busy detector. C2 prevents DC from
reaching Tl which, couples the balanced PBX euiane to the
unbalanced circuits of the PMU. R2 may be varied to diminish
the audio level from the PBX to prevent over deviation of
Bie Carrier.
The transmitter uses a varactor diode, D4, to FM the
basic RF carrier generated by Q2 and 93. C6 and Ll set the
basic carrier frequency. For channelization of a production
System these tuning components might be included in a plug-
in module that would be factory tuned for an indicated
29
@eemnet. C4 jlinks the varactor with the tuned circuit so
Mimisicnals across D4 vary the total capacitive reactance of
the tuned circuit and hence the frequency of the carrier.
ities basic clrcuit 1s used in both the EMU and PMU transmitters.
imricditaon a modification of the circuit is used in the EMU
and PMU receivers in their local oscillators. This dual use
of the circuit would result in more economical production
of the proposed system. R10 serves to increase the output
mpedance Of the circuit. High output impedances for each
transmitter are necessary because all channels are connected
in parallel at the junction boxes. Low individual output
impedances would result in mismatching the coaxial lines.
In an installed system the DC power supply would
also be connected across the RF terminals at the junction box.
Deevoltage from this source would be carried to the EMU's
on the same coaxial cable as the RF Signals. Design of a
Suitable power supply was not included in the system as pre-
sented. In practice a 12VDC supply would be used. The voltage
at each unit: would then be within the design limits of the
System, and in addition some leeway would be present to
compensate for any loading down of the power supply if it
etammot act as a perfect voltage source. A 12 volt supply
would also allow a convenient interface with an emergency
battery power supply.
B10.
e Receiver Operation
Figure 7 presents the schematic diagram of the PMU
receiver and Figure 8 tabulates the values of the components.
Figure 9 is a block diagram of the CA-3089 and Figure 10 is
Mmmemsoehematic trom Ref. 25. Figures ll, 12, 13, 14, 15, and
iaeontain performance charts on the IC from the same source.
Reference 26 also contains information on the application of
the CA-3089.
The FM signal from the EMU is received at the termi-
nals labeled "'RF'* and is amplified by Q4. R18 and R19 set
mem bias for 04 and C14 blocks the DC carried by the coaxial
Beetle, L3 and Cl2 form a tuned circuit that allows selective
emplitfication of the individual channel's carrier. Q3 and
Q2 and their associated components act as the receiver's
mixer. Taking the amplified RF at the base of Q3 and the
local oscillator signal at the base of Q2, the mixer produces
the sum and difference frequencies. In the proposed system
the local oscillator (LO) operates at a higher frequency than
the channel carrier's and the difference frequency of 10.7
Mz ts taken off the collector of 03 as the IF. R13 and R14
batas QO2 and R12 and R15 ae Q3 to produce the desired non-
linear operation of the mixer.
Q6,°Q7, and their associated components constitute
the 1O. The basic oscillator circuit is the same as used in
thiesmultiplex unit transmitters. In this case instead of
Bil
modulating the output of the oscillator to carry audio
Signals, the output frequency can be varied to compensate
for drift in the received carrier. The line labeled "AFC"
from the CA-3089 acts as a current source to drive the LO's
m@eecircuit. Figure 15 is a graph of IF drift versus
Mmm Output at pin 7 of the IC. R20, R21, R22, R23, R24,
feo, and R26 form a biaSing circuit that provides uniform
AFC loop gain over the tuning range, prevents the IC's AFC
Smreuits from saturating, and prevents the over-deviation
of the LO output. Instead of using a varactor diode as was
done in the transmitter circuit, a back-biased transistor,
QS, is used in the LO. As with the varactor the back-biased
transistor's capacitance is also varied by the voltage
appearing across it. This action is not as linear as it would
be with a varactor, however since the circuit is only used
to compensate for drift and not to transform an information
Signal the decreased linearity is tolerable and the use of
a transistor represents a considerable savings over the
use of a relatively expensive varactor. The output of the
Peomrs COupled through C20 to the mixer at Q2.
The FM-4 1s a crystal bandpass filter designed
especially for FM broadcast receivers. It has a narrow
bandpass about the standard FM receiver IF of 10.7 MHz,
therefore it filters out all but the difference frequency
miom the MLXeL.
BZ
rans lewand 2°Or the lC drive the first of three IF
iemiters in the chip. Pin 3 provides DC feedback. The limit-
ers in turn supply three level detectors whose outputs are
summed at pin 13. Ina FM broadcast receiver this output
would drive an S meter. For the proposed system however,
this output provides a convenient method for sensing the
mresence of a received carrier and is used to drive the relay
S@erecuit in the PMU transmitter. The first level detector in
the IC also provides AGC voltage at pin 15. In the proposed
system the AGC feature is only used for tuning and trouble
shooting purposes. The output of pin 8 comes from a quad
limiter. L2 acts as a RF choke to block harmonics of the IF.
lWieeec2, and Rl are tuned to 10.7 MHz and drive the IC's de-
M-evgr., Fin 10 is fixed at a reference bias voltage and would
be used as a return point for the AFC if that feature were
not used. R6 and RS set the squelch threshold of the IC. The
Bee GCireuit reduces the side responses that are character-
istic of limiter-discriminator receivers, as shown in Figure
16. In the proposed system the squelch control can also be
used aS a convenient method of decreasing the audio output of
the IC without having to change fixed value components. The
audio output of the IC is taken at pin 6. The internal out-
put impedance is 5 KOhms, so the total impedance after R7
woula be 7.5 KOhms.
a3
Ql and its associated components form an
merer to bing the audio output of the PMU up ne
level for connection to the PBX at the terminal
memoro TO PBX.'® Placing Tl at the collector leg
duces the desired balanced output with a minimum
Penfedi fication of this amplifier is also used in
ceiver.
eee PENSION MULTIPLEX UNIT CIRCUIT OPERATION
ie obansmitter Operation
audio amp-
a suitable
labeled
of Dis pro
of components.
the EMU re<
Figure 17 presents the schematic diagram of the EMU
transmitter and Figure 18 tabulates the values of the comp-
onents.
The EMU transmitter is connected to a coaxial cable
eet at the terminal labeled “RF+DC.'t As the label indi-
cates both carrier RF and DC supply voltages are carried by
the cable. RFC blocks the RF from the DC supply lines while
@2eblocks the RF out of the terminal labeled "RF TO RECEIVER,"
hence RF/DC separation for the entire EMU is accomplished in
the transmitter section. The DC supply for the receiver is
picked off after RFC and is routed via the terminal labeled
Bebe tO RECEIVER. Sil ais activated by the handset hook. In
the hook-on condition the switch is open and the transmitter
ms Ott, however DC still flows to the receiver which is active
Steall = times in order to receive ring tone signals.
34
The handset and dial tone keyboard are the conven-
[uenal types currently in commercial telephone sets. The
frequencies generated by the keyboard are shown in Figure 2.
If the proposed system were placed in production these items
would be purchased directly from a telephone equipment sup-
plier.
The transmitter circuit itself is identical to the
PMU transmitter circuit. The output is again taken through
R1, which increases the output impedance, back to the common
coaxial cable connection.
eee Receiver Operation
Figure 19 presents the schematic diagram of the EMU
receiver and Figure 20 tabulates the values of the components.
The EMU receiver obtains its RF and DC from the trans-
mitter section aS previously indicated. With the exception
of the meter and audio amplifier circuits the two receivers
feomrcdentical., In the PMU the meter current was used to control
_a relay circuit. In the EMU there is no corresponding relay
so the meter output is used for tuning purposes only.
The audio amplifier of the EMU supplies both the
handset and the ring tone speaker. Sl is controlled by the
handset hook and 1s ganged with Sl of the EMU transmitter.
When the hook-on condition exists Sl routes the audio to the
Speaker so ring tones may be heard. When the user picks up
35
the handset the switch disconnects the speaker and connects
the handset so a call can be completed.
Vee SU Sean: CONCLUSIONS
The proposed system meets the basic requirements for a
FM, frequency division multiplexed telephone system compatible
with both existing telephone networks and broadcast TV cable
installations. The frequency allocation plan presented indi-
cates that there are a reasonable number of extension channels
available within the suggested system bandwidth. Interference
Between individual telephone channels and between the telephone
Signals and TV signals should be minimal because of the con-
Servative carrier frequency separation used and the wide gap
between the lowest TV channel and the highest telephone carrier.
Before the proposed system could be placed in commercial use
extensive testing would have to be carried out to verify the
flack of interference. This testing would include the simul-
taneous operation of several telephone and broadcast TV channels.
im addition to determining mutual interference, interference
from RF sources outside the system would have to be determined
and minimized.
The performance of the system is tabulated in, Section
Pie Cy SPECIFICATIONS. Manufacturer's data on the CA-3089
come ee fLovmd 1m APPENDIX B, ILLUSTRATIONS. Comparison of
36
these data show that the system has a reasonable signal to
mouse ratio of -45db, but that the IC has a te in excess
Smee 7Odb for strong received signals, indicating that the
system has not realized optimum operation. The harmonic
distortion realized of -40db was found to be highly dependent
on the tuning of the various tuned circuits throughout the
system. If the system were placed in commercial prdduction
using plugin modules containing the tuned components, these
components would have to be tuned for minimum signal distortion
as well as for optimum signal strength.
Reference 27 contains the CCITT (International Telegraph
and Telephone Consultative Committee) standards for crosstalk
in the telephone systems. The proposed systems crosstalk
figure of -60 db is rated "Good't by these standards.
In summary the proposed system has achieved performance
figures that indicate it is a feasible Beeian for accomplishing
the multiplex telephone concept.
37
pe PENDIXA
CHANNEL FREQUENCY ASSIGNMENT
CHANNEL LOWER UPPER CHANNEL LOWER UPPER
CARRIER CARRIER CARRIER CARRIER
il 55 Ba 31 eer, 18.9
2 5.9 6.1 32 yo eal 19.3
3 6.3 6.5 33 19.5 LO?
4 Gn 6.9 34 19.9 20mm
5 Tau 7.3 35 2Or 2 20.5
6 7.5 TAG. 36 2OR7 20.9
7 7.9 8.1 37 Zee Pes)
8 8.3 8.5 38 21.5 PANE Gi
9 Su 8.9 39 2159 22a
ike 9.1 9.3 40 22-3 2255
al 9.5 9.7 Al 22 7 22.9
12 9.9 IS) 42 2s 23.3
13 Lib Ss La wy 43 23.5 23.7
14 11.9 12.1 44 2309 DAC
15 12.3 12a 45 PALS 24.5
16 ey. 12.9 46 24.7 2A ES
7 loa 13.3 AT 25.1 25.3
18 13.5 1327 48 25.5 25-7
19 13.9 4a 49 257.9 26 al
20 14.3 Ags 50 26.3 265
Qa AS 7 14.9 Sh Bod 26.9
22 1S, I 15.3 52 27 i 27.3
23 15) 5S 1S % 53 Pog ns 2a
24 15.9 ieye al 54 27.9 2 Seal
25 16.3 16.5 55 28.3 28.5
26 16.7 16.9 56 2on7 28.9
Oy 7 al 173 57 20r 1 29.3
28 WG Ss oe, 58 2025 ZO,
29 7° eal 59 207.9 BO aa
30 18.3 18.5 60 30.3 30.5
Table I. Channel Frequency Assignment
38
MGI Dy XB
Pel otkY Er LONS
SEND BAND REGEIVE. BAND
€ 400 KHz ,
SINGEE CHANNEL
MAXIMUM DEVIATION
150 KHZ -——_____>
gee ———e———eEE
SEND/RECEIVE BAND
ZO Wd Ze UNG SiGNAL
VOICE FREQUENCY RANGE
O wat pL) 3 4 Hz
AUDIO FREQUENCY BAND
Figure iemureequency Allocation
39
oe ee ae 4
| |
ABC DEF
697 ahlzZ ¢ 3 |
ee
aac aa ies |
| |
GH! JKL MNO |
Wie rz 4 5 6 | |
Low-band oe
frequencies | |
PRS TUV WXY ;
Sys ee 7 8 9 | |
a ee
r-— - aaa
7 | |
941 Hz orn $ | ,
|
ee
s
=
N
Oo
\O
ab
N
1 Son kt 2477 yy hiz 1633 HZ
High-band frequencies
Figure P erusnbeard Dralang Keyboard
40
UNEP ON
BOX
COAXIAL
Cre ie
TRUNK
<a
eles MULTIPLEX Nae
(PMU )
1
WIRE PAIRS
PBX SWITCHBOARD
TO CENTRAL SWITCHBOARD
Figure 3. System Block Diagram
41]
RING RING
DETECTOR TONE 5d OY SAEED)
SEIN RATOR
AUDIO
SIGNAL TRANSMITTER
SW ITCH
HOOK
RECEIVER er SPEAKER
DIAL
TRANSMITTER TONE HANDSET
GENERATOR
Figure 4. PMU and EMU Block Diagrams
42
cae: |
so
wezrbetq OrzeWsYyoS
via Clg
cD
ee)
v2
va
JOLATWSUeAL AWd
AR.
vio
s42. 2
Oly
vu
2Cl Oo LD ea
ila
cam
TO A&B
1X
“OL
ti z>
LO
1G
)
AQL +
Xdd
WOUd
43
R1 680
R2 Si DOL.
R3 390K
R4 1M
RS Oe 2k
RO 1K
cal Ot
c2 yon
C3 2O
C4 .~O0005
Os) Ol
Pale capacitors in microfarads.
¥Value for carrier frequency of 15-25 MHz
ial ie —2.5 Un
*¥Value for carrier frequency of 15-25 MHz
i. T2
pie D2,
D4
D5, D6,
Or, O02, 203, 24
<r Allied AMP 2007
R7 Dek
R8 10K
RO 1K
R10 5K
len Ok
R12 10K
C6 .00008
G7 00033
C8 .02
C9 .00025
C10 5.0
Allied 6T10PC
D3
D7, D8
P2Gure.0.
1N276
TO-92A
IN1694
ZN 72
44
dle)
R14
Kis
R16
Ral?
R18
R19
Cit
Ci2
Crs
C14
C15
1OK
1OK
1K
2K
LOK
100K
100
Ors,
2005
PO2o0)
Bou.
701
PMU Transmitter Component Values
weibetqd OT}eWUaYdS ASATSI9Y NWd ‘“‘Z eanbty
X8d Ol
8Z4u
O£4
IZ> Oz) =
LO
90
Tea
aa:
$zu
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(Zu
AOL+
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Tal
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ta wSle
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44 €1>
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vl> ae
6ly
AOL+
RI ook rlez S056 R23
R2 Syl Ret Si | TOTO) 56 R24
Rae 1OK R14 10K R25
R4 Bok R15 10K R26 8-2
R5 50K pot. R16 eels R27
RO ie R17 20 Ree. 2
R7 ee OK R18 3k R20) «2
R8& 75K R19 47K R30
RQ 110K R20 82K R31 6
relo 100 R21 1K
ele] 1K ie 2 1K
Call 201 G3. 5.0 Crs
CB .O001 C9 "62 C16
3 Boal Clo -- Ci,
C4 ok Cli 202 C18
5 “Ol C12 .O00008* C19
fo, 5.0 CAS ae Ope G20
C7 SOL Clay Ol C2
All capacitor values in microfarads.
mvalwes £TOr Carrier frequency of 15-25 MHz.
eal 27 uh 2 > wh ies pea
¥Value for carrier frequency of 15-25 MHz.
cial Allied 6T10PC
Ql 2N3404 |
@2) 03, 04, 25 2N5172
Rigure 6.. PMU Receiver Component Value
46
39K
39K
1OK pot.
rele
LOK
nok
BK
1K
gel
Rok
20001
-00OCG2Z5-
00025
fol
7O2
-00033
Lel=2 5 Un
S
‘diy? ay] UO
paussofsad as@ aul] P9OP AY AQ PasOjIUI SUONIUN AY YL “WUNINI
pajesbajul saAIdIas Wi 68OEVWD 242 Jo Wweibelp yo0;9 -& ‘bi4
aL 3S
ONY SNINOL
8300330 804
— 31BVSIO O383I1S:
QI0HS3eH Lf Oa se set es ace Toa }-—-—-~
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[ , ° : y300V |
|
39vV S3NNL
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(3) Fn NIV9 a 130 13A31 ~ |
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68087) ayd JO IMNeWwayas jeuonouNY oO} bty
ais = T a ¥ = a f, ;
4901 : 4 P ve
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48
a
.@)
wr
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hb
Oo
FM -75 kHz
AM-30 le
AM REJECTION—dB
O
nN
oO
2 a) 2 5 2 =) 2
10 100 ik lOK i0O0 K
INPUT — MICROVOLTS
Fig. 11 - AM rejection vs 1-f input level to the chip,
~
METER OUTPUT
{CLOSED LOOP AGC)
AGC VOLTAGE
CLOSED LOOP
AGC VOLTAGE
OUTPUT— VOLTS
\
\\
‘“
OPEN LOOP
AGC VOLTAGE
i)
i id 100 IK iOK i0O0 K
INPUT ——-MiCROVOLTS
Fig. 12- Typical AGC (pin 15) and meter output (pin 13) vs
tuner input signal.
49
AUDIO CUTPUT --75 kHz DEVIATION
OUTPUT —dB
| 10 100 1K 10K
INPUT —MICROVOLTS
Fig.13-S+N and N vs input signal to the chip at 10.7MHz.
Generator termination is 50 ohms (Fig. 6).
Jf | SIGNAL + NOISE
— SIGNAL + NOISE
(NO SQUELCH)
<| —SIGNAL + NOISE
20 ne (PARTIAL SQUELCH)
~~ SIGNAL + NOISE
= 30 (FULL SOQUELCH)
t
Pe NOISE
2 40
»
5
50
f=S8MHz
DEVIATION 2 75 kHz
60
70
80
2 5 2 > 2 5 2 5
0.1 | 10 100 1K
INPUT —-MICROVOLTS
Fig. \4-S+N and WN for no squelch, partial squelch, and full
squelch, for signal input to a tuner using the CA3089.
50
200
< 100
=U
|
is
=z
uJ
« 0
&
= pt=i) TO 20V
U 2 9V
ira
<<
TUNING ERROR — kHz
Fig.\5 - AFC output vs tuning error as a function of the supply
voltage.
2 20
| ‘ (o)WITHOUT SQUELCH
e
=>
a
- 10
=
oO
>
fe +)
q
at
uJ
= -i0
-400 -200 0 200 400
TUNING ERROR — kHz
3 10
I (b) WITH SQUELCH
=
= OO 30% MOOUL ATION
= 1000 Hz
Oo
> 10 kH
Ey) CAO FF 0 400
a 70 See a) te 008
[aa
Fig.16 - Typical tuning characteristic (a) without squelch end
(b} with squelch, showing the suppression of the annoying side
responses characteristic of limiter-discriminator receivers.
ope
wersertq
at
LISONVH O1
pie)
ce
Y3A13534 OL
20
ei
8¥JAI393uY Ol
44y
IG+ 438
244
OFA eMouos Boyt twsuels Cia. ZL elnoL sy
L3ISQNVH
|_+
wWOd3
O1lanv
id
52
Rl
2
R3
Cl
2
eS
WAL
RFC
| Sjal
Ql,
is) R4 2H2K R7 390K
10K i 1K R8& 1M
1K R6 Omak
50 C4 00008 * C7 .047
SOOO2> C5 ~O0005 C8 Tod
nOOO2SS C6 Ol
PiemeGapacitOrSin microfarads
mvearue LOL Carrier frequency of 15-25 MHz
ie 2.5 uh*
*Value for carrier frequency of 15-25 MHz
2.5 mh
TO-92A
Q2 ZN S17 2
Figure 18. EMU Transmitter Component Values
53
oc
6
Leu
TAR Pomc
AOL+
= su
a
1u
—j
yl>
614
AOL+¢
91)
t
WeEIHSTG OTPEWSYOS ASATSOS9Y AWA ‘°6L eanbrty
L3SGNVH
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ks L£ és
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LD
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O£-V5
17
AOL+
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54
Fea
re
KS
R4
R5
R6
i /
R&
RO
R10
R11
Onl
C2
eo
C4
cS
C6
7
Jel
ib3e
Ql
O2,703, Q4, 05
BPG Ene
5a
LOK
Bok
DOK. DO .
IAS
ch 5) 8
Dok
LOK
100
Jee
oO.
.OO00 1
.OL
sO
201
5) 49
2Or
All capacitor values in microfarads.
Ree
Ras
R14
Ris
R16
alk?
Res
R19
R20
R21
R2Z
C8&
C9
cro
Cuil
CUZ
O20 8S.
C14
51K
100K
10K
10K
1K
20
13K
47K
82K
1K
1K
ore,
202
Syo)
Oe
. 00008*
noe
OME
R23
R24
R25
R27
R20 22
n/a 8 ae 2
R30
R31 6.
G15
Cro
Cr?
C18
C19
C20
eZ
*Values for carrier frequency of 15-25 MHz.
27h
lez
Sh
L3, 14
*¥Value for carrier frequency of 15-25 MHz.
Stamecr
Figure 20.
Tie
2N3404
2Nol72
eae,
EMU Receiver Component Values
TOK. pot.
R26 “<2 .
Ort
0001
.000025*
~O0025
Boal
-O2
200033
Lede. ole
nO.
Bia LOGRAPHY
Yanekian, Adriene (ed.), The Telephone Pioneers of
America, Telephone Pioneers of America, 1961.
Martin, W. H., "The Seventy-Fifth Anniversary of the
ite ohone," bell System Technical Journal, v. 30,
paeeclS—-238. Apriid 1951.
Pecesmi. E., “Practical Application of Carrier Telephone
and Telegraph in the Bell System," Bell System
ieecwprecalesournal, v. 2, p: 41-52, April 1923.
@Golpttrs, 22H. and Blackwell, O. B., ‘Carrier Current
Telephony and Telegraphy," Transactions of the
Pe oemlcanelnott tute lot Electrical Engineers, v. 15,
p. 205-380, February 1921.
Charlesworth, H. P., "General Engineering Problems of
Veeone D>. S15=541, October 1925.
Demarest, €. S. and Green, C. W., "Carrier Systems on
Long Distance Telephone Lines,'' Bell System
lechitecaieyourmnal, Va 7, Dp. 564-629, July 1928.
Cmierardi., B. and Jewett, F. B., "Ihe Telephone
Commintcations System of the United States,"
Peig@moyvsten echnical Joummali 9 v. 9, p: 1-100,
ee Se ee ee
Jamueny 1930 ;
Glance and Kendall, B. We, "Carrier in Cable,"
Bomoseen | cchnutcalyJOurnaly v7 12, p. 2al=263,
July 1933.
Meopencenied, lL. and Striebly, M. Ev, “Systems. for
Wide-Band Transmission Over Coaxial Cables,"
Powe lechntoaloournale Vy. 13.) p. 654-679,
October 1934.
Green, C. W. and Green, E. I., "A Carrier Telephone
System For Toll Cables," Bell System Technical
ees ee ee
Jeommmaiey Vint’, p. GO-105, January 1938:
56
ti.
2
a3.
14,
ne
16.
NYE
nS.
a .
20,
2...
Stmmepiy., M. B., “Coaxial Cable System for Television
Transmission,'t* Bell System Technical Journal,
Vea (ee peat oo -+5/, July 1938.
perel, H. A. and Kendall, B. W., “A Twelve-Channel
Carrier Telephone System for Open-Wire Lines,"
Belemeoystem lechnical Journal, v. 18, p. 119-142,
January 1939.
Meamenmk, &., Dixon, J. T., and Huber, G. H., ''Frequency
Division Techniques for a Coaxial Cable Network,"
Peancactvomus Of the American Institute of Electrical
a a
Engineers, v. 66, p. 1451-1459, 1947.
Caruthers, R. S., ''The Type N-1 Carrier Telephone
System: Objectives and Transmission Features,"
Bell eovcucm Lechnrcal Journal, v. 30, p. 1-32,
gr re pr rm sm a mm ee
Manuary L951.
Wemeoox. Wa, Roetken, A. A., and Smith, K. D.,
"The TD-2 Microwave Relay System,'! Bell System
ieemieeeal Journal vs 30, p. 104) -1077, October 1951.
Eawards, P. G., and Montfort, L. R., “The Type O
Gatimcimsoystem,' Bell Technical Journal, -v. 31,
DrmOce-/25.,- July 1952.
evmencorf, C. H., and others, "The L-3 Coaxial System:
amma ce
Woe (Ob OSoe. wy LOSS.
BOvG wk. €.. Howard, J. D., and Pedersen, L., "A New
CGarmver for Rural Service, Bell System Technical
SiemnWeds, we SOC pis 540-500. Match 1957.
Cravis, Hep onOnenoa ter im Vere ncaa meerinGg.of Tl Carrier
syotem Repeatered Lanes, Bell System Technical
iotianerl Vente pe 45-4865 Maren 1963.
Hallenbeck, F. J. and Mahoney, J. J., "The New L
Multiplex: System Description and Design
Osjeetm ves. bell System technical Journal, v. 42;
Pee (= 222) Marci 1063.
Efercemn Gs. Wo and Irby, C. W., “ihe N3 Carrier System:
Objectives and Transmission Features,'' Bell System
Reewurca le Jourmal , V.845, p. 707-800, July-August
OOO".
57
ee.
BS.
24.
2D.
Zo"
age
womoeniwe kM. and Prime, KR. C., “TH-3 Microwave System:
System Considerations,'' Bell System Technical Journal,
Vow eee oc -2int,. Sseprember 1971.
Petmscenia G- W:, and others, ''The L-4 Coaxial System,"
Beiaiwoyvsecem Technical Journal, v. 47, p. 821-840,
a
April 1969.
PwiemmGreM., and others, “Stringing the Wired City: Two-
Wave.’ Wecends Prom the Blue Sky to the Keal World,"
Eveeryomtice, Yeas, p. 43-55, 27 September 1971.
Peace ee vances in FM Receiver Design," IEEE
fino noceuelomolmewoadcast and Television Receivers,
Wei De lod-l7il- August 1971.
The Radio Amateur's Handbook, 49th ed., p. 93, American
Radio Relay League, 1972.
Reference Data For Radio Engineers, 5th ed., p. 30-20,
International Telephone and Telegraph Company, 1972.
58
vie DiS TRIBUTION List
Defense Documentation Center
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mewoxandria, Virginia 22314
mieorary, Code 0212
Naval Postgraduate School
Monterey, California 93940
meecmerrOoL. &. D. Ewing, Code 52Ew
Beparement of Electrical Engineering
Naval Postgraduate School
Monterey, California 93940
BepR Charles M. Heath, Jr.
B02 Scott Street
Scottsboro, Alabama 35768
Chairman, Electrical Engineering Department
Code 52
Naval Postgraduate School
Monterey, California 93940
Se@astcom, Incorporated
2346 Stanwell Drive
Semcord, California 94520
ye,
No. Copies
Secunty Classification
- - = J 4
. "DOCUMENT CONTROL DATA-R&D |
(Security classification of title, body of abstract and indexing annotation nust be entered when the overall report Is classifled)
SINATING ACTIVITY (Corporate author) 2a. REPORT SECURITY CLASSIFICATION
Unelassaigred
Naval Postgraduate School
Monterey, California 93940
MORT TITLE
A Cable Carrier FM Telephone System
BCRIPTIVE NOTES (Type of report and inclusive dates)
Master's Thesis; June 1973
HOR(S) (First nama, middle initial, last nama)
Charles Maples Heath, Jr.
‘Borer DATE 7a. TOTAL NO. OF PAGES 7b. NO. OF REFS
mime 1973 60 Les
BBN TRACT OR GRANT NO. 9a. ORIGINATOR'S REPORT NUMBER(S)
9b. OTHER REPORT NO(S) (Any other numbere that may be eealgned
thle raport)
STRIBUTION STATEMENT
Approved for public release; distribution unlimited
PPLEMENTARY NOTES 12. SPONSORING MILITARY ACTIVITY
Naval Postgraduate School
Monterey, California 93940
A multichannel frequency division multiplexed FM telephone
system 1S presented. The system is intended for use in
organizations where large numbers of telephones are normally
installed and is compatible with conventional switchboards.
Advantages provided by the system are: reductions in installed
Wiring, the ability to relocate telephone sets by the
subscriber, and compatibility with other coaxial cable systems.
FOR 4473 ~~ (PAGE 1)
0101-807-6811 60 Security Claasification a-31408
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cable carrier FM telephone syste
DUDLEY KNOX LIBRARY