a follow-on to the "Planning
Integrated Signal Communications
" story, this article is the next
step in the U.S. Army Signal Corps' implementation of ubiquitous communications
systems. Along with powerful transmitters and super-sensitive receivers
at command communications hubs are the many hand-held, back-pack, and
vehicular radios needed to complete strategic and tactical operations
across the face of the Earth. It wasn't just wireless systems that Signal
Corps engineers and technicians were responsible for, but also all the
wired equipment and interconnecting cabling. The possibility of software
configuration for network switches, radios, modems, telephones, antennas,
and ancillary components had never been thought of in 1950 (by very
few, anyway). Everything was set up with patch panels, jumpers, and
hard-wired connections. That's not to say modern communications are
any easier to implement - just much different.Thanks to Terry W. for providing
Engineering the Integrated Communications System
By Colonel Edwin R. Petzing
Chief, Engineering & Technical Div.
Office of the Chief Signal Officer
Born in Illinois in 1896. Attended University of Illinois 1914-17.
Entered Officers' training in 1917. Went overseas in 1918 and
from 1919 to the out-break of second World War attended various
Army training schools and held diversified commands. Served
as Signal Officer for 9th Army Corps in Panama at beginning
of World War II and subsequently saw service in the Caribbean
Defense Command and in the China-Burma-India theater. He served
as signal officer for the 6th Army in 1946-47. He became Chief
of the Engineering and Technical Division in the Office of Chief
Signal Officer in September 1947, a post he still holds.
Top-flight engineers, military and civilian, work as a team to produce
the world's finest communications equipment for our Armed Forces.
The integrated communications system planning discussed in "Planning
Integrated Signal Communications
" of this issue resulted, shortly
after World War II, in concrete requirements for the individual items
of equipment necessary to form the global, theater, and combat communications
To bring the integrated concept into being, the Signal
Corps established at its Signal Corps Engineering Laboratories in Fort
Monmouth, New Jersey, a major program of research and development designed
to furnish the fighting forces with the best and most efficient military
communications equipment in the world, integrated into a system providing
the maximum speed and flexibility needed for future warfare. System-wise,
the development plans have taken into consideration the increasing complexity
of warfare; the increasing need for inter-arm and inter-service communications;
and the wider bands needed for larger numbers of communications channels
or for newer forms of communications.
Equipment-wise, the plans
have emphasized the requirement that all communications equipment for
our modern army be light, rugged, and operable in hot, cold, dry, or
rainy weather. Logistics-wise, due consideration has been given to engineering
for mass production, maximum use of common components and subassemblies,
and application of the "building block" principle.
accomplishment of a plan as ambitious as that outlined above would require
many times the facilities and manpower available to the Signal Corps
in its own laboratories. But, by means of contracts with industry and
educational institutions, the best communications brains and the best
facilities in the country have been obtained to aid the Signal Corps
in translating the many equipment requirements into the tangible hardware
needed to form the system.
Military development in peacetime
must, of necessity, be geared to limited budgets and limited manpower
and, consequently, is spread out over a considerable time period. However,
emphasis on communications developments has resulted in many equipments
of the integrated system being completed and placed in production. Most
of the remainder are advanced to a point where production will be started
this fiscal year.
Army Communications Center in Pentagon, shows patch board and
coordinating and receiving consoles. Teletype loop jacks are
provided at patch board to connect spare receiving equipment
to incoming circuits in case of trouble. Board is also used
with associated printer equipment (left) in order to communicate
directly with distant station to correct discrepancies in messages.
Console in foreground is used as a coordinating point between
traffic terminating section and radio control section (not shown).
Console's operator decides whether a circuit is operable or
requires action by some other section to correct troubles. Receiving
consoles in background are where messages are received in tape
form and, if necessary, are transferred to relaying equipment
for further transmission.
The chart shown in
Planning Integrated Signal Communications
illustrates the general
concept of the integrated communications system and depicts the general
use of the various types of equipment in the system. The following discussion
of the individual equipments will cover the main developments in radio
and wire illustrated on the chart.
One of the main communications
requirements of lower echelon combat commanders has long been a series
of hand-held, back-pack, and vehicular radios designed to give efficient
command communications and at the same time provide channels for use
between Infantry, Armor, and Artillery. World War II equipment was not
adequate for the job; handie-talkie set were amplitude modulated; walkie-talkies
were FM, and vehicular sets using FM were provided only for Armor and
The postwar sets, on which development has now been
completed and production started, provide many advantages. For example,
the handle-talkie, a 1- to 3-mile set is now FM and can communicate
with other appropriate sets in the group. While it is about the same
size as its AM predecessor, it represents significant progress in miniaturization
in that a 14-tube FM circuit has been packaged in the same space formerly
required for a 5-tube AM set. The walkie-talkie, a 3- to 5-mile set,
has been designed in three frequency bands to match the bands of the
vehicular sets of the Armor, Artillery, and Infantry with overlaps to
allow communication between them. While power output has been slightly
increased, size and weight have been reduced by one-half. Particularly
important to the man in the front line is the 50 percent reduction in
thickness which makes the set much less conspicuous when carried on
the back. The vehicular sets, composed of three basic assemblies to
cover separate frequency bands with overlaps, provide 10- to 20-mile
FM voice communications for the Infantry, Armor, and Artillery. In addition
to the basic transceiver, a separate short range transceiver is provided
which will communicate with the handie-talkie, one of the walkie-talkies,
one of the basic transceivers and all of the other short range transceivers
in this vehicular group. To obtain added range and flexibility, provisions
are included for retransmission from the basic transceiver to the short
range transceiver and vice versa. In addition, where 20- to 40- mile
FM voice ranges are needed. a back-to-back type relay set is provided.
It is interesting to note that the use of crystal saver sets in the
vehicular series has resulted in a requirement of 11 to 21 crystals
per set versus a comparable requirement of 80 to 120 in the World War
Main control board in the transmitter room of the Army Communications
Center. In the foreground at left are shown the 72" racks which
are equipped with Press Wireless radio teletype shifters. These
units are used as exciters to each transmitter and the output
is fed through a coaxial antenna system to the oscillator of
the transmitter. Center foreground is the main control panel
which is the nerve center between the transmitting station and
message center. The 15 kw. transmitter used for transmissions
on overseas circuits is in right front.
Experience with the limited number
of equipments available toward the end of the past war indicated that
radio relay was a most promising means of communications as a substitute
for and augmentation of wire systems, and that it was ideal for radio-wire
integration. In general, World War II equipment was not used below division
headquarters level and when used in rear areas did not provide an adequate
number of channels per set. Consequently, the development program has
been directed toward providing three types of relay systems: forward
area, intermediate area, and rear area.
With three relays, ranges
up to 50 miles are possible on the forward area relay system. The transmission
accommodates a relatively broadband signal and, with carrier equipment
discussed later in this article, will give four voice channels, each
of which can, in turn, provide up to eight teleprinter channels. Since
use down to regimental level is contemplated, the terminal station,
complete with associated carrier equipment, has been designed to fit
into a vehicle of the three-quarter-ton weapons carrier type.
Intermediate area radio relay equipment will be under procurement
before the end of the fiscal year in the form of a system with adequate
bandwidth for 12 voice channels or the equivalent in facsimile, data
transmission, or teleprinter channels. The same 12-channel carrier terminals
being developed for wire systems will be utilized. Primary employment
is contemplated for main-line communications from Army to Corps, and
from Corps to Division.
To meet rear area requirements, development
has been pointed toward 48- to 96-channel relay systems with ultimate
ranges up to 1500 miles. Due cognizance has been given to engineering
features necessary to assure the capability of satisfactory transmission
of television and wide-band facsimile. While the equipment has reached
the engineering model stage and tests have been satisfactory, it will
probably not be ready for production this year. To provide a usable
system in a shorter time, a modified version utilizing time division
multiplex to obtain 24 channels is being placed in production in the
next few months. Primary use will be for communications from Theater
to Army Group to Army, and for providing main line circuits within the
communications zone. Amplitude Modulated Radio
The addition of FM and radio relay principles to the military
radio system has not by any means reduced the necessity for conventional
AM systems in certain applications. It is obvious, for example, that
FM with its short range in the frequencies used - and radio relay systems
with their dependence on relays for range - would be of little use to
an airborne division landed 100 miles behind the enemy lines. Mobile
communications over intermediate ranges also obviously point toward
AM sets. Global networks covering distances up to 12,000 miles must,
of necessity, continue to utilize frequencies suitable for long ranges
and methods of modulation giving maximum frequency conservation.
The main development being pursued currently in the low power AM
field is a 100-watt set for use by lower echelons within divisions and
by airborne troops. Ruggedness, reliability, small size, and simplicity
are the keynotes that have governed the development. Quantity production
is expected to start within the near future.
Since the transmitter and receiver sites are widely separated.
a centralized control point is used, all radio circuits are
coordinated and associated and the transmitted and received
signals carried through the radio control switchboard to the
terminating equipment used in sending and receiving the message
traffic. The radio control operators carry out their coordinating
work with distant stations both overseas and domestic by voice
or teletype printers.
In planning development to satisfy requirements for sets working over
ranges calling for wattages from 500 to 50,000 the Signal Corps has
proceeded on the "building block" principle utilizing the 500-watt transmitter
as the basic component. Addition of a 5 kw. power amplifier provides
a set suitable for military communications in the 1000- to 2000-mile
range, while the addition of a 50 kw. amplifier and necessary auxiliary
equipment leads to a high-powered system for use on a global basis.
Provisions are made for teleprinter, facsimile, voice, and c.w. transmission.
Accessory equipment is provided for single sideband adaptation. In addition,
parallel development is proceeding on a simplified single sideband transmitter.
Within a few months production on 500 and 5000-watt sets will be under
way. Receivers for the above equipment will be taken from a general
receiver family being developed to fit communications, intercept, and
direction finder roles. Integration
While the above equipments have been discussed as individual items,
it must be emphasized that they are developed within the concept of
an integrated system and that devices for radio-wire integration are
either integral to the equipment or furnished as auxiliary items.
Wire systems are
still considered in general to be the backbone of most Army communications
despite the improvements being made in the radio field. Consequently,
postwar effort on development of wire equipment has paralleled the effort
on radio systems and is producing comparable results as will be indicated.
Wire and Cable
One of the really significant
advancements now paying off in Korea and elsewhere is the new Signal
Corps field wire which has been developed to replace both the well-known
W-110-B field wire and the W-130 type assault wire of the past war.
No rubber is contained in the new wire and substantial reductions have
been made in other strategic materials. While W-110-B wire weighed around
140 pounds per mile, the new wire weighs only 48 and has an increased
talking range, better abrasion and moisture resistance, and longer life.
To facilitate wire laying, a new canvas wire dispenser has been perfected
which allows high- or low-speed wire payout from the inside of the package
without the use of reels or axles. Besides the obvious advantages, particularly
to the forward area wire layers, a considerable saving in metal reels
is realized. Also" nearly developed is a lighter and tougher spiral
four field cable for use with 4- and 12-channel carrier systems. The
basic cable for both systems is identical physically and electrically,
with loading for 4-channel operation being accomplished by insertion
of a small weatherproof loading coil between cable connectors.
Radio control panels where all signals can be checked, switched,
and measured. The panel on the left is for radio frequency patching,
sometimes called switching. The next two panels are "audio"
patching panels and the emergency two-way PM communications
position to the Communications Center. The trick chief's duties
are monitoring and keeping all circuits and two-way communications
normal before reception at the center.
The system of switchboards contemplated
for the integrated system provides capacities required from battalion
to theater level and utilizes, when possible, the "building block" system.
Just going into production is a 12-line mono cord board of the magneto
type weighing about 22 pounds versus the 72 pounds of its predecessor
and utilizing retractable cords. Capable of stacking up to three units,
this board will be suitable for use up to regimental level. Also soon
to be available for use at regimental and divisional level is a 30-line
magneto board of the more conventional type capable of 60- to 90-line
expansion and using many of the basic components of the smaller board.
For use where larger capacities are necessary, a common battery board,
based on a 70-line position and capable of expansion up to 2000 lines,
is being developed. For ease and speed of installation, this board is
equipped with plug-in type cables for interconnection between positions,
and between main frame and switchboard. As with all Army equipment,
the ability to stand the bumps and adverse weather conditions inherent
in military operations has been built into the equipment.
The Signal Corps' main contribution
to the teleprinter field is the development of a simplified page printer
weighing only 45 pounds, usable at speeds from 60 to 100 words-per-minute,
and designed specifically for ruggedness and dependability and ease
of maintenance. Due primarily to its 225 pound weight, and multitudinous
parts the teleprinter previously standard for the Army was not suitable
for use in lower units, whereas the new unit with only one-fifth the
weight and 300 fewer parts will allow teleprinter service to be employed
down to the regimental level. A 17-pound tape printer now in development
will further extend the use of this most desirable means of communications
to battalion level. Recently completed voice frequency line units for
use with these two equipments will allow the utilization of radio voice
channels on tactical radios for teleprinter service. Of comparable importance,
the voice frequency principle will make possible the use of teleprinters
over local subscriber telephone circuits and through standard telephone
switchboards. Carrier Equipment
telephone and telegraph carrier equipment is designed for fixed station
operations under controlled conditions where size, weight, and ruggedness
are not determining factors. The Army requirements for carrier equipment
include lightweight, small equipment built to take rough usage, and
operate with little attention under adverse weather conditions and over
communications lines subject to considerable electrical variations.
To fill this need three carrier systems are currently under development,
a 4- channel telephone carrier, a 12-channel telephone carrier, and
a 48-channel system. A new 8-channel telegraph terminal can be used
as needed in conjunction with any of the above terminals. The terminal
equipment of each of the above systems will be used not only in the
4-, 12-, and 48-channel wire sets but also with the 4-, 12- and 48-channel
radio relay equipment. Commercial standards for transmission levels
and quality are being closely followed in development of such equipment
so that long distance communications over the integrated communications
network will approximate, insofar as practical, that found in American
commercial systems. Conclusion
brief article dealing primarily with the results of development in the
communication field has the danger of leaving the reader with the impression
that a completely short-range program is being pursued. Such is certainly
not the case. The Signal Corps maintains at its own laboratories, and
sponsors in the laboratories of universities and industry, a long-range
program of research and development having as its objective the constant
search for new basic knowledge, principles, techniques, and materials;
and their application to the Integrated Communications System. By continuing
a vigorous, long-range effort, the Signal Corps expects always to provide
the best military communications in the world.