Chapter 8: Signal Equipment: Wire and Radio (June–October 1942)
The Signal Corps’ responsibility to develop electronic equipment for the Army, to keep American fighting men supplied with the best that science and mass production could devise, was now being met with notable success. Before the end of 1942 Signal Corps research and development efforts had sketched out or completed the chief types of communication equipment with which the Army would fight to the war’s conclusion: automatic communication office equipment and radioteletype, spiral-four field cable and carrier, FM radio, radio relay, and microwave radar. The threads of all these developments extended back into the past, in laboratory cogitations and experiment; but the year 1942 saw them beginning to form a definite pattern, one that became a part of the fabric of World War II victories.
Automatic wire and radioteletypewriters, combined with carrier operation, would convey communication loads with unheard-of ease and rapidity, transforming civilian no less than military communications and bringing all the world closer to that ideal state of society wherein all men everywhere may be able to communicate readily and rapidly with one another.
FM had by this time become accepted for tank and car radios and was pointing the way to radio relay. The fortunate coincidence that the Armored Force and mobile FM had both made their initial appearance in 1940 (Armor, equipping itself from the ground up, was not committed to the older AM sets) had made possible the wholesale acceptance of the totally new and better type of radio. No other army in the world had been able to make so fresh a start,1 and the American Armored Force began in 1942 to profit from communications of unprecedented reliability and simplicity.
Microwave radar became as indispensable as the explosives it aimed against the enemy—not only airborne radar directing the deadly design of hurtling fighters and bombers, but also ground gun directors, accompanying every large antiaircraft and coastal battery.
Toward Automatic Teletype and Tape Relay
Each signal center of the Army Command and Administrative Network (ACAN) was transmitting and receiving ever greater traffic loads over its wire and radio facilities. The press of work weighed increasingly
upon the operators who sat at teletypewriters or at Boehme high-speed equipment or who simply, in the older manner of continuous wave operation, transmitted in Morse code by a hand key; or who received, with headphones clapped to ears and with fingers converting the dah dits upon a typewriter. The pressure became intolerable—not enough trained operators; not enough space to accommodate them, had their numbers sufficed; not enough time to waste in such hand methods. Obviously automatic devices had to be provided.
Even a commercial-type teletypewriter demanded too much. The teletypewriter was keyboard operated, hand punched, that is, an operator typed the message on the sending teletypewriter. True, at the receiving end, a similar machine automatically typed out the transmission. But if the message was to be sent on to a third station, an operator in the intermediate, or relaying, signal center had to take the automatically received message and type out a copy on another teletypewriter, which would then send the words on to their ultimate destination. In such a case, it would be better if the first receiving machine punched a tape that could then be fed into the relaying machine for automatic retransmission. The American Telephone and Telegraph Company had such machines in its 102-A system, which relayed messages by means of a perforated tape, carrying along its edge the printed text. It was a simple matter for the operator at the relay station to identify each message by means of a code symbol inserted at the beginning of the message, tear the tape at the proper point, and relay it by inserting the tape into an automatic transmitter connected to the appropriate trunk channel. In mid-July 1942 the Signal Corps installed this system, giving it the designation Q-102, on the circuit between the War Department Signal Center in Washington and Governors Island, New York. This circuit became the first link in what grew into the worldwide ACAN automatic network (automatic being stressed here, not the Q-102 equipment, which would yield to better devices) .2
Q-102 was automatic wire teletype. There had been, and there continued to be increasingly, an urgent need for teletype that could operate, not merely on signals flashed through wires, but on radio waves radiated through space. In April 1942 the Air Forces had asked the Signal Corps to provide a radioteletype circuit for weather services, linking three fields in the Caribbean area: Borinquen, Waller, and Albrook. Mounting air travel along the South Atlantic air route, Arnold wrote to Olmstead, required faster and more numerous weather reports than existing Army Airways Communications System equipment could provide.3
At this date AACS weather reports had to be manually enciphered, transmitted, and deciphered, all of which took so much time, often in the hands of rather unskilled operators, that the reports might be received hours later, too late to be valuable. The Signal Corps therefore set about developing radioteletype, RTTY, specifically to
Radiotype equipment. A representative of IBM demonstrates the equipment in the Office of the Chief Signal Officer in the Munitions Building in Washington, D.C., May 1942
assist the AACS.4 RTTY operation was speeded by the assistance of automatic cipher machines to encode and decode simultaneously, on the line, at both the sending and receiving teletypewriters. This combination made possible the secure transmission of a weather message at the speed of the sending teletypewriter. The sender typed the English text of the message on a teletypewriter, which, while producing a page copy also perforated a tape. The tape was fed into an automatic enciphering machine that conveyed the cryptic product to the transmitter to be broadcast. Inversely, at the receiving end, the faint skyborne signals would be picked up, amplified, and passed on to a perforator which would punch a tape in cipher. The enciphered tape, now passing through a second cipher machine, set to the same key as the enciphering machine, would yield a plain text tape, perforated in the five-unit teletypewriter code. The plain text tape would, in the last step of the process, actuate the receiving teletypewriter so that it would type up the message on a sheet, in all respects the exact counterpart of the original text. All this was done with the speed of light, with only one person working, the one sitting at the originating
keyboard.5 This is the way RTTY would eventually work, but in mid-1942 it did not yet exist.
There was, however, another device at hand—radiotype. The Air Forces’ need for speeding weather messages was obvious, made vividly so by the BOLERO mishaps in June along the North Atlantic air route to England.6 But there were obvious problems, too, presented by the wayward behavior of radio signals, which, undisciplined by the straight narrow path of wire, stray into the wide open spaces of sky and mingle promiscuously with static, interference, and fading. The International Business Machines Corporation had worked out an imperfect solution involving equipment that the firm called radiotype, using, unfortunately, not the standard five-unit teletypewriter code but a special six-unit code. Like a narrow-gauge railroad adjoining a standard line, this special code necessitated much hand labor at conversion points where standard teletypewriter texts had to be shifted onto radiotype circuits, and vice versa. Moreover, the standard automatic cipher machines could not function with the six-unit system.
Notwithstanding these inconveniences, the Signal Corps early in the war began making use of radiotype, leased from IBM. It was another step in the right direction, toward automatic, high-speed, heavy-duty communications for the Army. Like Q-102, RADIOTYPE equipment produced a punched tape which could be relayed automatically. The only hand work needed was the typing at the originating machine. Radiotype, speed 100 words a minute, would replace Boehme equipment, which was very fast, up to 400 words a minute, but which was not entirely automatic.7 So General Olmstead informed ACAN stations WTJ (Hawaii), WVN (Puerto Rico), and WVL (Panama) on 20 June, adding: “For your information this equipment performs the same function on radio transmission as a teletype machine performs on wire transmission.”8
In military radio, hand-keyed Morse dah dits had been the first step; Boehme the second. The second step was now yielding to the third advance in the art, radiotype. By September Signal Corps’ Washington station was using automatic equipment, both wire teletype Q-102 and radiotype, all leased, in communicating with eight ACAN stations at home:9
IBM Radiotype
WVR Fort McPherson, Atlanta
WVQ Wright Field
WVT Chicago
WVU Fort Omaha
WVB Fort Sam Houston
WVY Presidio of San Francisco
Q-102 Teletype
WVO Boston
WVP Governors Island
Radiotype continued to expand in military use during the last half of 1942 and early 1943 before radioteletype, using the five-unit teletypewriter code, began to replace it. Late in 1942 a radiotype circuit went into service between WAR and Honolulu, the installation at WTJ, Fort Shafter, accomplished by six enlisted men from WAR and an IBM engineer, who arrived in Hawaii early in October. On 18 December another radiotype circuit would go into regular operation between WAR and WVL, Quarry Heights, Panama.10
Radiotype was good. It was faster than hand-keyed radiotelegraph, faster even than Boehme when one considers the time taken to hand punch Boehme tape for transmission, plus the time taken to translate the received tape back into English. Even so, radiotype was not good enough, especially since it suffered, as already noted, from the disadvantage of employing a six-unit code, which did not conform with the universal five-unit teletypewriter system.
With the intensifying of the Army’s communication needs during 1942, fresh determination arose to find ways to put the conventional wire line teletypewriter, five-unit code and all, on the air, as radioteletype, RTTY. And it was done, too, with the efforts of American Telephone and Telegraph and Press Wireless. It was done in large part by capturing the elusive far-darting radio waves by means of two diversity devices: frequency diversity and antenna or space diversity. The former means simply that two frequencies were employed to transmit and receive mark-and-space signals; the latter means that the receiving station used two receiving antennas and two receivers in somewhat separate locations, several wavelengths apart. The purpose of diversity, whether of frequencies or of antenna positions, is to overcome the maddening tendency of high-frequency sky wave radio signals to fade. For fading is fatal to radioteletype, fatal to the synchronized operation of the machines. The receiving teletypewriter must have a strong, steady signal impulse at all times to keep its motions in step with those of the sending machine; otherwise, the printing of the former will go awry. Radio engineers had learned that when fading occurs on one frequency, another adjacent frequency will come in strong. Similarly, when the signal fades at the location of one receiving antenna, it will remain strong at another located some distance away. Hence the solution to
fading at high frequencies was to use either principle, or better, both of them.
Frequency diversity immediately presented a further great advantage. More than two frequencies, or two tones, can be imposed upon the air, using a single set of equipment. Four or six frequencies can be imposed and a separate communication channel assigned to each pair of them. An operator can then make radioteletype convey several signals simultaneously. Thus, multi-channel radiotelegraph emerged, exactly the counterpart in radio of carrier telegraphy in wire. Something along these lines was already being done in mid-1942 when the Signal Corps established a multichannel link with London, using American Telephone and Telegraph equipment which enabled three two-tone telegraph signals to flash over the Atlantic on one sideband of a powerful 40-kilowatt radio transmission. Brig. Gen. Frank E. Stoner had opened negotiations early in the year with American Telephone and Telegraph for multichannel telegraph circuits overseas “in anticipation of heavy radiotelegraph circuit requirements between Washington and the British Isles, the European Continent and North Africa and between San Francisco and Australia. …”11 By June he reported that the Radio Section of Signal Corps’ Plant Division was purchasing four such sets of heavy duty radios. According to his report for the week ending 22 July, “a multi-channel radiotelegraph system was placed in operation between WAR (Washington) and London using leased radio facilities of the American Telephone and Telegraph Company and the British Post Office authorities.”12
Thus the diversity principles would not only make possible single channel radioteletype, RTTY, but they would also enable radio operators to provide many channels over one set of equipment, accomplishing for military radio what spiral-four and carrier systems were doing for military wire.
Multichannel radiotelegraph for huge, fixed ACAN stations was one thing. To develop small single-channel radioteletype equipment for the Air Forces and for field troops was something else. The demand for it was now increasing. A relatively simple, efficient, and rugged RTTY was a device that Ground Forces officers, no less than airway weather stations, were increasingly seeking. On 6 June 1942 Col. Donald B. Sanger, Coast Artillery Corps, president of the Desert Warfare Board, asked for two radio teletypewriters for the First Armored Signal Battalion to test. Col. Edward F. French, chief of the Traffic Division in the Washington headquarters, replied, discouragingly, that the only such machine available was the IBM radiotype, production of which was not even meeting his Signal Center needs. Furthermore, Colonel French thought it “extremely doubtful if any such machine would prove satisfactory”
for use in the field since it demanded “extremely good signals and operating conditions.” Field officers would not be discouraged, however. On the contrary, they went so far as to aspire to mobile RTTY, planning to combine it with such powerful field radio sets as the SCR-299. Thus Col. Elton F. Hammond, at the headquarters of the Desert Training Center, Indio, California, telephoned to Colonel O’Connell, head of the General Development Branch in Washington, on 14 July: “I also would like to ask for radio teletypewriters. Would like at least six with the idea of installing them in the radio trucks, [SCR-] 299’s. I believe it would be of very practical use.”13
Whereas Colonel French did not favor the field demands, Maj. Vernon B. Bagnall, head of the Fixed Radio Branch in Army Communication Service, did. He asked the American Telephone and Telegraph Company and the Bell Laboratories to figure out a way to make radioteletype work, using the five-unit code. The problem was to devise suitable military equipment, single channel. On 28 August, Austin Bailey, an American Telephone and Telegraph official, sent to Bagnall his corporation’s proposal to meet the Signal Corps requirements for a radioteletype system. It would operate on diversity principles, using two tones, and would permit the use of cipher machines working with standard teletypewriters.14
Radioteletype for the military took shape during a series of conferences among representatives from the Signal Corps, American Telephone and Telegraph, and Press Wireless during the late summer and autumn of 1942. They decided to use single sideband communication on a frequency shift (two-tone) basis, making it possible to transmit teletype signals by means of ordinary continuous wave radio equipment, rather than by means of the more elaborate transmitters of radiotelephone quality. They conducted tests on an experimental single-channel radioteletype circuit between WAR and the Press Wireless receiving station at Baldwin, Long Island. The Signal Corps men in WAR transmitted through a 500-watt the transmitting station of the Army Communication Service at Fort Myer, Virginia. They assembled the receiving equipment from commercial and special components supplied by Press Wireless and the Bell Laboratories. Two Hammarlund Super Pro receivers were used, together with the modified CF-2A telegraph terminal equipment of the type originally designed for operating tactical typewriters on spiral-four cable. This conglomeration worked so well that the Signal Corps decided to initiate procurement. The Air Forces wanted 12 sets at once, especially for their Caribbean stations of the Army Airways Communications System. This would be only a starter, since hundreds of single-channel military RTTY would follow, for use by the AACS and by other military arms also.15
Carrier Equipment and Spiral-Four Readied for Use in War
While the Signal Corps developed efficient, increasingly automatic terminal equipment to handle Army’s wartime traffic, its laboratories improved the efficiency of the wire links also. In the forefront of Signal Corps’ biggest wire developments during 1942 was carrier equipment, whose application to military use was made possible by the perfection shortly before of heavy-duty spiral-four field cable.16
Carrier, a method which enables many messages to speed over a single wire circuit simultaneously yet without mutual interference, had been suggested to the Army years earlier—in 1931 by a Signal Corps reservist, 1st Lt. Clarence R. Kingston. His suggestion, however desirable more and better communications for the military might be, ran into the disapproval of Maj. William P. Blair, then charged with the Signal Corps Laboratories. The weight that the system components entailed would be very great, in terms of field wire equipment during the 1930s—no doubt about that. For the system would require what then seemed excessive amounts of terminal gadgetry: oscillator, modulator, demodulator, filters, ringing equipment, and auxiliary power supply. It would also require excellent wire circuits with minimum current loss, far less than the best that the standard field wire W-110-B could provide under field conditions. (The light insulation of the wire allowed too much current to leak out, especially in wet locations; heavy insulation would make the wire more efficient as an electrical conductor but too heavy for field use.) Blair, although he believed these factors made the carrier system unwarranted “at this time,” nonetheless evinced prophetic foresight when he reported the matter to the Chief Signal Officer in May 1931. “It is possible,” he wrote, “that there may be a requirement for the development of such equipment for operation on special circuits in the future.”17
The possibility which Blair had foreseen was more than that—it became an inevitability. By 1940 the laboratories at Fort Monmouth had projects afoot for “Carrier Telephone Systems,” several versions of which were already in wide commercial use.18 Application to military uses would be assured by the coincidence which, toward the end of 1941, brought together the efficient spiral-four field cable with urgent demands from field officers who insisted upon wire communications far exceeding the limited capacity of their outdated field wire equipment.
For years commercial communication companies had been relying upon carrier systems to handle the huge and facile telephone and telegraph traffic of America. Now the fast-growing Army wanted carrier facilities
too. For example, on 12 December 1941, Lt. Col. Fred G. Miller, signal officer at the Third Army Headquarters, San Antonio, Texas, had urged that tables of basic allowances include “carrier telephone and telegraph equipment for the higher echelons.” Major O’Connell, then charged with the communication projects at the Signal Corps Laboratories, replied to Miller that the Bell Telephone Laboratories were cooperating with him toward a military system that would provide three voice channels and four telegraph channels over one circuit (C carrier). The system had not yet been completely developed.19
However, O’Connell received assurances in February 1942 from A. B. Clark, Director of Systems Development at the Bell Laboratories, not only that there would be no hazard in placing large orders for the C carrier at once, without field tests, but also that the first models could be delivered to the Signal Corps by April or May, and the Signal Corps went ahead with the standardization of the equipment. Like a number of other Signal Corps items of equipment, such as the coast defense radar SCR-582, for which so dire and sudden a need had sprung up after Pearl Harbor, C carrier had become so desperately desired in 1942 that the Army decided to accept and standardize it without the customary service tests. It was accepted on its promises.
C carrier for the Army was to be perfected soon thereafter, phenomenally soon—in fact, by August 1942, and largely because of the million-dollar orders for the heavyduty carrier which the Army Air Forces had laid upon the Signal Corps for Air Defense needs. In the meantime, enthusiasm mounted as a military delegation on 12 April inspected the progress which the laboratories were making, both at Fort Monmouth and in the research labyrinths of the companies. On 11 May the Signal Corps Technical Committee recommended C carrier for standardization and did standardize it four months after, on 7 September. The equipment, in Signal Corps nomenclature, comprised: TC-21, or CF-1, C carrier terminal equipment (telephone); TC-22, or CF-2, C carrier terminal equipment (telegraph, teletypewriter); TC-23, or CF-3, C carrier repeater; and TC-24, or EE-100 (later EE-101) ringing equipment.20
Standardized but not yet procured or tested, C carrier by mid-1942 held the precious promise of heavy-duty commercial-type communications for the Army, without which the 50-million-words-a-day work load, commonplace by the war’s end, could never have been attained. Such was the promise held forth in 1942, not by C carrier alone, but rather by carrier techniques generally, working in conjunction with spiral-four cable, teletypewriter, and
radioteletype. The conditions which Blair had prophesied in 1931 had, indeed, arrived in 1942, creating demands which, like so many other demands on the Signal Corps, such as that for radar and FM tank radio, came with extreme urgency and explosive pressure.
Meanwhile, the first models, which Clark had over optimistically assured the Signal Corps for April or May, did not arrive. In June Western Electric, manufacturer for the Bell Laboratories, concluded it could promise no production before November, even with the highest priorities, which the development did not then have. (Other equipment devouring copper, aluminum, and electrical components such as meters, enjoyed higher priority.)21
Pressed to the utmost and blessed with higher priorities (AA-1, granted by the Joint Army and Navy Munitions Board), together with help in the person of a special expediter from Signal Corps’ Production Expediting Section, Western Electric was soon able to speed its carrier development.22 On 1 August, Fred R. Lack, vice president of Western Electric, promised the first three carrier sets by the twenty-second of the month, whereupon General Olmstead in turn committed them to the 62nd and to the 928th Signal Battalions for field tests in late 1942 maneuvers.23
Considerable time would yet pass before the production of carrier equipment got rolling. Neither the cable nor the terminal sets would become available in any quantity before 1943. Meanwhile, the initial driblets were invaluable for Signal Corps experimentation. Though the Signal Corps had standardized carrier equipment, anticipating that it would perform well, Signal Corps troops had yet to find out how to handle it in the field, to discover what sort of crews could best manipulate it and how. They also had to discover what the operation and maintenance requirements might be.24
Before the summer’s end, General Colton, head of the Signal Supply Service in Washington, thanked both Dr. O. E. Buckley, president of the Bell Telephone Laboratories, and Fred Lack for their efforts in speeding C carrier. The first deliveries of some of the system components had already, early in August, begun arriving at Fort Monmouth. Fortuitously and fortunately, only a few days earlier, late in July, the General Development Laboratory at the fort had received its first consignment of production spiral-four (150 miles of the first order, stipulating 1,500 miles) “for
immediate tests on the carrier equipment.”25 Wire engineers from the laboratories of the Signal Corps and the Bell System laid four 20-mile loops of the cable over the countryside around Monmouth and tested them for conductivity. Then on 4 August they linked three of the loops together in one continuous 60-mile circuit incorporating the newly delivered carrier equipment. They placed a telephone terminal, CF-1 or TC-21, at each end and two repeaters, CF-3 or TC-23, along the cable, presumably at each 20-mile joint. All this the experts supervised and operated successfully.26
Not until the very end of August did the first field test by the troops on maneuvers take place. During 28-30 August members of the 62nd Signal Battalion laid spiral-four, using the one-quarter-mile cable assemblies called CC-358. They found, despite their inexperience, that they were able to lay it, using conventional field wire equipment, as fast as five miles an hour during daylight. By night, under blackout conditions, they could lay up to three or four miles an hour, this despite rain and accidents, such as on the occasion their heavy 2½-ton truck carrying the cable reels and pay-out motor reel (RL-26-A) ran off the road and cut the cable. Transmission both over a ten-mile and over a twenty-mile stretch was reported to be “very satisfactory.”27 In October, during the Second Army maneuvers, the 262nd Signal Construction Company got its first field cable experience, laying in one night ten miles of the cable during five hours of heavy convoy traffic, dust, and blackout. Though some mechanical defects turned up, which experience both in manufacture and in field use would eliminate, 1st Lt. George W. Good reported that the cable was “enthusiastically received by the men and officers who have handled it.”28
Obviously this new cable was already a success in the field. And there was no doubt of the coming success of carrier equipment either, although for the time being full production tarried as a result of priority troubles and shortages of raw materials and components. Carrier terminal sets would be heavy—for example, the first telegraph-teletypewriter terminal, TC-22, involved two cabinets which totaled over a thousand
pounds, not counting the power equipment and sundry accessories.29
Nonetheless, a carrier cable line 100 miles long would weigh far less, and could be installed in far less time, than a 100-mile pole line of equal traffic capacity. Before the end of 1942 Colonel Magee, chief of the Equipment Coordination Branch in Washington, would write that “the need for this equipment in almost every theater of operation has been apparent to all concerned for over a year. When equipped with carrier telephone equipment,” Magee summarized these new blessings, “Spiral-Four Cable will provide long distance facilities which can be placed in service by troops in less than one-tenth the time and with one-fifth the material required for the most rapid type of pole line construction which will provide equal facilities. Equipment for a 100-mile Spiral-Four Cable carrier system, including cable reels, weighs 39 tons. Equipment for 100 miles of rapid pole line would weigh approximately 240 tons. Equipment for a standard pole line 100 miles long would weigh 870 tons.” Magee noted also that no deliveries (after the rushed delivery of three sets in August) had been made on the carrier during September, October, or November, because of “inadequate priorities to obtain a small number of components.” There had been an “urgent request for this equipment from task forces in October,” he remarked, yet it could not be fulfilled. Not until early December would five systems be delivered, and then only because extraordinary efforts were made to provide nonstandard engine generators and batteries.30
Ground Radio and Radio Link or Relay, Transformed by FM
By the last half of 1942 the efforts of the Signal Corps in research, development, procurement, and distribution pretty well met the radio needs of those who pressed hardest among the ground troops—the men of the Armored Force. The demand for Armored Force radio types, initiated in 1940 by Capt. Grant A. Williams, had already been or was being well satisfied—Type I (for long range) by SCR-299; Type II (for medium range) by SCR-505, which was still under development while the older SCR’s-193 and 245 substituted well; Types III and IV (for short range) by SCR-508, 528, 538, 509, and 510. In the III and IV types FM had completely captured the affections of the tankmen.
Late in August 1942 Lt. Col. William P. Withers, an Armored Force officer who, like
Vehicular mounting of radio sets. The SCR-299
Williams, had long labored with the Signal Corps toward modernizing the tankmen’s communications, expressed his appreciation of Signal Corps efforts just after he had taken command of the 37th Armored Regiment at Pine Camp, New York. Withers warmly thanked Colton, head of the Signal Supply Service, and his helpers, naming in particular O’Connell, Rives, Elder, and Hildreth, all associated with the heavy duties of both developing and procuring Army’s communication facilities. Here in the thick of the Signal Corps battle of production, wherein Olmstead and Colton received many more brickbats than bouquets, Withers’ appreciation must have been encouraging indeed.31
Withers’ thanks re-echoed throughout the Armored Force in proportion to the ever wider distribution of the “500” radio series. Everyone loved to push the buttons and talk over the air, especially the officers, despite regulations against excessive use of radio transmissions. After a month at Pine Camp, Withers again wrote to O’Connell saying that these sets enjoyed huge favor, with the result that the Signal Corps had risen high in the opinion of the field troops—quite a contrast with the Corps’ reputation during the 1940 and 1941 maneuvers.32 “Generally speaking,” he told
Vehicular mounting of radio sets. The SCR-510 and SCR-193
O’Connell, “the radio is splendid and is actually furnishing more communications than we have ever had. If we can ever persuade the high command that it is strictly a battalion set, and not a headquarters telephone, I won’t worry nearly so much about communication ... the Commanding General ... has to resist attempts of officers senior to him, mainly in the Division Headquarters, to grab sets from line units. ... Most officers are entranced with this FM and just can’t bear to see a microphone idle. ... From the field point of view, especially considering present and past difficult conditions, the Signal Corps is doing a fine job.”33
Rather often the pushbutton tuning mechanisms got out of order, generally because of inexperienced operators, who, with unwarranted confidence, tinkered with the adjustments, especially when they could not get good reception, a condition not uncommonly encountered by ground troops in deep valleys or depressions where very high frequency waves are naturally blacked out by absorbing objects or blocking terrain.
Expecting too much, in ignorance of VHF-FM characteristics, the receiver operators generally cursed the transmitters or fiddled with their receiver adjustments. Actually, the aligning adjustments in an FM receiver or transmitter are very exacting and even require special FM test equipment (AM test sets will not do). While the Signal Corps men tried to instruct and restrain the overzealous operators, Colonel Withers resorted to the expedient of assigning men to ride in the vehicles of the 37th “merely to watch the officers and the men use the radio, in the hope of learning what queer things they do to cause the trouble [with the tuning adjustments].”34
Even so, FM vehicular short range radios operating in the very high frequencies above 20 megacycles had completely captivated the Armored Force. These were, of course, the 500 series sets: SCR-508,528, 538, 509, and 510. Likewise, the corresponding 600 series of sets were now winning the affections of the Field Artillery men. Now, too, the British became interested; FM military radio was something new under the sun. To make comparisons, they brought over their conventional AM wireless radio No, 19, which operated in the high frequencies only, far below the very high frequencies of the American FM sets. From 28 August to 2 October 1942, the Signal Corps arranged a series of tests between the 508 and the No. 19 (also between the Infantry’s new walkie-talkie, the FM SCR-300, and the British No. 48; and also between the SCR-284 and the British No. 22, the last three all being AM radios). In the course of the tests, conducted in the vicinity of Fort Monmouth and among the mountain ridges of the Alleghenies near Bethlehem, Pennsylvania, the SCR-508 proved better than the No. 19. Although the British set was smaller and consumed less power, the disadvantages of its amplitude modulation (subject to static and interference), its numerous tuning controls, and its lower frequencies (falling in the crowded, noisy 2-8 megacycle band), all militated against it.35 O’Connell, returning from the field tests near Bethlehem, reported to Olmstead on 10 October that “the marked superiority of the SCR-508 and SCR-300 [compared with the No. 19 and No. 48 respectively] for reliability of communication was clearly determined.”36
As if the multiplicity of the 500 and the 600 radio series was not enough, both series doubled in number during 1942 with an SCR-700 and an SCR-800 series—all because of anticipated crystal shortages.37 Each 500 set required up to 80 crystals, one for each radio channel which the Armored Force might wish to use; each 600 set required up to 120 crystals to cover the Field Artillery’s span of allotted channels. The total crystal requirement naturally became astronomical, especially since other sets were calling for crystals too, for example,
SCR-245, 299, 511, and 536. This demand, it seemed for a while, could not be met from the critical supply of high grade quartz from which the crystals were cut. The supply was short, to say the least, and very remote (the only good sources being in Brazil and in India). Moreover, there was a still more critical shortage of craftsmen and equipment to prepare the delicate quartz crystal wafers. All these considerations led the Signal Corps into a frantic effort to devise means of reducing its crystal needs while retaining the indispensable advantages which crystal-controlled pushbutton radio sets could offer.
The new crystal-saving series (the 700’s paralleling the 500’s; the 800’s duplicating the 600’s) had begun to take form even before any of the original series reached mass production. On 22 November 1941 the Signal Corps Laboratories had contracted with the Zenith Radio Corporation for three multichannel master-oscillator FM transmitters and six receivers, embodying a crystal-conserving system. E. F. McDonald, president of Zenith, had hoped to complete the contract sooner than the ninety days which the Signal Corps had specified. Usually in electronic production, harassed by supply shortages, priorities, and design changes, such hopes prove impossible to realize; but not so in this case. McDonald wrote to General Olmstead on 21 February 1942 that he was “happy to say that the three transmitters are finished and the receivers will be Monday.” He could not refrain from concluding triumphantly, “I like to make good on a promise of delivery.” Needless to say, the Signal Corps was pleased too, as Olmstead hastened to reply.38
Master-oscillator systems, which had been devised to hold radio circuits to their exact operating frequencies, had long been a subject of research in the Signal Corps Laboratories and in industrial laboratories also. Now these efforts led to successful crystal-saving radio designs, reducing the 80 crystals of the 508 sets and the 120 crystals of the 608 series to but one crystal a set, which was used to calibrate four master-oscillator circuits, providing four pretuned channels (six less, unfortunately, than the ten channels of the original multi-crystal sets). In the 509/10 and 609/10, the reduction was less drastic, each set still requiring 19 crystals per set. Known at first as 508-XS, 608-XS and so on (the XS meaning “crystal saving”), the new versions acquired formal status in September 1942 as SCR-708 and so on (the 700 series) for the Armored Force III and IV sets, SCR-808 and so on (the 800 series) for the Field Artillery counterparts.39 By then the crisis in the crystal supply was subsiding. Drastic measures to provide radio crystals in quantity proved successful. Consequently, the 700 and 800 series were not needed in World War II. Yet the effort spent on their development was by no means lost since crystal-saving techniques would be incorporated in postwar vehicular radios.40
Meanwhile, by the late summer of 1942 the Infantry’s first and only FM radio to
be used in World War II had reached the stage of field tests. This was the new walkie-talkie SCR-300 destined to fulfill “the Infantryman’s dream for better communication and control of troops by radio.”41 Running the usual gantlet of tests prior to production, the SCR-300 had to take few blows. At the Signal Corps General Development Laboratory, the Field Radio Communication Section (located in Camp Coles, New Jersey) reported that only minor mechanical and electrical defects had turned up in the service test models which the Galvin Manufacturing Corporation and the Philco Corporation had offered. This new FM radio not only survived the tests well but at the same time dealt heavy blows against its competitors in the Infantry, even against the newest AM sets which had only recently come into the hands of the troops, SCR-284, 511, and 536. Compared with them, with the British No. 19, let alone with the older and original American walkie-talkie, SCR-195, the new SCR-300 conspicuously outdid them all. “These tests,” according to the laboratory report for September, “indicated the great superiority of frequency modulation for short range front line communication. ...”42
Not until the postwar period would all Infantry short-range radios, including the handie-talkie, become FM, integrating the foot soldiers’ sets with those of the Armored and the Artillery arms, so that all could intercommunicate. During the war, into which the Army was now daily plunging deeper, front-line infantrymen suffered from a diversity of radio types, both AM and FM, which could not talk with each other. Military FM, in the form of the SCR-300, entered the forward fighting units in time to confer great benefits and to prepare the way for the integrated communications of the future Army.
By 1942 FM had thus wrought a revolution in the Army’s vehicular short-range radio communications. Before the year was out, FM was helping to bring on another revolution. Used in radio link or radio relay equipment, it would link together breaks or gaps in wire lines. Indeed, it would soon replace wire altogether. The initial notion restricted the use of link equipment to the jumping of spiral-four or wire line traffic across rivers and over land obstacles. This idea quickly broadened into the concept of a chain of radio links, a succession of stations which could repeat signals from hilltop to hilltop over scores and hundreds of miles, entirely without wire. But the limited idea of using radio to link together the interrupted ends of a wire line came first, and the Signal Corps laboratory workers were giving it thought when, in mid-1942, the airmen started thinking too, in a bigger way, of depending upon radio instead of upon wire to link their ground units, even when they were in a fixed location.43
In particular, the Air Forces Aircraft Warning Service nets required huge amounts of communication lines, a requirement that had already given great impetus to spiral-four and carrier developments. Every radar site, every observation post in the Aircraft Warning Service, had to be linked to an information center, for example; and wire or cable, however improved, entailed too much bulk and bother. The
airmen had already been using AM radios when they could get them, such as SCR’s-177, 188, 197, and the commercial Hallicrafters HT-4, parent of the SCR-299.44 They could not get enough of them, and anyway these AM transmitters radiated widely in the high frequencies (which rebound from the sky’s ionosphere), so that the reflected radiations interfered with the operation of other radio nets far away over the horizon. Would not VHF FM, with its line-of-sight limitations, be better? In July 1942 General Arnold made just this suggestion. He suggested to General Olmstead that for fixed SCR-271 air search radar stations, “FM radio equipment can be used to provide radio communication channels where line-of-sight or ground wave transmission is feasible.”45 A month later Arnold asked for no less than 700 FM receivers and transmitters, saying that “392 each of these receivers and transmitters are required to provide communications between fixed radar sites.” The rest, he added, would “provide radio links between units of SCS-2 and SCS-3 systems.”46 This was not radio merely to link up gaps in wire systems ; it was radio replacing wire altogether.
Another Air Forces call for FM radio assistance to the Aircraft Warning Service came in August 1942 from the III Fighter Command in Florida. The airmen complained that in some forty observation posts along the Atlantic coast “it is highly impracticable to provide telephone communications.” They wanted specifically a number of SCR-298’s, FM sets built by Fred M. Link for umpire use in Army maneuvers. The Signal Corps received the idea coolly, especially since SCR-298’s were not standard Army sets. Would not some standard equipment do? “Radio Sets SCR-298 and SCR-298-A,” the Chief Signal Officer explained, “are non-standard equipments originally procured as ‘Umpire’ sets.” Remembering General Marshall’s insistence that radio types be reduced, Olmstead added, “In an effort to comply with the Chief of Staff’s directive to reduce the number and types of equipment, every effort should be taken to utilize the present standard equipment that is capable of performing the required functions.”47
Standard or no, the AAF would get what it wanted, FM radio for “point-to-point operation” in this case. In September it demanded and got, not 40 but 100 SCR-298’s. Again, later that month, the AAF asked for a small delivery of 38 FM sets as a special issue to be provided “for a special operation by an organization activated under a special table of basic allowances. The organization,” the Air Forces added, “is scheduled to move overseas before October 15.”48 Col. Will V. Parker, in
Plant Division, reported on 30 September 1942 that these 38 FM sets had been shipped the day before.49
Although the Air Forces insisted, some of the Signal Corps men responsible for new developments felt doubts. At least, they were doubtful of the need to develop radio link equipment for the sole purpose of closing gaps in wire lines (evidently the notion of far-reaching radio relay had not yet, in the summer of 1942, become firm). Developments of great importance so often begin only half-recognized or, worse, as tentative trials shrouded in the uncertainty which only time and tests can clear away. For example, both the subsequently indispensable handie-talkie and the SCR-299 had begun as tentative stopgaps.50 FM radio itself long suffered from hesitant skepticism. In August 1942, when the idea of radio link was beginning to mature as a laboratory project (requested by the General Development Branch in the Washington office as a means of jumping carrier cable signals across an obstacle), the General Development Laboratory at Fort Monmouth regarded the need for so special an undertaking as “doubtful.”51
The pressure for radio link prevailed and the new FM techniques swept away the objections which had been raised against militarizing AM radio link (the chief objection being that very high frequency AM radio connections would be impractical in any location but a fixed station under careful control). Now the picture changed almost overnight, according to John J. Kelleher, a radio engineer in the Engineering and Technical Division of the Office of the Chief Signal Officer. It changed with the coming of VHF FM equipment. The new development, Kelleher asserted:
... completely negated the prejudice against radio links; provided a radio transmission facility that had none of the faults of high frequency; was extremely small, rugged, easily portable, yet had many of the attributes of a high quality wire circuit. Audio levels could be maintained within close limits over long periods of time because fading was practically non-existent at those portions of the spectrum; signal-to-noise ratios were amazingly high, right out to the maximum range of the circuit; most important, multipath distortion was completely absent and the fidelity of the circuit could be held at a level that permitted relaying the signals by tandem
connected receivers and transmitters, far beyond the horizon range of a point-to-point circuit.52
In moving toward radio link, the Signal Corps General Development Laboratory at Camp Coles, near Fort Monmouth, sought to modify existing Signal Corps FM sets SCR-608 and 610, then turned to commercial equipment, to Western Electric’s Model 31A and to Fred Link’s Model 1498. By November the laboratory engineers, deciding that the Link model showed most promise, contracted with the Link Corporation for twenty development sets which Link would deliver in 1943 and which the Signal Corps would dub “antrac 1,” that is, AN/TRC-1. It was a development of tremendous significance for the future of communications.53
Radio link, amplitude modulated, had existed commercially before the war in a few limited applications adapted for fixed operation. Now the Signal Corps converted it to frequency modulation, took it out into the field, reduced its girth, and toughened it for mobile warfare. Its first application to war would soon come in North Africa, and not merely in order to plug small gaps in wire systems but in order to relay radio signals over hundreds of miles, supplanting long lines of poles and wire.54
Whereas previously wire had been preferred, in particular because its use was familiar to the unskilled soldier and because its inherent security was high, now the new FM radio types, which became as simple to operate as telephones, were preferred. Moreover, in some equipment, such as radio relay and radioteletype, automatic security devices (code or, more accurately, cipher machines) rendered the communication as inaccessible to the enemy as were the messages carried by wires. In short, the user of radio relay equipment communicates by means of the familiar telephone or teletypewriter exactly as though wire made the connections. Indeed, some of the connections may be by waves channeled along wires while other portions of a circuit are linked by radio waves beamed through space. In the radio relay system, according to a Signal Corps officer, “we have a marriage of wire and radio.”55
At the end of World War II, the members of the Institute of Radio Engineers were to hand a bouquet to the Signal Corps for its work in meeting the challenge that the communication needs of modern war presented. Field commanders would praise the superior equipment which the Signal Corps had provided, superior largely because of increasingly extensive use of frequency-modulated radio in the range of 20 to 100 megacycles.
Signal Corps Provides VHF Command Radio for Army Airplanes
The development of airborne radio and of all other airborne electronic equipment was, of course, the concern of the Signal Corps installations, especially the Aircraft Radio Laboratory, which served the Air Forces at Wright Field in Ohio. To the Signal Corps Aircraft Signal Service fell
the whole business of developing, procuring, inspecting, storing, issuing, installing, and maintaining those Signal Corps items of radio, radar, communicational and navigational electronic equipment which went into airplanes. SCASS, which had been organized at Wright Field in May 1942,56 proved effective. Until the Army Air Forces took over altogether toward the end of World War II, SCASS performed its task rather well, which was to coordinate the supply and maintenance functions of the Signal Corps with the materiel commands of the Army Air Forces.57 The success of SCASS led General Olmstead to reorganize his Monmouth activities similarly. Combining the General Development Laboratories with the Radar, or Camp Evans, Laboratory, he created in December 1942 the Signal Corps Ground Signal Service (SCGSS) with headquarters at Bradley Beach, New Jersey.58
The most basic of the very many airborne radio devices which concerned SCASS was the command radio set, a medium-range radiotelephone indispensable to fighter planes. The United States aircraft command sets which received most use during the early months of the war were older high-frequency types, even the “ancient” SCR-183 and SCR-283, good sets in their day but now out of date. Many thousands were in use and on order. As late as 24 April 1942 the Air Forces had asked the Signal Corps to procure 13,708 SCR-183’s and 717 SCR-283’s, over and above an existing requirement which totaled 38,342 for both sets. By the end of May the Signal Corps had issued letters of intent to purchase these additional thousands from Western Electric and Philco. Both companies at once multiplied their efforts and their facilities, getting materials and parts and increasing their tools. Philco’s additional tooling-up alone ran to $150,000.
If the AAF knew that high-frequency command sets were doomed, it gave no thought, apparently, to tapering off its orders so as to let down the Signal Corps and industry easily. These orders the airmen guillotined in June with dramatic, and disastrous, suddenness. The Signal Corps got the news informally at first, through a rumor picked up by the Scheduling Branch; then, in response to a formal inquiry, it learned officially on 27 June that the AAF now had no requirements for the 183 and the 283, of which it had wanted better than 50,000 only a few weeks before. More was yet to come. After the Signal Corps had canceled the orders and, along with the manufacturers, had written off the loss, the AAF again reversed its position and decided in July that it did want some SCR-283’s, in fact 3,230 of them. Later the AAF decided it wanted still more of these sets and on 20 November 1942 ordered 5,000 additional 283’s, together with 3,000 SCR-183’s.
On Signal Corps’ reckoning, the AAF’s failure to know its needs and to state them promptly led, in the case of these two radios, to (1) the wastage of $75,000 in critical materials such as aluminum abandoned in a partly fabricated condition; (2) the loss of $150,000 in tools that had become useless; and (3) the irreparable loss of man
hours spent in fabricating the now useless tools and half-finished parts. Moreover, while the production lines of two of Signal Corps’ principal suppliers stood disrupted, the United States Government would have large bills to pay covering cancellation costs and tool costs: $100,000 to Western Electric and $150,000 to Philco.59
Everyone in the Army Air Forces certainly should have known that the high-frequency command radio was doomed. Air Forces officers themselves, following the example of the British, had condemned it. They had directed in mid-1941 that all fighters be equipped with very high frequency radio, copied from the British. Unfortunately, the newest and best contemporary American command set, SCR-274, just beginning to supersede the 183 and 283, was only a high-frequency set. The Air Forces hoped to convert it to VHF operation and in June 1941 had asked that the Aircraft Radio Laboratory develop a VHF component for it.60 The laboratory’s engineers were drawing up the specifications by mid-1942. They were laboring also upon other VHF airborne equipment, continuing their long research upon the American very high frequency SCR-264, and at the same time designing suitable test sets and developing other new equipment, compasses, radio ranges, beacons, and so on, which would operate in the hundreds of megacycles.61 The principal task, however, was to copy the equivalent British equipment, the British VHF command set which the AAF had been demanding since February 1941. For BOLERO it now seemed mandatory, to be installed in both fighters and bombers flying into England, where command radio operation, both plane-to-plane and air-to-ground, was universally VHF. Production of it as the SCR-522 commenced at Bendix in March 1942.62
Hardly had the first SCR-522’s flowed from Bendix into the field than complaints came foaming back, a veritable flood of them, beginning in May 1942. Shocking percentages of the first SCR-522 installations were defective, practically immobilizing otherwise perfect aircraft. Very much to-do ensued throughout the summer, with recriminations and unpleasantness all along the line—from the airmen, from the Signal Corps, from the radio and aircraft builders, even from the British. Trouble shooters went forth from the Inspection Section of the Aircraft Radio Laboratory and from Bendix. Bendix blamed the inexperience of the civilian and military personnel at the air bases. The military were inclined to blame Bendix. Since SCR-522 was a copy of a British original, poor design was attributed to the parent set. The chief troubles were failure of the dynamotor, PE-94, which powered the set, and defectiveness of the
amplifier tubes 832 (VT-118). Moreover, many installations were made very badly; tuning adjustments were way off. Everyone agreed to tighten up on inspection, and to improve the training of the workers. Production manager E. F. Kolar, after inspecting SCR-522 troubles at the Bell Aircraft plant in June, had urged Bendix to institute additional precautions at the factory “to insure the highest quality workmanship,” and to send a representative to each aircraft factory in order to train personnel there in the niceties of installation and tuning.63
Improvements came slowly. In September W. L. Webb, Chief Engineer of Bendix Radio Corporation, and Maj. W. D. Inness, inspecting matters at the Curtiss Aeroplane Corporation at the Buffalo airport, were shocked to behold the careless handling of the SCR-522’s as they came in. They were strewn around a disorderly radio shop where two girls poked over their wiring and adjustments to see if anything was loose. The girls “weren’t real sure what they were looking for.” Obviously, they might damage a set by tightening a tuning adjustment which they might suppose loose.64 Test methods were bad, and no wonder. There was no suitable test equipment—quite a chronic defect touching new electronic devices. This was especially true of radar during 1942 when basic equipment was being rushed to the field before test and tool sets were available or even designed. The Aircraft Radio Laboratory was busy developing test sets, but not until 9 September 1942 did the first SCR-522 test set, IE-reach the radio installation people at Curtiss.65
When Webb and Inness inspected the Curtiss Aeroplane plant on 7 September, they were told by the AAF representative there, Colonel Mitchell, that lack of experience with the VHF SCR-522 was the chief source of trouble, augmented by lack of test equipment and by one very real mechanical defect involving the dynamotor. He mentioned, too, that an average of three antenna mast stubs broke on every eight to ten flights. The American copy of the British dynamotor simply had not worked out well. As General Olmstead informed the Air Forces some months later, the dynamotor design was unsuited to American manufacture, which employed American materials and methods. Bendix had objected to copying it in the first place, but at that time, in 1941, all had agreed that the only way to meet desired production schedules was to copy it anyway, while developing a new design. Aircraft Radio Laboratory engineers were now working out the new dynamotor. By December they would complete it; tooling for production would begin, and in 1943 the AAF would receive improved, trouble-free dynamotors for its
VHF command radio SCR-522.66 Until then, throughout 1942 and early 1943, the Eighth Air Force in England obtained much of its VHF radio equipment, dynamotors especially, from the British. Until improvements were accomplished in the American equipment, radio communications in Army Air Forces P-47’s had sometimes been impossible.67
Thus, Signal Corps’ introduction of VHF into army airplanes brought a great deal of fuss and trouble, just as the advent of radar was doing. VHF brought headaches to the Aircraft Radio Laboratory, to the manufacturers both of the electronic equipment and of the aircraft themselves, and to the Army Air Forces personnel who operated it. The reasons all stemmed from its novelty. Apart from a few experimenters and researchers, the Americans were so generally inexperienced in the very high frequencies that they lacked even the essential test equipment which could function accurately at frequencies above 100 megacycles. But all these deficiencies the Signal Corps was fast mending in 1942, bringing air radio up to date, whether between aircraft, or between aircraft above and the AACS stations below, joining them all in one dependable net of radio communications.
Such are the principal threads of the history of the problems and accomplishments touching Signal Corps wire and radio equipment during the months immediately prior to TORCH, the Allied invasion of North Africa. During the same period the Signal Corps concerned itself intensely with problems associated with radar, the military importance of which was as incalculable as that of the more conventional types of electronic devices.