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Corps' labs help develop wartime technology

by Walter Andrae

The Signal Corps contributed thousands of new developments and inventions to the nation's communications-electronics technology in World War II. These contributions began in the corps' laboratories in the years shortly after WWI.

By the end of WWI, wire had proven its worth as a communications tool and was at the forefront of signal equipment both tactically and administratively. In contrast, AM radio didn't lend itself to secrecy and had serious drawbacks in reliability and ease of use.

Research on "wireless"

Despite these problems, change away from reliance on wire came in the form of long-range research at the signal laboratories. Radio telegraphy, teletyping and telephony were the corps' areas of focus in the 1930s. The labs' communications experts unknowingly were breaking new ground that would contribute heavily to the war effort in the following years.

Immediate tactical needs sometimes drove research, as in the case of battery-powered telephones like the EE-8A. Simple changes were often major improvements for the users; for field use, removing a bell and replacing it with a small light was an improvement. There simply wasn't anything to gain from telling the opposition where you were.

Improving equipment

Interestingly, the signal laboratories received constant requests to improve equipment handed down from WWI. Three of the switchboards the Army used at the start of WWII were copies of French models — large, cumbersome devices.

Responding to the requests, the laboratories had started work on new switchboards for corps and division levels. Work on a military version of the teletype printer had also begun.

Development of the military field typewriter spun out new requirements for more research. Reliable power supplies that produced a stable flow of current with less than a 3-percent shift of frequency were now needed. So along with the new teletypewriters came new generators to run them. Signal technology marched on.

The laboratories had pushed to improve the two-man portables and large vehicular radios that had to be removed from the truck and set up on the ground before they could be used. Improvements for hand- cranked generators and manual tuning had already been achieved, but equipment in the troops' hands was still several stages back.

Demand for radios

Initially, the chief users of wireless equipment — because of weight and bulk — were command and defensive sites, followed by air and artillery. Infantry, cavalry and armor, when they did get wireless equipment, suffered the limitations of stationary ground use and limited range.

Fortunately, some of the radios like the SCR-179 were capable of being carried on horseback. The infantry, cavalry and armor, however, demanded better, lighter, more compact radios.

Air Corps equipment

The rapidly expanding Army Air Corps, which was also rapidly gaining clout, viewed equipment weight as a major concern. Wave range was another Air Corps concern, especially as the speed and range of pursuit planes improved.

It was often aircraft design that drove radio design, although it should be noted that some of the older radios were still in use in 1943.

One of the laboratories' responses was the crystal-controlled command set — no more time spent fine- tuning the dials. This freed the pilots up for other more engaging activities.

Navigational radio emerged from WWI. It could be used for intelligence gathering or as a means of taking bearings from fixed radio sites. (This concept, first used for ships and planes, has now been refined to a point where individuals can use it.)

Navigational aids and landing systems resulted from research and development on radio compasses and beacons. Magnetic airborne detectors and sonic radio buoys for submarine detection were tied into this quest in electronic location-finding. Microwave indicators to measure the angle of descent and deviations to the right and left were also a part of this enormous undertaking.

The research had a life of its own, seemingly feeding and building upon itself as long as the necessary impetus for growth — money and the threat of war — remained constant.


Of all pre-WWII advances in radio technology, radar was the most spectacular. The test results of May 1937 convinced the chief of staff, Gen. Malin Craig, of radar's potential and the need for secrecy. He was correct on both counts. His decisions resulted in an advantage that remained ours throughout the war.

Improving radar so it could become an effective antiaircraft tool was a difficult task for the signal laboratories. There were many mechanical problems, but radio problems were minimal, proving the theory was sound and the project was worth the rare budget dollars.

Importantly, there was no shortage of engineering talent or leadership support. The result, the SCR-270 and -271, was accepted by the Army in May 1940 and was good enough to serve throughout the war.

Pace of war

As WWII progressed, the need to meet the immediate demands of a rapidly expanding force pushed long- range research to the rear. Researchers and assistants were called upon to provide assistance in maintaining existing equipment. They became the faceless civilian experts who introduced new equipment to the commands, helped troops get the best possible use of the equipment, and provided advice on maintenance, modifications, parts and procedures.

Signal research experts found themselves in the field alongside the troops in 1943 and 1944. Information gathered in real-time settings provided the improvements the Army had ordered; scientists and engineers were looking at practical applications.

The intent was to have full effective use of the equipment then in the field. Improving the existing equipment had become a major signal laboratories' responsibility.

Laboratory cutbacks

By mid-1943, cutbacks in laboratory personnel were imminent. Shifts to short-range projects or immediate problems had already become a reality. Doing so with less people meant prioritizing. Manpower and materiel were slowly being shifted to the invasion that everyone knew had to come.

Ironically, it was MG Harry Ingles, Chief Signal Officer, who expressed concern with the inefficiency caused by the constant introduction of new systems to the troops. The cuts were coming and the general knew it.

Cutbacks raised critical questions about which programs to end, pare, or continue. Some programs were eagerly taken over by the Navy or the Army Air Forces. Others were simply dropped.

And still others were driven to continue by developments in areas such as rocketry. Even in 1943, guided bombs were a point of interest. Electronic guidance of all sorts remained a Signal concern.


Meteorology has long been a special area of expertise for the Signal Corps. Despite the deep cuts of 1943, the increased role of airpower placed a premium on accurate weather assessments. The laboratories continued a variety of meteorological projects right up to the end of the war. Many improvements in tracking systems, generators, plastics, balloons and battery-powered generators were made.

Here, too, a significant use was found for radar: two meteorological radars were developed, the SCR-525 and the SCR-825, to search for storms.

FM radio

War is won on the ground. The use of signal FM radios enabled American troops to move rapidly by providing reliable, static-free communications. In contrast, the Germans still depended upon AM radio. (See George Raynor Thompson's comments on FM's impact on the battlefield, and Carol Stokes' article about the Signal Corps' role in developing FM.)

The signal laboratories' contributions to victory in WWII were as numerous as they were significant. A process that had been almost entirely long-range, research-oriented in the 1930s was adapted to meet the needs of a wartime army and invasion force. It succeeded and justified the dreams, time and expenditures of a nation at war.

Dr. Andrae, the administration officer at the National Science Center, Fort Gordon, Ga., has been interested in military history since he was in elementary school. He holds an EdD in adult education from the University of Georgia.

Last modified on:
April 04, 2012

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