Friday, March 24, 2006

Dude, Where's My Carpet?

This week, eDefense has an "In Depth" story on the first radio-frequency jammers used by the US during World War II. In his article, "Magic Carpet to Survival," Dr. Alfred Price briefly relates the story of how some of those first jammers were sent to England -- and lost. Here is the full story from O.G. “Mike” Villard, the man sent to find them, as it appeared in JED, The Journal of Electronic Defense, back in January 2002:

I recall that before the Second World War, my father, Oswald Garrison Villard, Sr., was a well-known author who edited the liberal journal The New York Nation for many years. When I went to Yale, he naturally wished me to follow in his footsteps, although I was tempted by engineering at the time. I majored in English and graduated in 1938. But I was always interested in technical maters and since the age of 12 had been a radio ham. During my sophomore year, I won a prize in English and spent the money on Dr Fred Terman’s well-known textbook Radio Engineering. I was so impressed with it that I resolved to try to get to Stanford University to study under him. Though my qualification was in English, Terman arranged for me to be given the status of graduate student in engineering, though I had to do a lot of the undergraduate requirements all over again. I started at Stanford in the fall of 1938 and spent most of the next three years catching up with my new discipline.

Towards the end of 1941, the University took on a research project for the National Defense Research Committee: to build a vertical-incidence variable-frequency ionospheric sounder to assist in understanding the effect of ionospheric changes on high-frequency communications. Terman contributed several valuable ideas. He also put me in touch with Harold Elliott, a mechanical engineer, who helped me build the circuits that tracked one another as they swept over the frequency range of 2-20 MHz. At the time, this was difficult to do, though now the pulsed sounder we built would be considered quite conventional. It radiated a peak power of about 1kW, had a pulse-repetion frequency of approximately 30, and a pulse length of 200 microseconds. It had all the elements of a radar, though at the time I had no idea that an extension of such a device might also be used to detect aircraft or ships.

In May 1942, Terman told me he was in the process of setting up a very secret laboratory at MIT to assist with the war effort. He asked me if I would like to join him there. I accepted the invitation and arrived at the Radio Research Laboratory (RRL) in mid-July 1942, while it was still part of MIT. My first few weeks were spent getting the necessary security clearances and reading reports on radar. I was fascinated by it all. Radar represented such an incredible extrapolation over the crude sounder on which I had been working. Unlike many newcomers at RRL, I felt moderately at home with the idea of radar; my previous work had given me an ideal grounding. When my clearance came in, I remember being particularly impressed by a report written by Terman, describing what he had been told concerning radio and radar countermeasures during his visit to England in the spring of 1942. Nobody at RRL at that time had any first-hand experience with such countermeasures, but it was clear that we were getting the benefit of a lot of very ingenious thinking on the subject from the other side of the Atlantic.

Immediately after RRL moved to Harvard in the fall of 1942, I was assigned to Clark Cahill’s group and charged with exploring the vulnerability of the current US radars to various types of jamming, as well as means of reducing that vulnerability. We installed a couple of standard radars on the top of the RRL building and tried various forms of jamming against them: a US Army SCR-268 searchlight and gun control set, and a British ASV Mark II airborne radar used for detecting shipping. Both of these first-generation radars proved painfully easy to jam.

Although there was little that could be done to reduce the radars’ vulnerability to noise jamming, we did devise some fixes to enable them to stand up to the less-effective jamming signals. For example, in the SCR-268, the detector was DC coupled to the following video-amplifier tube. As a result, even a little continuous-wave jamming was enough to bias off or completely overload the video amplifier. The obvious remedy was to put in capacitive coupling, which stopped this particular form of overloading. On our recommendation, I believe this simple modification was ultimately incorporated into all SCR-268s.

Our findings on the effects of the various types of jamming were passed to the radar people at the Radiation Laboratory at MIT, with the result that the newer sets were designed - to the extent that was possible - to be less vulnerable to enemy interference. Another important result of our work was that it set off a program to educate service radar operators on the likely effects of enemy jamming on their sets. It was, of course, vitally important that the operators should be able to recognize the difference between deliberate jamming by the enemy and unintentional interference or some equipment malfunction. In addition to reports, technical manuals, and motion pictures on the effects of jamming, the group produced some training signal generators that simulated the various types of jamming on the radar screen.

Early in 1943, I moved to Earl Cullum’s group, which later became known as Transition and Liaison. The Transition task had evolved form experience at the Radiation Laboratory, after they had rushed some of their early radars into production. They soon found that it was not enough simply to develop a new radar and get it working. The design team had to see it right through the production process and the subsequent service testing. If they didn’t, something would foul up for sure. So we at the RRL set up our own Transition office to handle that side of things. The liaison task involved continuous visits to the various Amy and Navy offices in Washington to acquaint them with the latest developments at RRL and discuss their own changing requirements. On my return to Harvard, I would write a newsletter that was circulated among the group leaders so that everyone would know about new developments.

By the spring of 1943 one of the first of the jammers designed at RRL, the APT-2 Carpet, had successfully completed its testing. Both we and the people at Wright Field could see there was going to be a service requirement for the jammer sooner or later, but at the time no such requirement existed. And until it did, there were no official grounds for a production order. Fortunately for us, Lieutenant Colonel McRae in the Pentagon clearly saw the need. He stuck his neck out and authorized the procurement of the first couple of dozen Carpets. These were the production prototypes, and at the time, they were considered to cost a lot of money; the contract probably came to something on the order of $40,000. If someone had chosen to make an issue out of it, McRae could have gotten into serious trouble. But luckily nobody did. And before worked on the contract had gone very far, the 8th Air Force in England came up with an urgent requirement for the jammer, and the Carpet program took off from there.

The initial batch of Carpets was rushed to England in the fall of 1943 and installed in the B-17s of two bomb groups, where they immediately demonstrated that they could reduce losses from German radar-guided flak. Suddenly, everyone wanted Carpets. A large follow-on order was placed with the two companies producing it, Delco and Galvin Manufacturing.

Early in 1944, the new batches of Carpets started to come off the production lines and were sent to England. We at RRL felt that we had done our job and could now get on with other tasks. But then we started to get plaintive signals from the people at ABL-15, RRL’s offshoot organization in England: “Where are the Carpet jammers you said were being sent?”

The Army had an efficient system using IBM cards for following the movement of its shipments, but on this occasion, the system effectively broke down. We learned that the jammers had left the manufacturers, been moved to New Jersey, and loaded on ships, and we even knew they had arrived in England. But then they had simply vanished. Eventually a more-demanding signal arrived from 8th Air Force headquarters: “Where are the Carpet jammers that were sent?”

Obviously matters had come to a head. The business of finding the missing jammers was considered to be a liaison task and was given to our department. Terman and Cullem took council and decided, “Someone’s got to go to England and straighten things out!” The someone they picked was me. In June 1944, I was flown to England and sent to 8th Air Force headquarters near London. My main qualification to take part in the search was that I would be able to recognize a Carpet when I saw one. Not many others in England could do that.

After a couple of weeks at the various Base Air Depots in England, examining pile after pile of equipment stacked floor to ceiling in the numerous huge storage hangars, we finally came upon the missing Carpets. They were hidden away in the corner of one of the buildings. I asked the noncom in charge what they were doing there. “I’m blessed if I know,” he replied. “Those numbers aren’t in my Signals Corps catalog!”

Once we had informed 8th Air Force of the whereabouts of their missing jammers, they moved with impressive speed. Shortly afterwards, trucks began to converge on the depot to collect the precious Carpets and rush them to the front-line bomber airfields.

I stayed in Europe doing various odd jobs for the remainder of 1944 and returned to Harvard early in 1945. By then it was clear that the war was not going to continue for much longer, and Terman asked me to help in writing the wartime history of the RRL. By the time that was done, Japan had surrendered and the Laboratory had started to disband itself. I returned to Stanford to complete my graduate work.

From an interview by Dr. Alfred Price conducted during research for his three volume series of books entitled The History of US Electronic Warfare.


Post a Comment

<< Home