Last time you said you’d talk about your return to civilian life.
Right. Well, before I left Chicago I sent resumes to several companies. And by then I had a good deal of experience in electronic testing. Two aircraft companies in California made offers, but also I received an invitation to visit and interview at Westinghouse in the Baltimore area.
What was that installation called?
It was a complex adjacent to the Baltimore airport. They changed names over the years. Air Arm. Electronic Systems. But the one I think was most descriptive was the Westinghouse Defense and Space Center.
The activity that interested me was their development of airborne radar. That’s the kind that fits in the nose of fighter aircraft.
And the plant was adjacent to the airport for good reason. So they could use the airport facilities to test their airborne systems. They had a test-bed aircraft that could hold their electronic equipment so they could test the systems in the air.
So how did you fit into this picture?
It was my background in testing that they wanted. As the other engineers were developing the several parts of the radar — receiver, signal processor, and such — they wanted to be able to test them on the ground, before loading the whole system into the plane and flying it. So I was to build a so-called Target Simulator that would generate a signal that would look to our radar like the transmitted signal reflected off the target aircraft.
And you took the job?
Yep. Sounded interesting, and it was. You see, the radar signal was somewhat complex so my simulator’s signal had to match it.
How’s that?
The radar was called Pulse Doppler. PD, for short. It was to track a target in both range — the distance to the target — and velocity — the Doppler shift due to the target’s speed. Want an explanation?
Please.
Well, it’s easier to explain with sound waves, rather than radio waves. The principle is the same. Except that radio waves travel at the speed of light and sound waves travel at the speed of sound.
Now, the speed of sound varies with atmospheric conditions, but let’s say that sound travels at 1100 feet per second. Okay? Now, assume you’re standing on one side of a canyon. And that you yell “Hey!” What happens?
An echo comes back.
Right. And if, for instance, the echo comes back 2 seconds later, then the distance between you and the other side must be 1100 feet. You see? 1100 feet each way.
Okay.
And that’s how the radar works. Except that it does its thing at the speed of light, which is a whole lot faster.
Got it.
Now, the Doppler shift is the change in frequency because the target is moving. If it’s coming toward you, the frequency coming back is higher than what you transmitted. If the target is moving away, the frequency coming back is lower.
Okay, I guess.
An easy example with sound waves is the bell that a railroad engine rings. You’ve probably heard it. When the train is coming toward you the sound is higher than normal.
And, after it goes through the station, the sound is a lower note.
I’ve noticed that.
That’s the Doppler effect. Coming at you, the sound waves travel at the speed of sound plus the speed of the train. Going away, it’s the opposite: the speed of sound minus the speed of the train.
So that’s another way a radar can track a moving target. Radar echoes are also coming back from the ground, but the ground isn’t moving while the target is. With the proper filters, the radar can distinguish one from the other.
I see.
Previous radars had tracked target aircraft with pulses and others with the Doppler effect. What Westinghouse was developing combined the two. Thus, the Pulse Doppler radar.
Okay. Thanks for the mini-course in — what did you call it? PD?
Right. Anyway, they set me up with a desk in the office and with a workbench in the lab.
The lab had electronic test equipment and hardware and other supplies to do the job. And you know what was interesting? Remember the oscilloscope I used at the Quartermaster Depot in the Army? Remember those photos of me testing the cushioning material? I used a Tektronix, and, it turns out, Westinghouse had them too.
They were a favorite because they had plug-in modules that enabled you to do various tasks.
Anyway, the radar the engineers were developing was called a flying breadboard. That is, it wasn’t to be a finished package such as in the photo I showed you when we started today. Rather, each unit was built on a chassis or breadboard.
And each chassis fit into a rack.
Then the whole rack was flown in our aircraft to test the system. Well, my Target Simulator was put together the same way. Except, of course, it didn’t fly. It was assembled in our rooftop lab — we called it The Penthouse — where the radar was being assembled.
And how did it work out?
Pretty well. The signal it fed to the radar had the characteristics of an actual echo from a target aircraft. That is, with the time delay and Doppler shift that I talked about before. After we proved the concept of a workable PD radar, engineers in another department designed a working radar that fit in the nose of a fighter aircraft.
Later the same concepts went into the design of the AWACS radar. Have you heard of that?
I think so.
That’s the one with the big rotating antenna on top.
I went on to build a Target Simulator for the radar in a Bomarc missile. That’s an air-breathing missile — not ballistic — that is intended to track and collide with the target aircraft.
The Bomarc was eventually phased out of the inventory, but the F-16 aircraft with our radar has been going strong. And sold to other countries too.
What did you do after that?
Actually, I moved on to another phase of my engineering career. But let’s leave that for the next time.
Okay. See you then.