How did you get into engineering?
I don’t think I ever thought of myself as anything other than an engineer. It was not a serious question to me. When I was young, I made electronic amplifiers from scratch. This was back in the era of vacuum tubes, and they were all discrete components. I went to the US Naval Academy in Annapolis and education there was principally engineering, so I felt right at home. I graduated and went out in the Air Force as an engineering officer, and there I was trained in aircraft avionics.
Whose idea was it to create GPS?
There had been a previous satellite navigation system called Transit. It was, by our standards, quite crude, but it was worldwide. GPS can provide 24/7, 365 days a year coverage to the whole Earth, and Transit couldn’t do that. It would give you a relatively crude fix once every two or three hours. It was good enough for some Navy ships, but it wasn’t good enough to land aeroplanes. A study was done, and 12 techniques were highlighted as ways to navigate using space satellites. We selected the hardest, which provided four dimensions: latitude, longitude, altitude and very precise time. Two important breakthroughs had to occur. First we had to come up with a signal that was very unique. Back then we were experimenting with a new signal that was so quiet that if you looked at the radio spectrum you wouldn’t see it at all. Now everyone accepts it as a GPS signal, but there was great scepticism that it could be good enough to navigate. Today we navigate to a millimetre with it. Secondly, we wanted the satellites to go around the Earth, be autonomous and have clocks with stability better than one second in 300,000 years. We were trying to measure time to a fraction of a billionth of a second.
How did the Air Force respond?
The Air Force did not want this system; they fought it tooth and nail. I got in a lot of trouble in the Pentagon. I remember the two-star general taking his finger and sticking it in my chest and saying: “Parkinson, if you keep advocating this your career is going to go down in flames.”