- First Name
- A. J.
- Dec 8, 2019
- Reaction score
- Tesla X LR+, Lexus SUV, Toyota SR5, Toyota Landcruiser
- EE (Retired)
No idea who or what JB is (Justerini and Brooks?) but I am old enough to remember Dick Tracy's "Wrist Radio". And I remember a 1950 issue of IRE (yes, I'm even old enough to remember when IEEE was IRE) Spectrum in which the big names in the industry were asked to predict where we would be by the end of the century (2000) with respect to communications, computing, consumer electronics etc. One of the hotshots predicted that there was no way we would have hand held telephones by 2000. Today my wife has Dick Tracy's wrist radio on which she can make video calls anywhere in the world that has internet.Yeah pretty crazy whats in your phone. I remember dreaming as a boy, whilst playing with the grownups CB, of a handheld device I could videocall anywhere in the world to. You know JB style.
I was going to suggest you look up "PPI Stealer" on the web but when I tried to do so, I found nothing. This is what we used to call multistatic passive radar in the old days. The problem I see with passive multistatic in a car is with the A matrix I referred to in No. 154. In the old PPI stealer days you knew exactly where you were and exactly where the TV stations were and had a general idea as to wherer the airways ran. In a moving car with moving targets and moving "illuminators" the problem is much more difficult and with the accuracy required it seems that an active sensor is a much better solution. TOA is much easier to measure than TDOA. You know exaxtly where the clock is and you control it! The range element of Kp is small because the range component of A is 1.00000. Always. The azimuth and elevation elemnts? Well not so good. But, of course, range in the direction of the velocity vector is the most important measurement of all. Tesla claims they can get a measurement of that of sufficient quality from the cameras. I guess I don't see how they can do that at night if the guy in front of you decides to turn off his tail lights or in fog. But they, who certainly understand the problem better than I do, say that doesn't matter.But thats sort of the point of passive SDR radar, you use all mobile signals as RF sources to see the environment. Its surprising how well it works with so little hardware, its a bit like little torches lighting up the world but in invisible RF.