said by Blackbird:said by aurgathor:What would be some effective ways to detect nearby police car(s) when their radar is turned off, and when they are not visible for one reason or another? ... I'm thinking about the combination of various electronic signatures, but I'm not sure if they use unique frequencies, or what exactly is in their cars. ...
Even if their cars contained police-only unique radio gear besides any radar, if that equipment wasn't itself transmitting, there'd be few useful emissions to detect and process. Unless, of course, you dug way down into the noise to correlate out their receiver local-oscillator/synthesizer leakage, etc... and unless you could also DF and range-capture on such signals in a meaningful way to allow your processing system to decide if the source was nearby or just some random capture from miles away.
The technology to do all that actually does exist, but it's generally used in other arenas. You can't afford it. And you probably can't obtain it legally. And if you did have it, you'd probably need a trained EWO to operate it while you drove merrily on down the road.
Wouldn't it be just a tad easier to make sure to drive under the speed limits...?
its interesting you say that.
many years ago, i did exactly just that.
in my county during that time, police vehicles were equipped with VHF transcievers.
i discovered what the local oscillator frequecny output was from these radios (the frequency changed depending on the transciever channel).
i setup a highly sensitive scanner with a short range omni cut for a certain radius of those frequencies.
while this method did indeed work, i found the distance not too pleasing, 50 feet to the police vehicle and i started to pickup a signal, by then, its a bit too late.
now my county uses a trunked 800Mhz system with GPS and a data terminal.
the next step i have is to go to a vehicle (officer is a friend of mine) with my hand held freq counter and see what solid freq pops up continuously (data term, GPS).
but lately, i havent really found a need to do this as my instincts and eye seem to be much better.