Detecting police through radio tranmissions and "leakag

Anyone know of systems that would detect some of the radio signals from police vehicles?

I am not interested in eavesdropping since that can be illegal and tough with encrypted channels.

What I am interested in knowing is if anyone makes a device that finds sources in the 800Mhz range or other "public safety" bands and then lets you detect their direction and distance?

I've also heard that many police vehicles today have an onboard computer to let them access databases. Again, I don't want to eavesdrop but it would be nice to be able to "home in" on such signals so that I can determine their distance and bearing.

I am hoping to supplement radar and laser detectors with equipment that lets me know when police vehicles are close by.

Gene

The closest thing to what you are looking for the the "Highway Patrol Alert" or "Beartracker" feature of some Uniden scanners: the BCT-7, BCT-8, BCT-10, and BCT-12 all have this feature, as well as the RadioShack Pro-2051 since it was somewhat of a clone of the BCT-8. The BCT-8 is the only one of these scanners that is still produced.

and the BCT-15 also has it.

but these are all analog scanners the digital scanners do not have it the beartracker system. how they work is that if an offecer is away from his car and he uses his radio, which uses a repeater in the trunk to transmit the beartracker can pick up these low level signals and alert the user. the thing is the new digital systems I don't think use repeaters.


what state do you live in? having a scanner in your car is only really illegal in Indiana. I believe all the other states that have laws against them allow you to have one in your car if you have a Ham license. NY is the only iffy state as to the legality of having one in a car.