frank@snowy.rice.edu (Franklin Tae-Sung Kang) (06/20/91)
In article <8641@awdprime.UUCP> daryl@vixen.Berkeley.EDU () writes: >A couple of years ago, I saw an ad in Car & Driver (or one of the others) >that offered a detector which tuned in to the repeater frequencies that >the car radios in police cars use to forward received transmissions to >the officer's portable walkie-talkie. Does anyone know the frequencies of this broadcast? It sounds like it would be relatively easy to make. Perhaps this is the CHiPs detector advertised in the back of C&D all the time. Also, does anyone truly know the range of these broadcasts? Frank
khan@mrcnext.cso.uiuc.edu (Scott Coleman) (06/22/91)
frank@snowy.rice.edu (Franklin Tae-Sung Kang) writes: >In article <8641@awdprime.UUCP> daryl@vixen.Berkeley.EDU () writes: >>A couple of years ago, I saw an ad in Car & Driver (or one of the others) >>that offered a detector which tuned in to the repeater frequencies that >>the car radios in police cars use to forward received transmissions to >>the officer's portable walkie-talkie. >Does anyone know the frequencies of this broadcast? It varies from state to state and area to area. For a list of frequencies which are used where you live, stop by your nearest Radio Shaft and pick up a copy of the Police Call book. It lists all the frequencies for a 4-state area. >It sounds like >it would be relatively easy to make. Or you could buy a portable scanner for your car. In some states this is illegal, however. -- Scott Coleman tmkk@uiuc.edu University of Illinois at Urbana-Champaign "The military particularly liked Prodigy because the censorship came for free." - Andrew Grove on the use of email services to send mail to troops in the gulf
mcovingt@athena.cs.uga.edu (Michael A. Covington) (06/23/91)
The trouble with trying to detect police cars by listening to their radios is that the range is too good. There is *always* a police car close enough to you to give a strong signal. In fact there are always ten or twenty, unless you live in the Mojave Desert. Not only that, but signal strength is not a good indicator of proximity. Base stations put out a strong signal over a 20-mile radius. Cars put out a signal that varies depending on exactly what is between you and it. Finally, the police car standing still at a speed trap is not likely to be transmitting anything. -- ------------------------------------------------------- Michael A. Covington | Artificial Intelligence Programs The University of Georgia | Athens, GA 30602 U.S.A. -------------------------------------------------------
mzenier@polari.UUCP (Mark Zenier) (06/23/91)
In article <1991Jun22.175649.8327@athena.cs.uga.edu> mcovingt@athena.cs.uga.edu (Michael A. Covington) writes: >The trouble with trying to detect police cars by listening to their radios >is that the range is too good. There is *always* a police car close enough >to you to give a strong signal. In fact there are always ten or twenty, >unless you live in the Mojave Desert. The police car detectors only work in cases like the California Highway Patrol, where the car <> base signals use Low Band VHF, and in each car the signals are repeated on a higher frequency, one that works better for handheld radios. There is still a lot of empty space in California, so it's easier to carry your repeater along with you than build a system that can pick up watt level signals on every lonely highway. Mark Zenier markz@ssc.uucp mzenier@polari.uucp
khan@mrcnext.cso.uiuc.edu (Scott Coleman) (06/23/91)
mcovingt@athena.cs.uga.edu (Michael A. Covington) writes: >The trouble with trying to detect police cars by listening to their radios >is that the range is too good. There is *always* a police car close enough >to you to give a strong signal. In fact there are always ten or twenty, >unless you live in the Mojave Desert. The secret is not merely to listen for the presence of a police car, but also the location. Whenever a cop changes status, he radios in to the dispatcher to let them know what he's up to. If he's 10-8, it means he's coming back on duty after a break (at the donut shop?). If you hear one unit call for another unit to 10-25 in the 7-11, that means that the two cars in question are going to go park in a convenience store parking lot, each facing in the opposite direction, and chew the fat. Around here, if you hear a unit going "code 34 at <location>" it means he's going to whip out his radar gun and start enhancing the city coffers. OK, so it requires more effort than using a radar detector. On the upside, if you hear over your scanner the exact location where the cop is waiting with his radar, isn't that BETTER than a radar detector? This technique even works against instant-on and LIDAR (so-called "laser radar"), which no detector on the market will protect you from. >Finally, the police car standing still at a speed trap is not likely to be >transmitting anything. Au contraire. For each and every speeder he pulls over, he calls into the dispatcher for a licence and registration check. If you're cruising around, and you hear One-Adam-Twelve calling in a bunch of 10-27s, chances are good he's taking pictures. Just keep listening until he relays his 10-20 to dispatch, and steer clear of the area. Now, you nitpickers in the audience who are just itching to hit 'F' and tell me how this ain't gonna work in all situations, please save your energy. ;-) I already know there are limitations to this idea; I merely present it as a possible component of a multi-faceted revenue enhancement defense plan. A scanner, a radar detector, a CB, some RAM for your bra ;-), a CHiPs Detector, a radar communicator, and a Corvette would be quite an effective combination, don't you think? -- Scott Coleman tmkk@uiuc.edu University of Illinois at Urbana-Champaign "The military particularly liked Prodigy because the censorship came for free." - Andrew Grove on the use of email services to send mail to troops in the gulf
frank@snowy.rice.edu (Franklin Tae-Sung Kang) (06/24/91)
In article <khan.677690564@mrcnext.cso.uiuc.edu> khan@mrcnext.cso.uiuc.edu (Scott Coleman) writes: > >defense plan. A scanner, a radar detector, a CB, some RAM for your bra ;-), >a CHiPs Detector, a radar communicator, and a Corvette would be quite an >effective combination, don't you think? Don't you mean a mouse gray Taurus SHO, Infinity Q45 or perhaps a Lexus coupe? You gotta maintain the visual blandness you know! I'm working on the ultimate defense - an invisible car. Just like Wonder Woman's plane. That failing, I'll contact the Romulans to purchase a Romulan Cloaking Device. :-) :-) Frank
dil@mace.cc.purdue.edu (Perry G Ramsey) (06/25/91)
In article <khan.677690564@mrcnext.cso.uiuc.edu> khan@mrcnext.cso.uiuc.edu (Scott Coleman) writes: >mcovingt@athena.cs.uga.edu (Michael A. Covington) writes: > >The secret is not merely to listen for the presence of a police car, but >also the location. Whenever a cop changes status, he radios in to the Of course, what you are talking about is using a police band receiver in commission of a crime, something that is illegal in most states. We who what to carry radios for legitimate purposes have no end of trouble because of those who want to carry one in support of illegal activities. For more flames on this issue, see rec.radio.amateur.misc. Yes, I know that 55 (even 65 under most circumstances) is a stupid speed limit. -- Perry G. Ramsey Department of Earth and Atmospheric Sciences dil@mace.cc.purdue.edu Purdue University, West Lafayette, IN USA perryr@purccvm N9LFF
tmkk@uiuc.edu (K. Khan) (06/25/91)
In article <7830@mace.cc.purdue.edu> dil@mace.cc.purdue.edu (Perry G Ramsey) writes: >In article <khan.677690564@mrcnext.cso.uiuc.edu> khan@mrcnext.cso.uiuc.edu (Scott Coleman) writes: >>mcovingt@athena.cs.uga.edu (Michael A. Covington) writes: >> >>The secret is not merely to listen for the presence of a police car, but >>also the location. Whenever a cop changes status, he radios in to the > >Of course, what you are talking about is using a police band receiver >in commission of a crime, something that is illegal in most states. Driving is a crime? 's news to me!! >We who what to carry radios for legitimate purposes have no end of >trouble because of those who want to carry one in support of illegal >activities. For more flames on this issue, see >rec.radio.amateur.misc. I remind you that my post said nothing about breaking any laws. We who want to post to Usenet for legitimate purposes have no end of trouble because of those who want to jump all over us because they ASSUMED we were talking about something we weren't. ;-) >Yes, I know that 55 (even 65 under most circumstances) is a stupid >speed limit. Agreed. As the report published in C&D noted, many speed limits are set artificially low. For more flames on this topic, see rec.auto.driving. ;-) ;-) ;-) To those of you reading along, let me reiterate that I do not condone the use of police band receivers in the commission of any crime, which as is pointed out above an illegal act. The discussion was merely academic.