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Thread: police laptop\radio frequency

  1. #21
    FLAC
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    see, EQN is getting it. I'm not sure if your area does this, they actualyl scatter the firequences across 29 channels. its called Trunking. Uniden and Bearcat make a scanner that follows it so you get the whole conversation, that's called TrunkTapping. There si software out there that allows you to connect these scanners to yoru computer. i BELIEVE, cause we wanted pinpoint accuracy, not just "spidey sense" warning, so we pretty much glazed over this, you CAN build a radar like system based on, among things, signal strenght as each vechicle is an emitter wiht, if you get the cop car manufacturer's specs, a predicatble output and at a predictable frequency (29 predicatible ones). A cop answers a call, you won't know where he is, but you will know if he's close. If you're really clever, and have a few friends driving at the same time, you can triagulate using streamed data, to be processed and the redistributed form a single source, via the internet. Once agian, we were taking a different route, so we never researched it. If a few of you want to come up with something, please, make a nice thread that we can all read. I mean, FM can be used to measure

    http://www.eng.ox.ac.uk/~comwww/radar/fm.htm

    and track
    http://www.jbgizmo.com/page21.html

    so let's seen a intrepid mind take this up
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  2. #22
    Constant Bitrate S2K12's Avatar
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    do radar detectors detect cop cars or just speed traps?

  3. #23
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    Quote Originally Posted by Genesisfactor
    see, EQN is getting it. I'm not sure if your area does this, they actualyl scatter the firequences across 29 channels. its called Trunking. Uniden and Bearcat make a scanner that follows it so you get the whole conversation, that's called TrunkTapping. There si software out there that allows you to connect these scanners to yoru computer. i BELIEVE, cause we wanted pinpoint accuracy, not just "spidey sense" warning, so we pretty much glazed over this, you CAN build a radar like system based on, among things, signal strenght as each vechicle is an emitter wiht, if you get the cop car manufacturer's specs, a predicatble output and at a predictable frequency (29 predicatible ones). A cop answers a call, you won't know where he is, but you will know if he's close. If you're really clever, and have a few friends driving at the same time, you can triagulate using streamed data, to be processed and the redistributed form a single source, via the internet. Once agian, we were taking a different route, so we never researched it. If a few of you want to come up with something, please, make a nice thread that we can all read. I mean, FM can be used to measure

    http://www.eng.ox.ac.uk/~comwww/radar/fm.htm

    and track
    http://www.jbgizmo.com/page21.html

    so let's seen a intrepid mind take this up
    Its Trunktracking not TrunkTapping.

  4. #24
    FLAC
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    hehe my bad, thanks! Worse part is i was reading the specs on a uniden model AS I WAS TYPING IT. I really got jacked up in that accident:P

    Radar detects detect radar guns (what cops use for speed checking). I've heard the only good one was taken off the market cause it actually worked, although i can't recall its name

    Ofcourse none of this helps with speed cams...unless you drive 175+ mph
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  5. #25
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    What locality is it? Are they conventional or trunked?

  6. #26
    FLAC
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    i think most locals moved to trunked.
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  7. #27
    Constant Bitrate
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    I'm interested in the FM Tracking, but you would need to make something that could receive on all 29 frequencies first, and give you the amplitude of the wave.

    Can I ask, does anyone know how the Bear Scan knows which frequency will be used to transfer data the next 10ms? Does the previous frequency carry data that tells the reciver what frequency to switch to next?

    It would be possible to triangulate using the methods Genesisfactor posted using three scanners on a single car, however the measurements would have to be very precice since the radio's would be so close together.

  8. #28
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    If the FM freq Hops are anything like that of the Military radios that do somthing similar, they are syncronised regulaly, and then are all put in to the same hop scope.

    We would ahve to set the inital freq, sync with a Master freq, and then the radio would know the Hop scope based on timming and code entry.

    This is Over simplified as it's been 15 years since I was an radio Op in the military, and its kinda hard to remember all that

  9. #29
    FLAC
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    i lost my response. in short, there's no way to do in car triangulation from a single source. Too manu variables and interferance factors. I mean, for all the work, it'll be like a better radar detector that tracks all cops, not just those around. Fun project though.

    I did have a few questions on the possibility of reverse engineering the CTCSS and if we could send a squlech that would make all the corresponding radios squelch back (making like a radar system), but i don't know and i wouldn't be building this. I'm got another project outsideof the CPC i want to focus on:P. I'll be reading, so good luck guys! I'm very interested in your progress!
    Carputer Progress: Here we go again...

    THE GF THEME
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    Join the fight against carputters. EMAIL ME!

  10. #30
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    Quote Originally Posted by Genesisfactor
    i lost my response. in short, there's no way to do in car triangulation from a single source. Too manu variables and interferance factors. I mean, for all the work, it'll be like a better radar detector that tracks all cops, not just those around. Fun project though.

    I did have a few questions on the possibility of reverse engineering the CTCSS and if we could send a squlech that would make all the corresponding radios squelch back (making like a radar system), but i don't know and i wouldn't be building this. I'm got another project outsideof the CPC i want to focus on:P. I'll be reading, so good luck guys! I'm very interested in your progress!
    I think I have come to the conclusion that you have no idea what the hell you are talking about in this realm. First you state that most agencies are switching to trunking. THat just is not true. They are not required to, and most will not because of the robust infrastructure they currently have in place.

    The polcie and emergency vehicles DO NOT SEND A SIGNAL TO EACH OTHER, except over the regular radio system. The system to alerts the lights to approaching vehicles is almsot always a strobe light that triggers a sensor on the light pole. Trust me, I have tried it and gotten it to work once or twice. (please read http://www.kvoa.com/Global/story.asp?S=4783704)

    What the eff is reverse engineering a CTCSS tone. There is nothing to reverse engineer. Tones are freely published. Sending a CTCSS tone (which actually can't be done with out a rf signal (CTCSS is a "subcarrier")) will do nothing to a mobile or portable except to break it's squelch. The radio DOS NOT SEND OUT A SIGNAL OR RESPONSE WHEN IT HEARS A SIGNAL WITH THE PROPER TONE. What kinda stupipd thought is that. Do you think that every single radio sends a response/signal when another officer tranmits, or the dispatcher transmits. That would just clog the system. You really have no clue about this stuff, do you?

    I am soooo glad to hear that you have left the discussion, because you are totally clueless when it comes to this stuff.

    Michael
    ...I love the French language...especially to curse with...Nom de Dieu de putain de bordel de merde de saloperies de connards d'enculés de ta mère. You see, it's like wiping your *** with silk, I love it.

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