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Thread: "How To Build a $19.00 Police Scanner"

  1. #11
    'Grumpy old bastid' kb2vxa's Avatar
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    "...in 2010 the whole city and county went to a 800 MHz Digital Trunk system and every VHF and UHF scanner in the city became useless, people were giving them away."
    Smart hobbyists who know there's more out there than the local cop shop sure got a windfall bargain when the dummies who think that's all there is did that... LO firkin L!
    "The universe is under no obligation to make sense to you."
    Neil deGrasse Tyson

    73 de Warren KB2VXA
    Station powered by atomic energy, operator powered by natural gas.

  2. #12
    Master Navigator koØm's Avatar
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    Quote Originally Posted by silverf0x
    Just throwing this out there:


    Blah-blah-blah


    But I was thinking for those of us with our HAM licenses (we're good guys too!), it could/would make sense if we were legally allowed to own a scanner that would decrypt the P25 signal. This is a big IF Uniden/Whistler/etc. even made scanners to decrypt the signal.


    Anyway, I wanted to throw that out there in case it was a popular opinion and would maybe pick up steam and be lobbied to the FCC to make it happen (crossing fingers).

    Quote Originally Posted by mmckenna
    I understand what you are saying, but as a guy who runs a system that includes encrypted law enforcement channels, HELL NO.


    Amateur radio operators don't have any need to have access to encrypted traffic. Amateur radio operators are no different than anyone else, the passing of a multiple choice test doesn't make them "special".


    As someone who works on and around these systems, including inside a dispatch center, I've got to have all kinds of background checks, training, security rules/regulations, etc. The fact that I actually have an amateur radio license (General) doesn't mean anything to the people that I work for.


    I fully understand that encryption is a issue for hobbyists, but keep in mind that listening to a scanner -is- a hobby. It should not be confused with being an actual public safety professional. I hold encryption keys for our system, and there is no way I'd give them out to anyone, even an amateur radio operator. I don't even give them to our officers. They get loaded in the radios when we program them, and that's it.


    FCC isn't going to approve this. You are welcome to try, but I think you'll be disappointed.


    And just because someone is an amateur doesn't automatically make them an upstanding citizen; just look up KB7ILD for starters....
    Funny stuff from over there.


  3. #13
    "Island Bartender" KG4CGC's Avatar
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    So, it is some time later. Has the SDR revolution evolved?

    I've been looking at this: https://www.amazon.com/Receiver-Diss...ps%2C82&sr=8-9

  4. #14

  5. #15
    Administrator N8YX's Avatar
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    DSD Plus and SDRs are being used by a number of folks to track the trunked stuff.

    What renders it moot is when an agency decides to encrypt ALL communications, rather than just tactical (i.e., SWAT or narco) comms. Something about "If you have nothing to hide..." come to mind?

    Fortunately, there IS a fix for this. It doesn't involve decryption but it does involve a lot of community cooperation in terms of system development and infrastructure support. The proposal makes use of an intrinsic function of trunking systems and a function of a number of receivers that can receive the data streams.

    First, ALL TGID/fleet/unit information must be broadcast "in the clear" in order for users from different agencies to subscribe to a common system. Their payloads - the actual voice or data traffic - can be encrypted without affecting the sharing capabilities of mutual-subscriber systems. Second, many scanners now incorporate a so-called "Close Call" function and will output signal-strength information (along with Close Call status) through their serial ports.

    We take advantage of this and build a visualization system similar to the old Etherape network protocol display. A GPS-derived map of a user's location is accessible at an URL or through mobile app; receivers which support the required data feeds can be installed throughout an area. An analysis system similar to a repeater voter is employed to do dynamic triangulation of received signals. Obviously, the more receivers in a given area and listening to a given system the more precise the locating abilities will be.

    Types of mobiles are identified by their TGID numbers and are color-visualized on the map. Higher confidence triangulations are brighter and don't fade with time; each occurrence of a mobile transmission merely boosts the location confidence factor in the algorithm. Mobile users will have the ability to provide unit verification (e.g., agency and patrol car number, truck or squad number) via the app when within range of a broadcasting unit, and a confidence ranking will be attributed to their data inputs based on co-user and RF ID correlation. This attempts to keep users "honest".

    I'd like to see a PC app developed to interface the scanner...ultimately ending up with a Raspberry Pi which could be networked, connected to a scanner and left to gather data to forward along.

    Should an area voluntarily broadcast their daily operations comms in-the-clear, I do not and will not support the use of this type of auto-locating setup. But for everyone else: We don't care what you have to say. We just care WHO and WHERE you are.
    "Everyone wants to be an AM Gangsta until it's time to start doing AM Gangsta shit."

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  8. #18
    Forum Addict n6hcm's Avatar
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    yeah. I just bought a fancy scanner over the Xmas holiday. life is too short to fuck around with crap instructions,...
    "... and another thing about you democrats ... you all believe in science!" -- denny crane

  9. #19
    Master Navigator K4PIH's Avatar
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    2 years more than that Hitler thing.
    "Don't put it on the plate if you can't eat it!"

  10. #20
    "Usual Suspect" WZ7U's Avatar
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    Quote Originally Posted by K4PIH View Post
    2 years more than that Hitler thing.
    Prediction on the length of tRumps reign of terror?

    Like that post was...
    Moving on, my posts are not helpful

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