3 ms·

So does this mean you could listen to police/fire radio and such like back in the old days?

runjake 11y ago
Depends on the city/county. Most in the US are on P25, which has been listenable by clued members of the populace, but many (most?) are now encrypting traffic (usually w/ AES, iirc).
- jlgaddis 11y ago
  Unencrypted transmissions are easily received by scanners (note, though, that older scanners can't pick up P25) -- they aren't cheap, though (I think mine was ~$450 USD). In my area, one local police department is the only agency that has chosen to encrypt their communications. It is, supposedly, also possible to pick up P25 using RTL-SDRs, though I've never tried so I can't say for certain.
  - viraptor 11y ago
    If the wikipedia information is right (6.25kHz signal at ~700MHz), then it should be trivial on RTL-SDR. Just need the right antenna.
    - gbin 11y ago
      From my experience: You usually need 2 dongles and the software under Linux to do it is barely existing unfortunately.
      - viraptor 11y ago
        So is wiki not correct, or am I reading it wrong? Is the channel bandwidth larger than 6kHz?
- nosy_russian 11y ago
  I wonder what they use in Russia? Cursory look [1] suggests it's the old analogue standard. Does it mean CB? Is there a public list of which protocols the police use, by country? [1] https://habrahabr.ru/post/145973/ https://habrahabr.ru/post/145973/
- toomuchtodo 11y ago
  Can you request the AES decryption key with a FOIA request?
apaprocki 11y ago
Lots of places are still unencrypted -- e.g. in NYC the PD & FD dispatch are unencrypted UHF. Looking at a huge waterfall of Brooklyn NYPD on a $20 SDR dongle -> https://imgur.com/VukYvB6 https://imgur.com/VukYvB6
maxerickson 11y ago
You can stream them today: http://www.broadcastify.com/ http://www.broadcastify.com/ (I guess there must be other services, that's the one my local department shows up on)
jlgaddis 11y ago
Yes. Check Radio Reference [0] for frequencies in use in your area (assuming you're located in .us). [0]: https://www.radioreference.com/ https://www.radioreference.com/
kabdib 11y ago
Oh yes. Also, cell phone conversations, the radio trunk lines used by private dispatchers (taxi cabs, delivery and construction trucking firms), public utility fleets, you name it. Even into the late 90s you could buy a cheap Radio Shack scanner, dyke-out some diodes (put there to lock out certain frequency ranges, per some FCC rules) on the motherboard and listen in to all kinds of things.

Depends on the city/county. Most in the US are on P25, which has been listenable by clued members of the populace, but many (most?) are now encrypting traffic (usually w/ AES, iirc).

jlgaddis 11y ago
Unencrypted transmissions are easily received by scanners (note, though, that older scanners can't pick up P25) -- they aren't cheap, though (I think mine was ~$450 USD). In my area, one local police department is the only agency that has chosen to encrypt their communications. It is, supposedly, also possible to pick up P25 using RTL-SDRs, though I've never tried so I can't say for certain.
- viraptor 11y ago
  If the wikipedia information is right (6.25kHz signal at ~700MHz), then it should be trivial on RTL-SDR. Just need the right antenna.
  - gbin 11y ago
    From my experience: You usually need 2 dongles and the software under Linux to do it is barely existing unfortunately.
    - viraptor 11y ago
      So is wiki not correct, or am I reading it wrong? Is the channel bandwidth larger than 6kHz?
nosy_russian 11y ago
I wonder what they use in Russia? Cursory look [1] suggests it's the old analogue standard. Does it mean CB? Is there a public list of which protocols the police use, by country? [1] https://habrahabr.ru/post/145973/ https://habrahabr.ru/post/145973/
toomuchtodo 11y ago
Can you request the AES decryption key with a FOIA request?

apaprocki 11y ago

Lots of places are still unencrypted -- e.g. in NYC the PD & FD dispatch are unencrypted UHF. Looking at a huge waterfall of Brooklyn NYPD on a $20 SDR dongle -> https://imgur.com/VukYvB6 https://imgur.com/VukYvB6

maxerickson 11y ago

You can stream them today: http://www.broadcastify.com/ http://www.broadcastify.com/ (I guess there must be other services, that's the one my local department shows up on)

jlgaddis 11y ago

Yes. Check Radio Reference [0] for frequencies in use in your area (assuming you're located in .us). [0]: https://www.radioreference.com/ https://www.radioreference.com/

kabdib 11y ago

Oh yes. Also, cell phone conversations, the radio trunk lines used by private dispatchers (taxi cabs, delivery and construction trucking firms), public utility fleets, you name it. Even into the late 90s you could buy a cheap Radio Shack scanner, dyke-out some diodes (put there to lock out certain frequency ranges, per some FCC rules) on the motherboard and listen in to all kinds of things.