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Thousands are monitoring police scanners during the George Floyd protests

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Re: Thousands are monitoring police scanners during the George Floyd protests

#41

Post by oasisbob »

swebs wrote: post #32
empath75 wrote: post #7

I'm surprised they didn't mention that someone in Chicago seems to have stolen a police radio and has been trolling them for days.

I'm pretty sure any $30 Baofeng will let you broadcast on these frequencies.

Any trunked radio system hops between frequencies enough that this wouldn't work.

Individual radios get "paged" on a control channel and told where to receive. Eg, "Radios tuned to the police talk group, go to frequency X now." The speaker, when transmitting, gets assigned a frequency on the fly.

A baofeng could stomp on a transmission, but nobody would follow it otherwise.

Re: Thousands are monitoring police scanners during the George Floyd protests

#42

Post by oasisbob »

dmkolobov wrote: post #9
Simulacra wrote: post #3

Most of our local departments use encrypted radios. "Over the past few years, an increasing number of municipalities and police departments, including the District’s, have begun encrypting their radioed communications.."[1.] https://www.washingtonpost.com/local/social-issues/last-of-t...

Completely outside of my area of expertise, so this may be a silly question, but are police transmissions distinguishable from others in their encrypted form? If so, there could still be a use case for knowing _where_ the cops are. Wonder if some sort of mesh could be used to triangulate the positions of these signals.

You could look for the repeater uplink, maybe.

Keep in mind that these public radio systems are often used by firefighters and other agencies.

Finding police specifically would probably involve some sort of metadata leak in the radio signaling protocols.

Re: Thousands are monitoring police scanners during the George Floyd protests

#43

Post by blantonl »

oasisbob wrote: post #41
swebs wrote: post #32

Earlier quoted context omitted.

I'm pretty sure any $30 Baofeng will let you broadcast on these frequencies.

Any trunked radio system hops between frequencies enough that this wouldn't work. Individual radios get "paged" on a control channel and told where to receive. Eg, "Radios tuned to the police talk group, go to frequency X now." The speaker, when transmitting, gets assigned a frequency on the fly. A baofeng could stomp on a transmission, but nobody would follow it otherwise.

Chicago uses a straight analog repeater system

Re: Thousands are monitoring police scanners during the George Floyd protests

#44

Post by ryanlol »

dmkolobov wrote: post #9
Simulacra wrote: post #3

Most of our local departments use encrypted radios. "Over the past few years, an increasing number of municipalities and police departments, including the District’s, have begun encrypting their radioed communications.."[1.] https://www.washingtonpost.com/local/social-issues/last-of-t...

Completely outside of my area of expertise, so this may be a silly question, but are police transmissions distinguishable from others in their encrypted form? If so, there could still be a use case for knowing _where_ the cops are. Wonder if some sort of mesh could be used to triangulate the positions of these signals.

Often they are, yes. It’s relatively easy to use an USRP to generate alerts when someone is using TETRA nearby.

But sure, other agencies may generate false positivies.

Re: Thousands are monitoring police scanners during the George Floyd protests

#45

Post by lozaning »

larrywright wrote: post #21
Press2forEN wrote: post #14

With the rise of corporate censorship I don't think its wise to rely on app stores for access to police frequencies. Dedicated radios that monitor police frequencies are widely available and you don't need an amateur license to use one (since you're only listening, not transmitting). My city is on 700MHz P25 which requires a fairly pricey radio, but its been worth every penny over the past week. After listening in la…

Any specific models/manufacturers you can suggest?

Get a Hack RF or other SDR and then just run Unitrunker on a computer.

Re: Thousands are monitoring police scanners during the George Floyd protests

#46

Post by oasisbob »

blantonl wrote: post #25
_curious_ wrote: post #16

Earlier quoted context omitted.

Interesting product/service! I've been familiar with it in the past but really used it a lot over this last week - thank you for offering a free n accessible tool. When, Why and how did you get into it? Does it generate meaningful/worthwhile revenue or is to more to cover overhead? (I only noticed the occasional 30 second commercial intro) Maybe you have a lot of premium subs? Why sometimes do certain cities/counties…

My Grandmother had a police scanner that she used to listen to drama going on in her small town in Virginia. Old ladies with police scanners is still quite common. It sparked an interest and my parents got me one as a Christmas present. I spent many years in the IBM ecosystem as an technical SE, but developed an online database (RadioReference.com) in the late 90's that consolidated frequency information for all the…

> including using SDRs to vacuum up wide swaths of RF and then store call data

Been there, done that. The technique is scary-good, even with cheap hardware.

Capture everything, sort by talkgroups, form listen queues ("police", "fire", "police NOT university",) prioritize, and place recordings in queues. Stream queues through ice cast. Drop low-pri messages if you fall too far behind real-time.

Speaking of: if anyone wants nearly two years of uninterrupted Seattle police radio archives (and everything else from KCERS), they should get in touch.

Re: Thousands are monitoring police scanners during the George Floyd protests

#47

Post by oasisbob »

blantonl wrote: post #43
oasisbob wrote: post #41

Earlier quoted context omitted.

Any trunked radio system hops between frequencies enough that this wouldn't work. Individual radios get "paged" on a control channel and told where to receive. Eg, "Radios tuned to the police talk group, go to frequency X now." The speaker, when transmitting, gets assigned a frequency on the fly. A baofeng could stomp on a transmission, but nobody would follow it otherwise.

Chicago uses a straight analog repeater system

Analog repeaters still use trunking protocols.

Edit: Whoops, I didn't realize CPD still had so many assigned frequencies in-use with just a code to activate. That could be done with a Baofeng.

Re: Thousands are monitoring police scanners during the George Floyd protests

#48

Post by vidanay »

blantonl wrote: post #2

Hi there! I'm the owner and operator of Broadcastify, which is the platform that powers all the apps that provide police scanners and public safety communications online. I'm an active HN reader and would be glad to answer any questions folks have. It's an interesting business to be in these days...

Is the poor audio quality a function of the participating scanners that feed your service, your infrastructure, or the current workload? My local feed is nearly unintelligible.

Re: Thousands are monitoring police scanners during the George Floyd protests

#49

Post by protomyth »

I remember as a young kid my family, and a few others, had police scanners. It was fairly interesting and you got a feel for which of your neighbors were trouble. A lot of my relatives were rural fire department volunteers so the scanners were a useful warning before the actual alarm page was sent out. I do remember one of my relatives drove out to pick up a cop on a back road when his cruiser died, or the night they chased a light all over hell and back. The first reality programming.

Re: Thousands are monitoring police scanners during the George Floyd protests

#50

Post by bg4 »

protomyth wrote: post #49

I remember as a young kid my family, and a few others, had police scanners. It was fairly interesting and you got a feel for which of your neighbors were trouble. A lot of my relatives were rural fire department volunteers so the scanners were a useful warning before the actual alarm page was sent out. I do remember one of my relatives drove out to pick up a cop on a back road when his cruiser died, or the night they…

> or the night they chased a light all over hell and back

Please elaborate.

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