
Thousands are monitoring police scanners during the George Floyd protests - elorant
https://www.vice.com/en_us/article/pkybn8/police-radio-scanner-apps-george-floyd-protests
======
blantonl
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...

~~~
kennxfl
Is there a way of legitimately detecting Stingrays? I understand this is the
kind of situation where they are actively deployed despite all the social
awareness.

~~~
swebs
I guess if you were to build a map of static cell towers, it would be easy to
see if a new one suddenly pops up.

~~~
jackhack
additional temporary "towers" are sometimes added when very high but transient
network loads are anticipated (such as a music festival, or county fair,
etc.). not all new towers are sniffers.

~~~
g_p
If anyone is interested in trying to work around this, I have a few ideas for
how to try distinguish a real and fake cell. Temporary event "pop-up" networks
should announce valid neighbouring cells.

Your baseband (radio) might expose neighbour cell data - iPhone field test
menu shows the announced neighbour data.

Hypothesis is that a rogue tower will not have valid neighbour cells
announced. They could try listen in for valid ones and advertise those.

A lot of the ways to detect will depend on the generation of network being
spoofed - 4G networks will also advertise signalling for legacy 2G and 3G
circuit switched networks. Rogue sites might not.

------
LgWoodenBadger
Anecdotal, but an ex-friend cop told me YEARS ago that they never use their
radios for "sensitive" communications anyway, they just call each other on
their cell phones so that there are no records of their conversations.

~~~
myself248
I remember, years ago, that they'd use their Mobile Data Terminals for
anything "sensitive", again to get around scanner listeners.

Apparently they didn't know about MTDMon software. Which was even cooler than
listening on a scanner, because you could set it to beep the PC speaker if
your keywords appeared in the feed.

I assume all that is encrypted now, but it sure wasn't at the time!

~~~
JshWright
Most MDTs just use LTE connections these days.

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Simulacra
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...](https://www.washingtonpost.com/local/social-issues/last-of-the-
scanners-are-police-security-measures-killing-an-american-
obsession/2018/12/28/4e344a62-09f5-11e9-a3f0-71c95106d96a_story.html)

~~~
dmkolobov
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.

~~~
alvern
I think the repeaters would block out any of the mobile radios. So you could
see the dispatchers easily, but the individual mobile operators (EMS, Fire,
Police) would be hard to distinguish.

If the mesh was every Digital TV tuner inside a municipality, then maybe the
mesh could triangulate position.

------
sterwill
I haven't done the work to sign up at Broadcastify, but if you're in Durham NC
and want to listen hit
[http://home.tinfig.com:9999](http://home.tinfig.com:9999) with VLC (or
mplayer or whatever you like).

It's an HTTP+Ogg+Opus stream from my BCD536HP. It's scanning the local P25
trunked radio system (Durham police, fire, EMS, ops, etc.).

P.S. As I write this I'm hearing chatter about responding to an airplane
crash... no more details yet.

~~~
voltagex_
Will you have a chance to write up anything further about your setup?

~~~
sterwill
It's just an old HP Proliant home server with a USB sound dongle, and VLC
transcoding from ALSA PCM to Opus and serving HTTP. VLC does it all!

My radio has a WiFi interface, but it's weird and unreliable (only supports
RTSP, 401s if the requested host isn't its internal IP, crashes after 12
hours, etc). So I just use a short analog audio cable instead.

~~~
sterwill
More technical details in case anyone needs to quickly pipe out some audio to
the Internet:

    
    
      /usr/bin/vlc -I dummy -vv --no-alsa-stereo alsa://default:CARD=Device -L --sout-keep \
        --sout #transcode{acodec=opus,channels=1,ab=24000,afilter=equalizer}:standard{access=http,mux=ogg,dst=:9999} \
        --equalizer-2pass --equalizer-bands 0 0 0 0 0 0 -20 -20 -20 -20
    

\--no-alsa-stereo because my input source is mono. --sout-keep probably isn't
necessary now, but it was when I was streaming from the radio's crashy RTSP
service.

The #transcode block sets up a simple pipeline: first transcode to Opus at the
specified output bitrate (24 Kbps is plenty for recorded voice), then mux it
up and serve it via HTTP. I added a low-pass filter at ~6 KHz because there's
some of high frequency noise from either my radio's analog output stage or the
cabling. I had to look through the VLC source code[1] to find the preset
frequency bands since I couldn't find them in VLC docs.

[1]
[https://github.com/videolan/vlc/blob/777f36c15564b076bf13af6...](https://github.com/videolan/vlc/blob/777f36c15564b076bf13af6641493d97cd5ee224/modules/audio_filter/equalizer_presets.h#L36)

------
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.

~~~
bg4
> or the night they chased a light all over hell and back

Please elaborate.

~~~
protomyth
Well, this is a couple decades ago - so the play-by-play is a bit lost, one
cop at a locally infamous speed trap after dark started seeing a light in the
woods near the road. He reported it over the radio, and speculated it might be
someone spotlighting deer. Hunting deer at night is very, very illegal as the
deer freeze when the light is shined at them. He didn't hear shots, but was
understandably reluctant to pursue the light by himself as people committing
illegal acts that are obviously armed might be unsocial. Another two patrol
cars showed up and they decided to surround the area where the light was. The
"light", when flushed by the officers, took off down the road. The officers
only saw the light and not what is was attached to nor did they hear an
engine. This pursuit went from road, to another field, down the side of a
river, and back into the wooded area. The light would turn on and off traveled
at high speed about four feet off the ground. They finally lost sight of it
outside town, last seen headed down the road. Apparently some folks called in
sightings (land line days to the dispatcher), but the latency made these a bit
unhelpful and the officers did comment that some of the callers might not be
trusted observers and some might be ..uhm.. less than perceptive having their
head inappropriately situated. The officers did say some words that were not
strictly professional and threatened all manner of violence on whoever was
behind this. It probably cost them some revenue as they were not available to
assure the public's safe speed particularly after the bars closed. They did
not catch the light nor did it happen again.

~~~
wyldfire
> Hunting deer at night is very, very illegal as the deer freeze when the
> light is shined at them.

Is that really the rationale? I would think risk of accidentally harming
humans or property would significantly increase at night.

~~~
protomyth
Its a combination, that's one of the big rationals I've always heard. Also,
enforcement of rules would be really painful at night. It probably would be
very dangerous to be out there with some of the idiots who think they are
hunters.

~~~
jmm5
Same reason you can’t just set up a salt lick in your back yard and camp out.

------
Press2forEN
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 last Saturday we
cancelled a trip to visit family after hearing about a riot on the local
highway.

Make sure to look up the frequency your town uses first before dropping so
much coin on a radio. If your local LE is encrypted, you're out of luck. But
many aren't.

~~~
larrywright
Any specific models/manufacturers you can suggest?

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

~~~
xxpor
Don't you need at least 2 to track trunked systems?

~~~
dantle
It is helpful, but not necessary. I am listening in on Seattle's trunked radio
system with just one, and I get most of the comms.

I documented my setup here: [https://dantler.us/seattle-police-
scanner/](https://dantler.us/seattle-police-scanner/)

~~~
mmmrtl
Please consider streaming on [https://openmhz.com/](https://openmhz.com/)

------
bzb3
How come LE in 2020 is not using encrypted communication systems such as
Tetrapol? Yes I know Tetrapol is European, but you get the idea.

~~~
blantonl
Europe and the United State government are drastically different.

Local municipalities in the United States are very independent and will settle
on a a communications system that they locally want to use. Budgets and
planning are allocated at those local levels, and power struggles and turf
wars will result in agencies right next door to each other using different
systems, just because.

------
VectorLock
Although I think a lot of police radios don't use encryption I think the
majority are using trunked/digital radios which your garden variety scanner
isn't going to be able to decode.

------
sonthonax
Wow, I’m really shocked that police still used unencrypted radios.

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hmmmmm70006
Anybody else having issues downloading one these scanner apps from the Apple
App Store? I seem to be encountering an error I’ve never seen before...

------
dvno42
Look into the p25 standard. I wouldn't know but I wouldn't be surprised it
many agencies use it for digital/analog data and can probably be brute forced
with cheap hardware. Search for p25 DES-OFB. Now would be a great time for a
rainbow table.

~~~
jlgaddis
The same radios often/usually support AES as well, although at an additional
cost. That's what one nearby PD uses.

------
mring33621
These digitized scanner feeds are interesting, but I worry that they can/will
be used for propaganda/misinformation. What's to keep a feed supplier from
injecting fake content?

~~~
kasey_junk
You can inject misinformation directly into the radio waves in many
jurisdictions.

In Chicago this weekend someone was spreading a rumor that a caravan of
protesters were coming from Indiana such that the police diverted resources to
check it out.

------
twox2
A while back I bought a baofeng handheld on amazon - it's not ideal as a
scanner, but good enough. I've been finding plenty of crazy shit during these
protests.

~~~
jules-jules
Can you share some examples?

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vmchale
Mostly listening in to news about the looters here (Chicago). Obviously I care
about the protesters/rioters but they're not who I need to watch out for.

~~~
Scoundreller
Checkout this service for Chi:

[https://crimeisdown.com/audio](https://crimeisdown.com/audio)

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sonthonax
Do police really still use unencrypted radios?

~~~
Cobord
[https://abcnews.go.com/US/court-oks-barring-high-iqs-
cops/st...](https://abcnews.go.com/US/court-oks-barring-high-iqs-
cops/story?id=95836)

~~~
sonthonax
That has nothing to do with it. Your mobile phone voice comms are encrypted.
Push to talk over cellular is another solution which British police use.

Police are increasingly militarised, pretty much any military uses encrypted
radios. It's a cheap technology now.

[https://www.harris.com/solution-grouping/tactical-
multiband-...](https://www.harris.com/solution-grouping/tactical-multiband-
radios)

------
totorovirus
Now US doesn't have right to slander china's public surveilance

~~~
haram_masala
Huh? These are private citizens monitoring the police, which is pretty much
the opposite of the Chinese surveillance you’re referring to. In fact it’s
pretty much an antimetabole (“In the United States, people spy on cops!”).

------
empath75
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.

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

~~~
oasisbob
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.

~~~
blantonl
Chicago uses a straight analog repeater system

~~~
oasisbob
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.

