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Show HN: Super Trunking Scanner

scanner.rachelbythebay.com

I got tired of missing things which were going on around me, and my scanner was more annoying than helpful at times, so I threw a bunch of software (and a bit of hardware) at the problem. Questions welcome!

Very cool. I'd put the demo on the front page, actually, so people don't even have to hit the 'Demo' button to see the list construct itself.

Is this a Smartnet system? Are you running a wideband front end with a dedicated DDC for each physical channel?

(I did something like this for the Seattle-area trunked radio system a few years ago -- http://www.ke5fx.com/equinox/equinox.html -- but users have to download a dedicated Win32 client, and it only allows a single user to control the hardware at any given time.)

Good idea on the demo thing there. I dropped the "possum" call into the top page after watching a few hits come in and it got way more interesting in terms of people checking stuff out. I'll find a way to make the whole thing work without that extra click -- thanks!

The city is using a Smartnet system as far as I can tell, and I'm using a software-defined radio system to pull in the whole band and then split off the chunks I care about. I'm also decoding the control channel so we know which talkgroup is responsible for a call, which frequency they're on, and all of this.

Your approach sounds interesting, and I bet you could get a web frontend onto it which would bring about more attention and cross-platform compatibility, too! It's worth a thought if nothing else.

Ooh, neat. What kind of hardware are you using? (And are you using gnuradio? Does the gr-smartnet module on CGRAN actually work?)

gnuradio + gr-smartnet does actually work, and it will decode a control channel. I got it to give me usable data for both the city of Santa Clara system and Alameda County.

There are a lot of little bits and pieces you have to smash together to wind up with something like this, though. I wound up playing with a lot of programs in this field before deciding to build this. Discriminator taps are fun!

Yeah, I've wanted to do a web-based UI for it for a long time, but it really doesn't make sense with a single physical channel. My implementation is a historical relic compared to this one! Right now it hands off control privileges every 15 minutes if there are multiple users logged on.

I do have a dedicated receiver for the control channel, at least.

Do you plan to make any hardware/HDL details available?

I do intend to write a series of posts about the building of this system and all of the things I encountered and either fixed or hacked around later on. It's still a bit early to do a "retrospective", I think. They'll go up at my "writings" page when I do -- the URL is in my profile.

Very interesting concept. What hardware are you using on the back end to accomplish this?

If you mean the computers, I have a couple of boring x86_64 Linux boxes. If you mean the radio stuff, I'm not quite ready to describe the "secret sauce" just yet. When I am, I'll post something on my /w/ pages (URL in profile).

Sounds good. I own and operate http://www.radioreference.com and we have a large live audio streaming platform for scanners (2800+ feeds). Something like what you've developed definitely interests me. Great work!

I've always thought this was a great idea. I've got this going along with LiveATC for SJC and I feel omnipresent!

Edit: Feature request - the ability to filter out certain talkgroups. The streets guys have verbal diarrhea.

How does LiveATC handle multiple frequencies? Can you follow ground, approach, departure and all of that at the same time? It seems like you'd need to do that to deal with all of the handoffs.

For the talkgroup filtering: noted, thanks! It'll become even more important when you want to switch other cities and agencies in and out. The other day with that nutcase in San Jose, I really wished I could just add their special channels to my personal feed. That's my next big hurdle to clear.

LiveATC is just scanners plugged into streaming boxes - the freqs covered depend on the feed.

For SJC there's 5 separate feeds - one for ground (4 freqs), two for approach (2 freqs), one for departure (1 freq) and one for tower (1 freq). To listen to the handoffs, you either have to stream them simultaneously or manually switch between feeds.

There's no awesome queueing / playback feature like you've got - it'd be super nice to have!

> Would you like to know more?

Is this a Starship Troopers reference? Because kudos, if so.

It is! Good spotting.

This is awesome. The water treatment guys are hilarious. Makes me want to get my ham license so that I can start playing around with these kind of cool softradios.

I don't think you need a HAM licence to get a trunking receiver.

This is SERIOUSLY cool.

However: I really can't make out what people are saying on the radio. (Not just this one, in general.) Am I alone?

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