SDR for Sturgeon County

mciupa

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Jay911

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Feb 15, 2002
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Bragg Creek, Alberta
In your separate post, also about Sturgeon County, you talk about using your scanner while mobile. Using an SDR stick is not very ideal while mobile. The stick needs to be plugged into a computer when you want to use it, and the computer needs to be operating. So while it's possible to carry around a laptop (or, if you're lucky, a small tablet Windows PC) with an SDR stick plugged into it, it's far from handy.

In my experience you need two SDR sticks to reliably follow voice conversations - one to monitor the control channel and tell the second one which voice channel to tune to. I know some folks have made it work with one, but your mileage may vary as they say.

Having said what I've said above, I do use SDR sticks quite a bit myself. I have a small box full of the R820T ones (older versions of the ones @mciupa posted), and I have also graduated up to using Airspy Mini devices, which are kind of a more robust version of the basic SDR. In my application, I'm primarily "listening" strictly to the control channel, monitoring it for new talkgroups, new radio IDs, etc., and not listening to the voice at all via the SDR - I have scanners which I use for that purpose. Despite saying it's not very portable, I do on occasion take a laptop and one of my Airspys out on the road and use it to snoop details on the towers for various systems (AFRRCS and others) in and around my part of the world. It's not something that's easily portable, and definitely not something you can use while driving, but it does work.

And finally as mciupa said, it's not at all "plug and play". You need to spend time understanding what it's doing, how it's tuning to the frequency you want to hear, and possibly how the system you're trying to listen to is built. There's no (easy) SDR software that is going to act like a scanner, where you just plug in the SDR to the computer, start the software, and tell it to start scanning. You have to learn about the "drift" of the tuner in the SDR stick and how to correct that in software, how to tune the SDR to the correct frequency to monitor the control channel for the system you're wanting to monitor, and possibly you're going to have to tell the software how to learn the frequencies of the other (voice) channels in the system, so it can re-tune to the voice conversations as they go on. In addition, you'll have to tell it what channels (talkgroups) the voice conversations you want to hear are on, otherwise it's going to try to feed you everything that's going on on the system - and some of those channels are encrypted, so you'll just be hearing noise if you try to listen to them. But you'll need to know which channels are for Fire, which are for Police, which are for public works, etc., so you can tune into precisely what you want.

Do take the opportunity to look through the SDR related forums here, though. SDR is a powerful tool. Uniden's latest scanners are built around SDRs and they basically revolutionize (in the back-end) how scanning is done. You can tune into stuff you probably didn't even know existed if you play around in SDR long enough. You can listen to FM stereo, land mobile radio (i.e. the stuff we're talking about on this site), slow scan TV (images sent over the airwaves), the positions of aircraft, and so on, all with that one stick.
 

cmjonesinc

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Apr 25, 2011
Messages
1,097
I run a bunch of the Nooelec SMArt v4's and some of the old R820T's using Unitrunker. I does take some setting up and even if you don't go with Unitrunker most of the software do have a learning curve.

For the systems I care to actually log, watch traffic, find new talkgroups on and ID units Unitrunker is great. For just listening, I have my scanners. If you're not interested in logging and watching traffic on the system but don't want to buy a scanner, a good in between is the P25RX by Bluetail tech. I absolutely love mine and it was way easier to set up and doesn't require a computer after initial setup BlueTail Technlogies

A thread on it can also be found here P25RX P25 Phase 1 Receiver With Bluetooth Audio Support
 
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