Category Archives: Software

Software

A Tale Of Two Decoders – OP25 & DSDPlus

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It was the best of decoders, it was the worst of decoders……… As you can tell I’m quite the literate bastard and highly up to speed on my Dickens.

I love digital signal decoding as it is almost something that you seemingly aren’t supposed to do, hence the attraction of it all.   There are several hunks of software that can decode digital signals and each one has it’s strength and weaknesses.  The ones I have dabbled around with are:

There are certainly others, not to mention maybe the most powerful one (but by far the one that requires the most geek foo) is GNURadio.

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DSD+ Trunking Tutorial

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One of my favorite programs for decoding digital audio is DSDPlus.  I’ve been using it a couple of years to dissect and decode SINGLE digital signals.  Like for instance if I’m in the airport or airport hotel I can listen to DMR radio where the baggage handlers are talking to each other, or the mall cops are planning how to be real cops.  Or you can hear the hotel staff on their radios which is sometimes really fun.

BUT…….DSDPlus also follows Digital Trunked Radio.  That is where there is a Control Channel which is monitored and then the calls are “trunked” to available frequencies allowing for more users to use the system without confusion.  Also users can be placed into Talk Groups which keeps down the confusion even more.  Entire cities can use one radio system to control municipal services such as Police, Fire, EMS, Public Works, Events, etc.

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Whistler TRX-1 Mini Review

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So at this point it is safe to say I’m a police scanner junkie.  This started with my love of Software Defined Radio (SDR) devices.  You get an SDR then you tune to FM stereo, then you track aircraft ADSB, then somewhere along the lines you start listening to anything you can which includes emergency services stuff.

First you just listen to analog police, then you find out there are digital trunked systems.  That evolves into using programs such as DSD+ with Unitrunker or another program called SDRTrunk or OP25.

 

Then you realize that you’re into hardware scanners.  I started out with a Uniden SDS100 which is probably the most technologically advanced consumer grade scanner on the market at this moment.  It probably unseated the Whistler TRX-1.  If you read the forums there is kind of a Ford/Chevy thing going on with Uniden/Whistler.  I had to see what all the fuss was about so I got the Whistler TRX-1.

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ProScan for Uniden Scanners

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So I bought the Uniden SDS100 hardware scanner, and I love it.   But it cost $700, and then I added DMR decoding for $60, and NXDN decoding for $50.  So I’m into this in a big way.  The SDS100 is POWERFUL.  It is not a toy by any stretch of the imagination.  It comes with free control software called Sentinel (yeah the download is hard to find on that page).  Sentinel is adequate for managing favorites and reading and writing to the scanner and it is all you NEED.

However I stumbled across this hunk of software called Proscan which looked interesting but it also costs $50.  Where does the cost with this scanner end?  Well, like most programs Proscan has a 30 day trial version so I gave it a shot.  After playing with it for like an hour I knew it was worth the cost so I bought it.  It does NOT disappoint.

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OP25 on a Raspberry Pi (part 3)

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In my last part I set the Pi up to stream to Broadcastify.  In this one we are just going to pump audio out through the headphone jack.

I’m doing this with an old generic black RTL-SDR and it works and it works fine but it is kind of susceptible to heat and cold and the ppm correction drifts a bit.  I really recommend getting a v3 RTL-SDR or a NESDR Smart as they seem more stable.  At any rate it doesn’t matter, you’ll just have to deal with the drift if you have any.

My assumption here is that you have Raspbian installed on at least a Pi 3.  I haven’t tried it on a lesser Pi but I had it on a Pi 3 B + and then I found a couple Pi 3 B’s laying around and figured I’d reclaim my B+ for another project on another day.  OP25 runs fine on the Pi 3.

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OP25 Raspberry Pi Streaming Part 2

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So I finally figured out OP25 and I have this brand new Raspberry Pi 3 B + laying around doing nothing.  In this segment we’ll install OP25 on Raspberry Pi and then take our police scanner feed and send it to the internet on Broadcastify.

As someone pointed out to me yesterday, “There’s an app for that” they are indeed correct.  You can get Police Scanner Apps for IOS and Android.   Guess where the feeds in those apps comes from?  If you said Broadcastify you’d be correct.  So if no one is feeding your municipality   then there will be no feed in the app.  We will be that feed.

So the assumption is that you have a Pi with Raspbian installed and you kind of know how to use it.

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OP25 For Dummies – Or how to build a police scanner for $30 (Part 1)

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OP25 is a program that decodes P25 Phase 1 and Phase 2 digital radio.  Some municipal areas are upgrading to P25 Phase 2 so almost gone are the days that you can track them with a police scanner since P25 is a Trunked Radio system and not just a lone frequency to monitor.   The only things that do Phase 2 are hardware scanners and hardware radios and OP25 for software radios.  Bear in mind Phase 2 could be encrypted and nothing you can do will decode it.

OP25 is HARD.  I’m a geek and I messed with it on and off for a year or more and it whipped me more than once.  Now that I have it working I find that it is REMARKABLY easy and I’m mad at all the geeks out there who never made a simple tutorial.  There are tutorials out there, some good but everybody leaves out the good stuff or the stuff they took for granted.

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DSD+ in Ubuntu 18.04

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DSD+ is a popular Windows digital decoding program that handles various digital protocols.  I’m going to install and use it with WINE on Ununtu 18.04.  The example I’ll show here today is a digital trunking control channel that the local Emergency Services uses.  Without DSD+ the signal will sound like this:

[kad_youtube url=”https://youtu.be/YaXX4pG4i-o” ]

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