RTL-SDR Tutorial: Following Trunked Radio with Unitrunker

RTL-SDR Tutorial: Following Trunked Radio with Unitrunker

The popular trunking decoding software Unitrunker now supports the RTL2832U R820T RTL-SDR directly in its new version. This means that extra SDR receiver software like SDR# is no longer required to use Unitrunker.
You can download the latest version of Unitrunker here.
In a normal radio system, one company (or talkgroup) might use a single frequency for radio communications. However, this is very inefficient as the frequency may not be in use for the majority of the time. In a trunked radio system, a small set number of frequencies are shared between a large number of talkgroups. Each radio receives a special computer controlled control channel. The control channel determines a vacant frequency that a particular talkgroup should use. This helps to make radio frequency allocations more efficient.
Because a talkgroup might switch between various frequencies often, it can make listening to a conversation difficult for radio scanners. Unitrunker can be used to decode the control channel and follow a voice conversation as it hops across various frequencies. With two RTL-SDR dongles you can set up a trunking receiver station with just Unitrunker. What follows below is a tutorial on how to set this up.

DSD Plus decoding DMR digital voice w/RTL-SDR & SDR+

DSD Plus decoding DMR digital voice with RTL-SDR & SDR+

Decoding MOTOTRBO with Digital Speech Decoder 1.6 beta

Just some clips of the new Digital Speech Decoder in action. I have mixed in the raw audio that DSD is decoding from, along with the decoded audio, so be aware that when you are decoding you won't normally hear the noise. The undecoded DMR is much quieter than the speech but it is only there so you can hear the strength of the signal that DSD is decoding from.
For people looking for a mototrbo "scanner" there are none on the market at the moment, this is the closest you will get to having a mototrbo scanner.

MotoTRBO/DMR decoding on PC with DSD

Decoding some MOTO TRBO with the Windows port of DSD - Digital speech decoder. I recommend that you listen with headphones or earphones to hear the full sound quality of the recording at the end.
The sound clip at the end of the full quality audio was recorded from the stereo mix of the computer while it was decoding. I just left it on decoding all day with a VOX recording program and listened to what had happened when I at the end of the day. That audio clip is basically a section of that.