OK, crazy as it sounds, it is very possible to monitor the digital DMR & NXDN networks with very little hardware. All that was used in this demonstration was a $25USD RTL-SDR v3, coupled to a Windows 7 PC running DSDPlus Fastlane.
There is so much to listen to on the digital networks. I have monitored nuclear power stations, gas plants, oil refineries, emergency services, Film & Television production teams, airline gate agents & baggage handlers, and so much more!
DSDPlus is the decoding software. It comes in multiple versions. The free version is good, and will certainly whet your appetite for monitoring DMR & NXDN signals.
For $10 you can have a 6 month subscription to the DSDPlus Fastlane program. Or for $25 you get a lifetime subscription. The regular updates increase the functionality and enable better decoding and tracking.
In this Episode of the 2020 SDR Guide I demonstrate setting up the software to receive and demodulate the audio. While some systems might be encrypted, I have found that the majority of talkgroups are in the clear.
Hopefully you find the video useful. If you know anyone else that could benefit from seeing it, feel free to share.
Stay safe out there.