APCO 25 trunking receiver
Posted: Fri Mar 01, 2013 6:32 pm
Looks as if with the bladeRF, all the hardware is there to do it for the 800 MHz band. I'd love to see a project started to implement this entirely in GNU radio. It can already be done in windows by chaining together various bits of software. Two instances of SDR#, each with it's own RTL-SDR dongle. One sits on the control channel and pipes the audio into Unitrunker, which then controls the other SDR# to tune the voice channel, whose audio is piped to DSD for decoding.
However with several 10's of MHz of realtime bandwidth, it can all be done with a single front end. With GNU radio I wrote a Python script to record multiple NBFM channels to disk with squelched audio, and mix the audio for real-time monitoring. Have tried it with 26 channels so far with no over-runs (VOLK is the key to doing this) from the USRP2. Thus I can simultaneously monitor every repeater in the 2m band and all the simplex channels, with no scanning.
So my dream app is to simultaneously monitor multiple trunking sites, each with their multiple voice channels, and streaming all the audio to disk, tagged with time and radio ID.
Ambitious? Yes, but it would be the ultimate scanner. What stinks is that is is presently beyond my ability. I'm an RF/Microwave hardware guy, whose GNU Radio dabbling is limited to GRC and Python. The C++ makes a whooshing noise as it goes over my head.
However with several 10's of MHz of realtime bandwidth, it can all be done with a single front end. With GNU radio I wrote a Python script to record multiple NBFM channels to disk with squelched audio, and mix the audio for real-time monitoring. Have tried it with 26 channels so far with no over-runs (VOLK is the key to doing this) from the USRP2. Thus I can simultaneously monitor every repeater in the 2m band and all the simplex channels, with no scanning.
So my dream app is to simultaneously monitor multiple trunking sites, each with their multiple voice channels, and streaming all the audio to disk, tagged with time and radio ID.
Ambitious? Yes, but it would be the ultimate scanner. What stinks is that is is presently beyond my ability. I'm an RF/Microwave hardware guy, whose GNU Radio dabbling is limited to GRC and Python. The C++ makes a whooshing noise as it goes over my head.