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robotastic / trunk-recorder

Records calls from a Trunked Radio System (P25 & SmartNet)
GNU General Public License v3.0
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P25 Phase 2 SDR Coverage #704

Closed amateur-rad closed 2 years ago

amateur-rad commented 2 years ago

Hey everyone, is there a way to cover a P25 Phase 2 frequency with more than one SDR to ensure simultaneous TDMA transmissions are recorded?

I am covering a rather large trunked system that uses both P25 Phase 1 and P25 Phase 2 voice paths, using a USB hub with 3 SDRs connected to a Raspberry Pi 4. I have noticed that I am having a lot more missed transmissions lately and have traced the problem to a single Phase 2 frequency that is covered by one SDR and now appears to be the 'preferred' home frequency for users. The SDR appears only able to grab one transmission at a time off the frequency, so when another, simultaneous, Phase 2 transmission is taking place, it is lost. I tried moving another SDR in the config file to also cover the frequency, but that did not seem to work as it was never assigned by trunk-recorder to record anything on that frequency.

Dewey3 commented 2 years ago

How many receivers do you have setup in your config.json file? I monitor the very busy Prince George's Co, MD P25 Phase II-TDMA system on a RPi 4 and regularly receive more than 1 transmission at a time per SDR. Like you, I use 3 SDRs, but that is to cover the frequency spread. I have to look at my config file, but I am pretty sure that each SDR is set up for 7 receivers. I also monitor the less busy Charles Co, MD Smartnet system on another RPi 4, but that has analog and digital transmissions so I have that set up for 5 digital receivers and 2 analog receivers per SDR. The final FYI is that I started out using a powered hub, but found out over a year ago that my RPis work fine using 3 USB ports without a hub.

amateur-rad commented 2 years ago

Looks like user error on my part, I had not adjusted the receiver numbers past 1 in my config file since setting it up as a test system. That fixed it, thanks Dewey3!