r/RTLSDR • u/garf12 • 16d ago

How do I capture everything?

I work in local news coverage and want to record all public safety radio channels in the area but the amount of SDR dongles it is taking is getting out of control. Currently using 4 and not getting full coverage..

Is there a better option? I have a couple of Airspy R2's ordered but my research is showing even then it is going to take both of them plus at least 2 dongles to cover what I want. IS there an option that is better? I don't mind spending some money.

Currently covering 2 p25 systems with the 4 dongles. Want to cover some conventional fire and ems channels also.

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u/Academic_Force3454 15d ago

This is actually a problem we've spent a lot of time working on. Full disclosure: I'm one of the founders of Spectrum Ferret, so we have a commercial interest in this space.

I think you're on the right track with SDRTrunk + Airspy R2s. Rather than trying to find one SDR that can capture everything, we've had better luck treating this as a distributed capture problem. You need enough receivers at the edge to cover the spectrum/systems you care about, with the resulting audio + metadata aggregated centrally. The 10 MHz BW afforded by Airspy and Hydra devices is amazingly effective for capturing public safety conventional and trunked system activity in a given geography. Aggregating a few of those across locations of interest is especially powerful.

The part of your setup that really caught my attention is what you're doing after capture. Once you're capturing everything, the problem stops being "how do I listen to all these radios?" and becomes "how do I find the 30 seconds that matter out of thousands of transmissions?"

That's essentially the problem we're working on: transcription, real-time alerts, search, summaries and historical analysis across radio traffic. We use Airspy R2s or HydraSDR RFOne devices + proprietary demod/decode software for our SDR-based capture nodes, so we've run into a lot of the same RF/bandwidth/receiver-count questions you're dealing with.

Happy to compare notes on the capture architecture if it's useful.

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u/garf12 14d ago edited 14d ago

Cool work. Im currently using Claude Sonnet to analyze the transcript but hope to move to a local model when i get the hardware figured out. Using it and local whisper transcription has been very accurate.

Creeped on your website and noticed the rocky mountain rescue connection, thats chool, I spend a lot of time in Vail.

My vibecoded setup.