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Comment by ortusdux | Hacker News Reader

I would love to do this for my local police scanner.

The codecs and narrow frequencies used on most public safety trunked radio networks is truly terrible. IMBE and AMBE+2 should have never made it past Y2K, yet Motorola and Project 25 have ensured these remain in widespread use on these networks: https://en.wikipedia.org/wiki/Project_25

If Whisper achieves 85% or higher accuracy on this audio, it would be a miracle. Garbage in, garbage out tbh. Project 25 needs to move to a modern codec, ideally not one seeing little development done by one small company.

It does pretty well* on ATC. E.g. https://twitter.com/lemonodor/status/1578516727549153280 and https://twitter.com/lemonodor/status/1581354245181218816.

* Better than anything else I've seen, but certainly far from perfect.

Being a very constrained domain with it's own speech rules, transcripting ATC conversation would probably benefit at lot from fine-tuning on ATC speech data.

Yeah the tech is there for radio, same for POTS as well (still 8 bit/8000Hz at its core). I do listen on the scanner from time to time and assuming a clear signal traditional NFM always beats digital in terms of intelligibility.

Speaking of the telephone, they definitely could put improved audio quality as part of the 4G and 5G specs, but they don't. A modern telephone network is all IP anyways and backwards compatibility can be maintained.

I've done this with Google's video transcription model, which works surprisingly well.

I wonder how much training on degraded/radio encoded samples would be needed to improve performance in this area. You’re probably not the only person who wants to monitor police radios in their city.

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