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Comment by danielvf | Hacker News Reader

For comparison, your standard police/fire/medical digital radio in the US sends voice at 4.4Kb/s. So this is a approximately a third of that.

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and uses codec with up to couple hundred MIPS (AMBE 1/+2) computation cost, not GFLOPS

So maybe this line of work will mean more spectrum available in the future.

Only if Motorola gets out of the way and supports modern codecs and standards. Current public safety radio networks are using ancient TDMA tech that Motorola has cobbled together, along with audio codecs that shred voice quality. The only good part is the durability of the pricey radio, some are even intrinsically safe.

Public safety digital radio networks are primarily APCO Project 25 (P25) which use IMBE/AMBE developed by DVSI. Motorola's original digital radios used a proprietary vocoder called VSELP (also used by iDEN/Nextel). When APCO standardized public safety digital radios, they rejected VSELP and chose IMBE from DVSI instead. Personally I think VSELP sounds better than IMBE, and I'm not sure IMBE was chosen due to technical superiority or if it was political reasons (i.e. picking a non-Motorola solution due to Motorola's dominance). Also, APCO Project 25 Phase 1 was not TDMA, however Phase 2 is.

https://en.wikipedia.org/wiki/Project_25

Public safety radio is a true mission critical service that moves slowly - equipment lasts years or decades and is expensive and not frequently replaced or upgraded, hence new technology adoption is slow. Vocoder choice is driven by a standards committee for interoperability (which has seen more emphasis since 9/11), and of course committees aren't typically known for working fast. Public safety radio is definitely not a place for a "move fast and break things" mentality.

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