A while back (July 2008) I discussed a report from the International Association of Fire Chiefs on NIST/NTIA testing of digital vocoder performance in high-noise environments such as firegrounds.
NIST has announced that they'll be re-testing in 2010 with new DVSI vocoders. Urgent Communications reports that next year’s tests will be similar to the previous tests, in that the same noise environments will be explored. Key differences include the use of a mask with an internal microphone, use of radio reference systems to avoid manufacturer settings and the addition of "radio-channel impairments" that are designed to emulate the impact of a firefighter receiving a weaker signal when entering a building. This latter aspect (effects the so-called "digital-cliff" in low signal or degraded propagation environments) was a key component missing from the 2008 tests and I'm glad to see it being included on this round.
I'm still not sure about the wisdom of using proprietary vocoders (DVSI) for radio systems. We have enough interoperability challenges as it is; do we really want to tie next-gen radio systems to licensing from a single manufacturer? The digital radio world really needs to come up with a viable open-source vocoder.