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Re: Re: Digital Voice Via Satellite



>> The latest QST (January 2002) has an article titled "Digital Voice:
>> The Next New Mode?" on pg. 28 that is worth a read.  The author gives
>> an overview of the technology, encoding schemes, where it can be used
>> (basically everywhere that analog phone can be used),
>> advantages/disadvantages, etc.  The article directs you here for more
>> info:
>> http://www.arrl.org/tis/info/digivoice.html
>
> This is very exciting!  I wonder if some standard digital protocol 
> could be
> established for amatuer use?
>
> I.e. register with a repeater, establish
> power levels, ring a paticular callsign, change
> frequencies when two people can speak simplex.
>
> - Nick

I don't think the technology is quite to that point yet.  ;-)  My 
impression of digital voice on the ham bands is that we're at the 
protocol development stage, and a major stumbling block seems to be 
getting digital voice data to fit in a SSB-type channel.  There was an 
interesting related article on PTC, which seems to be a promising 
technology to help with voice data compression, but I don't think 
anyone's gotten a digital voice "TNC" type box going yet.  (My info may 
well be out of date, though..)

I do like the feature list you mentioned, though -- the commercial 
version is called a cellphone -- and agree that that's probably a good 
set of features to try and include in the finished device.  Changing 
actual radio settings like frequency and power would require a 
radio-specific interface as part of the box, if it isn't included as 
part of a finished radio a la D7A, but repeater auto-negotiation and 
selective calling should be fairly simple to include as part of the 
finished protocol, at least on an optional basis.  You might want to 
include a "hamcast" or "QST" mode to allow net operation on a repeater, 
though -- ham communications aren't always specifically person to 
person.  Since it's selective calling, you could also have a group mode 
that supports specific functions like ARES, weather spotting, traffic 
reports, and so on, so a single repeater could be a whole lot more 
multifunctional.  It would also enable automated repeater operation on 
HF, more than likely, if the data format is narrowband enough to be SSB 
compatible ..

And since this is getting terribly OT, we probably ought to take it 
off-list other than the satellite discussion, but I'm definitely 
interested in the technology and want to see what comes out of this ..

Heard from a flight instructor:
"The only dumb question is the one you DID NOT ask, resulting in my 
going out and having to identify your bits and pieces in the midst of 
torn and twisted metal."

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