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[aprssig] NEW! IC-V82 - VHF/APRS Transceiver

Stephen H. Smith wa8lmf2 at aol.com
Thu Mar 3 07:57:53 UTC 2005


After wading through all the broken English in the technical description 
and PowerPoint presentation on the Icom site,  my conclusion was that 
the whole D-Star system is far too complex for widespread adoption by hams.

It turns out there are TWO separate on-air transmission formats - a 
4.8Kb/sec stream for low-speed data (like callsign ID, selective calls 
and GPS posits) and AMBE-vocoded digitized speech   --and--   a 
high-speed 128KB/sec mode that amounts essentially to ".1BaseT"  
Ethernet.    Separate receivers and transmitters are used at the 
repeater site for each format.; i.e. you have to somehow combine two RX 
and two TX into your antenna system(s) for a single "channel".

The low-speed format is for use on 2 and 440 while both the low and 
high-speed formats would be available on 1260 only. 

The system architecture  (clusters of 144/440/1260 repeaters in one area 
tied together by 10 GHz RF links  are  connected to clusters in other 
geographic areas via high-speed Internet connections)   has a strangely 
close resemblence to the architecture of Motorola SmartZone commercial 
networks, even to the QOS prioritizing of voice vs non-voice packets in 
it's IP neworks.

Oddly,  one of the most interesting documents on the Icom site (though 
incredibly dry) was the "history" of the development of this system 
which involved an absolutely ludicrous amount of politics between JARL 
(Japan Amateur Radio League), various government ministries and Icom to 
be authorized to put this experimental system on the air on existing ham 
bands.  It appears that there was a lot of support and seed money 
provided by the Japanese Communications Ministry.  Near the end of this 
account was the final outcome that no more than two hops over-the-air 
would be allowed (more than that would require Internet linking) because 
more than that would constitute "a commercial communications 
company"!     [ At least it addresses abusively long paths .... ]

------ BOTTOM LINE ------

I wonder if this whole thing is kind of a beta test for a kind of  
Made-In-Japan "Smartzone Lite" to be sold in the commercial landmobile 
market to public safety users in smaller communities  that can't afford 
the incredible complexity and expense of Motorola's current offerings.  
[ Motorola has completely abandoned the analog and small-systems market 
already to the Japanese land-mobile mfrs and New Zealand's Tait Radio.   
Moto quite making analog base stations last September.]




Stephen H. Smith             wa8lmf (at) aol.com
                                                    
Home Page:                   http://wa8lmf.com

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