On May 8, 2010, at 6:10 PM, Woodrick, Ed wrote:
> There have been a number of studies that show that D-STAR can have better
> coverage. The FEC in D-STAR can have wonderful effect on communications. But
> there also have been a few that show in some circumstances, the coverage can
> be less. That’s why I just tell people that it’s about the same.
Studies? Like real engineering/scientific ones with math? I wanna see 'em.
Both the ones that say "good" and the ones that say "bad".
(I'm not saying there aren't any good engineering articles on the topic, I'm
sure there's a few... but the only folks I've personally seen do the
ENGINEERING math, are the Utah VHF FM Society. No other group has published as
much real RF engineering information nor with as much discipline as their
testing was done with... that I've seen.)
Got links?
I have links for P25, because there's so many real RF engineers working in
Public Safety... but real RF engineering documentation for D-STAR/Amateur
systems by their very nature... is really light.
Still waiting on reproducible Bit-Error-Rate numbers from the manufacturer...
when we get those, we can tell people EXACTLY how good or bad a particular
repeater's performance is.
Which is, of course, the whole reason to go to digital in the first place...
one shouldn't need a SINADDR or their ears (guessing) at 12 dB SINAD... one
should be able to plug a PC into a digital repeater and see the exact signal
strength in BER and tell if the system is performing up to snuff by just doing
the link margin math...
--
Nate Duehr, WY0X
n...@natetech.com
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