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[aprssig] 9600b UHF APRS IS THE FUTURE OF APRS

Gregg Wonderly gregg at wonderly.org
Mon Oct 9 15:29:32 UTC 2006


Bob Bruninga wrote:
...
> VHF is 9 dB better than UHF for omni antnenas (think mogbiles) AND
> it has less multipath and fades.
> 
> So APRS at UHF may have practical applications, but serving as a 
 > general distribution it will never be as "good" as VHF.  SUre all
 > those problems can be fixed with 3 times more digis to cover the
 > same area, but I doubt it will ever be practical for general
 > coverage like VHF.

UHF does much better in structure penetration and requires a smaller
antenna system for the same gain (not power).  9 db of gain can be
realized with a stacked collinear about the same height as a 5/8s wave mobile 
VHF antenna (which is 6b of gain).  In the end, if antenna and gain is the 
problem, the answer is more antenna, or better yet (for density 
diversification), more digis.  The "better" coverage of VHF is, in fact, the 
bigger problem the current APRS network has.

Cellular and wide area network technologies use higher frequencies and lower 
power to simplify life and create a more dependable system, not to cause 
themselves to spend more money on more cell sites.

RF spectrum is finite.  Space in the universe is infinite.

Gregg Wonderly
W5GGW




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