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[aprssig] /A= altitude question

Stephen H. Smith wa8lmf2 at aol.com
Sat Aug 7 05:17:07 UTC 2010

  On 8/6/2010 9:48 PM, Greg Clark wrote:
> Guilty as charged -- negative altitude numbers are not something I have a lot 
> of experience with.  I'll take a look at it, but living at an altitude of 
> 100+ meters ASL, it's a little difficult for me to 'simulate' without driving 
> to the coast myself.

One place you can get to below sea level on a major highway (rather then 
somewhere remote like Death Valley) is Interstate 10 east of Palm Springs, 
CA.     In the Indio area where CA route 86 intersects I-10, the elevation is 
about -20 to -30 feet.     If you turn off the Interstate and head south on 86 
toward the Salton Sea, the level steadily drops.  At the Salton Sea, you are at 
about -200 feet.

I have driven this route (I-10) between Los Angeles and Phoenix many times, and 
have watched various GPS devices flirt with sea level and finally go negative a 
few feet for a stretch of about 3 miles.  It did not give UI-View, APRSpoint or 
APRSplus any problems.

It HAS given the FCC problems.    When I was working for Southern Cal Gas 
Company some years ago, we were trying to license a microwave shot with one end 
at a gas company headquarters south of the Salton Sea near El Centro, CA.    
The location here was at about 150 feet below sea level  -- the FCC online 
licensing system absolutely would NOT accept negative numbers.  We finally had 
to lie and record it as being at sea level!



Stephen H. Smith    wa8lmf (at) aol.com
EchoLink Node:      WA8LMF  or 14400    [Think bottom of the 2M band]
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