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[aprssig] APRS high speed

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Fri Mar 24 12:18:14 UTC 2006


	From: Andrew Rich
	Posted At: Thursday, March 23, 2006 3:38 PM
	Subject: [aprssig] APRS high speed
	
	Been looking at radar technology the last few days and it begged
me to ask the question.
	 
	Has anyone thought / played with APRS mobile at high data rates
?

	The planes uses pulsed transmissions and very fast.

Aircraft transponders respond to the radar "poll" and rely on a clear
path to the radar site.  Mode C transponders only report a 4 digit (0-7)
identification with a 3 digit altitude (100 foot increments) (_very_
short burst of data).  Mode A transponders only report the 4 digit
identification.  The transmission is done using true digital encoding
which removes the extended training times that our TNCs require.  Speed
and direction displays are computed at the radar computer by comparing
subsequent radar sweeps.

It is quite common for low flying aircraft and aircraft climbing or
descending or making steep turns to be "lost" on the radar screen.  When
this happens, you hear the controller state "I have lost your
transponder, please recycle it."

Could the same type of technology be used for APRS?  Sure.  However it
would not be using our current TNC technology.

73,

Pete Loveall AE5PL
mailto:pete at ae5pl.net 




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