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At 05:20 AM 2/10/2008, you wrote:<br>
<blockquote type=cite cite><font face="arial" size=2 color="#0000FF">What
would be cool is if APRS supported an error correction uplink
capability</font> <br>
<font face="arial" size=2 color="#0000FF">You would need a DGPS capable
input GPS</font></blockquote><br>
Tom Clark W3IWI did just that 10 or more years ago in the Washington DC
area, long before WAAS & GBAS, and while selective availability was
still in effect.<br>
<br>
He had access to precision GPS corrections (from his job at NASA)
and broadcast a one line dgps message about once a minute over the
regular APRS frequency. The message would go thru your TNC into your GPS
and correct your position to WAAS class accuracy. It worked like a
charm, well before the Coast Guard's ill-fated DGPS program. I could
pilot my boat with impunity.<br>
<br>
It was experimental and didn't last long for a number of reasons (One
19th century curmudgeon, WB..something or other, for instance, didn't
like the once a minute transmissions clobbering his bandwidth :-), but it
was a real trailblazer.<br>
<br>
Bob Kirk<br>
N3OZB<br>
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