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<DIV><FONT face=Arial size=2>Hi</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I have been doing some work with RADAR protocols,
that by nature have to be small in payload and contain as much info as
possible.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I am seeing some principles coming through that
might apply to a future spec for APRS</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Asterix is the name of the protcol and is widely
used in commercial position reporting systems.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>What I found is that even in my own dabblings here,
I can pack data much more efficiently.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>You would loose the ability to read in plain text,
but the on air bandwidth would be greatly improved.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Astrerix works something like this</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>40 00 16 30 27 34 56 43 45 45 67</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>40 = This a a category 40 data burst, its rules and
data items are laid out in the category 40 spec</FONT></DIV>
<DIV><FONT face=Arial size=2>00,16 = there is 16 octets of data in this data
burst</FONT></DIV>
<DIV><FONT face=Arial size=2>30 = FSPEC or field spec.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>"27 34 56 43 45 45 67" is the data that
follows</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>The FSPEC is a bit indicator of what data is
following</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>0010 0101 might be an example to say that a station
id, followed by position report, followed by a weather report is
coming.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>In one byte you have specified the messages that
follow, and you can BCD pack location info into the data that
follows.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I am going to be re-visting my glider tracker in an
effort to get the payload right down.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Cheers</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Andrew VK4TEC</FONT></DIV>
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