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<DIV><FONT size=2 face=Arial>On thing we do in Mode S RADAR is ALL CALL and ROLL
CALL.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Do you think this sort of thing has application in
APRS ?</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>A smart digi sends a broadcast.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>If a tracker is new to the digi, it acquires the
target.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>It then calls for a response from the tracker in a
ROLL CALL ( poll )</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>- Andrew - </FONT></DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=vk4tec@tech-software.net
href="mailto:vk4tec@tech-software.net">Andrew Rich</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=aprssig@tapr.org
href="mailto:aprssig@tapr.org">TAPR APRS Mailing List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, December 30, 2011 12:55
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> GPS NMEA and APRS Trackers</DIV>
<DIV><BR></DIV>
<DIV><FONT size=2 face=Arial>Hello</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Looking at making use of as much data as I can
send over 19k2 EasyRadio modules.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>I would like to hear from the hardware guys how
they handle the fact that not all NMEA strings seem the same.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Some have fixed character lengths, and some have
zero padding.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>How do you get around the fact you can't control
what sort of GPS someone might hook up to a tracker ?</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>How do you get by without having to specify a
NMEA format that a devices complies with ?</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>I have taken a GARMIN GPS18 as an
example.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Andrew VK4TEC</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>//</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>$GPRMC - LAT, LON, Time, A/V , Speed , Track
angle, Date, MAG VAR<BR>$GPGLL - LAT, LON, Time, A/V<BR>$GPVTG - True track,
Mag track, GS Knots, GS km/h<BR>$GPGSV - Satellites in view<BR>$GPGSA - PDOP,
HDOP, VDOP<BR>$GPGGA - Time, Lat, Lon, Fix quality, Number is sats, HDOP,
Altitude</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Characters</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Lat - 1234.5678 ( -90.0000 to +90.0000 ) <BR>Lon
- 12345.6789 ( -180 to + 180 )<BR>E/W - E or W<BR>N/S - N or S<BR>Time -
HHMMSS<BR>A/V - A or V<BR>Speed - 123.4 Knots<BR>Track Angle - 123.4
Deg<BR>Date - DDMMYY<BR>Mag VAR - 123.4 Deg <BR>True Track - 123.4 Deg
T<BR>Mag Track - 123.4 Deg M<BR>GS knots - 123.4 Knots<BR>GS km/h - 1234.5
Km/h<BR>Sats in view - 12<BR>PDOP - 1.2<BR>HDOP - 1.2<BR>VDOP -
1.2<BR>Altitude - ??<BR>Fix quality - 1 </FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>GARMIN GPS18w</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2
face=Arial>$GPRMC,034546,A,2734.4630,S,15306.2268,E,000.0,299.7,170704,011.2,E*65<BR>$GPGGA,034546,2734.4630,S,15306.2268,E,1,07,1.5,47.8,M,39.2,M,,*63<BR>$GPGSA,A,3,04,05,06,,,10,17,24,30,,,,2.3,1.5,1.0*33<BR>$GPGSV,3,1,09,04,21,138,44,05,70,225,44,06,15,250,35,07,05,092,00*72<BR>$GPGSV,3,2,09,09,30,323,00,10,40,038,39,17,83,263,33,24,57,150,47*74<BR>$GPGSV,3,3,09,30,32,222,44*40<BR>$GPVTG,300,T,289,M,000.0,N,0000.0,K*7E</FONT></DIV></BLOCKQUOTE></BODY></HTML>