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--></style></head><body lang="EN-US" link="blue" vlink="purple"><div class="WordSection1"><p class="MsoNormal">See web page for summary of the balloon mission: <a href="http://aprs.org/balloons.html">http://aprs.org/balloons.html</a></p>
<p class="MsoNormal"> </p><p class="MsoNormal">APRS Lessons Learned: -- What the GPS map shows MAY NOT BE what your radio knows. </p><p class="MsoNormal"> </p><p class="MsoNormal">We were running a GreenLight Labs GPS on the D710: <a href="http://www.greenlightlabs.com/gps-710/">http://www.greenlightlabs.com/gps-710/</a></p>
<p class="MsoNormal"> </p><p class="MsoNormal">For the chase, we added an AVMAP GPS for the map display and plugged it into the “pass-through” socket on the Green light labs GPS. Everything seemed to be working.</p><p class="MsoNormal">
</p><p class="MsoNormal">20/20 HINDSIGHT HINTS: Occasionally we notice the D710 was not updating and so we cycled power and continued. Some times the AVMAP was not updating. Sometimes when the AVMAP was plugged into the Green Light Labs GPS, then the D710 did not get GPS updates. But generally, a power cycle fixed it. Did it maybe 3 times during the all day chase.</p>
<p class="MsoNormal"> </p><p class="MsoNormal">PROBLEM: What screwed us up was “assuming” that the balloon ICON SHOWING on the AVMAP GPS was the same last-updated balloon data showing on the Kenwood D710. So we were visually driving and chasing the BALLOON ICON on the AVMAP not realizing that it was the 2<sup>nd</sup> from last actual position data heard. But each time we LOOKED at the data on the kenwwod we WERE seeing the last known position (looking mostly to see the altitude). But you see, they were not the same. Apparently the last two packets did not make it to the AVMAP. So we were searching based on the time and altitiude on the radio and the visual map data on the AVMAP, not realizing they were different.</p>
<p class="MsoNormal"> </p><p class="MsoNormal">Finally when I happened to compare LAT/LONG numbers on the radio, to our searching area, it was 7 miles to the east!</p><p class="MsoNormal"> </p><p class="MsoNormal">And searching through the 150+ AVMAP APRS entries provided nothing to correlate the two. (it shows no lat/long and the altitude it shows is the LAND elevation, not the balloon!) And since I was completely trusting the balloon ICON on the GPS map display, I never noticed that the distance and bearing on the Radio was showing it 7 miles away.</p>
<p class="MsoNormal"> </p><p class="MsoNormal">20/20 Hindsight. Always use the final data in the RADIO as the last known information. It has to be right. There may have been a transmission error between the radio and the GPS display.</p>
<p class="MsoNormal"> </p><p class="MsoNormal">WB4APR, Bob</p><p class="MsoNormal"> </p><p class="MsoNormal"> </p></div></body></html>