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--></style></head><body lang="EN-US" link="#0563C1" vlink="#954F72"><div class="WordSection1"><p class="MsoPlainText"><span style="color:#1f497d">6db is half the range.</span></p><p class="MsoPlainText"><span style="color:#1f497d">A good thing to remember when operating low power for an APRS event out of area…</span></p><p class="MsoPlainText"><span style="color:#1f497d"> </span></p><p class="MsoPlainText"><span style="color:#1f497d">We have been using 10W trackers for our local events with great success and local digipeaters. So this year, rather than putting 50W APRS radios in the four football tracking vans, we just put in some 10W trackers instead. A lot less hassle. Just plugged into the cig/lighers.</span></p><p class="MsoPlainText"><span style="color:#1f497d"> </span></p><p class="MsoPlainText"><span style="color:#1f497d">OOOPS. Tracking was poor. This is probably due to some aging of our local digi infrastructure (which I had not paid close attention to for years) and running lower power than our typical 50W mobile commuting. With a difference between 10W and 50W is 7 dB, and remember that it takes 6 dB to double range.</span></p><p class="MsoPlainText"><span style="color:#1f497d"> </span></p><p class="MsoPlainText"><span style="color:#1f497d">Then we also found out that the self-reported “PHG” range circles for most digis were off by another factor of two….</span></p><p class="MsoPlainText"><span style="color:#1f497d"> </span></p><p class="MsoPlainText"><span style="color:#1f497d">The PHG circles in APRS are designed to be approximately HALF the theoretical horizon due to the fact that packet takes at least 6 dB more signal than voice for error free packets. But on the <a href="http://APRS.FI">APRS.FI</a> map, almost all the digipeaters plot outlandish predicted ranges. We might ought to re-check these PHG circles.</span></p><p class="MsoPlainText"><span style="color:#1f497d"> </span></p><p class="MsoPlainText"><span style="color:black">Th</span><span style="color:#1f497d">is</span><span style="color:black"> map shows coverage</span><span style="color:#1f497d"> in maryland</span><span style="color:black">, but look at the actual dots. No hits in central </span><span style="color:#1f497d">Maryland </span><span style="color:black">area: <a href="http://aprs.org/digis/usna-digis-2016.png">http://aprs.org/digis/usna-digis-2016.png</a></span></p><p class="MsoPlainText"><span style="color:black"> </span></p><p class="MsoPlainText"><span style="color:black">Just some data points</span><span style="color:#1f497d">… and a reminder that we cannot take the APRS infrastructure for granted….</span></p><p class="MsoPlainText"><span style="color:black"> </span></p><p class="MsoPlainText"><span style="color:black">Bob, WB4APR</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p></div></body></html>