<html><body><div style="color:#000; background-color:#fff; font-family:Courier New, courier, monaco, monospace, sans-serif;font-size:16px"><div><span></span></div><div><font size="2"></font>Another problem (if you ask me) is that when you send a beacon, and that beacon gets digi'ed, and your own station recieves it back and igates it, the station that digi'ed it gets stripped out of the packet.</div><div id="yui_3_16_0_1_1433624546349_17595">This beacon is set to go out via 'RF only' but looks like is was sent direct to the APRS-IS. Also note the time stamp at the beginning of the payload as well as the timestamp from findu showing 5 seconds difference. There was one or more digi's in there<br> <br>20150607070734,KG4PID-14>APRX28,TCPIP*,qAC,T2TEXAS:/070729h3417.45N/08742.32W#PHG7250 Bear Creek, Al</div><div id="yui_3_16_0_1_1433624546349_17633"><br></div><div id="yui_3_16_0_1_1433624546349_17669">Here is the packet as it was recieved back by my igate (aprx) and there were 2 digi's in there.</div><div id="yui_3_16_0_1_1433624546349_17673"><br></div><div id="yui_3_16_0_1_1433624546349_17672">2015-06-07 07:07:33.789 KG4PID-14 R KG4PID-14>APRX28,W4UNA-7*,N4IDX-7*,WIDE2*:/070729h3417.45N/08742.32W#PHG7250 Bear Creek, Al</div><div id="yui_3_16_0_1_1433624546349_17674"><br></div><div id="yui_3_16_0_1_1433624546349_17711">Here is the same beacon sent 20 minutes later that made it to an igate before the digie'ed packet could be recieved back by my station.</div><div id="yui_3_16_0_1_1433624546349_17710"><br></div><div>20150607072701,KG4PID-14>APRX28,WIDE2-2,qAR,N4XWC:/072659h3417.45N/08742.32W#PHG7250 Bear Creek, Al </div><div id="yui_3_16_0_1_1433624546349_17714"><br></div><div>So for satilite work, if you hear your own digi'ed packet, it will just look like it was sent direct to the APRS-IS.</div><div id="yui_3_16_0_1_1433624546349_17715">I've questioned this behavior before and was told that it is normal. But why would the path get changed just because you heard your own packet?</div><div><br></div><div dir="ltr">Max KG4PID<br> </div><div id="yui_3_16_0_1_1433624546349_17462" style="font-family: Courier New, courier, monaco, monospace, sans-serif; font-size: 16px;"> <div id="yui_3_16_0_1_1433624546349_17461" style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div id="yui_3_16_0_1_1433624546349_17511" dir="ltr"> <hr size="1"> <font id="yui_3_16_0_1_1433624546349_17510" face="Arial" size="2"> <b><span style="font-weight: bold;">From:</span></b> Robert Bruninga via aprssig <aprssig@tapr.org><br> <b><span style="font-weight: bold;">To:</span></b> TAPR APRS Mailing List <aprssig@tapr.org> <br> <b id="yui_3_16_0_1_1433624546349_17509"><span id="yui_3_16_0_1_1433624546349_17508" style="font-weight: bold;">Sent:</span></b> Saturday, June 6, 2015 10:03 PM<br> <b><span style="font-weight: bold;">Subject:</span></b> [aprssig] PSAT & igating and Optimum antenna<br> </font> </div> <div class="y_msg_container" id="yui_3_16_0_1_1433624546349_17460"><br>Steve's insight is very revealing...<br><br>> The APRS-IS filters duplicates based on payload, not on path,<br>> Suppose I have an IGate station... [and I use it to also send a packet to<br>> the ISS]<br>> [when it is digipeated by the ISS, it never makes it to the APRS-IS!]<br>> [because the transmitted copy made it to the APRS-IS first<br>> [and so the digipeated copy gets ignored as a dupe<br>> [BUT, since the original one did not get tagged with RS0ISS*<br>> {Then the FINDU page looking for successful RS0ISS* packets wont see it!<br><br>This also means then that although an IGate provides a WINDOW to downlinks<br>over millsions of square miles, it also creates a DEAD ZONE to every station<br>it can hear direct!<br><br>So, what we need for OMNI IGates are antennas that hear great at high angles<br>and poorly at low angles (exactly the opposite of what terrestrial antennas<br>are designed to do.<br><br>But the good news is that the 3/4 Wave vertical I always tout is ideal in<br>this case. It provides almost 7 dBi gain above 30 degrees and more like - -<br>4 dBi on the horizon. This means it favors Satellite signals by more than<br>10 dB.<br><br>PLUS, if you mount it low in your yard, so that it sees WELL above 30<br>degrees but is blocked to the horizon in all directions by trees and houses<br>and other stuff, then you can probably reduce the terrestrial gain by<br>another 10 dB or more.<br><br>SO again, a 3/4 wave vertical mounted low is an IDEAL no-moving-parts IGate<br>antenna for PSAT and ISS. SO make it 59" tall with a ground plane. Don't<br>even have to climb to the roof. Done.<br><br>Thanks Steve!<br><br>The antenns is described about 85% down this page I have had for more than<br>15 years:<br><a href="http://aprs.org/astars.html" target="_blank">http://aprs.org/astars.html</a><br><br>Though it is talking more about using a 19" vertical as a 3/4 wave for UHF.<br>But the same goes for a 59" whip for 145.825!<br><br>Bob, Wb4APR<br>_______________________________________________<br>aprssig mailing list<br><a href="mailto:aprssig@tapr.org" ymailto="mailto:aprssig@tapr.org">aprssig@tapr.org</a><br><a href="http://www.tapr.org/mailman/listinfo/aprssig" target="_blank">http://www.tapr.org/mailman/listinfo/aprssig</a><br><br><br></div> </div> </div> </div></body></html>