APRS Band Opening

It is too bad I didn't have time to pack up the radio gear and head up on the mountain yesterday morning. First I noticed that I was hearing a station out of New York come in on the local Frederick repeater. There is 440 MHz transmitter up there on the same frequency that links the Frederick repeater with the rest of Western Maryland. After hearing that, I thought to check my APRS program. I was delighted to see stations all the way up to Maine. Now this isn't exactly good for the ARPS network, but it is an interesting phenomenon. It is all the more reason to use appropriate APRS paths like WIDE2-2, because you never know when your packets could be retransmitted 100s of miles away and cause network congestion in some other region.



If you notice the yellow circle on the picture, that is known as the ALOHA circle, which is basically the edge of the network for me. Packets I send that are heard outside of that network do more harm than good to the network. My ALOHA circle typically includes the Baltimore and Washington DC metro areas, but it all depends on the number of stations that are active at the time, during commuting hours, the circle gets a little smaller. It all has to do with the number of stations using the same frequency and the limitations of 1200 baud packet radio data signals.

More on APRS: http://www.ew.usna.edu/~bruninga/aprs.html