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APRS snap

I just recently started using APRSdroid, and I've been just looking at maps, and I've noticed that in my area there are spots with just a cluster of stations on top of each other (in this specific case, in the middle of a lake??). I'm the car icon SW of the cluster.

What is going on? I've noticed a similar behavior another town over, but on land. Are people all just saying that's their location for personal reasons or is there another reason?

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Two relevant facts about APRS:

  • APRS stations are not obligated to get their location from GPS. And in practice, many fixed stations have manually entered locations.
  • It is possible to transmit an explicitly coarse location (removing digits from the right).

I do not think that this can be a coarse location because I cannot reproduce that center of lake point by dropping digits (from a latitude and longitude expressed as degrees and decimal minutes, as APRS does). Nor is it the center (or corner) of a Maidenhead grid square.

Therefore, my best hypothesis so far is that it is FOR SOME REASON a deliberately entered location for those stations. Perhaps there is a local group which did not want to reveal their home addresses and they agreed they'd all use the lake as their location, as an obviously-not-real location.

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  • $\begingroup$ Your answer just gave me an idea. For US addresses, QRZ.com gives latitude and longitude coordinates that are derived from the mailing address on file in the FCC database. I believe the coordinates are the centroid of the zip code area corresponding to the zip code from the address. Perhaps the center of the lake is the latitude and longitude given by qrz.com for stations in that zip code, the APRS stations are fixed, and the operators copied the coordinates from qrz.com. It's a long shot, but stranger things have happened... $\endgroup$ – rclocher3 Dec 4 '17 at 23:36

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