Wednesday, August 2, 2017

Plotting a maidenhead grid square in aprsisce

Plotting a maidenhead grid square in aprsisce

The WSPR protocol uses Maidenhead grid squares to plot location.  The granularity of a 6-character grid square is approximate 3x4 miles, which is fine for WSPR balloons in the air.  Unfortunately, if a payload crashes on the ground, it's not as useful.  Twice, now, I've tried to locate a WSPR payload on the ground by driving around and trying to hear the signal.  I find it useful to have Aprsisce running in my car, and plotting the grid square on the map, so that I know when I'm reaching the borders of the search area.  Unfortunately, I can never remember how I did it.  This blog entry is a "note to self" for the next time this comes up.

Convert grid square to KML

Visit this site, and enter the 6 character grid square.  It outputs a .kml file.

Convert the KML file to a GPX file

Visit this site and conver the kml to gpx.

Load the GPX file as an overlay in aprsisce

Inside aprsisce:  Configure / Overlay / Add GPX file...

Set the opacity and color so that it shows nicely on the map.

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