Whispers in the wind – How WSPR performed on Flying Squirrel #2
In addition to the detailed locations provided by the FSQ telemetry, Flying Squirrel #2 also sent WSPR messages 4 times an hour.
WSPR is a very weak signal digital mode, often decoding signals below the noise (i.e. you can’t even hear the signal with your ears). The WSPR mode sends a position as Maidenhead Gris squares, which is a very rough position of the sender. FS2 used the 6-digit grid locator which will locate the position to a, roughly 5×7 mile grid square. The purpose of WSPR on FS2 was to give an approximate location, that had good chances of being received by a large network of stations already listening for WSPR signals. Had we lost track of the balloon for a time on FSQ , WSPR would allow the ground stations to get into the neighborhood of the balloon and re-acquire FSQ.
As it turned out the FSQ performed really well and we never lost contact until the end when it was clear the balloon returned to ground.
However, it is worth reviewing how WSPR performed.
The map above shows that a number of stations heard FS2 and reported its position. All of the position reports were significantly to the east, the closest being east Texas. FS2 was heard as far away as Jacksonville FL.
The table above shows that certain stations received the FS2 WSPR multiple times. Also worth noting is that many of the reception reports indicated receive signals strengths at -20db and above. WSPR easily can decode to -28 and below, so the signals seem to have been strong on the whole.
I do wonder why more stations, especially stations within line of sight did not pick up the balloon. Radio propagation conditions were not good at the time we flew. It had been approximately 6 days with no sunspot activity and there was some possibility of space weather caused disturbances. That may explain the lack of reports, but it is impressive that a 20mw signal was heard on the far side of the US!
73s de Don KJ6FO