End of flight S12
Live tracking
Photos of the launch
Photos of the payload during construction and testing
Telemetry schedule


Like the former flights, this one used a special U3S firmware version on an Arduino Nano board, with QRP Labs Si5351A Synthesiser.

End of flight S12

S12 came down in Kazakhstan, after entering a high altitude cloud that extended up to 38,000 ft. Moisture (as ice crystals) on the balloon envelope increases the weight and it falls to the ground. It only takes a few grams of moisture for this to happen. The last transmission received from the balloon was at 11:08Z on 27-Jun-2016. The altitude had already dropped from just under 10,000m to 8,120m. The flight would probably have taken another hour or two to descend to the ground, but it was in a remote place without nearby stations to report it, so reception reports were received only infrequently. Click below for the cloud map in the area at that time, the approximate S12 balloon location is indicated by the red circle.

Eduardo EA3GHS has done an interesting analysis of the WSPR reception reports from S12, see http://ea3ghs.qrp.cat/balloon/s12.html 

Live tracking

The map below is updated automatically with the latest received position during the balloon's flight. During the balloon's night time the battery is quickly depleted, so from just after sunset there are no more reports until daylight.



Telemetry schedule

This is the telemetry schedule provided by Dave VE3KCL


See the S-4 page for more details of the telemetry protocol. The transmission schedule for the flight is based on a 12 minute transmission cycle, commencing on the hour and repeating every 12 minutes, i.e. at 00, 12, 24, 36 and 48 minutes past each hour. A distilled version of the schedule is:

Minute Band Frequency Mode Message
00 30m 10,140,460 JT9 Callsign VE3KCL + 6-character Maidenhead locator
01 30m 10,140,480 JT9 Altitude + groundspeed
02 20m 14,097,155 WSPR Standard WSPR message with callsign VE3OCL
04 20m 14,097,155 WSPR WSPR telemetry message on channel 3
06 30m 10,140,255 WSPR Standard WSPR message with callsign VE3OCL
08 30m 10,140,255 WSPR WSPR telemetry message on channel 3
10       90 seconds of GPS calibration


Note that the "WSPR telemetry message on channel 3" shows in WSPRnet with a callsign that has first character "0" (zero) and 3rd character "3". The remaining characters of the callsign, and the 4-character Maidenhead locator, and dBm power field, are all re-purposed for the telemetry. The WSPR decode (callsign/locator/power) will therefore be "0x3xxx xxxx xx" where the "x" is any permitted WSPR protocol character and conveys the telemetry according to the protocol discussed on the S-4 page. This special WSPR data telemetry encodes 5th and 6th Maidenhead locator, altitude, temperature, battery voltage, ground speed, GPS status and Satellite coverage.