search

ve3wmb / OrionWspr

Arduino WSPR Beacon for Amateur Radio pico-Balloons using SI5351a
GNU General Public License v3.0
16 stars 5 forks source link

Calibration randomly jumps frequency #8

Closed TimMW1 closed 4 years ago

TimMW1 commented 4 years ago

During calibration the derived clock frequency of 3.2Mhz randomly jumps. This seems to correspond to negative counter values. This may be due to loss of GPS time pulse. Will need to investigate.

ve3wmb commented 4 years ago

TimMW1

More details are needed, including debug logs, if possible.

FWIW, I can't see how it is possible to get negative count values, but it is possible to over-count if PPS pulses are delayed due to intermittent GPS PPS signals. We have seen this before and it results in counts that are somewhat bigger than should be expected. This does have an impact on calibration but it is minimal as the maximum frequency correction per calibration cycle is to about 2 Hz. The above scenario sometimes happens before detection of GPS LOS. This should be a very rare occurrence at 10,000+m as GPS LOS (or intermittent LOS) is not expected to occur frequently.

Michael VE3WMB

ve3wmb commented 4 years ago

No further details so this is closed on June 9, 2020