Hi Peter and all,
I am using DCF39 to set the calibration of my rx and argo.
There are two reasons why DBF39 may be of limited use for very precise
frequency calibration:
- Due to the phase-continuous FSK, the phase has shifted arbitrarily after
each data burst. On Argo with 21mHz or finer resolution you will not see a
narrow line but rather an irregular strip several ten mHz wide.
- Even in the intervals between the telegrams, the freq appears to be
slightly higher than nominal. Using a scope to directly measure the rate of
phase advance relative to an OCXO reference derived from terrestrial TV
"ZDF", I got 138830.030 Hz for DBF39 and 128930.014 Hz for DCF49, but these
offsets may even be variable. On the other hand, 122.5 (DCF42 pilot), 153.0
(DLF radio) and of course 77.5 kHz (DCF77) seem to be very accurate.
73 and good luck
Markus
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