The sharp phase transition may well be a broadcasting centre handover.
Using TV frame reference is a neat idea, because in order to stop
the most destructive type of co-channel interference the broadcasters
have to run them at exactly the same frequency line frequency. However I
do not see why they would worry about phase transitions on a occasional
basis.

73

Stewart G3YSX

[email protected] wrote:

Hello group,

I made two phase plots of 1.5 hours length yesterday, the first with MSF (60kHz), the second with DCF77 (77.5kHz).
To calibrate sample rate and the receiver's LO, the 15625 Hz TV sync ("ZDF") and its harmonics at 62.5 kHz (for the MSF plot) and 78125 (for the DCF plot) were used.

The graphs are attached.
"Ampl1" (red) is the amplitude of the TV sync,
"Phase1" (green) its phase which shows that the software is not perfect,
"Ampl2" (blue) is the amplitude of the MSF- or DCF carrier,
"Phase2" (purple) shows the variation of the MSF- or DCF phase. The absolute value is meaningless, it depends on when the measurement started.

It appears that the long-term phase stability of the ZDF TV sync against MSF and DCF is very good. The phase graph shows some "ups and downs", the maximum phase deviation is 50° over the 1.5 hour observation period.
I expected a significantly lower phase variation in the DCF graph. The reason is still unknown, maybe the 'calibration' algorithm needs more tweaking.

Regards,
 Wolf