Re: LF: RTE 252kHz

[Andy Talbot <andy.g4jnt@gmail.com>]

After posting that image I tuned in the signal on an AM receiver and realised what was causing the circle.  There was audio another weaker transmission underneath it - in French I think.   So the circle on the vectoscope plot was nothing to do with skywave propagation interference, but just the oterh carrier, some 6db down and 0.25Hz off frequency.  At 1500z the interferer is significantly weaker  and the vectorscope plot correspondingly cleaner

Oh well...

Still searching for a clean MF carrier

Andy   G4JNt

The mean phase of the carrier is solid for hours, suggesting the transmission is at least Rb controlled as the points do not rotate around the vectorscope screen. 

The interesting bit is the smaller circle with a radius of about 15 - 25% of the mean signal amplitude, caused, I assume, by ionospheric frequency shifting of a substantial skywave portion of the signal.     The plot represents 8.2 seconds worth of carrier history,  the small circle taking about 4 seconds to form, suggesting there is 0.25Hz worth of skywave frequency shift associated with it.

I'll try Droitwich as dusk arrives, but its annoying carrier modulation means the resulting plot will not be so 'clean'

Andy  G4JNT