Hi All,

Occasionally recently I have been seeing strange patterns around the harmonic line received on my SpecLab grabbers on 504kHz from the broadcast station at 252kHz.

The patterns are not just seen using the Softrock SDR Rx but also with my JRC NRD-345, the only common device is the Mini-Whip active antenna.

I seem to remember some while ago comments on this LF Forum regarding that station carrying out some experiments or tests involving digital data or something similar.

I wonder if this is an effect of those tests as there were concerns that it may cause interference on the 500kHz amateur band.

Capture attached.

73,

Gary - G4WGT - IO83QO.