Polish NDB "SA"

The 472-479kHz amateur band (available only in a few countries so far) has several aircraft beacons (see my main web site). One of the most prominent transmits "SA" in Morse on AM. The carrier is on 474.5kHz, and the Morse callsign sidebands can be heard approximately 1kHz above and below that frequency. It is quite loud after dark, but here is a Spectrogram (set to QRSS3) of the carrier during the daytime here. The straight line is "SA", and the big wobbly ones are from my plasma TV.