What's interesting is, there is clearly some energy bleed into the region beyond its 10 kHz bandwidth. In the past I chalked this up to intermodulation in the antenna, but I'm starting to reconsider. There are plenty of strong double-sideband stations (all of the 31 m band) that don't exhibit this behaviour.
Here it's easier to see that fades start from outside the signal bandwidth and cross through from one side to the other over time. Intermod in the receiver chain would mean that fades outside the bandwidth start at the same time as fades inside.
What is probably happening is the transmitted spectrum mask is not 55 dB down, but more like 40. Usually this is still below the noise floor, but if subcarrier power exceeds -80 dBm the "skirt" becomes noticeable.
Also, check out this 9800 kHz Vatican DRM broadcast where, upon review, the signal mask is only about 35 dB down.
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