Last night I thought to check the signal periodically over the course of two hours. At the beginning there was just noise, and then the faintest indications of a DRM signal on the waterfall, and from there it just slowly rose out of the noise until what you see here. Propagation conditions were really good.
But the other interesting thing was how even though the signal power didn't change much, I'd still incur periods of frequent frame loss due to a fall in SNR.
In the demod spectrum on the right, the nearby noise power is about -115 dBm in the second image, versus -120 dBm in the first. It did translate neatly to a 5 dB difference in SNR reported by Dream, which is all the difference between no frame loss to bursts of frame loss. The funny thing was the transition was sudden, like a switch, and it was being toggled every six some odd minutes.
I tracked it down to the air conditioner. So the A/C raises the noise floor by 5 dB across at least the 16 m band.
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