When I looked at the SDR waterfall this morning, I noticed an apparent DGPS station on 325 kHz. Checking the UNID window, I could see it was sending ID 000. I assume this is the return of a test transmitter. Got quite a few decodes, several hundred over the span of just a few hours.
This brings up (again) the issue that the way Amalgamated DGPS works, there's no easy way to find new stations that aren't in the defined station list.