All-digital AM is an accepted, but not widely-used, standard. It could make the AM broadcast band better suited for music and performance, instead of just talk.
As far as I know, WWFD-AM radio, 820 kHz, based in Frederick MD, is the only fully digital AM broadcast radio station in the US. A radio amateur based in Mayland or Washington DC, using SDR techniques, would be well-placed to make an I/Q recording of WWFD and share it so that the rest of us can study the format.
Here is something to shoot for:
- record I/Q samples (not Q-branch), so that signal structure and phase information is preserved
- from on-air digital WWFD-AM, not the repeater on WWFD-FM
- preferably a recording that crosses the top of an hour (includes a time hack and station call)
- sample passband of 22 kHz centered on 820 kHz (809-831 kHz) or wider (captures adjacent sidebands)
- sampled at 45,000 samples/sec or faster, for about 300 seconds or longer
- share on GitHub or the like, and notify https://github.com/theori-io/nrsc5 (for whom I do not speak)
A 300 sec recording should come in under 100 MBytes. Recordings from various times and locations would be welcome.
Please help make this request better with your suggestions. Thank you!