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Posted by Bruce WA1HGJ on February 04, 2026 at 13:51:53.
In Reply to: TDF Digital Data posted by Gedas W8BYA on February 04, 2026 at 05:26:59.
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This is fascinating, Gedas. Thanks for posting that video recording. I had known TDF was somehow transmitting time data on what sounds like a pure carrier but thought maybe it was phase modulation which one might not hear audibly. But I had noticed some time ago that if I tuned the transceiver (in CW mode) to exactly zero-beat the TDF carrier against the 700 Hz CW sidetone, I could hear regular fluctuations, whereas no such fluctuations are heard with “regular“ carriers from “regular“ LWBC stations. Watching your video now, it’s clear that’s what I hear with my sidetone zero-beat listening strategy. So my question now is, what kind of modulation is it? Seems too narrow to be FSK, but maybe some kind of micro-FM (if such a mode exists)? Seems like phase modulation would not do what you are seeing. Oh yes, and the brief unmodulated carrier at the top of the minute is the real clincher. Guess I had never been lucky enough to be doing my sidetone zero-beat thing at precisely the right time of the minutes! Thanks again for posting the TDF video, very cool. Loving this LW board now with all the new activity and postings. 73, Bruce WA1HGJ
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