Many thanks to SWLing Post contributor, Patricia, who writes with the following inquiry:
I wonder if anyone has heard and identified the station or signal I heard on 7075 kHz at 0745 October 30, 2021 on my C. Crane Skywave, and I live in southern California. I would like to know where this signal originates, sounding something like a numbers station, no voice, but a whooshing sound. I have heard it may be a ham frequency or a signal from space. Any ideas?
Thank you for your question, Patricia.
I believe what you’re hearing is the ham radio digital mode called FT8.
FT8 is a weak signal digital mode that is extremely popular in the ham radio world these days. The mode isn’t designed around relaying lengthy messages, rather it’s designed for short, very formulaic exchanges.
Each message of up to 13 characters takes 13 seconds to send. For FT8 operators to be successful, they try to keep very accurate timing on their computing device controlling the transceiver. When the whole group is coordinated well, you’ll hear groups of signal tones singing all at once in 13 second intervals with a couple seconds of space between messages.
Here’s what FT8 sounds like in SSB mode:
It’s possible it sounded quite different, however, if you were listening in AM mode.
If this doesn’t sound like what you heard, perhaps you can check the comments for any other possibilities, but my guess is it’s FT8 as it’s a pretty strong chorus of tones!
Great question, Patricia!