HFU HF Underground
Loggings => Other => Topic started by: Hitchhiker on November 03, 2015, 1914 UTC
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Here's a question I should probably know the answer to but don't. What is the sound at 26750 kHz? Came across it while playing with Twente today. I don't spend a whole bunch of time with number stations and beacons, but it seems like this is one I've heard in a YouTube video or somewhere.
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In the 26-27.000 range I was told Twente doesn't pick anything up there unless it's extremely local. You could be hearing the university's pager signal, which is always there in that area because it's used by security.
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While the Twente SDR and antenna are not optimal above 25000 kHz, it can hear signals that are not local above that point with fair regularity. The band itself, of course, is somewhat spotty in performance, but every time it is open I can find DX signals on Twente above 25000 kHz. So a signal found up there does not have to be local. With that said, this 26750.25 kHz signal does appear to be local to the receiver, as it can be present regardless of time of day or current propagation conditions.
The signal on 26750.25 kHz on Twente is not the "normal" pager that has always been present. That pager is up on 26950 kHz, and image products are scattered throughout the spectrum. There are several other pager systems that can periodically be seen on the Twente SDR, but none match this 26750 signal.
This signal is relatively new, although I have no idea how long it has been active.
The signal could be a pager, however if it is I am not familiar with the type of system it is. It appears to be a constant FM transmission with occasional data bursts.
(edit) Looking back at my past recordings and images there appears to have been a signal on 26750 kHz on Twente for a long time, however it now is different from what it was in the past. In the past it was periodic data bursts, somewhat similar to what is seen today, but the constant portion of the signal was not present.
T!