'swisher' type signal on 22820 khz at 1827utc
audio file at:
http://http://vincewerber.org/swl/22820khz-1830utc.mp3
First minute is on LSB while the second minute is on USB.
73 vince ka1iic _._
“Page not found”, but that is OK, I think I know the signal you are talking about anyway.
This signal is a bit of a mystery. At one time several listeners in the community thought they had a good grip on where it was from, and a couple of good ideas about what it might be doing. But then information came to light that muddied the water a bit more. Just a note, while exactly what it is may be difficult to say it is as close as possible to say it is certainly NOT a radar, as has been suggested on one forum.
First, lets say the frequency is actually 22819 kHz USB. Yes, for those swept signals you could go with center frequency and that would be near 22820 kHz (typically ~22820.5 kHz c/f for the sweeps), but those swept signals are not the only things you will find from this source. And for some of the other signals (and sometimes the audio noise on the transmission) you can see that the transmitter is indeed tuned to 22819 kHz and in USB mode.
22819 kHz is not the only frequency you will find these signals on, I have found them on 14756, 16926.5, 16929, 17299, 17383, 19281.5, and 22819 kHz. I have heard of other freqs but have not captured those others myself. Sometimes ALL of these frequencies are active at the same time, and sometimes all of the data on each freq are in sync, other times there is individual data on each freq. The 16929 kHz signal is always in sync with the 16926.5 kHz signal, and might be a spur that helps indicate the transmitter is indeed in USB mode.
The swept signal is not the only kind of signal you will find on these freqs. At various times there have been sweeps of different rates, there is often a drifty MFSK-like signal, and occasionally a few QPSK like signals.
The swept frequency is not an honest linear sweep, it is actually a stepped signal. Since I cannot get your recording to play I cannot tell you which you are hearing, but I have heard sweeps with anything from 16 to 64 steps, with 32 being the most common that I have seen.
Here is the signal on 19281.5 kHz. Also a max hold image of the 32 steps in this particular version.
WPG in Indiana is licensed for all of these frequencies and is a very good candidate for the source of these signals. However these signals were first thought to be WLO and Swisscomm sourced. At various times on each of these frequencies I have gotten good bearing cuts to both WLO and WPG locations. European listeners have reported bearings consistent with HEB Swisscomm. So, possibly there is more than one source associated, although WLO does not appear to be licensed for these freqs.
The swept signal has made for interesting monitoring in the past. Sure, it is a boring sweep that could drive you brain dead in short order. However, occasionally you can get both long and short path on these signals. And when this happens on the swept signal it is fairly easy to calculate an approximate range to the source. Combine said approximate range with a bearing cut and you get a specific geographic area that might be the source.
Image below shows the short and long path signals, and the delta between them (roughly 115 millisec).
In the above case the range is consistent with either WLO and WPG (by chance the range to each is about the same for my location) but the bearing was squarely on WLO, in Mobile, Alabama.
T!