HFU HF Underground
Loggings => HF Mystery Signals => Topic started by: Traveling Wave on November 02, 2022, 1607 UTC
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1604 UTC - S7 signal into WNY, some type of OTHR at the tail end of the 17 meter amateur band. Can anyone ID this thing ?
Sounds like the Russian 29B6 Container Radar reported before ...https://www.hfunderground.com/board/index.php/topic,98675.0.html
1638 UTC - Signal was S7 then off at 1640 UTC.
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1604 UTC - S7 signal into WNY, some type of OTHR at the tail end of the 17 meter amateur band. Can anyone ID this thing ?
Sounds like the Russian 29B6 Container Radar reported before ...https://www.hfunderground.com/board/index.php/topic,98675.0.html
1638 UTC - Signal was S7 then off at 1640 UTC.
This was a radar, yes, but not the Russian 29B6 Container. Instead, this radar is the British PLUTO radar (also called the PLUTO II radar) from the base at Akrotiri. It actually started on that frequency at about 1345 UTC, and ended, as you note, at about 1640 UTC.
The Russian 29B6 radar and the British PLUTO radar are similar, but can be told apart. 29B6 typically has a width of about 12 - 14 kHz, while the most common PLUTO bandwidth is 20 kHz. However, both radars have other bandwidths also, for example PLUTO might be 10, 20, 40, or 100 kHz wide (this is not a complete list of possible PLUTO bandwidths, just some of the more common ones). Note that PLUTO typically uses a bandwidth that is some multiple of 5 kHz, while 29B6 does not.
Also the repetition rates of each radar are different. This is the audible "buzz" rates of the radars. 29B6 most often uses 40 Hz, while PLUTO most often uses 50 Hz. However each can use other rates also, but the PLUTO is typically some multiple of 12.5 Hz, i.e., most often 12.5, 25, 50, or 100 Hz.
And when you look at each signal closer, look at the modulation itself, the 29B6 uses FMOP while the PLUTO uses FMCW. IN the below image the chirps (diagonal lines) at the top are 29B6, and the ones on the bottom are PLUTO.
(https://a4.pbase.com/o9/50/78250/1/152255870.2gFV6M5z.PLUTO_and__3_0404.jpg)
T!
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Thanks T!, found this explanation on youtube https://www.youtube.com/watch?v=RsmMvOuFtOs
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Thanks T!, found this explanation on youtube https://www.youtube.com/watch?v=RsmMvOuFtOs
Unfortunately, YouTube will not allow me to change that video. I put that video up on my YouTube channel in 2015, with YouTube hosted annotation (arrows and text words point out some features). YT stopped their hosted annotation, so all of that annotated information went away, leaving long periods, in the current video, when you are just looking at the signal with no explanation.
Also, in about 2018 the Russian 29B6 went through an upgrade (it was off-air for many months for this upgrade). When I made that video both 29B6 and PLUTO normally used a 50 Hz rep rate, as shown in the vid. After the 29B6 upgrade the 29B6 switched to a 40 Hz rep rate as its default, most common, condition. Also, 29B6 became capable of more simultaneous beams of operation. Currently PLUTO can do up to 4 simultaneous beams, and 29B6 can do up to 8. PLUTO most often does about 2, and 29B6 normally has all 8 operating.
As I said, YT will not allow me to change that video, I can delete it, or I can upload an additional vid, but not change that one. So I have left it up and active for now, intending to do a new vid eventually, with the new 29B6 features more thoroughly pointed out. One day.
T!