HFU HF Underground
Loggings => HF Mystery Signals => Topic started by: Edgar Souse on August 04, 2019, 0240 UTC
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I've been hearing this for the last 20 minutes as of now. It sounds like a CW signal while someone spins the knob back and forth. http://
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A screen shot and a recording would help ID the signal.
T!
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Whoops, thought I had. Here it is:
https://imgur.com/a/YY7QPMe (https://imgur.com/a/YY7QPMe)
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Aren't there phone chargers that do this?
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If so, its new to me. Hearing it again on 8952
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No, almost certainly not an OTHR. If it is a radar of any kind it is one of the worst thought out waveforms I have encountered. Below is why I say that.
Notice how unstable the pattern is? Restart / stop variable times with glitches and odd shapes on either peak of the sweep? Really, really, not desirable for a radar. Every one of those steps on either side, and any irregularity there (several places you can see it doing odd things after that step), would be lost or erroneous data.
Notice the variable and very narrow bandwidth, under 3 kHz on average? Not desirable for radar as this would cause very poor range resolution. You essentially never see a radar with such a narrow width (except in test modes), although you might see a sounder that narrow.
That 5 second cycle time is also very suspect.
Notice the use of a near sine wave pattern? Not typically desirable for a radar, although it is sometimes used for them. Linear patters, be they triangle or sawtooth, are much more common as they are easier to process and sine waves offer little or no advantage over the more common linear chirps unless combined with other features. Non-linear patterns, such as sinusoidal patterns, can increase dynamic range by countering masking affects, however the rest of this specific waveform fights against that, and would more than negate any such advantage. It just ain't raht...
If this is not accidental, if it is a real transmission and not RFI, the ~3 kHz bandwidth is probably a hint it is from some kind of transmitter normally used for digital or audio work. Maybe a test signal sweeping the response?
I suspect it was accidental myself. Some kind of unstable thing going into a digital modem or SSB audio transmitter.
T!
(edit) Added some images of the signal to show more detail.
(https://a4.pbase.com/o12/50/78250/1/169815562.Ft4hKWom.8956kHz_US_19_001.jpg)
(https://a4.pbase.com/o12/50/78250/1/169815563.ox5jhFBU.8956kHz_US_19_002.jpg)
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No, almost certainly not an OTHR.
Yes, agreed, it isn't OTHR.
Also agreed, it looks like a sweep tone within a standard 3 kHz or 2.8 kHz speech communication bandwidth.
The curious discontinuous wiggles in the sweep frequency might be some kind of data, or be just a glitch.
That makes it interesting.
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The distorted sine parts might be a phase reversal?