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HF Mystery Signals / Re: Pulsating - feedback signal on 13236khz @ 0130 UTC 28/7/15
« on: July 29, 2015, 1834 UTC »
Thank you Token for all the great info.
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http://1drv.ms/1MVZgl3
This is a short recording of a raspy buzzy ugly signal on 6959 kHz at 2355 z which shifts in frequency occasionally about 1 kHz, and is about 6 kHz wide. It is s9 in central Florida on an attic dipole. While I was typing this post, the signal suddenly stopped as 2356 z. I had been listening to it for about 10 minutes.
Mystery signal
Dag
As I said before, I do not know what this signal is, but I can make some pretty good guesses as to what it is not, and I would bet this signal is not from the DISS at Goose Bay or anyplace else. The DISS is a Standardized D256 Ionosonde, its waveform is well understood, and does not look like this signal. But, even if the D256 waveform were not known I think we can make a pretty strong case for this not being a DISS.
Goose Bay is only one of 17 locations using the DISS, there are over a dozen more users of the legacy D-256 Ionosonde, with a waveform very similar to the DISS ( http://umlcar.uml.edu/stationlist_instrument.html ). With over 30 users of a “standardized” item, including locations in Colorado, Texas, Florida, Alaska, and Puerto Rico, why do we only see one of these signals?
The “take” from the ionsondes (including Goose Bay) are available online, and it shows results for a much wider frequency range than what this signal is sampling. The fact is this signal covers far to narrow a range of frequencies to be useful as a traditional ionosonde, most ionosondes cover about 2000 kHz to about 30000 kHz (the frequency range is user selectable, as are any skipped frequencies) in a single pass, and they typically do this very quickly several times an hour.
T!
The transmitter at Goose Bay you mention, that would not be a node of the DISS (Digital Ionospheric Sounding System) Network, coordinated by the USAF, would it?
T!
I have noticed this signal many times in the past few years. While I do not know what it is, I have always dismissed it as a probable unintentional signal. A couple of years ago I took a pretty close look at it and never could find what I thought was intelligent data.
While I am certainly open to this being a “real” signal with some use / meaning, there are a lot of things about it that make me think unintentional, however long lived it is.
This signal drifts up and down the band in a roughly sinusoidal pattern, however the end points of each cycle are not fixed and do not typically repeat. The cycle time is inconsistent, for example last night it was “about” 10 minutes peak to peak, but that varied by quite a bit, 5% or more (30+ seconds) was common over an hour period (~6 cycles). The width of the cycle changes, there does not appear to be a fixed or consistent swept width.
Here is a 2 hour and 5 minute waterfall image of its action last night. This is a pretty large image, ~6.5 MB, so if you are on a mobile device you might not want to click the link. Time UTC is down the left side, freq in kHz across the top.
http://www.pbase.com/token/image/159457911/original.jpg
The source seems to be from the east of my location. It is typically there after the band starts to open up in the evening and it goes away before local sunup. It is often receivable all night long. Last night I did not set down at the gear until some time after 0230 UTC, and it was present, and this morning when I left for work just before 1200 UTC it was still present, but fading. For me it is often hard to see / hear in the pre-dawn, but that is mostly because the Chinese OTHRs often hit the same range of frequencies, and they are typically strong in the morning here.
As I said, I have no idea what the signal is, but it might be interesting to try and narrow down the source a bit.
T!