Author Topic: Unknown pips / pulses in the ham 40 meter band, 01 Jan, 2018, 2238 UTC  (Read 275 times)

Token

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01 Jan, 2018, about 2238 UTC, Tom S in the HFU Ryver chat commented on hearing an odd set of pulses or dits on multiple frequencies in the 40 meter ham band.  I looked and sure enough, there were 4 frequencies with short duration dits on them, and a pretty strong signal is was.  Eventually using remotes and talking to other listeners in chat this signal was heard from the US west coast and Pacific North West to Eastern Europe.

Each frequency was pulsed once per second.  Each pulse or dit was about 20 millisecond long.  The initial set of frequencies was 7035 kHz, 7040 kHz, 7065 kHz, and 7105 kHz.

Looking closer showed that the pulses on all 4 frequencies were not transmitted simultaneously, rather the pulses were sequencing or cycling through the 4 frequencies.  Frequency 1, then freq 2, then freq 3, then freq 4, and back to freq 1 to start the cycle over.  Each 20 msec pulse was followed by 20 msec of dead air before the next frequency in the set transmitted.

In the first set noted, active from 2238z until 2250z, the sequence was 7065 kHz, 7040 kHz, 7035 kHz, and 7105 kHz, in that order.  Back to 7065 kHz to start the cycle again.

This picture shows the timing relationship between 7065 and 7040 kHz in that first set.
https://a4.pbase.com/o10/50/78250/1/166795861.ToN2Bl3p.40M_dits_7040_vs_7065.jpg

At 2250 UTC the frequency set changed, and now the sequence was 7066 kHz, 7040 kHz, 7000 kHz, and 7070 kHz.

At 2323z the signal went off air for a minute, and came back on at 2324 UTC, now with the sequence of 7065 kHz, 7040 kHz, 7105 kHz, and 7000 kHz.  This set continued until 2355 UTC.

At 0005 UTC, now 02 January, the signal came back with the sequence 7065 kHz, 7040 kHz, 7105 kHz, and 7120 kHz.  At 0016 UTC this frequency set changed to 7065 kHz, 7040 kHz, 7010 kHz, and 7105 kHz.

The signal went off air at 0019 UTC and was not seen again.

Note that in the 5 sets of frequencies observed 7065 and 7040 kHz were always the first two used, the last two frequencies changed with each set.

Both while the signal was active and for several hours after it ended I attempted to find it on other freqs, I did not see any active.

These pulses were 1 pulse per second per frequency and the timing appeared very stable over the hour and a half observed.  The lead pulse, always 7065 kHz, always arrived at my location about 9.6 msec after UTC time zero.  Although there is really nothing to indicate it (and nothing to NOT indicate it), if we assume the lead pulse is made on the start of the UTC second then we can plot, based on propagation time, the range from my location.  This results in a range ring looking something like this:

https://a4.pbase.com/o10/50/78250/1/166795887.nPGPPsB0.40M_dits_delay.jpg

Pure speculation, and nothing to prove it either way.  But interesting how the circle goes right through WLO's location in Mobile, AL, as well as near a few other known radio sources near the Great Lakes.

Anyway, I have no idea what this signal was / is used for, and it might be just some kind of test signal.  But I found it interesting and it was, in my opinion, well over ham power levels.  I will be keeping my eyes open for it.

I made a video of the signal and put it up on my YouTube channel.  The video is boring with lots of text added carrying the details.  There are sections of the video for each of the 5 sets of frequencies seen and audio comparing the timing of each frequency set.  So not something to keep the average YouTuber engaged, but maybe someone interested in shortwave oddities might find it revealing.

https://www.youtube.com/watch?v=mSP8pHtqOd4&

T!
T!
Mojave Desert, California USA

MDK2

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I'm seeing a similar set of pips at 1427 03 JAN on 6235 kHz. The same thing? (I'm currently waiting for V24 on 6310, so I won't be scrolling around to see if there are other frequencies now.)
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skeezix

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I saw you guys talking about it and I checked when you said you said it was active, but I saw nothing.
Minneapolis, MN

Token

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That is weird, the person who originally noted it is in Kansas, and it was heard by listeners or found on remotes from the US west coast to Eastern Europe.

T!
T!
Mojave Desert, California USA

skeezix

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I've been watching for them off & on since the original report and have yet to see these. Unknown if it was a one time test(?) or I'm just in a bad spot for them.  I could be in their skip zone too.

Minneapolis, MN