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Author Topic: Very short pips (mostly double; some single), 4 second interval, numerous freqs  (Read 1684 times)

Offline alleycat

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I'm currently (24 March @ 0030z) monitoring 4300 kHz and hearing a series of very short pips at a 4-second interval. Folks on the UDXF discussion group at groups.io have reported this phenomenon on a large number of HF frequencies being audible around the world (including SDRs in North America, Austria and China). Audio clip at https://www.lutins.org/temp/radio/pips.mp3; waterfall as follows:
allen lutins - KC2KLC
Binghamton, NY
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eQSLs welcome: kc2klc@lutins.net

Offline ~SIGINT~

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01:06 UTC - I can confirm that I as well am receiving that UNID signal from Toronto, Ontario Canada. It is faint, but audible and visual on the spectrum and waterfall displays. The signal appears to have additional characteristics, 2 kHz high and 2 kHz low from the centre frequency. Unfortunately the signal level is currently too low and short in duration for a proper analysis.

RSPduo | End-fed longwire antenna | Toronto, Ontario Canada
« Last Edit: March 24, 2021, 0132 UTC by ~SIGINT~ »

Offline Token

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If you search "pips network" on these forums you will see they have been discussed here off and on for 10 years or so.

The transmission consists of a dit or dash and a pause some multiple of that dit or dash.  In the case of this transmission it is a 40 millisecond long dit, with a 4.000 second long pause (many different combinations of pulse length and pause have been seen).  The signal starts at some low frequency, makes a pulse, steps up to the next higher frequency, makes another pulse, etc, to the highest frequency, after which it starts over at the low frequency.  So you see it allows, in this specific case, for up to 100 different frequencies to be in each sequence.

Based on past receptions, this network appears to be sourced in the US, from 2 different locations.  Some frequencies are shared between both networks / locations, and so those frequencies show double dits.

I have never been able to confirm the purpose (or exact sources) of this signal, but my supposition is that it is some kind of ionospheric tool.

« Last Edit: March 24, 2021, 0324 UTC by Token »
Mojave Desert, California USA

Offline Dag

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I am hearing double and occasional single pips about every 4 seconds on 8825 kHz USB.
Seminole county, Florida, USA, Earth, Solar System, Universe.Icom 7610 + attic dipole. Black coffee. Ketosis.


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