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Spy Numbers / South Korean V24 may be inactive since late Sep, 2020
« on: November 29, 2020, 2346 UTC »
I have not been doing much radio stuff recently, but I have been doing my scheduled and programmed recordings and spectrum captures.  Those go on automatically as long as the hardware is turned on, and it has been on 24/7 even if I have been doing other things.  For V24 I capture and chart signal levels on all known past V24 freqs, including freqs they have not used in years, and record IQ files of scheduled transmission windows plus a bit more spectrum just in case.

Today I sat down to update the V24 schedule, which I last updated in March of 2020.  To do that I basically played back all the recordings and spectrum captures since March during the time period of 1000 to 1700 UTC daily.

It turns out V24 has not transmitted, to the best of my knowledge, since late September.  In September V24 made two of its nine schedules, or 6 of a possible 27 transmission.  It transmitted on 6215 kHz, on days 5, 7, and 9, at 1500 UTC each day, and it transmitted on 4900 kHz, on days 23, 25, and 27, at 1530 UTC.  So the last V24 transmission I am aware of was September 27, at 1530 UTC, on 4900 kHz.  And for several months prior to that it was at a much lower than normal rate of activity.

Of course there are several possibilities, the simplest is they may have shifted to a new schedule with new times and frequencies I have not captured.  Or they may have just taken one of their unexplained pauses.  In 2015 V24 did not transmit from 16 June to 26 November, one theory is that they changed transmitter facilities during that time period.

So, is V24 gone?  Or is it just taking a rest?  Or did COVID slow it down?


HF Mystery Signals / MOVED: STANAG on 3805?
« on: August 12, 2020, 2256 UTC »

So far UNIDed on 6926 kHz USB, started about 0225 UTC, 27 April, 2020.

S8 or a bit better into the Mojave Desert of California.

I did not know the first song played, but the second, at 0229 UTC, was "Wake Up" by Rage Against the Machine.


So far UNIDed station on 6950 USB.  Possibly heard an ID at 0353 UTC, but was not able to understand it.  Either the ID was over processed or the audio is a bit hot.

ID at 0357 UTC, sounded like Undercover Radio


This is an oddity on shortwave that I don't think I have seen before.  If it is common then somehow or another I have missed it.

About 0420 UTC, 03 April, 2020, I noticed what appeared to be a DSB transmission on 9024 kHz.  DSB is not a commonly used mode these days, so I looked a bit closer.

The signal did appear to be DSB, it also appeared to be a repeating audio loop.  About every 21.6 seconds (start to start) the loop repeated, with about 1.6 seconds pause between audio segments.  The audio was not understandable, either it was distorted, processed in some way, or encrypted.  Longer observation showed that every 11th repeated segment included a longer pause, about 3.1 seconds.  This made a repeating cycle of 11 segments about every 239.6 seconds.

Every segment transmitted appeared identical.  Just the same 21.6 second segment (time includes the audio pause) over and over, with every 11th including an increased length pause.

I have uploaded a video of this signal to my YouTube channel.  If you watch the video I include spectrograms of the audio loops, and visual comparisons of multiple examples.  I also demodulate the signal using multiple modes, USB, LSB, AM, and NFM, to show the sound in each mode.  And the last minute or so of the video is the signal demodulated with LSB in the left audio channel and USB in the right audio channel, for comparison.

Video here:


The South Korean numbers station V24 has a fairly regular schedule.  However, it does change habits over time, adding and subtracting time slots periodically.  This month V24 has been more active than in many months past.  In fact, this month they reactivated a frequency and time slot that they had not used since May 2018.  So far this month they have hit every scheduled time slot except for the 1600 UTC 5900 kHz slots, which are traditionally less reliable.  It has been over a year since the last time the station was this active.

March 18 at 1400 UTC V24 was heard on 5150 kHz.  It used the same intro music and callup that was last heard on that frequency in May of 2018.  So for whatever reason they stopped using it (this frequency and time) for a while, and have now started again.

My recording of March 21 is better quality than the first recording I made on March 18th, so I have uploaded the later date to my YouTube channel.  The transmission was the same for March 18 and 21, and will be the same in two days for March 25.  It is normal for this station to send identical messages three times a month.



For at least 9+ years a type of transmission that I have called the Pips Network in my log has been periodically operation on multiple frequencies. There have been many loggings of this signal on the HFU forums, particularly in the Mystery, Utilities, and Other forums. Sometimes they are seen daily, sometimes it is months between being reported. I know there is more than one source involved, and I strongly suspect not all transmissions seen are related. There is one main network for sure, the one originally seen and for which the "Pips Network" name was coined, and possibly a couple other unrelated networks. However, they all have roughly similar habits, so they get logged under the same name in my log. What they are for is in question, I suspect that they (at least the original ones seen) may be some kind of ionospheric test or measurement signal, but that is a guess on my part.

The habits observed are typically that a dash or dot, sometimes long and sometimes short, is sent on multiple frequencies, from as few as 2 to up to 60+ frequencies. The pulses are not coincident in time, each pulse is sent on a frequency and the source then cycles to the next frequency on the list. Always to the next closest freq on the list. So the pulses/dashes cycle either up or down in frequency.

Often the pulse width and pulse interval are related, and sometimes that relationship defines how many frequencies can be used. For example a one second pulse might be sent with an interval of 15 seconds, or a 0.125 second pulse might be sent with an interval of 6 seconds. In the first case this would allow for up to 15 frequencies to be hit in sequence, in the second case it might allow for up to 48 frequencies to be used.

A slightly different version of this class of signals (in my logs, anyway) is one that uses few frequencies in relationship to the interval. In other words, it has time to do many frequencies but only does a few, but the other habits remain roughly the same. I am less convinced these are ionospheric tools, but it is still a good possibility.

One specific subset of this version includes a long pulse (over 2 seconds, 2.7 and 2.9 are common) and a very long interval (27 seconds seems to be common) on only a very few frequencies, and sometimes including a short burst of some kind of modulation at the beginning of each pulse.  I have called these signals Long Dashes in my logs.

For the past few days I have been following and recording this later subset. I typically see four frequencies in use, there may be more but if so they are not making it to my location. The signals are heard here in California and at the same time on remotes in Europe. A video of the other days signals here, at the time of this video I was aware of only 3 frequencies in operation, I now know it is normally 4+:


They may sit on one set of frequencies for hours at a time, or they may change sets every few minutes.  The signal may be off air for hours at a time, or may run for hours on end.  One frequency seems to be normally near 12500 kHz, one near 11950 kHz, one near 9980 kHz, and one near either 6500 or 6700 kHz.  These freqs are loose, and I often find the signal +/- 100 kHz from those.  I hear the signals best in the mornings, and this may indicate Asian or Pacific origins.


So far unided station on 6932 USB, started with some male voice speaking, was too weak to make most of it out.  At about 0154 UTC went to music, got that fair to usable.  About S5 into the Mojave Desert of California tonight.

(edit) 0158z SSTV was Carpe Noctem, Seize the Night.  Might this be the name of the station?

(edit)  0218z deep and long fade, down to S3 or less here, I can tell it is still there, but weak.


The Russian Buzzer, ENIGMA ID S28, on 4625 kHz, is currently in one of its extended breakdowns.  They periodically happen and can cause a splash within certain communities when they do, certain doom porners really run with it.  Since at least 0130 UTC this morning, 17 February, 2020, and as of the time of this posting, 1430 UTC, the Buzzer has not been sending its normal periodic buzzes, instead it has had a deep transmitter hum.  Several times in that period the normal, or a relatively normal, interrupted buzz has returned for short periods, always to give way to the transmitter hum. 

At about 1240 UTC I tuned to the signal to see if it was still malfunctioning.  I happened to have caught one of the S28 messages the Buzzer periodically transmits.  After the message it returned to the same broken transmitter hum.



So far unided station, or I have not heard one, on 6950 AM.  Playing at least a portion of the song Wildfire, sounds to be a repeating bar from that song.

Heard starting about 01473 UTC, on 6950 AM, Feb 08, 2020.  About S5 into the Mojave Desert tonight so far.

I assume this is the interval signal for the upcoming Ball Smacker Radio transmission, if so I will change the title on first ID.

Music change at 0200 UTC into 80's rock.


So far unided station on 6950 kHz USB.  Noticed about 0110 UTC, February 2, 2020.

S6 or so into the Mojave Desert of California.

(edit)  Change of pace 0126 UTC, a bit harder cider as it were, a bit more Punch.


So far UNIDed station playing music on 4103 kHz LSB, I noticed about 0044 UTC on 2 February 2020.  Right where a person looking for the Windy Beacon would be sure to notice it.

(edit)  0051z Zeke heard.


Was insomniac this morning, so had a chance to radio at hours I normally don't ;)

And I ran into what appears to be the sequencing frequency Pips Network that has been reported on these forums in the past.  In this case it seemed to be a 0.25 second long pulse every 7.5 seconds (the most common seen is a shorter pulse, often about 0.125 seconds every 6 seconds).  A possible anomaly with this set of transmissions is that the pulses looked like they may have been doubled, I mean two back to back pulses on each freq.  Among several possibilities this could be a phase shift in the middle of the pulse (BPSK for some reason) or it could be two transmissions on each freq.

As is indicative of this network the pulses sequence through frequencies, low to high.  However, another anomaly, in this case each frequency seemed to be pair, in time, with one other freq.  I don't think I have ever seen this before.  For sure in the past there were two networks working together, synchronized in time and sometimes overlapping on one or more frequency, but never, that I remember, with paired (coincident in time) frequencies.

What I mean is that in the following list of freqs 2000 and 2275 kHz were transmitting at the same time, and then the signal sequenced up to the next higher pair, 2575 and 2800 kHz at the same time.  And then up to the next pair, etc.  Typically in the past it would have been more along the lines of sequencing 2000, then 2275, then 2575, then 2800, etc.

Freqs observed:

9600 ?
9950 ?
10250 ?

The last freqs (with the ? marks) may have shown up just before the signal ended, I have not had time to confirm they are related in time but they looked like they possibly were.  I have not had time to go through my recordings and see if I can locate other frequencies I might have missed.  I suspect there were more frequencies in use at the high end, however propagation above 8000 kHz dropped of very quickly.

Eventually I will go through the recordings and confirm the timing of all freqs, probably locating one or two more I missed under other signals in the process.  I want to see if the pairing of freqs holds up across the entire working set.


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