Someones jamming Yemen/Saudi's 11935khz

[DXerPaulAK]

Someones been jamming Yemen State Radio on 11935khz via Riyadh for a few months now. Previously it was a loud buzzing noise but that disapepared about a month or so ago and in the last two weeks, a new jamming sound apepared.

This was recorded 9 9 24 at 1801 UTC in alaska of Yemen's 11935khz broadcast via Riyadh.

11935 Jamming 09 09 24 1801UTC In Alaska.mp3

drive.google.com

 

[Teotwaki]

Someones been jamming Yemen State Radio on 11935khz via Riyadh for a few months now. Previously it was a loud buzzing noise but that disapepared about a month or so ago and in the last two weeks, a new jamming sound apepared.

This was recorded 9 9 24 at 1801 UTC in alaska of Yemen's 11935khz broadcast via Riyadh.

11935 Jamming 09 09 24 1801UTC In Alaska.mp3

drive.google.com

Sounds similar to spaceships blasting each other in Star Wars

 

[Token]

Someones been jamming Yemen State Radio on 11935khz via Riyadh for a few months now. Previously it was a loud buzzing noise but that disapepared about a month or so ago and in the last two weeks, a new jamming sound apepared.

This was recorded 9 9 24 at 1801 UTC in alaska of Yemen's 11935khz broadcast via Riyadh.

11935 Jamming 09 09 24 1801UTC In Alaska.mp3

drive.google.com

What mode was your receiver in when you made this recording?

T!

 

[DXerPaulAK]

What mode was your receiver in when you made this recording?

T!

AM Mode, which is what 11935 broadcasts in.

This is clear cut jamming

 

[Token]

AM Mode, which is what 11935 broadcasts in.

This is clear cut jamming

So no AMSync or anything like that? I understand that 11935 is in AM, I was just trying to get a handle on if the receiver was trying to track a carrier or anything like that, to get a better idea of what kind of jammer it is.

T!

 

[Token]

So no AMSync or anything like that? I understand that 11935 is in AM, I was just trying to get a handle on if the receiver was trying to track a carrier or anything like that, to get a better idea of what kind of jammer it is.

T!

More specifically, and what is driving my questions, I have a recording I did of Yemen Radio on 08 September, 2024, at 0424 UTC, the day before your recording. In the recording I have (recordings of both waterfall and audio) the audio sounds something like your example, but there is no jammer present. It is all the Yemen Radio transmitter making that noise, with the carrier being unstable and stepping/sweeping.

I made my recording in AM mode and in USB, and the USB version sounds similar to your recording. Not quite the same as I intentionally was tuned 1 kHz low, trying to capture the carrier of Yemen Radio. But, when I was in AMSync it really sounded similar to yours, just at a different rate of repeat.

T!

 

[N6JPA]

Someones been jamming Yemen State Radio on 11935khz via Riyadh for a few months now. Previously it was a loud buzzing noise but that disapepared about a month or so ago and in the last two weeks, a new jamming sound apepared.

This was recorded 9 9 24 at 1801 UTC in alaska of Yemen's 11935khz broadcast via Riyadh.

11935 Jamming 09 09 24 1801UTC In Alaska.mp3

drive.google.com

Iran.

 

[Token]

More specifically, and what is driving my questions, I have a recording I did of Yemen Radio on 08 September, 2024, at 0424 UTC, the day before your recording. In the recording I have (recordings of both waterfall and audio) the audio sounds something like your example, but there is no jammer present. It is all the Yemen Radio transmitter making that noise, with the carrier being unstable and stepping/sweeping.

I made my recording in AM mode and in USB, and the USB version sounds similar to your recording. Not quite the same as I intentionally was tuned 1 kHz low, trying to capture the carrier of Yemen Radio. But, when I was in AMSync it really sounded similar to yours, just at a different rate of repeat.

T!

One further note. Looking at my logs I observed the same activity on 11935 kHz on 16 August, 2024, 0457 UTC.

T!

 

[DXerPaulAK]

More specifically, and what is driving my questions, I have a recording I did of Yemen Radio on 08 September, 2024, at 0424 UTC, the day before your recording. In the recording I have (recordings of both waterfall and audio) the audio sounds something like your example, but there is no jammer present. It is all the Yemen Radio transmitter making that noise, with the carrier being unstable and stepping/sweeping.

I made my recording in AM mode and in USB, and the USB version sounds similar to your recording. Not quite the same as I intentionally was tuned 1 kHz low, trying to capture the carrier of Yemen Radio. But, when I was in AMSync it really sounded similar to yours, just at a different rate of repeat.

T!

whatever is making that noise.. that noise is the jammer

One further note. Looking at my logs I observed the same activity on 11935 kHz on 16 August, 2024, 0457 UTC.

T!

Up until about mid august, the jamming was a buzzing noise.

sometime in early september or so is when it changed to whatever this is.

Iran.

Interesting that this jamming only started after Yemen reapepared on Saudi's 11935... it didnt happen when they were on 11860

 

[Token]

whatever is making that noise.. that noise is the jammer

I did not (yet) claim it was not a jammer, I was just trying to resolve what you heard with what I heard and saw locally.

Up until about mid august, the jamming was a buzzing noise.

sometime in early september or so is when it changed to whatever this is.

OK, but I have a recording of the same signal (chirps, possibly jammer) on 11935 kHz, on 16 August, 2024, in the 0400z time slot.


Lets look at why I was trying to resolve what was happening in your recording with my receptions. I am not sure the signal I recorded on 08 September, 2024 was a jammer, let me show you why I say that.

08 September, 2024, 0420 UTC, I was tuning across the band and saw something odd on the waterfall, on around 11935 kHz. There was no steady carrier present, and there appeared to be curved, chirping, pulses or something like that. In AM mode I could hear audio, but very weak and choppy, the chirps were not heard. In USB all I heard was the chirps, and no sign of a steady carrier.

The signal was weak at my location in California, so I shifted to the University of Twente WebSDR to see if it was any better there, it was, although not a great deal.

Again, I could see no steady carrier on the waterfall, only the chirps. Screen shot here:

http://www.tokenradio.net/Radio/SharedFiles/SWBCTfer/Waterfall_11935_JPG_08Sep2024_0425z_t_anot.jpg

In AM mode station audio was present (stronger than at my location), still choppy but clearly there. Recording here:

http://www.tokenradio.net/Radio/SharedFiles/SWBCTfer/11935_AM_08Sep2024_0427z_t.mp3

In USB mode only the chirps were heard. I was tuned 1 kHz below the bottom edge of the chirps, trying to detect any carrier that might be present in, under, or around the chirps. You can hear that my recording is at least somewhat similar to your recording, although the rep rate is a bit different and of course the pitch is higher since I was intentionally tuned 1 kHz low. Recording here:

http://www.tokenradio.net/Radio/SharedFiles/SWBCTfer/11935_USB_08Sep2024_0426z_t.mp3

Here is a 2 second spectrogram of my USB recording, you can see no carrier is present, and only the chirps are there. There also appears to be audio modulated on the chirps, but that is harder to be sure of. Image here:

http://www.tokenradio.net/Radio/SharedFiles/SWBCTfer/Spec_11935_USB_08Sep2024_0426z_t.jpg

Here is a similar 2 second spectrogram of your recording. The curves are lower, of course, but that is explained by the fact I was intentionally tuned 1 kHz low trying to catch a carrier. You can see that the curves in your recording are very similar to those seen in my spectrogram.

http://www.tokenradio.net/Radio/SharedFiles/SWBCTfer/Spec_11935_USB_09Sep2024_1801z_DXerPaulAK.jpg

Again, in my case on 11935 kHz there was no steady carrier present. There were curved chirps sliding down toward 11935 kHz. In AM mode I could clearly hear station audio. In USB mode I could only hear the chirps but a spectrogram plot may show modulation on those chirps.

This is what led to my questions. In my case I am reasonably sure that only one signal was present, the curved chirps, and they appeared to be modulated with station audio. There was no steady carrier present to support the audio. I suspected the curved chirps were the Yemen Radio carrier, but unstable.

T!

 

[BinaryMode]

Iran.

Isn't Yemen and Iran the bestest of buddies? Or am I missing something?

Riyadh makes sense.

 

[Token]

Isn't Yemen and Iran the bestest of buddies? Or am I missing something?

Riyadh makes sense.

40,000 foot picture here, because I am not really that up on the region, only a basic understanding.

It depends on what part of Yemen you mean. And even then, it is still a complicated situation. It is very much a Shia / Suni thing there also, mixed in with other issues..

The nation is fractured into at least 4 major pieces, each under the control of a different faction. The internationally recognized government of Yemen is the Cabinet of Yemen, and I think that the US has a luke warm but a generally better relationship with that part of Yemen than Iran does. The Houthis (Supreme Political Council), however, are pretty much armed / backed by Iran (and other radical sources).

So no, Iran and most of Yemen are not the bestest of buddies, but Iran and the Houthis are pretty tight.

T!

 

[DXerPaulAK]

I did not (yet) claim it was not a jammer, I was just trying to resolve what you heard with what I heard and saw locally.



OK, but I have a recording of the same signal (chirps, possibly jammer) on 11935 kHz, on 16 August, 2024, in the 0400z time slot.


Lets look at why I was trying to resolve what was happening in your recording with my receptions. I am not sure the signal I recorded on 08 September, 2024 was a jammer, let me show you why I say that.

08 September, 2024, 0420 UTC, I was tuning across the band and saw something odd on the waterfall, on around 11935 kHz. There was no steady carrier present, and there appeared to be curved, chirping, pulses or something like that. In AM mode I could hear audio, but very weak and choppy, the chirps were not heard. In USB all I heard was the chirps, and no sign of a steady carrier.

The signal was weak at my location in California, so I shifted to the University of Twente WebSDR to see if it was any better there, it was, although not a great deal.

Again, I could see no steady carrier on the waterfall, only the chirps. Screen shot here:

http://www.tokenradio.net/Radio/SharedFiles/SWBCTfer/Waterfall_11935_JPG_08Sep2024_0425z_t_anot.jpg

In AM mode station audio was present (stronger than at my location), still choppy but clearly there. Recording here:

http://www.tokenradio.net/Radio/SharedFiles/SWBCTfer/11935_AM_08Sep2024_0427z_t.mp3

In USB mode only the chirps were heard. I was tuned 1 kHz below the bottom edge of the chirps, trying to detect any carrier that might be present in, under, or around the chirps. You can hear that my recording is at least somewhat similar to your recording, although the rep rate is a bit different and of course the pitch is higher since I was intentionally tuned 1 kHz low. Recording here:

http://www.tokenradio.net/Radio/SharedFiles/SWBCTfer/11935_USB_08Sep2024_0426z_t.mp3

Here is a 2 second spectrogram of my USB recording, you can see no carrier is present, and only the chirps are there. There also appears to be audio modulated on the chirps, but that is harder to be sure of. Image here:

http://www.tokenradio.net/Radio/SharedFiles/SWBCTfer/Spec_11935_USB_08Sep2024_0426z_t.jpg

Here is a similar 2 second spectrogram of your recording. The curves are lower, of course, but that is explained by the fact I was intentionally tuned 1 kHz low trying to catch a carrier. You can see that the curves in your recording are very similar to those seen in my spectrogram.

http://www.tokenradio.net/Radio/SharedFiles/SWBCTfer/Spec_11935_USB_09Sep2024_1801z_DXerPaulAK.jpg

Again, in my case on 11935 kHz there was no steady carrier present. There were curved chirps sliding down toward 11935 kHz. In AM mode I could clearly hear station audio. In USB mode I could only hear the chirps but a spectrogram plot may show modulation on those chirps.

This is what led to my questions. In my case I am reasonably sure that only one signal was present, the curved chirps, and they appeared to be modulated with station audio. There was no steady carrier present to support the audio. I suspected the curved chirps were the Yemen Radio carrier, but unstable.

T!

Im telling you, this is jamming...

Plus, there were times when i wouldnt hear it by day but would at night, while hearing 11935 yemen via riyadh all day.......... its not developing a fault at night, solving itself in the mornign and repeating... now im hearting it 24/7.

This is very much jamming

 

[Token]

Im telling you, this is jamming...

Plus, there were times when i wouldnt hear it by day but would at night, while hearing 11935 yemen via riyadh all day.......... its not developing a fault at night, solving itself in the mornign and repeating... now im hearting it 24/7.

This is very much jamming

While I am willing to accept it might be jamming, I am also looking for a good technical indication, other than by ear, that it is jamming. Alternately, I am also looking for good technical indications it might not be jamming.

Right this minute, 0010 UTC, 18 Sep, on 11935 kHz, all I can find is CNR, it looks like Yemen Radio is down. I tried the Kiwi in Riyadh also, and nothing heard, although AWR on 11925 kHz is heard on that remote.

I can't explain why the chirps come and go in your reception. I do not know what technical changes the station makes or at what hours. I do know that when I hear it locally it has had those chirps for a month or so now, but then I only hear it locally at about the same time each day, and I typically do not look for it by remote receiver when I can't hear it here.

Do you agree that in the two images I showed, the waterfall ( http://www.tokenradio.net/Radio/SharedFiles/SWBCTfer/Waterfall_11935_JPG_08Sep2024_0425z_t_anot.jpg ) and the audio spectrogram tuned 1 kHz low in USB mode ( http://www.tokenradio.net/Radio/SharedFiles/SWBCTfer/Spec_11935_USB_08Sep2024_0426z_t.jpg ) there is no steady carrier visibly present?

But the AM audio I recorded at the same time ( http://www.tokenradio.net/Radio/SharedFiles/SWBCTfer/11935_AM_08Sep2024_0427z_t.mp3 ) probably has Yemen Radio audio? Yes, no ID is heard, but the programming is pretty typical.

Again, I was tuned in AM mode for that recorded audio. With no carrier I would not have been hearing intelligible audio, but there was audio present, however broken. The only carrier that could be supporting the audio was the curved chirps.

I have several days of recordings similar to this. Incidentally, I happened to be recording 11935 kHz the other day when that X-4.5 Solar flare killed the band. The signal went from S9+ to the noise floor in a period of about 4 minutes.

However, I do know that when there is another carrier on freq, another station present in addition to the chirps (typically CNR for me), the chirped carrier beats against the steady carrier, then I hear the chirps as chirps, and sounding very much like a jammer. Could it be that when you are hearing the jammer chirps there is another station on frequency also, providing something for the chirped carrier to beat against?

T!

 

[DXerPaulAK]

While I am willing to accept it might be jamming, I am also looking for a good technical indication, other than by ear, that it is jamming. Alternately, I am also looking for good technical indications it might not be jamming.

Right this minute, 0010 UTC, 18 Sep, on 11935 kHz, all I can find is CNR, it looks like Yemen Radio is down. I tried the Kiwi in Riyadh also, and nothing heard, although AWR on 11925 kHz is heard on that remote.

I can't explain why the chirps come and go in your reception. I do not know what technical changes the station makes or at what hours. I do know that when I hear it locally it has had those chirps for a month or so now, but then I only hear it locally at about the same time each day, and I typically do not look for it by remote receiver when I can't hear it here.

Do you agree that in the two images I showed, the waterfall ( http://www.tokenradio.net/Radio/SharedFiles/SWBCTfer/Waterfall_11935_JPG_08Sep2024_0425z_t_anot.jpg ) and the audio spectrogram tuned 1 kHz low in USB mode ( http://www.tokenradio.net/Radio/SharedFiles/SWBCTfer/Spec_11935_USB_08Sep2024_0426z_t.jpg ) there is no steady carrier visibly present?

But the AM audio I recorded at the same time ( http://www.tokenradio.net/Radio/SharedFiles/SWBCTfer/11935_AM_08Sep2024_0427z_t.mp3 ) probably has Yemen Radio audio? Yes, no ID is heard, but the programming is pretty typical.

Again, I was tuned in AM mode for that recorded audio. With no carrier I would not have been hearing intelligible audio, but there was audio present, however broken. The only carrier that could be supporting the audio was the curved chirps.

I have several days of recordings similar to this. Incidentally, I happened to be recording 11935 kHz the other day when that X-4.5 Solar flare killed the band. The signal went from S9+ to the noise floor in a period of about 4 minutes.

However, I do know that when there is another carrier on freq, another station present in addition to the chirps (typically CNR for me), the chirped carrier beats against the steady carrier, then I hear the chirps as chirps, and sounding very much like a jammer. Could it be that when you are hearing the jammer chirps there is another station on frequency also, providing something for the chirped carrier to beat against?

T!

Ive been in broadcasting 20 years and while im a program director and not an engineer, i understand technical things more than most djs do and run a technical group for engineers on FB.

I couldve seen the buzzing being jamming, transmittter fault, bad audio grounding on wiring... but this pew pew sound...... i can not figure out what would be causing it if it was a fault.

 

[radar_hunter]

I don't know if this is jamming or not, but some thoughts...

The Republic of Yemen Radio station should be on 11935 kHz but it seems to be slightly off. I can't see anything like a carrier on 11935 kHz but the "center" of the signal seems to be approximately at 11936.3 kHz. This already suggests that there may be problems with the transmitter.

The jamming/chirping action seems to happen mostly above 11936 kHz, on the assumed upper sideband. Thus, using LSB and tuning to that frequency should give us clear audio? But it doesn't. LSB audio sounds very "bubbly".

That's why I think this may not be jamming but a faulty transmitter, even though jamming by Houthi rebels or Iran would make sense.


And yes, sounds very much like Star Wars weapons in USB mode.

 

[IC-R20]

I checked on the Riyadh kiwi and the weird USB signal was there. But it was much stronger in Kenya, no trace of a lower sideband or carrier from AM station anywhere underneath just shortly after night.

 

[Token]

Ive been in broadcasting 20 years and while im a program director and not an engineer, i understand technical things more than most djs do and run a technical group for engineers on FB.

I think it is generally a bad idea to compare CVs online. In this case I will say, I do have some professional experience in the field of RF.

I couldve seen the buzzing being jamming, transmittter fault, bad audio grounding on wiring... but this pew pew sound...... i can not figure out what would be causing it if it was a fault.

I can think of several technical issues that can cause this kind of problem. At the most basic level, if you look at this signal, you will see that the carrier is unstable. There are a number of things that can cause this, but my money would be on an unlocked reference source or unstable oscillator in a basic RF generation stage. Something at the RF level, pre-modulator and pre-audio.

T!

 

[radar_hunter]

Right now I'm receiving the "jamming" signal quite strongly, but the actual Republic of Yemen radio sounds much weaker. This suggests that the "jamming" signal might indeed come from a different source and thus it might be an actual jammer. But it does not explain why the Yemen radio carrier is not correctly on 11935 kHz and other issues.

I noticed that I have also marked this frequency as possible jammer before.

 

[BinaryMode]

Question: if they knew they were being jammed wouldn't they just broadcast on another frequency? Maybe one near by?

I don't know much about RF jamming, but I'm willing to bet that it's quite broad over a segment of the band, no?