11935 KHz - STRANGE GOINGS-ON!

Oxford Languages Definition!

goings-on /ˌɡəʊɪŋzˈɒn/. Noun

events or behaviour, especially of an unusual or suspect nature.

Back on August 18, 2023, I observed some strange noises emanating from 11860 kHz, the frequency then used by the Republic of Yemen Radio - Radio Sana'a. If you click back to that blog post, you will see a video of the offending sound as heard here at Mount Evelyn and on the Qatar Kiwi SDR.

Well, since then, the station has wandered around on a few other 25mb frequencies before recently settling into 11935 kHz. And, the noise has remained. But it is not there all the time. What is it? A faulty transmitter? Jamming? We still don't really know for certain!

The station first appeared in November 2015. It initially claimed to operate from the port city of Aden in Yemen, on the southern part of the Arabian Peninsula. However, it is commonly believed that Saudi Arabia, sympathisers of Yemen’s pro-Hadi forces, provides the service via one of its transmitters at either Riyadh or Jeddah.

Over the last week, I have been keeping a close eye on this channel. There is definitely some funny "goings-on" here!! Firstly, contrary to some lists, the station does NOT currently operate across the 24-hours. Sign-off appears to vary between 2200 and 2300 UTC. Sign-on can vary between 0355 and 0430 UTC.

Below are a selection of screenshots I've taken to try and discover what's happening. On June 1, the noise disappeared at 22:57:40 UTC after Radio Sana'a programming had ceased.

NOTE: You can click on each screenshot for a closer look

I monitored the channel throughout the day. Around 0405 UTC, there was no sign of Radio Sana'a. Instead, four faint harmonics, 120 Hz apart, appeared on and off for a few minutes, both sides of the centre frequency, then disappeared. I was so busy watching this phenomenon that I forgot to get a screenshot! DOH!

Then, at 0430, on came the carrier with Qur'an chants with a nice clear signal.

At 0441, traces of the harmonic noise could be seen on the Cyprus Kiwi waterfall, but it was not strong enough to be heard over the signal's audio.

Thirty seconds later, the harmonics disappeared.

There was no further evidence of interference until 05:03:40 UTC, when four stronger and two fainter harmonics suddenly appeared.

0505 UTC was the first time that the harmonics became intermittent.

By 05:06:30, the harmonics became quite unstable.

By 0513, the harmonics were becoming stronger and more prominent. For the first time that day, I could hear the buzzing sound.

At 05:13:30, the buzzing suddenly stopped again.

Then, at 05:16:45, full-on buzzing, spreading across almost 3 KHz on both sides of the centre frequency, masking the signal.

At 0517, the signal had gone, and the buzzing was still there but less strong.

Later that day, the buzzing was strong, and the signal could be heard underneath....but only some of the time.

Weird, isn't it?

I have no definitive explanation for this behaviour. Yes, it could be jamming. But it is not a form of jamming that I have witnessed previously. Some say that this is potentially from Iran. The Wilson Center, an organisation that provides nonpartisan counsel and insights on global affairs to policymakers, wrote on March 9, this year:

A year after restoring diplomatic ties, Saudi Arabia and Iran still experience tensions. Conversations and diplomatic reopenings haven't translated into significant agreements due to ongoing regional conflicts and deep-seated distrust, especially concerning their allies and the situations in Yemen and Lebanon.

So, yes, it is feasible that this is jamming from Iran, perhaps using their extensive shortwave transmitting resources.

But the 120 Hz spacing of harmonics is interesting. Saudi Arabia is the only Middle East country that runs on 60 Hz power - all the surrounding countries are 50 Hz. Poorly adjusted or overdriven transmitters can often produce harmonics in relation to the cycle phase from the electrical power input. I'm just speculating here! If it is a transmitter fault, why wouldn't the Saudis fix it? This has been going on (and off!) for months now.

And why is the buzzing intermittent? One would expect jamming to be on all the time. But sometimes, hours go by without buzzing. I am not convinced that it is jamming! So, what's going on here? Let me know if you think you have the answer!

UPDATE (June 4, 2024 @0409 UTC)

Today, Radio Sana'a signed on again at 04:00:30 UTC with a strong signal plus buzzing. The buzzing started at EXACTLY the same time as the station. The chances of jamming starting at exactly the same time as the transmission are extremely low. This seems to indicate to me that this is, indeed, an intermittent transmitter fault.

73 and wishing you good, buzz-free DX!!

Rob Wagner VK3BVW