Tag Archives: OTH

Strange Interference Near 13860 kHz: Mario Tracks It to Kaliningrad

Many thanks to SWLing Post contributor, Mario, who writes:

Dear Thomas,

It has been about two or three days since it was impossible for me to hear Radio Romania Int in Spanish (1900 UTC) from my home, at Zaragoza.

A strange interference appeared close to my favourite SW station (13860). A little bit on the left of the waterfall an strange emission appeared jamming.

After some research in your past entries I found that it could be a radar over the horizon.

Using the TDoA function of the kiwisdr environment, I found the following:

If it worked properly, the emission source could come from Kaliningrad.

According to old news, another 29B6 facility has been planned to be built in Kaliningrad.

Mario then sent the following update:

Well, it seems that the mystery has been resolved.

I am pretty sure that is a new 29B6:

It can be see on some satellite imagery services (https://earthexplorer.usgs.gov/, at the coordinates of the previous link).

It is not visible on Google satellite images or Bing maps.I hope they change their frequency shortly because they are messing my SW listening at radio Romania Intl in Spanish.

Best regards.

Looking at HF OTH RADAR

Many thanks to SWLing Post contributor, Trevor, who shares this link to a blog post from Daniel Estevez describing the characteristics of HF OTH RADAR:

Most amateur operators are familiar with over-the-horizon radars in the HF bands. They sometimes pop up in the Amateur bands, rendering several tens of kilohertzs unusable. Inspired by Balint Seeber’s talk in GRCon16, I’ve decided to learn more about radars. Here I look at a typical OTH radar, presumably of Russian origin. It was recorded at my station around 20:00UTC on 8 December at a frequency around 6860kHz. This radar sometimes appears inside the 40m Amateur band as well.

Above this post you can see a waterfall plot of the radar signal. It’s the wide red signal. It is 15kHz wide and pretty strong, but severely affected by frequency-selective fading. Looking at the IQ recording in Audacity, it is clear that the radar uses pulses with a 50Hz repetition rate. This explains the characteristic sound of this radar when received with a conventional SSB radio. It sounds similar to AC hum (here in Europe, of course).

Continue reading on Daniel’s blog…

Hearing Ghadir: Iran’s Sepehr Phased Radar System

Mehdi-Waterfall

In response to Andrea’s UVB-76 recording, SWLing Post contributor, Mehdi, comments:

Thomas, another signal which may sound mysterious:

Iran’s OTH Radar, named “Ghadir”; part of Iran’s Sepehr Phased Radar System.

They’d polluted the 10-meter band [in the past]; now they transmit on 26MHZ. (See spectrum in screen capture above.)

Sound: https://clyp.it/ldpxab2a

By the way, here’s my recording of UVB-76:
https://clyp.it/knvubeur

Many thanks for sharing those audio clips, Mehdi! Now I’ll know what Ghadir sounds like, should I hear it on the bands.