DISCLAIMER: I have no association with UVB-76 station, neither do I have any clue what is the content I am relaying. I can only assure, that the signal is received on 4.625MHz AM-modulated 900km NW from supposed origin and retransmitted unaltered. In no way can I guarantee this service, nor be considered responsible of any content re-transmitted. The only purpose for this relay to exist is because lot of people who do not have equipment or are located too far from station seem to be interested about listening to it. Should the UVB-76 station- or transmission content owners feel violated in any way, please contact me at uvb76.repeater@gmail.com and we will work it out.

Note, that because of shortwave radio signal propagation specifics the station can be more or less reliably received from around 4pm to 6am GMT on summertime. It is almost 24h audible during the winter, with short "skip-zone" blank-out around 6pm GMT.

The USB feed is considered as main source of audio today, as the voice messages are much better audible there than on the AM stream. However, the buzzer sound from the AM stream is somewhat more pleasant to listen at, so both feeds are kept simultaneously.

Tuesday, January 24, 2012

VLF World

It was exceptionally poor reception around here for anything above Long- and Medium Waves, so the only thing to do was to seek, whats happening on the longer wavelenghts.
Since discovering that my magnetic loop antenna works miracles on the VLF region, I find myself now browsing regularly through the very low frequencies, from the 10kHz to 20kHz region on my case. Its a strange world of all sorts of noise, but also with surprisingly large number of signals.

The most exciting discovery from last night was another buzzer-like signal found at around 15kHz. Apparently, this is a keying/sync signal for the chirp sounder. You may have noticed on the waterfall screen of your software radio a passing narrow stripe, what looks like someone is quickly scanning the band with the transmitter. Which is exactly what is happening. The chirp sounding is used for determining the propagation quality and delay of the signals what travel by reflecting off the different layers of the atmosphere. It is pretty common technology and there are many such transmitters all around the world, but I have always been wondering, on what frequency and how the scan cycle starts. Not sure if it has not been there before, or have I just missed it earlier, but here it is - the frequency where the (possibly closest to me) chirp sounder signal starts from:

The buzzer-like signal is clearly visible on the 15.612kHz, followed by the chirp pulse (the slightly diagonal line scanning away from the signal). The horizontal lines are some sort of digital downconverter artifacts and I have yet to figure out where they are coming from. Please also pay attention to the nice submarine communication session ending on 18.2kHz.

It seems that for a reason or another, atmospheric sounders seem to love buzzer-like signals, so may be there are some grounds for UVB-76 and atmospheric research theory. On the other hand, the similarity may also have led to speculations - go figure ..

And as an eye-candy and a proof that the VLF band is worth looking at, here is another picture from the same evening:

I have no idea what is the signal on the left, but does not seem like a random noise to me ..


  1. Isn't that related to the Solar Storm that arrived to the Earth this tuesday?

  2. It seems too well defined and symmetric for being a natural phenomena. What actually strikes me is that many VLF signals what first look like an industrial have started to behave meaningfully under my very eyes, what proves that VLF range is much more actively in use than seems at the first glance!

  3. CRT TV horizontal blanking frequency is around 15KHz. Maybe is this what you received.

  4. VLF is used by military all over through world to communicate with their subs, then we use thks signals passively in subsurface geoPhysics... fascinating to stand in a field using submarines to map...