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 ..

Sounds from Space

Hopefully many people visiting this blog enjoy sounds from radio as much as I do, so let me share a wonderful archive of DD1US about the recordings of various spacecrafts, right from the beginning of an era, Sputnik.

http://www.dd1us.de/historical%20sounds%20from%20space.html

The sounds are really spectacular, especially considering how much effort and innovative thinking these simple recordings actually carried at the time and still do!

(Picture courtesy of http://silver-rockets.com/tag/spacecraft/page/2/)

I still find it almost unbelievable, that more than 50 years after, the space programs in both countries starting it all, are on a verge of shutdown ...

http://www.reuters.com/article/2011/04/10/us-russia-space-gagarin-idUSTRE73910C20110410

What in heavens sake (pun?) happened to our dreams?! Is it really THAT much more important to let small number of ethically challenged but otherwise ingenious minds experiment with free economy, only to come to conclusion that if you steal and cheat, its not gonna work? And this picture above is only part of, what's it gonna cost to bail it all out ...

Jazzsequence - The Signal, a Pledge

UVB-76 has been a great deal of inspiration for musicians around the world, resulting many beautiful tracks. If you think there is room for more, please check the link what was just sent to me today by a good old friend Margus, who' s one of the greatest analog synth fans I know and runs a after-life site for old Roland synths (http://www.wolzow.com/)

http://www.kickstarter.com/projects/jazzs3quence/the-signal

Its a pledge by Chris Reynolds (a.k.a. Jazzsequence) for rising $900 for releasing an album inspired from listening to the shortwave and UVB-76 in particular. As far as I understood, the money is going to be spent on couple of cool gizmos helping to make a music in a specific way, but its a reasonable cause nevertheless as far as I can tell :)

SDR MK1.5 'Andrus' Software Radio Design Finished!

Its done! I have finally finished the SDR MK1.5 design! For those not familiar with what I am talking, here is a little intro.

The Software Defined Radio, or SDR, sometimes also referred as Software Radio, is a new generation of radio receivers what allow the reception of the radio signals with your computer software. The Software Radio is acting like an interface between the antenna and your computer. I have created a more technical overview about Software Radio architectures on SDR MK1 page, but the basic idea is, that the SDR Receiver is receiving the high frequency signal from antenna, makes it a digital signal and does some pre-processing, like frequency downconversion and digital filtering. The processed signal is then fed to the computer (on our case through USB or Network interface) and then visualized, decoded etc. on the computer software. 

The long-over-the-schedule radio boards went finally into production last night. It has taken four months longer than originally expected for a very good reason: The first fifteen MK1 units on the field got very warm feedback, but even more suggestions of what and how could be done differently. Therefore getting the design updated was a endless struggle between adding things and making a decision what shall be left out for a reason or another.

Here is a short recap on a design logic the new radio follows.

There are three main areas the radio has evolved from the MK1 design:

- First, it is now just a radio of better quality. The long list of small technical changes (many of which can probably be appreciated only by RF professionals and radio amateurs) will altogether account to a better noise floor and more precise signal reconstruction. While this is not important for an analog transmissions that much, the people working on a shortwave digital domain, DX-ing and signal hunting will

hopefully appreciate it.

- Second, the radio is now having a network interface besides USB and a 32-bit 60MHz clock CPU from Atmel. Both additions will drastically enhance the received signal bandwidth and connectivity: We are now capable to process up to 820kHz bandwidth on single channel through network and get the much desired 192kHz through the audio interface. The added mobility what network interface together with PoE (Power Over Ethernet) extension possibility will give, can allow this radio to be called a "network antenna" adapter!

- Third major change in design logic is that the radio extension capabilities are much re-visited and the MK1.5 can now be treated as a motherboard for a future experimentation, would it be an extension boards by myself or your own creation. This includes the jumpers on few selected places what allow adding the new RF boards to the chain, would it be filters on downconverters, and the I2C, SPI, UART and GPIO connectivity. The radio, although being a diversity shortwave receiver right out of box, is also now also a great general ADC platform for future expansion.

One of the first extension boards the SDR MK1.5 will get to utilize this capacity is the Elonics E4000 based downconverter, what will extend the receiver frequency range up to 1.7GHz!

Here is an updated specifications for the SDR MK1.5

• Dual Channel diversity mode shortwave receiver 
• Receiving Frequency range 500Hz .. 31MHz both channels
• USB Audio Interface, 24bit 192kHz
• 10/100 EThernet interface, with PoE extension possibility
• IF bandwidth through USB audio 192kHz
• IF bandwidth through Ethernet 820kHz

Aah, and one more thing - I got a suggestion, that the radio is supposed to have a name. Oddly enough, one of the prospects suggested was my own, so here we go - The SDR MK1.5 is hereby named 'Andrus' :)

Our own little Wikileaks (and the story of the dog)!

So far there have been relatively little material surfaced about what the number stations really look inside. There have been photos of the now-abandoned transmission site at Povarovo, some pictures of antenna fields and some inside stories of the guys serving at the radio units during their military service, all presented on the ever-lasting radioscanner.ru Buzzer thread.

Yesterday, however, the material surfaced at this very same forum what gives us a first-hand glance on the life and work of the UVB-76 station during year 2005!

http://www.radioscanner.ru/forum/topic12415-61.html#msg833346

The published material is what seems to be the logbook of the UVB-76 station at Povarovo covering the period of October 3, 2005 until December 7, 2005.
The guy who posted it to the forum claims, that they found it from the same abandoned building pictured everywhere with the dog in front.
The logbook does not seem to carry any labels of confidentiality or classified stamp (the red marking on front says "SAMPLE" and is meant to show how to fill the log), but that does not make it less interesting for the crowd interested in UVB-76 inside story!

The direct link to the page-by-page archive of this document can be found at:

http://fotki.yandex.ru/users/bydunaika/album/155472/
Talking of dog, there is a entry on page 008, from October 4:

It reads: "18:30 Guard dog has put on place on post 173"

So, it looks like the famous last resident of the UVB-76 Povarovo station, The Dog, has entered the service on October 4, 2005.

(Picture by Desert_Fox from radioscanner.ru forum)

UVB-76 Wired Article

This is a relatively old news already, but for the sake of completness here be the link to Wired article about UVB-76 and the blog :)

http://www.wired.com/magazine/2011/09/ff_uvb76/

Great thanx to Peter, Alexa and Cameron for doing all the hard work on Wired side!

The feedback has been very nice and ihe number stations community at Priyom.org has gained a number of new members to welcome. Wish you all lots of intresting findings!

VLF Experience

Yesterday morning the mistaken frequency field in PRIYOM scheduler made the prijemnik receiver to tune on to 0kHz for a while.

As there was a thunderstorm in progress (quite surprising for mid-September) the result was a beautiful display of EMI scattering, when surplus electrical fields discharged. The sound was more or less like a dolphin song, too bad I did not have a recorder on to provide an audio sample ..

The horizontal line at the bottom of the screen is a lightning strike happening, but please also pay attention to the very clear and neat VLF transmission happening at 18kHz region. This is likely a submarine communication and sounded like any other RTTY modulation.

Surprisingly, my magnetic loop antenna design seems to work very well down to the VLF region, making it a really nice and compact exploration tool as indoor urban antenna. The long aerial outside was absolutely mute below 50kHz and did not display any sign of VLF transmission other than static.