DISCLAIMER

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.

Thursday, March 31, 2011

SDR MK1 Shortwave Radio Receiver Alive and Kicking!

After almost memorizing the National Semiconductol LM97593 chip datasheet and getting intimate with the DSP registers setup inside, the SDR MK1 is now working!

NB! There are some minor changes to the schematic and layout on the SDR project page, I will post errata and new files in next few days together with software developed so far.

This is what it looks like when assembled :)











 


It has two channels, both equipped with 32MHz lowpass filter, so two different antennas can be connected to the reciver. Replacing the filter with the bandpass, any 30MHz frequency region between 5kHz and up to 300MHz can be acessed, as the rest of the chip is capable of handling this range. The power connector is only needed if your USB connector is not able to supply 500mA of power, what most of the USB ports will, but some dont. In that case you will need external 6V adapter.

Normally, the board is connected only through the USB what is supplying power to the SDR and is used to transmit audio feeds and control information.

Technical specs so far:
  • 5kHz to 30MHz frequency range
  • 0.02Hz tuning resolution
  • 123dB total dynamic range
  • 64MHz internal sampling rate
  • User Programmable AGC (automatic gain control) with enhanced Power Detector
  • 48kHz/16-bit output sample rate (upgradable to at least 96kHz/16bit in near future)
  • Compatible with most free SDR software, such as SDR-Radio, HDSDR, PowerSDR, Winrad etc.
  • Possibility for tuning and setup using serial port console screen
  • Powered from USB port or external adapter
  • 2x BNC Antenna connectors (Mfg: Rosenberger)
  • Max current consumption 470mA
  • Open software and hardware design for DIY development, filter upgrades etc.
Internals:
  • Two channel digital downconverter (DDC) with integrated 12-bit
    analog-to-digital converters (ADCs) and automatic gain control
  • Double DVGA (digitally controlled variable gain) front end amplifiers with +36dB maximum gain and 600MHz bandwidth
  • RF filters: 7-pole Chebyshev lowpass filters
  • Channel Filters (DSP): Fourth Order CIC followed by 21-tap and 63-tap Symmetric FIRs

How well does it deliver? Well, the two receivers I am intending to compete with are Perseus from Microtelecom and SDR-IQ from RFSPACE.
Both are top of the class and share the same arhitecture as SDR MK1. I havent been able to play around with neither of them myself, but looking at the screenshots in the web, the MK1 measures up quite well, especially considering that the screenshot below is made with the very first set of DSP chain parameters what are not totally off, but are still far from optimal values.

This is what the UVB-76 looks on screen when received with SDR MK1





















The screenshot taken last night is somewhat special, as it shows two signals visible next to buzzer. The top one is an encrypted voice traffic, referred as "Sailors Cry". The bottom signal is the Russian USB (open) voice traffic on 4627kHz what was very active last night and was part of the of massive commcheck around different radio posts in the region. The two may be related or may be not, but they seem to share exactly the same frequency.

Further left is the Tallinn Volmet  and some new "jet" type of transmission, what has appeared lately, harrassing it.

There is still some software work ahead on firmware to get the SDR audio output to at least 96kHz/16bit and possibly 192kHz/8bit. While I am now investigating if the 96/16 ispossible to achieve with AT90USB1287 processor with the standard Windows USB 1.0 audio drivers, both look doable with proprietary driver.

Sunday, March 20, 2011

UVB-76 on RADIAATOR Festival

Here are some pictures of the setup at the festival bar :) The radio is of course the R-250 with the power supply sitting on top of it. I took the liberty of borrowing one of the Karl's original forum logo versions and printed a small banner of it as well.
The strange hat with goggles in front is the ancient Russian vehicle driver gen1 night vision helmet brought just for a amusement and for headphones' sake. However, as the goggles are actually working (off the 9volt battery, in fact!), they got some quite heavy use :)



























As an aftermath, dragging the radio to the site was worth every bit of effort! The reception was exceptionally good using the magnetic loop antenna exactly as described in the blog. It made surprisingly good 61m (4750-5060 kHz), 49m (5900-6200 kHz) and 41m (7200-7450 kHz) shortwave broadcast band antenna (another good reason for building it!) and also picked up buzzer crystal clear without any tuning of the antenna needed.

The overall amusement from the fact that anything such shortwave even exists, together with excitement of all the broadcasts received made it a nice conversation piece and reminded several people that once in the highschool they wanted to be radio amateurs, but have ever since forgot about that dream! The radio was also the ambience sound of the bar most of the time.

For everybody dialing through the wilderness of shortwave bands, here is a piece of recording I made at the festival. The group is called "Eesti Elekter" (Estonian Electricity) and the gig at the festival consisted of stage full of samplers, loopers, filters and whatever else, all fed by different transistor radios and processed live!
The result, I shall say, is stunningly close what we hear on a daily basis, so next time the noise you are picking up starts feeling like if someone has composed it, it actually may be! :)


Thursday, March 17, 2011

UVB-76 featured in RADIAATOR Festival in Tallinn




Just to let you know, that UVB-76 and its genre is represented in RADIAATOR Radio Art Festival in Tallinn today and tomorrow, at the Estonian Museum of Modern Arts.

The old faithful R-250 receiver is set up for overall amusement and shortwave listening experience at the festival bar room.
Three tracks what have been sent to me over time by different forum members, all featuring and inspired by the UVB-76 buzzer, are also played on the festival local radio show (broadcasted from the local umm.. semi-legal FM transmitter) and somewhere on the floor.

Just to have this collection available to everybody here, please find the tracks below. I think I have all the authors permissions to distribute, let me know if there are updated versions or additional tracks!


Enjoy!


Tuesday, March 15, 2011

Condolences to Everybody in Japan

As the situation around the Fukushima power plant develops on the edge of possible meltdown, we can all only imagine what have the past few days have looked like for the nuclear engineers working on and off the site .. :(

Here is the piece fit to listen at the moment ..


The consequences of this disaster to the overall nuclear power developments are huge. Yet, do not forget that these reactors are ancient, all from the seventies. 


http://en.wikipedia.org/wiki/Fukushima_I_Nuclear_Power_Plant#Reactor_data

They have been designed at the time when majority of the industrial control was relays and majority of the radios run on vacuum tubes.. Certainly, their control systems have been upgraded several times since, but the reactors itself have more or less been running perpetually ever since.

Not being especially pro or contra of nuclear energy, I do sincerely believe the nuclear fusion reactors to be the future of the energy, see http://en.wikipedia.org/wiki/ITER.
The fact that electrical plant designed some 20 years after the first nuclear bomb test has gone out of hands after biggest ever in history earthquake has hit it, should not put the entire industry back in stone age.

However, I am afraid it does for a while ..

Tuesday, March 8, 2011

SDR MK1 Shortwave Radio Boards Arrived

To balance out the mishap with the cable, the first batch of the PCB´s for the SDR just arrived!















Somehow it did not look all that complicated when I was looking at the layout on the screen! :)

99% of the components have also arrived with the exceptions of some exotic parts like CPClare solid state relays and Minicircuits RF transformers (both are on its way tho).

One can guess three times what I am doing over the weekend ...

Temporary Outage of the UVB-76 Internet Repeater

And this is basically why:


























The nearby construction site diged the copper out for some erratic rationale. Telco did a quick patch pronto, but today it will be another couple of hours down when they apply a proper fix.