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.

Monday, August 2, 2010

Data bursts near UVB-76 frequency

There seems to be a lot of different broadcasts trying to allocate the same spectrum as UVB-76, as this would be the only frequency on a shortwave band .. At the moment, I can spot at least 4 additional carrier frequencys distorting the signal!

Two of them are, however, of special interest. Previous posting already covered the morse code, but even more sophisticated transmission is happening on a lower sideband of the signal. Something somewhere is transmitting very dense data bursts on 4.623325MHz, what are audible as scratching sound on UVB-76 signal. It happens once or twice an hour and is never more than about 10sec. long, so it is a telemetry data of sort.

What makes this signal spectacular are three things: First, it has relatively high-speed data rate for a shortwave band. Second, it has chosen its existance at the same frequency spectrum as UVB-76. Although UVB has lower sideband seriously supressed (i.e. most of the signal is radiated above 4.625MHz frequency, as opposed to regular AM signals what radiate equal amount of energy on both, upper and lower the base frequency), it has still a reasonable amount of signal there to give headic to whoever is trying to use it. And third, the signal itself is asymmetric, i.e. upper and lower sidebands are transmitting different data!

This is what the spectrum on WinradHD screen looks like:

2 comments:

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  2. Do you have any theory why this exists?

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