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.

Saturday, June 18, 2011

SDR MK1 Radio has now Diversity Mode working!

I had people asking me over and over again, why is there no diversity mode for the SDR MK1, if I am using the diversity receiver chipset as the core of the radio ..?!
To be honest ... the idea just did not occur to me! I was so fond of the idea having two radio frontends, that the whole usefulness of diversity mode in urban area did not come to me :)

So, by a popular demand, SDR MK1 is now supporting diversity mode!

For those not familiar with the concept, diversity mode means, that you can use one channel of the radio with your ordinary antenna, while the other channel can be equipped with something receiving a background noise, would it be your own laptop power supply or neighbours plasma TV. The radio then subtracting the noise from useful signal, and you will get noise canceling.

In reality, it looks like that:

(The LO frequency is actually 4.625MHz, the display is just not in sync).
As you see, there is a clear distinction where the diversity mode was switched on and off.  The noise is coming from the halogen kitchen light power supplies in the apartment. The useful signal is received with magnetic loop in the apartment, the noise is received with short telescopic antenna borrowed from ICom scanner.

Please note, that this is not a universal remedy to receive anything from far away - it is not improving any gain, it is just a useful feature to cancel strong local interference sources.

1 comment:

  1. I am confused.. Diversity to me is not signal-interference cancellation (though useful), it is the ability to have two separate antenna feeds so that multipath cancellation is overcome by selecting the antenna/receiver with best signal.