Farewell Alpha RSDN-20 ?

edited May 2018 in Signals Received
According to a blog post from 17 March (Italian, English translation) the Russian VLF navigation system Alpha (aka RSDN-20) may have finally been decommissioned. A real shame, but not unexpected. Its counterpart in the west, Omega, was shutdown in 1997. The Kiwi even had a specialty mode for Alpha in the integrator extension.

But there is also this tweet from 10 May showing it back on air. So the long-term status is unclear I suppose.




  • Hi John,

    It had been off for a while, then it reappeared, as I definitely heard on a few web SDR's whilst checking for the mystery 36KHz signal reported by ratwolf on the 18th of May.

    But I checked again today and it's not there any more.

    Maybe they are having reliability problems ? The kit must be well past its sell by date and I guess it must be a struggle to keep it running.


    Martin - G8JNJ
  • They've been known to disappear and then pop up again. I've read some fourth-hand speculation that paying the power bill may be an issue.

    But I've also been listening for the Beta system time/frequency transmissions and haven't heard them either. And we now have a Kiwi located essentially "across the street" from one of the Beta transmitting sites.
  • After more careful listening it seems half of the Beta sites are still transmitting. Not heard are in orange. Changeover to summer schedule may be on June 1 if I recall correctly.

  • jksjks
    edited February 2019
    After a 9 month absence of all Alpha transmissions (as far as I know) I finally caught Alpha Khabarovsk back on using the brand new public Kiwi in Shenyang, China (Khab is the easternmost in the chain at 136 deg E longitude). I did not hear any of the other Alpha stations using Kiwis further to the west.


  • I have seen and heard RSDN-20 Khabarovsk many times during the last months. Before that, Novosibirsk was transmitting for a few weeks. Having only one transmitter active makes navigation difficult, so the transmitter is probably used for some other purposes.

    Mauritz / SM2BYC
  • jksjks
    edited February 2019
    Okay, good to hear. I'm not checking all that often but I do look every time I'm tuning around down there for something else. Perhaps the system is in "hot standby" now in case of GPS problems. And they run them individually periodically for maintenance checks. Photo of Khabarovsk supposedly: http://photos.wikimapia.org/p/00/02/65/81/79_big.jpg
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