Mystery Signals of the Short Wave

Dedicated to the more unusual, strange, bizarre and apparently meaningless signals on the short wave bands !

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The Backward Music Station or Whales   -   XM

Frequency:   (Many & Various)  

Pre - 2001 Include;
4376 kHz 4410 kHz 4420 kHz 4706 kHz
4740 kHz 4552 kHz 5178 kHz 5180 kHz
6584 kHz 6695 kHz 6752 kHz 8984 kHz

Post - 2001;
7631 kHz 10363 kHz 10512 kHz              

Transmits an unearthly series of tones and sounds,   Occasional snatches of what appears to be broken voices can be heard.   Reports of this station are often likened to whale song, or acoustic feedback, or sounding like a tape of a song played backwards, which has given this unusual transmission its nicknames.

The "Backwards Music" effect is fairly rapid and seems to be more complex than "Whales" which is a slower simpler sound. This difference has led some monitors to regard "Backwards Music" and "Whales" as two different stations, although both signals rise and fall in pitch and are rich in harmonics.

  "The Backwards Music Station"  (47 kb)

Can often can be heard on two or more frequencies at once, but with different signals. At least three of these transmitters have been heard operating at one time.

These signals are heard on a variety of frequencies, and are heard all around the world.  Possibly a recognised form of communication, but not resolvable.

There appears to be two sources of these signals. One being somewhere in the United States possibly the US Navy - freqs are close to naval freqs, and reports have been received that they emanate from US naval bases as Jacksonville,  Florida & Virginia Beach.

Other signals heard in England at good strength, are poorly received in America, indicating a European source An early suggestion was that the signals are a NATO communication device, coming from a base in Palermo, Sicily.  More recently, utilities monitor Ary Boender reports the source of these signals as the U.S. Naval Air Station Sigonella, Sicily.

It has also been suggested that these signals may be a form of communication called LINCOMPEX.  Standing for Linear Compression & Expansion, this system is used as a communication method both by commercial & Defence bodies. One correspondent to ENIGMA suggested it was caused by the Lincompex "pilot tone seeking lock".

In personal email, Tom Norris tells me he used to operate HF systems with Lincompex, but can find no reference to a "Pilot Tone" in the system he used, and describes the device as simply a very complex phone patch. What he does recall is that if the "null" of an Lincompex is not properly adjusted, there can be some feedback produced as well.

In Aug 2014, I received another email on LINCOMPEX, this time from Robert G. Damrau.   Bob, a licenced ham, WA1LOT now works for Nevada Solar Designs in Sparks, Nevada & has considerable past experience of working with LINCOMPEX systems. He tells me;

'Having worked with Lincompex for 20+ years and probably having one of the few remaining working units, I'm almost certain that this not a Lincompex transmission. A Lincompex transmission has two components a compressed original audio (typically voice) and a frequency modulated "pilot tone" deviated based on the original audio (voice) amplitude. The received signal would sound as strong voice with a slightly warbling higher tone. The Expanded signal as Lincompex processing would be the original voice with bits of the "band noise" trapped to it.'

The LINCOMPEX theory was never one that I felt happy with & Bob's comments, added to those from from Tom Norris (above) have, for me, finally put the LINCOMPEX theory to rest

Other theories quoted are that the signal is just feedback from naval transmitters using open channels - or due to faults in the transmitter.

I believe that the naval transmitter theory to be the most likely of those put forward. Another correspondent had previously told me that he believed these signals to be nothing more than groups of military or government transmitter back-up networks that are kept servicable in case the main communication systems fail or are destroyed. Every so often they are powered-up & are kept running for several days to ensure that they are in working order. The sounds we hear are feedback caused by the transmitters picking up the output from their own or other links in the chain. Once the testing is over, the back-up systems are shut down until the next tests are carried out, thus explaining the intermittent & nature of the signals. It is with regret that I no longer have the emails & I am unable to give the correct credit to this particular correspondent.

Following a reported absence from the bands during 2001, the signal returned with frequent reports received during 2002, and 2003.

The first report of the signal in 2004 is a good illustration of the nature of this station. First reported on 10512 kHz at the beginning of May 2004, the signal was soon joined by another similar, but not simulcast, on 10363 kHz The two signals were strong in Europe, and were received at different signal strengths. The two stations continued with no noticeable change in content or output, until the end of June 2004. When they both disappeared.

Seems to be less commonly reported than in previous years, 2005/7 have been very quiet. Still seems to pop up on a few occasions every year, but may be on the decline.

Update Aug 2014