|4376 kHz||4410 kHz||4420 kHz||4706 kHz|
|4740 kHz||4552 kHz||5178 kHz||5180 kHz|
|6584 kHz||6695 kHz||6752 kHz||8984 kHz|
|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.
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.
Another theory quoted is that the signal is just feedback from naval transmitters using open channels - or due to faults in the transmitter.
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.