The Backward Music Station (Enigma : ‘XM’)

This recording is from a shortwave transmission on 6752kHz USB on 25th September 2009.

Sometimes known as The Backwards Music Station and also as Whale Music, it has no discernable schedule, and often disappears for long periods.

It’s not known what the purpose of these broadcasts are – but they wouldn’t sound out of place in a classical electroacoustic concert.

If you know anything more about the Backward Music Station, leave a comment!

via Mystery Signals of the Short Wave:

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.

via Waveformless

9 thoughts on “The Backward Music Station (Enigma : ‘XM’)

  1. Actually, if you EVER heard a numbers station in your life, you’d know it’s NOTHING like that at all.

  2. LINCOMPEX uses a perpetual (no "null") high frequency pilot tone (3.5kHz – 4kHz) that is added on top of the audio speech in the radio channel (and subsequently filtered out when the speech is demodulated in the baseband). The tone frequency relates to the amount of compression employed on the channel. LINCOMPEX equipment works very well and rarely needs much adjustment. The multiband privacy equipment and HF ISB links on the other hand …

  3. It's not LINCOMPEX.
    It sounds like multiple tones with echoes.
    If I had to guess I'd say it was some kind of atmosphere-sounding HF radar. That sort of radar data might be for ionospheric (including sporadic-E) and/or tropospheric ducting studies useful for non-Great Circle bounce HF radio communication – a necessary backup for satellite communication failure.

  4. Actually, it is most likely not a number station. A typical number station would transmit an artificial, usually female, voice reciting a three digit number for 5 minutes, and then 5 digit numbers for the remaining hour, and then sign off by saying 000 000. It may be in English, German, Russian, Spanish, or any other common language. Nothing like this has ever occurred on the Backwards Music Station. It could, however, be transmitting data, which could be translated into numbers, but the fact that it stops for long periods of time, while number stations are almost constant, means that it is probably not a number station.

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