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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Wop Wop   -   XWP

Frequency:   (Various)  

6818 kHz 6900 kHz 8034 kHz 8158 kHz
9250 kHz 9390 kHz

This signal was first reported in the ENIGMA 2000 newsletter in January 2002, and consists of a regular pulsating ("Wop Wop") sound. The recording here was recorded in upper-side-band mode (USB), but can sound very different if listened to in the lower-side-band (lsb), or Amplitude Modulation (AM) modes.

  Wop Wop   (59Kb

Starting on the hour, this signal is transmitted on one of the frequencies for twenty or thirty minutes, changing frequency every hour - rotating from the highest to the lowest, then repeating the process over again.

The signal is very strongly received in Southern England, and with a bandwidth of around 3 kHz is very difficult to miss.

At first the station followed a predictable schedule, but now seems to be irregular.

Ary Boender, a Dutch monitor, has identified this signal as French CODAR (COastal raDAR), which can be used to measure wave heights and sea conditions. There are many reports of experimental HF CODAR stations appearing around the world, and if successful we can expect to hear many more of these types of signals on the shortwave bands.

Update July 2004