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 Crackle   -   XC

Home Frequencies:   5500 kHz   /   5505 kHz  

Other Frequencies used;
4426 kHz 4986 kHz 5135kHz 5308.5 kHz 5340 kHz
5494 kHz 6261 kHz 6584 kHz 6987 kHz 8070 kHz
9145 kHz 9223 kHz 12220 kHz 14645 kHz 14568 kHz

This station has been on the air for many years mainly on or near  5500 kHz or 5505 kHz, frequently causing interference to Shannon Air Radio on 5505 kHz.

One Enigma reader described the signal as sounding like "dragging a load of tin cans across the floor".

To hear a recording of The Crackle click on the Icon below:-

  The Crackle   (98kb)

(This sample recorded on 01 Nov 2009. Listen for the distintive sound of "dragging tin cans".)

      A simple sound spectral analysis of the signal.

Crackle Analysis

This station is a bit of a wanderer, starting on one frequency, then over a period of several months, moving to another, and another, then disappearing again. Sooner or later it will reappear on one of its home frequencies.

Usually heard during night-time hours in Europe.

Heard on 01 November 2009 with a good signal on 5135kHz in both England and Finland at 1530z. I took advantage of this appearance to replace the sound sample above and to post a spectral analysis of the recording. On 02 November the signal was again heard at 0500z on 5153kHz, but by 0600z had moved to 6987kHz where it remained for most of the morning.

The Crackle has been very elusive in recent years, making only one or two appearances.   It is however, still active at times and was last heard on 8 Oct 2011 with a fair to good signal on 6261kHz. I monitored this signal from 1500z to 1700z continuously by which time the signal was starting to fade here in S.E. England. It was monitored by other member of ENIGMA 2000 in the UK for some time after this.

In 2014, there were several reports received across July & August. An email from Alex, Jack & Molly arrived with a sample recording from Brooklyn, USA, heard on 26 July 2014 on 4986kHz sounding remarkably like The Crackle.

Earlier the same month I had received a sample & email from Danix111 from with an excellent sample of The Crackle in progress on 14645kHz. Danix111 reports that this signal was active on 09 July 2014, throughout the day. A further report from Danix111 was received on 18 August 2014, where a similar - though slightly faster signal was in progress on 14586kHz. This sample also contained bursts of activity at a higher speed lasting a second or so.

What is interesting about both of the reports from Danix111 is that both the frequencies used are in regular use by the Russian military for Morse communications. Danix reports that Russian CW was active on 14645kHz on the day before he logged The Crackle signal & that the CW had resumed the following day - when The Crackle was missing.

Similarly, after receiving the email from Danix on 18 August, I tuned into 14586kHz later the same day to hear, not The Crackle, but Russian military CW in progress. So are these signals now coming from Russian military transmitters?

The Crackle appears to have long abandoned the 5500kHz / 5505kHz slot it was heard so regularly on prior to & during 2009, & although it is not possible to say with any certainty that the signals we are hearing now are from the same source as those originally reported, it does appear that The Crackle, or a very similar sounding signal is still active from time to time.

A complete mystery - very little is known about this signal apart from its habits and sound. Of all the 'mystery' stations featured on this site The Crackle is the one on which I have received the least information.

Update Aug 2014