Mystery Signals of the Short Wave

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The Irregular Dash  

Frequency:   (Various)  

Frequencies Used
5105 kHz 5445 kHz

At the beginning of January 2014, a short wave listener, Tim (westt1us), based in the USA, reported hearing some irregular 'beeps' nightly on 5447kHz, &: had also heard them via the Netherlands online tuner. On the day of the report, 05 Jan, the sigs were also clearly heard in the UK at around 0330 - 0530z with a fair to good signal strength.

On 06 Jan the signal was audible from around 2120z in the UK - but had changed freqs now to 5445kHz, and whereas the signal had consisted only of the irregular dashes, westt1us reported it was now interrupting the dashes with some data bursts.

Unfortunately, the signal as heard in the UK, was struggling under a strong adjacent RTTY signal on this freq so recordings and analysis of the data was not possible. Having monitored the signal for a while just after midnight, it was found that the station was sending 10 seconds of data transmission, exactly every three minutes.

Irregular Dash
0003:17 – 0003:27 (10s Data)
0006:17 – 0006:27 (10s Data)
0009:17 – 0009:27 (10s data) etc.

On Tue 07 Jan, the signal was missing on 5445kHz at 0500z, & was not found in a limited search of the adjacent area, but was rediscovered on another new freq, 5105kHz at 2230z the same evening in the UK. (/p>

Now the signal had reverted to sending just the irregular dashes with no data bursts heard during the period of monitoring. This was confirmed by westt1us. The signal was still transmitting at 0500z on 08 Jan but had gone by 0630z.

We are sure that this signal has been observed & reported before. From observations so far it would seem that the irregular dashes are a channel marker of some sort, with the real purpose of the station being the transmission of the data bursts heard on the evening of 06 Jan.

As a marker the irregular dashes are certainly distinctive, but it has to be wondered how & why this particular choice of marker was selected. Surely a regular dash would have been simpler to generate & would be just as effective.

When listening to the irregular dashes, we are reminded of the Nevil Shute novel ' On the Beach', where the crew of a submarine, in a post-apocalyptic world, tracked a random Morse transmission across the world. An apt comparison, as one can easily imagine the abandoned room with the Morse key and the window sash blowing in the breeze.

Here are two recordings of the Irregular Dash:-

  Irregular Dash -   5105kHz   2230z   10 Jan 2014 (104Kb)

  Irregular Dash with data -   5445kHz   2350z   06 Jan 2014   (92Kb)
  Note RTTY interference on frequency.

Update June 2021