Tag Archives: David Crawford

Yet another mystery utility signal to solve–!

Back by popular demand!

On our quest to solve UNID utility signals, SWLing Post contributor David Crawford, is asking for help again to ID yet another interval signal. David writes:

Here’s yet another memorable utili-tune from the deep archives here, again not my recording, origin uncertain.

This one has a date, time and frequency on the filename [19670811-2347-15910-VM unID] and therefore would have been 1967. I heard this one myself occasionally also, which would have been sometime during the mid-to-late 1970s. It would have overlapped with the same time period during which CTNE was using the 14985 kHz tune previously provided, so despite the broad similarity I would assume it wasn’t them. Unless of course they used different tunes for different circuits:

Readers: Can you positively ID this interval signal? If so, please comment!

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Dean solves second interval signal mystery

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(Image source: Madrid.org)

In response to our second mystery interval signal challenge, SWLing Post contributor, Dean Bianco replies:

Mystery solved!

This is the “interval signal” (more accurately, a placeholder with a musical station identifier) for the Compañía Telefónica Nacional de España (CTNW) from Madrid, Spain.

They were a point-to-point HF radiotelephone terminal that provided overseas telephone and telegraph services in the days before satellites became common.

As a young SWL, I would receive all manner of strange musical identifiers for these utility stations. Most of these HF telecommunication services had gone to satellite by the early 1980’s. The HF bands were chock-a-block with signals, whether they be broadcast or utility services.

Glad to help!

To verify his claim, Dean shares the following embedded audio file made by Willi Passmann in the mid 1970s (via the excellent UtilityRadio.com website):

Well done, Dean! Thank you once again for coming to the rescue!

In case you didn’t know, dear readers, Dean Bianco is a force to be reckoned with in the shortwave radio world. 🙂 This year, he won the 3rd Annual Fest Trivia Quiz at the 2020 Winter SWL Fest! An impressive accomplishment, indeed. Not only that, but Dean’s an incredibly nice guy, great friend, and always willing to help out those new to the hobby!

Thank you, Dean!

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Let’s solve another interval signal mystery!

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Last month, we published a post asking SWLing Readers to help Brian (W9IND) identify an elusive interval signal. Turns out, the interval signal belonged to the Voice Mirror of the PTT Habana, Cuba station.

This month, SWLing Post contributor, David Crawford is asking for help to ID another interval signal which likely belongs to a utility station. David writes:

In follow-up to the La Habana utility mystery, here’s another one from the same era, 14985 kHz or thereabouts. Somewhere along the line I came to the conclusion that it might be El Salvador, but I don’t remember what led to that. The [recording embedded below] isn’t my own recording of it.

The tune is composed of individual DTMF tones, and when I was a bored youth I discovered that it could be played on an AT&T desk touch tone phone by pressing two keys at a time to remove the second tone. This one would repeat for hours at a time, interrupted by manually patched telephone calls.