Cuban Numbers Station HM01: serving up a little confusion

WFL_015On occasion, I hear the Cuban numbers station HM01 on 5,855 kHz on weekday mornings.

It seems that many of the mornings as I listen, I hear HM01 making mistakes or at least experiencing “technical difficulties” (click here for a recent case in point).

Though I don’t often record HM01, I did record it on the morning of September 20, 2013––and, yet again, I heard what seemed to be HM01 tripping over its own tongue.

Instead of the broadcast starting with numbers to identify the transmission, then implementing intermittent RDFT data bursts as per usual, this broadcast begins in the middle of a data burst, then shuffles awkwardly into a “normal” broadcast.  I imagine an operative in the field scratching his or her head…

But hear this for yourself.  Either click here to download an MP3 of the recording, or simply listen via the embedded player below:

Shortwave Radio Recordings: Listen to Cuban Spy Numbers Station HM01

WFL_015Numbers stations have always been a dark oddity that pop up from time-to-time in the course of shortwave radio listening. There is unquestionably an air of mystery and intrigue which surrounds them. With the release of the movie The Numbers Station, many non-SWLers may be enticed to explore the HF bands.  A good thing, as it may draw fresh interest to this classic radio hobby.

I have heard numbers stations since I first started listening to shortwave radio broadcasts some thirty years ago, and I find that I often pause to listen (and to wonder) when I come across one on the bands.  The numbers station I hear most often, though the country of origin cannot be confirmed, is in Cuba–well, at least, we’re pretty certain of that. The same female voice, reading numbers in Spanish, has been Cuba’s calling card in the spy numbers world for some time.

Two weeks ago, on a Sunday morning between 10:00-11:00 UTC, I captured the Cuban spy numbers station widely recognized as HM01 (Hybrid Mode Number 01) on 5,855 kHz. HM01 broadcasts a mixture of AM voice and digital file transfer modes intermixed within the same transmission. The voice heard is the familiar Spanish female voice described above; the digital portion of the broadcast uses a mode called RDFT, a differential phase shift keying mode that has never become popular or standard in the ham radio world. If you’re feeling adventurous, the Windows software DIGTRX (download here) can decode RDFT.  Let us know what, if anything, you discover…

You can click here to download the entire HM01 broadcast as an MP3, or simply listen via the embedded player below: