Enigma ID HM01

Spectrum image Spectrogram

Frequencies 9065, 9155, 9240, 9330, 10345, 10715, 10860, 11435, 11462, 11530, 11635, 12180, 13435, 14375, 16180, 17480
Status Active
Voice Female
Emission mode AM; RDFT
Location Havana, Cuba


Activity pages

Download audio sample

Known counterpart stations

HM01 is run by the Cuban DGI.

Transmission format:

Intro Message #1 Message #2 Message #3 Message #4 Message #5 Message #6
17568 92788 76627 50636 44143 14766 Sync tone 17568 RDFT
92788 RDFT
76627 RDFT
50636 RDFT
44143 RDFT
14766 RDFT
Six 5-digit message headers   First header   Second header   Third header   Fourth header   Fifth header   Sixth header  
Repeated for 3 minutes   Repeated for 20 minutes

The messages transmitted by HM01 are computer files with 8-digit names and either .TXT, .F1C, or .F1G as the file extension. The files consist of unidentified binary data. The 5-digit headers consist of the last 4 digits of the file name, followed by a single digit age counter.

RDFT (short for Redundant Digital File Transfer) is an off-the-shelf open source system, initially intended for amateur radio use. The DGI uses DIGTRX to transmit and receive it.


HM01 broadcasts the same set of six messages on all schedules, starting at 16:00 UTC, and concluding at 10:00 UTC the following day. Each one hour schedule of HM01 consists of two airings, on the hour and at the half hour, with a period of silence in between.

Operation quirks

HM01 shares transmission centers with the Cuban international broadcaster Radio Havana Cuba. It is not uncommon for RHC to be unintentionally broadcast on HM01's frequencies.

The audio for HM01 is provided by a computer running Windows XP, the sound effects of which are occasionally heard before transmissions.


HM01 was first heard on 17 November 2012, initially on some of the V02a and M08a schedules that had existed at the time. The current HM01 schedule was developed starting in December 2012, and has not been changed since early 2015.

Until 1 November 2018, HM01 updated each of the six message slots on a daily basis, independently of each other. Each message usually spent 10 days on a slot. Typically, the age counter was set to 1 for the first two days, then incremented by one with each day, and the day after the counter reached 8, the message was replaced.

Since 1 November 2018, HM01 broadcasts sets of messages with unchanged age counters for prolonged periods of time, with the entire set being replaced when a need comes. Occasionally, HM01 returns to its old message rotating behavior, but only for a few days or weeks at a time.

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