|Voice||Female, automated, with Cuban accent|
|Emission mode||AM, LSB|
|Known counterpart stations|
|Six 5-figure message headers, spoken using the V02a voice.||First header||Second header||Third header||Fourth header||Fifth header||Sixth header|
|Repeated for 3 minutes||Repeated for 20 minutes|
The transmissions begin near the full hour, and repeat again near the 30-minute mark. Messages for one set of headers are sent for 24 hours on all schedules, starting at 16:00 UTC, with the last transmission at 10:00 UTC the next day. See here for the current HM01 schedule.
The digital mode used in HM01 is referred to as Redundant Digital File Transfer (RDFT), a mode initially created for use by ham radio operators, which Cuban intelligence adopted in 2007 for SK01. The program used by HM01 to create these portions is DIGTRX.
The digital portions carry files with 8-digit file names and extension ".txt". The last 4 digits of the file names are the headers spoken in voice. The contents of these files are encrypted binary data.
Each HM01 transmission contains six messages, identified by 5-digit headers. The first 4 digits are, as described above, a part of the name of the transmitted file. The last digit is an age counter that is increased each day.
The last digit is usually between 1 and 8, but 0 and 9 are not unusual. This age counter is increased every day the message is retransmitted, while the transmitted file remains the same. When it hits 8 and 9, the next day a new message comes in place of the old one. When the message is new, the digit 1 is usually transmitted for two days.
Behind the scenes
HM01 is believed to transmit out of the same facility as the Cuba's international broadcasting station "Radio Habana Cuba". HM01 has been heard multiple times with Radio Habana Cuba on its schedules instead of the intended transmissions.
HM01 uses a computer running Windows XP to produce the audio.
Windows XP log-out and log-in sounds prior to a late transmission, 3 June 2014, 21:34 UTC, 16180 kHz
HM01 has been heard on the schedules of its sister station M08a, either replacing it completely, or mixing into the M08a audio feed. Same has been noted vice versa.
HM01 mixing with M08a, 18 June 2014, 23:00 UTC, 8010
HM01 was first heard on 18 November 2012, initially on the V02a time slots that existed at the time. In early 2013, the current schedule style developed.
In early 2014, HM01 dropped its 23:00 UTC time slot, which used to be the following:
In mid-2014, HM01 replaced the frequency 12120 kHz on the 09:00 UTC time slot with current 11462 kHz, and also introduced this frequency as an alternative for 05:00 and 06:00 slots. On December 1st, 2014, HM01 replaced the 06:00 UTC slot frequency on Tuesday, Thursday and Saturday with 9330 kHz - formerly 14375 kHz.