|Voice||Female, automated, with Cuban accent|
|Emission mode||AM; RDFT|
|Known counterpart stations|
|Preamble||Message 1||Message 2||Message 3||Message 4||Message 5||Message 6|
|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 digital mode used by HM01 is RDFT (Redundant Digital File Transfer). It was originally developed for amateur radio use; however, it was adopted by the DGI in 2007. The data bursts, created using the DIGTRX software, encode binary files with 8-digit file names, and either .TXT, .F1C, or .F1G as the file extension.
The spoken message headers consist of the last 4 digits of the respective file names, followed by a bogus number. The last digit previously acted as an age counter, increasing between 1 and 8 inclusive every day, after which the message was replaced on the given slot; on newly added messages, the digit 1 was sent for two consecutive days.
HM01 broadcasts the same set of six messages on all schedules, starting at 16:00 UTC, and concluding at the end of the 10:00 UTC schedule the next day. The transmissions take place on the hour and at the 30-minute mark, with only a blank carrier between the two airings.
Behind the scenes
HM01 uses the same facilities as the international broadcaster Radio Havana Cuba. It is not uncommon to hear the Radio Havana Cuba audio feed being broadcast on the HM01 frequencies by mistake.
HM01's audio feed comes from a computer running Windows XP.
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. The 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. The schedule has remained unchanged since then.