G02 was first run by the Polish State Security^[1] (SB), then by the Office for State Protection (UOP). Last heard on 9 April 1998.

Triple message format:

Single message format:

There was a variant to the usual intro, designated "G02a", which was the music box played thrice, followed by "12345 67890 12345 67890", altogether repeated for 5 minutes.

Full transmissions with three messages always took roughly 38 minutes, and those with one message - about 17 minutes. 10 minutes prior to the start, a 1000 Hz test tone, lasting 0.5 seconds, would have been emitted every 3 seconds. The transmissions were broadcast on up to three frequencies in parallel.

While the piece of music is frequently described as "Swedish Rhapsody No. 1" (composed by Hugo Alfvén, completed in 1900s), declassified documents^[1] reveal the title of the piece of music actually being used as "Luxembourg Polka" (composed by Emile Reissdorf, completed in 1950s). However, the portions used by G02 are identical in both works.

History

G02 was first reported in early 1960s, but it's possible it had been transmitting even since late 1950s. G02 was noted for very professional operation, with transmissions starting always on time, and with very few mistakes observed.^[2]

Prior to 1988, only the 3-message format was being noted. However, in 1988, some of the schedules started sending only one message, and some started including counting during the intro.

G02 had a very complex schedule. The schedules only took place on selected weeks, and the counting of the weeks started on the first Saturday of the month. The fifth week extended into the first week of the next month. One message was repeated across many time slots, up to even 15 times in a single month. The following is G02's schedule that was known in 1996:^[2]

On 1 April 1998, the schedules above were fully replaced, leaving only a few transmissions, mostly during European office hours. The schedules listed below were all of the G02a intro format, all were in USB mode, and all contained three messages. The same three messages would have been repeated throughout the entire week. The counting of the weeks still started on the first Saturday of the month. Note that the start times were not rigid, and could start as early as :47. All frequencies kHz.^[3]

However, G02 was finally shut down on 20 April 1998, when E23 took over its schedules.

References

1. Numbers & Oddities #200 (May 2014) [accessed August 30th, 2014]
2. ENIGMA Newsletter #10 (January 1996), p. 7-8 - read a scanned version here
3. Simon Mason, G2/E23 [accessed September 13th, 2014]

Recording courtesy of Numbers & Oddities