|Emission mode||USB; BFSK, 100 Bd, 620 Hz, ACF=16|
|Known counterpart stations||E11, G11, S11, S11a, M03, F03, P03|
F11 was a Polish 11 digital mode that was used from the late 2000s until December 2018. It was formerly attached to most E11, S11a, and M03 schedules, sending the same traffic 10-15 minutes before those schedules.
F11 entered a long period of decline starting in 2014, either with removal of the relevant E11/S11a/M03 schedules, or just disappearing without affecting the analog counterparts. The decline began around the time the newer Polish 11 family of digital modes, F03/P03, was introduced, which operates largely standalone.
All F11 schedules were weekly, followed year-round UTC (no DST adjustments), and used three different frequencies depending on the month - one for November to February, one for May to August and one for the remaining months. For most of the time there was no traffic, and one random week of the month a message was sent that always consisted of 20-50 groups (excluding "88888"). Those always had a repeat transmission in the same week.
Each F11 transmission was followed 5 minutes later by a repeat of it on the same frequency. 10 minutes after the repeat, an E11, S11a, or M03 transmission came up, carrying the same message, always on a nearby frequency, normally up to 1 MHz away. However, not every single analog schedule had a digital equivalent.