Enigma ID F03

Name F03a, F03b, F03c
Status Active
Voice N/A
Emission mode USB; Various BFSK and MFSK-4 modulations
Location Poland
Activity pages

Known counterpart stations E11, G11, S11, S11a, M03, F11, P03

F03/P03 is a Polish 11 modem that succeeded F11 in mid 2010s. It contains a number of different serial PSK and FSK waveforms, all of which use variations of the same protocol.

The F03 designator refers to the BFSK and MFSK-4 modes. The following flavors have been spotted on the air so far:

F03a: BFSK, 100 Bd/200 Hz, Center +600 Hz, 448-bit blocks

F03b: BFSK, 200 Bd/400 Hz, Center +800 Hz, 448-bit blocks

F03c: BFSK, 400 Bd/960 Hz, Center +1120 Hz, 448-bit blocks

BFSK, 400 Bd/800 Hz, Center +1200 Hz, 496-bit blocks

MFSK-4, 100 Bd/200 Hz, Center +800 Hz, 448-bit blocks

MFSK-4, 200 Bd/400 Hz, Center +1000 Hz, 448-bit blocks

Recording N/A

However, only F03a and F03b have multiple stable schedules that use those modes year round. The remaining modes' schedules tend to shuffle to different F03/P03 modes along with seasonal frequency changes.


All F03 schedules are twice weekly, follow year-round UTC (no DST adjustments), and use one of three different frequencies depending on the month - one from November to February, another from May to August, and yet another one for the remaining months. However, a very small minority of schedules follows this frequency usage pattern less strictly. There are always two identical broadcasts 5 minutes apart.

Each weekday typically carries a different message, which appears at the beginning of the month and is repeated throughout it; sometimes, both weekdays carry the same message, and sometimes a new message arrives in the middle of the month. Every week, the message is rescrambled, retaining only the headers and the length.

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