priyom.org

F06

Enigma ID ...

Name F06
Frequencies
Status Active
Voice N/A
Emission mode FSK, 200 bd, 1000 Hz, ACF=288
Location Moscow, Russia; Far Eastern Russia; Cuba (depending on schedule, vast majority is from Moscow)
Activity pages

Download audio sample

Known counterpart stations E06, E17, G06, S06, V06, V23, M14, F01

F06 is a Russian intelligence broadcast system, using a proprietary 200Bd/1000Hz FSK modem. Its active counterparts are E06, G06, S06, M14 and F01.

Traffic

Messages consist entirely of 5-digit groups, and follow Russian intelligence common metadata formats. Messages always start with a common Russian 5-group header, using 11166 or sometimes 11100 as message type. The serial number uses only two digits: the 3-digit value increments from 001 to 099 then wraps around back to 001, the hundreds digit always remaining 0 (except for operator errors).

Traffic messages normally end with a serial number, group count postamble followed by a 00000 outro group, and a number of extra 0 padding digits. Example traffic message:

11166 40133 35621 16018 00409
45491 95053 77949 73572 09242 54642 07365 05053 41153 76835
02955 56314 13453 12527 28901 02040 30133 99584 08872 16956
20515 61667 37382 34431 85341 70547 20508 50105 41528 72591
88512 76189 57057 72710 13523 36085 04726 95605 18038 00000

Null messages always consist of 4 groups after the header (00000 00000 00000 00000). The message date in the header is always the broadcast date in UTC. The value used as the serial number is either:

  • 01,
  • the serial number of the last message sent on that schedule,
  • but more often, a random number.

Example null message:

11166 40133 95203 03001 00049 / 00000 00000 00000 00000

Some of the schedules also have the habit of sending a triple timestamp header at the beginning of the encrypted part of every message.

Scheduling

F06 operates in regular schedules of three identical transmissions, spaced 10 minutes apart. Each takes place on a different frequency, usually in descending order. When traffic is sent on a schedule, the transmissions may repeat also 24 hours later at the same times and frequencies.

Pre-transmission tests

After tuning up the transmitter and about 10 minutes before a scheduled transmission, and usually once again about a minute later, a short test message is sent. The payload of this test message does not use the normal encoding for 5-figure groups, but instead contains raw 8-bit ASCII-based text: a sequence of "4646464646..." of variable length, usually short enough to fit inside a single message block, but not always. Sometimes the 464646 sequence contains typos. The block sequence of the transmission is only repeated a few times before returning to an idle carrier.

The 464646 sequence is the figure-shift analog of the classic RYRYRY ITA2 test sequence. F06 does not use ITA2, but the test sequence seems to have been carried over out of habit, from other modes that do use it such as the counterpart station F01.

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