FSK 200/1000

Nickname: FSK 200/1000

Status: Active

Voice: None

Emission Mode: FSK, 200 bd, 1000 Hz, ACF=288

Location: Russia

Schedule: See below

Known Counterparts: E06, E17, G06, S06, V06, V23, M14, M24


FSK 200/1000 is part of the Russian E06 Family, as are E06, E17, G06, S06, V06, V23, M14, M24 and FSK 200/500

The name of FSK 200/1000 comes from:

  • Baud rate: 200
  • Shift, 1000 Hz

FSK 200/1000 appeared 6 years later than FSK 200/500; in 2006.

FSK 200/1000 allows more than one encrypted message to be sent in each transmission, however usually the messages are only null messages.

The header is the two first blocks – the first contains data about the entire transmission (number of blocks + the amount of messages), the second is about the first message.

A partial decoding using “Rivet” results in a typical message looking like this [(c) Priyom]:

“Block No 0 : Total Message Size 13 blocks : This transmission contains one message.
Block No 1 : Link ID 45114 : 26th of month : Msg Number 010 : Msg Type 07145 : Group Count (?) 74
52293 03705 20465 26848 56490 01394 10063 23612
Block No 2
Block No 3
Block No 4
Block No 5
Block No 6
Block No 7
Block No 8
Block No 9
Block No 10
Block No 11

The fields indicate the following:

  • Total Message Size:  the amount of blocks in the entire segment, counted from one, and also includes the separator block, represented by the string of hyphens.
  • Link ID: presumably ID of the recipient, tied to one or more schedules.
  • 26th of month: the date of the month when the message was written (not when it’s being sent). It is normally two days prior to the first transmission of it. In null messages it’s always the date of the transmission.
  • Msg Number: per-Link-ID (not per schedule) serial number, increased by two with each message sent. Doesn’t grow on null messages.
  • Msg Type: in normal scheduled messages it’s always 07145. Messages on link ID 00000 (always unscheduled) always have it as 07104.
  • Group Count (?): possibly the amount of groups actually being sent, as this value grows by about 4 with each new block. Always 4 in null messages.
  • The first 5-digit group has error correction bits in the sixth group.
  • The second 5-digit group has error correction bits in the seventh group. In null messages, this group is always 00000 and the seventh is 00893.
  • The third 5-digit group is always 00000 in null messages.

Null messages are always 4 blocks long, of which the second is always the same. They look something like this when decoded:

“Block No 0 : Total Message Size 4 blocks : This transmission contains one message.
Block No 1 : Link ID 53277 : 4th of month : Msg Number 160 : Msg Type 07145 : Group Count (?) 4
44364 00000 00000 00444 22771 00867 00893 59577
Block No 2

(c) above: Priyom


FSK 200/1000 operates on fixed schedules and sends each transmission three times, 10 minutes appart. The first transmition is usually at the top of an hour or half past, only exceptions so far were :15 and :50. The frequencies of each following transmission decrease:

  • If the previous frequency was over 7mHz usually by around 2mHz
  • If the previous frequency was under 7 mHz usually by around 1mHz

The entire transmission is repeated for 7 or 8 minutes. Most schedules repeat transmissions, if they contained a message, at the same times and frequencies.

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