priyom.org

XP

Enigma ID XP

Name
Frequencies
Status Inactive
Voice N/A
Emission mode AM
Location Russia
Activity pages

Known counterpart stations E07, G07, S07, V07, M12, XPA, XPA2, XPH

Digital counterpart to E07, G07, S07, V07 and M12. Active in years 1993 - 2005, replaced by XPA. This system is also referred to as "NUM-13" by Hoka Electronics, and "SP-14" by Wavecom.

Scheduling

XP operated in regular schedules of three identical transmissions, spaced 20 minutes apart. The first transmission could have taken place at any 10-minute interval within an hour. If the first transmission took place before 12:00 UTC, the frequencies of the subsequent repeats increased - otherwise they decreased. If the transmission was too long to fit into the 20-minute frame, it continued, then the subsequent repeat was started as soon as possible.

Mode specification

XP was a 14-tone MFSK system, using two speeds within each transmission - 1 bd for the intro, and 7.5 bd for the message. The following is the list of tones used and their corresponding values, assuming correct tuning:

# Hz Value
1 303 Space
2 319 Transmission end tone
3 335 0
4 351 1
5 367 2
6 383 3
7 399 4
8 415 5
9 431 6
10 447 7
11 463 8
12 479 9
13 495 Message start tone
14 511 Repeat previous tone

Each transmission goes through several phases, in order: (all at 7.5 bd unless noted)

  1. 1 bd intro section: 3-digit ID, space (repeat thrice), amount of messages ("000" - no messages, "1" - one message, "2" - two messages), space (repeat all 10 times)
  2. Tones #14 and #13 alternating 20 times in total, starting with #13
  3. 10 spaces
  4. Message: 5-digit groups, followed by a space
  5. End of transmission: Tones #2 and #14 alternating 20 times in total, starting with #2

When no message was to be sent, the step 4 was skipped.

In the actual messages, the first group always started with "0", and the second group was the amount of groups in the message minus two. Multiple messages were separated by "00000 00000".

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