CONTESTIA and RTTYM

Creator : Nick Fedoseev (UT2UZ) in 2005

Description :

The Contestia and RTTYM modes are directly derived from the Olivia mode (Pawel Jalocha SP9VRC) but with a different compromise between speed and robustness.

Here is a comparison board between Olivia, Contestia and RTTYM:


Parameters OLIVIA CONTESTIA RTTYM
Block size (symbols) 64 32 16
Scrambling pseudo-random sequence 0xE257E6D0291574EC 0xEDB88320 0xEDB88320
Scrambling shift (in number of bits of sequence right rotation) 13 5 5
Characters set 7 bits (ASCII) 6 bitschar -> decimal code0 (remplissage)-> 0Space -> 59 -> 60CHR(33) to CHR(90) ->1 to 58Multipsk specificity: (<--- key) -> 61Small letters are transformed in capital letters 5 bitsSame set of characters as for standard RTTY,except that the "letters" character is the CHR(0) instead the CHR(31) oneThe idling character is the CHR(31) character.Multipsk specificity: is coded as @ (second ' in Mixw)
Characters transmission speed x1 x2 almost x4
Minimum S/N / Olivia for same the sub-mode +1.5 dB (about) + 3 dB (about)
Note: among the 40 possible sub-modes proposed by the author (UT2UZ), Multipsk proposes the same 7 sub-modes as in Olivia (to reduce the mode identification problem, proposing the best selection).

For Contestia (terms "Slow"...qualify the sub-mode speed by comparison with the mean speed in Contestia):

* "8-250": "Slow" 8 tones, bandwidth=250 Hz, speed=31.25 bauds, 29.2 wpm, lowest S/N=-13 dB,
* "16-500": "Average" 16 tonalités, bandwidth=500 Hz, speed=31.25 bauds, 39 wpm, lowest S/N =-12 dB,
* "32-1K" ("Standard" default mode): 32 tonalités, bandwidth=1000 Hz, speed=31.25 bauds, 48.8 wpm, lowest S/N =-12 dB,
* "8-500": "Normal" 8 tonalités, bandwidth=500 Hz, speed=62.5 bauds, 58.6 wpm, lowest S/N =-10 dB,
* "16-1K": "Fast" 16 tonalités, bandwidth=1000 Hz, speed=62.5 bauds, 78.2 wpm, lowest S/N =-9 dB,

* "4-500": "Fast 2" 4 tonalités, bandwidth=500 Hz, speed=125 bauds, 78.2 wpm, lowest S/N =-8 dB.
* "4-250": "Average 2" 4 tonalités, bandwidth=250 Hz, speed=62,5 bauds, 39 wpm, lowest S/N =-10 dB.

For RTTYM (terms "Slow"... qualify the sub-mode speed by comparison with the mean speed in RTTYM):

* "8-250": "Slow" 8 tones, bandwidth=250 Hz, speed=31.25 bauds, 58 wpm, lowest S/N=-12 dB,
* "16-500": "Average" 16 tonalités, bandwidth=500 Hz, speed=31.25 bauds, 78 wpm, lowest S/N =-10.5 dB,
* "32-1K" ("Standard" default mode): 32 tonalités, bandwidth=1000 Hz, speed=31.25 bauds, 97 wpm, lowest S/N =-10 dB,
* "8-500": "Normal" 8 tonalités, bandwidth=500 Hz, speed=62.5 bauds, 117 wpm, lowest S/N =-9 dB,
* "16-1K": "Fast" 16 tonalités, bandwidth=1000 Hz, speed=62.5 bauds, 156 wpm, lowest S/N =-7.5 dB,

* "4-500": "Fast 2" 4 tonalités, bandwidth=500 Hz, speed=125 bauds, 156 wpm, lowest S/N =- 6 dB.
* "4-250": "Average 2" 4 tonalités, bandwidth=250 Hz, speed=62,5 bauds, 78 wpm, lowest S/N =-8.5 dB.

SUMMARY OF THE CHARACTERISTICS OF CONTESTIA AND RTTYM COMPARED TO OLIVIA

* CONTESTIA is a bit less sensitive than Olivia (+1.5 dB on minimum S/N). It is a also a bit less robust (due to a smaller block size) but it is twice more rapid (with a reduce set of characters).
This mode is an excellent chat mode (because sensitive and rapid).

* RTTYM is a less sensitive than Olivia (+ 3 dB on minimum S/N). It is also less robust (due to a small block size and due to the RTTY problem of random shift from letters to figures or reversely, on an error) but it is almost four times more rapid (with the RTTY set of characters).

This mode is interesting for very quick QSO.