CONTESTIA et RTTYM


Traduction anglaise

  
    This mode is included into the software MULTIPSK by Patrick F6CTE, there is the description of this mode and its variants as well as the specifications coming from his software :

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 code

0 (idling) -> 0

Space -> 59

<CR> -> 60

CHR(33) Ó CHR(90)
->1 Ó 58


Multipsk specificity:
<BS> (key<---) -> 61

Small letters are transformed in capital letters

Same set of characters as for standard RTTY,except that the "letters" character is the CHR(0) instead the CHR(31) one

The idling character is the CHR(31) character.

Multipsk specificity:

<Bell> 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 tonalitÚs, bandwidth=500 Hz, speed=31.25 bauds, 39 wpm, lowest S/N =-12 dB,
* "32-1K" ("Standard" default mode): 32 tonalitÚs, bandwidth=1000 Hz, speed=31.25 bauds, 48.8 wpm, lowest S/N =-12 dB,
* "8-500": "Normal" 8 tonalitÚs, bandwidth=500 Hz, speed=62.5 bauds, 58.6 wpm, lowest S/N =-10 dB,
* "16-1K": "Fast" 16 tonalitÚs, bandwidth=1000 Hz, speed=62.5 bauds, 78.2 wpm, lowest S/N =-9 dB,
* "4-500": "Fast 2" 4 tonalitÚs, bandwidth=500 Hz, speed=125 bauds, 78.2 wpm, lowest S/N =-8 dB.
* "4-250": "Average 2" 4 tonalitÚs, bandwidth=250 Hz, speed=62,5 bauds, 39 wpm, lowest S/N =-10 dB.
* "8-1K": "Very fast" 8 tonalitÚs, bandwidth=1000 Hz, speed=125 bauds, 117 wpm, lowest S/N =-5 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 tonalitÚs, bandwidth=500 Hz, speed=31.25 bauds, 78 wpm, lowest S/N =-10.5 dB,
* "32-1K" * "32-1K" ("Standard" default mode): 32 tonalitÚs, bandwidth=1000 Hz, speed=31.25 bauds, 97 wpm, lowest S/N =-10 dB,
* "8-500": "Normal" 8 tonalitÚs, bandwidth=500 Hz, speed=62.5 bauds, 117 wpm, lowest S/N =-9 dB,
* "16-1K": "16-1K": "Fast" 16 tonalitÚs, bandwidth=1000 Hz, speed=62.5 bauds, 156 wpm, lowest S/N =-7.5 dB,
* "4-500": "Fast 2" 4 tonalitÚs, bandwidth=500 Hz, speed=125 bauds, 156 wpm, lowest S/N =- 6 dB.
* "4-250": "4-250": "Average 2" 4 tonalitÚs, bandwidth=250 Hz, speed=62,5 bauds, 78 wpm, lowest S/N =-8.5 dB,
* "8-1K": "Very fast" 8 tonalitÚs, bandwidth=1000 Hz, speed=125 bauds, 234 wpm, lowest S/N =-3 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.
   



Recommanded frequencies for
CONTESTIA et RTTYM (USB)

For 1000 Hz bandwidth sub-modes, with an AF frequency of 1000 Hz, frequency displayed on the transceiver :14 103.5  Khz

For 500 and 250 Hz bandwidth: 7039.5,  14075.5 Khz

Back to the liste of modes included in MULTIPSK