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 |
Same set of
characters as for standard RTTY,except that the "letters"
character is the CHR(0) instead the CHR(31) one 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 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.
* "8-1K": "Very fast" 8 tonalités, 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 tonalités, bandwidth=500 Hz, speed=31.25 bauds, 78 wpm,
lowest S/N =-10.5 dB,
* "32-1K" * "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": "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": "4-250":
"Average 2" 4 tonalités, bandwidth=250 Hz,
speed=62,5 bauds, 78 wpm, lowest S/N =-8.5 dB,
* "8-1K": "Very fast" 8 tonalités, 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