DOMINO DF ("mode par DéFaut")
Traduction anglaise.
DOMINO DF (DominoF 11) is a
sensitive mode which, due to its incremental frequency keying and thanks to its
interleaved multiple tones sets, is easy to tune and is few sensitive to
interference and ionospheric effects. The minimum ratio Signal-to-Noise ratio
is about - 12 dB.
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 :
Click on the copie of the screen in order to
listen to the corresponding audio
signal.
Creators : Con Wassilieff ZL2AFP and Murray Greenman ZL1BPU in 2004
Description :
Baud rate : 10.766
Speed : 40 wpm (by deleting the synchronization characters)
Modulation :
IFK (Incremental Frequency Keying) 16 tones but with two tone sets (J1
and J2) in alternance so as to reduce the ISI (InterSymbol
Interference) and to allow a quick synchronization.
The
total number of tones being 16 separated by a frequency offset (FO)
equal to the baud rate, each set has 8 interleaved tones separated by 2
DF:
O O ...J1
O O ...J2
Note : in fact, 18 tones (2 x 9) are used to limit the rotations.
A character is composed of 2 symbols
of 3 bits each, each symbol being sent on a tone set (first symbol on
J1 then second symbol on J2).
Reception mode : sensible to the side (USB or LSB), USB is recommended
Character set :
62 characters (lower case, numbers and some punctuation) + an error
reset character (6 bits long characters) + a synchronization character
Shape of pulse : rectangular
Space between tones : 10.766 Hz
Bandwidth : 213 Hz,
Demodulation : non-coherent,
Synchronization :
for the 3 bits symbols, using the signal. For the symbol order, thanks
to a block of 4 synchronization characters sent after 12 characters
standard.
Convolution code : no
Interleaving : no
Offset tolerance : 65 Hz. This is the big advantage of this IFK mode which can accomodate a mistuning inferior or equal to +/- 65 Hz.
Drift tolerance : 20 Hz/mn (depending on signal the signal-to-noise ratio)
Note : inside the band limited by the offset tolerance, the drift tolerance is superior to 200 Hz/mn
Pmean/Ppeak : 1
Lowest S/N : -12 dB
Note : it exists 2 other Domino modes (not decoded by Multipsk) at 7.8125 and 15.625 bauds. They are conceived in the same way.
Recommanded
frequencies for DOMINO (USB)
1838, 3580, 7037, 10147, 14080, 18105, 21080, 24929, 28080 Khz
The MFSK8, DominoF, DominoEX
and THROBX modes are QRP transmissions. They are very little used. Patrick F6CTE
proposes to focus calls in the same conditions as for PSK10, PSKFEC31,
PSK63F, PSKAM10/31/50 modes :
* 14075 Khz USB (AF around 1000 Hz) at 17h00 UTC,
* 10148 kHz. USB (AF around 1000 Hz) at 22h00 UTC.
* 144620 kHz. USB (AF around 1000 Hz) at 20h00 UTC.
.