THROB and THROBX

THROB and THROBX


Created by : Lionel Sear G3PPT, in 2000 for THROB and 2003 for THROBX

Preliminary : THROBX is an evolution of THROB.

Description :
Baud rate : 1, 2 or 4 (1 or 2 in THROBX)
Speed : 10, 20 or 40 wpm (=10 x baud rate) or 60, 120 or 240 characters/min (=60 x baud rate) (10 or 20 wpm in THROBX)
Modulation : for THROB: FSK 9 tones with 1 or 2 tones send in the same time (which give 45 possibilities including the idle tone)
for THROBX: FSK 11 tones with 2 tones send at the same time (which give 55 possibilities including the 2 possible idle characters)
Reception mode: only one side (USB or LSB), USB is recommended
Character set : for THROB: 46 “ fixed length ” characters: A..Z 0..9 , . ’ / ( ) ? @ = (with use of a “ shift ” character for ?@=). No error reset character.
: for THROBX: 53 characters: A..Z 0..9 , . ’ / ( ) ? @ = # " + - ; : ! . No error reset character.
Shape of pulse : for the 1 or 2 bauds modes: rectangular at the center with leading and trailing quarters as raised cosine. For the 4 bauds mode (THROB only): raised cosine
Space between tones : for THROB: 8 Hz (1 or 2 bauds) or 16 Hz (4 bauds), for THROB: 7.8125 Hz ,
Bandwidth : for THROB: 72 Hz (1 or 2 bauds), 144 Hz (4 bauds), for THROBX: 94 Hz
Demodulation : non-coherent,
Synchronization: automatic on incoming “ throbs ”
Correction code : no
Convolution code: no
Interleaving : no
Automatic Frequency Correction: +/- 3 Hz,
Drift tolerance : 4 bauds: 40 Hz/mn max, 2 bauds: 20 Hz/mn max, 1 baud: 10 Hz/mn max according to signal-to-noise ratio,
Pmean/Ppeak : 0.35 for 1 and 2 bauds modes, 0.19 for 4 bauds
Lowest S/N : THROBX: -18,5 dB for the 1 baud, -17.5 dB for the 2 bauds
THROB: -16 dB for the 1 baud, -14.5 dB for the 2 bauds et -12 dB for the 4 bauds