Hello Votjech, Yes you are right the crest factor in MT63 is very low (mean power/ crest power = 0.1 (OFDM general problem) for 0.76 in Olivia...
Other problems: due to the big number of carriers (64) you need a good calibration of the sound card. Otherwise, you decode nothing. The minimum S/N is not very good either and the latency time is big. If Olivia is too slow, another better option is to transmit in Contestia. For about S/N, it is only about 1 dB under Olivia but the speed is twice. Example: * MT63 à 10 bauds: - 5 dB and 100 wpm, 1000 Hz bandwidth * Contestia "16-1K": "Fast" 16 tones, bandwidth=1000 Hz, speed=62.5 bauds, 78.2 wpm, lowest S/N =-9 dB, No problem of crest factor (0.76), small latency time and no problem of sound card calibration. It's available in Mixw, Multipsk and perhaps Fldigi. 73 Patrick ----- Original Message ----- From: Vojtech Bubnik To: digitalradio@yahoogroups.com Sent: Friday, September 14, 2007 12:45 PM Subject: [digitalradio] Re: The decline of Olivia and DominoEX > Question - what's so special about MT63 - where / when is it used? From my point of view, MT63 has high number of carriers, which implies low crest factor - the effective transmitted power will be much lower than of single tone mode like Olivia, if you make sure PA is not overdriven by peaks where the amplitude maxima of multiple carriers meet. Some argue that the mode is fast, but are not there Olivia submodes with the same throughput? 73, Vojtech OK1IAK
