A few quibbles. Accuracy is a more-or-less thing. I used RTTY a lot back in the late 1950s, and even when copy isn't perfect you can have an enjoyable QSO because you can pretty well make out what the other guy is saying. With somewhat worse conditions you can't and you give up. But imperfect copy is really bad if you are passing traffic because you need to clean the errors out of the messages before relaying. And it would be unacceptable if you were handling encrypted traffic where every character has to be correct. I'm amazed at the efficacy of FEC in these new modes.
I'm not sure bandwidth is exactly the measure we want to use either. Another possible measure is power density, power/bandwidth. If we use the same amount of power then MFSK is wider band than PSK. But if we were to reduce the power in MFSK corresponding to the increased bandwidth, the two might have about the same potential for interference with other QSOs. We don't have a good way to do this. If I remember correctly Clover has a feature where it will automatically cut power when transmission quality is good and increase power when quality deteriorates. Simplicity might be another consideration. A feature of Hellschriber is that it works with a CW transmitter. Two- tone FSK can be implemented by shifting the frequency of a crystal or VFO. The more complex modes just about have to have a SSB transmitter. Maybe that's not a big deal with today's technology. A friend has a little software-defined radio the size of a few postage stamps - it is a crystal-controlled direct conversion receiver that uses both channels of the sound card for I and Q demodulation to suppress the unwanted sideband. It is the size of a few postage stamps, but of course isn't tunable over much of a range. I suppose you could use the same technique for SSB generation, although the spectral purity might not be sufficient. ------------------------ Yahoo! Groups Sponsor --------------------~--> Great things are happening at Yahoo! Groups. See the new email design. http://us.click.yahoo.com/TISQkA/hOaOAA/yQLSAA/ELTolB/TM --------------------------------------------------------------------~-> Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
