Rick, I wasn't around back then but from what I have read, the standard for RTTY was set that the Mark was the high RF frequency and the Space the low RF frequency. To avoid problems with audio harmonics and the fact that some rigs could not handle 2975, LSB had to be used. Most demodulators would treat the absence of Mark as Space. I wish I could find the article, but I remember reading how one amateur got around the FCC regulations in the early days before FSK RTTY was authorized by only decoding the presence and absence of Mark, so it was like decoding CW. The LSB thing is just one of those things that happened because of equipment limitations, and then got a life of its own, like LSB for phone below 20 meters. MixW was the first program with RTTY that I had used that send AFSK with the Mark high and the Space low. I thought, gee about time.
73, Mark N5RFX >Would LSB be a requirement of 850 Hz shift if they could have chosen >either sideband? Why couldn't they select USB with the audio tones >"reversed" from LSB? This would have made the two RF frequencies normal >to FSK RTTY with a mark of 2975 and a space of 2125. 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/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> 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/
