Hi gang. The whole group delay fuss is pointless in my opinion because of the constraints that are put on the operating modes by our lovely ionosphere. I do not think that group delay is an issue at 100Bd symbol speed.
The flattness of the passband is more an issue but it is something that the modems must deal with because of ionosphere fading anyway. There is one real issue - linearity of the whole transmitter - ionosphere - receiver chain. If more subcarriers are modulated, their mixing products will overlap if the chain is not linear, delivering considerable noise like products to the decoder. Thinking about the multi tone modes. Their average output power is considerably lower than if a single carrier mode like PSK31, RTTY or MFSK16 is used. Remember the average power of voice. One will never reach 100W average transmitted power with a 100W transmitter, but it is certainly possible with RTTY. One would need to create a linear transceiver with extremly high peak power to excercise 100W lot-of-tones digital mode. That is the reason why MFSK16 or PSK31 really shine with our YaeComWood 100W transceivers, because these single carrier modes utilize most of the power the transceivers are able to emit. 73, Vojtech OK1IAK 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/
