Rick, Yes group delay is an issue, but with adaptive training this too can be overcome. Sound cards, or external modems using DSP or preferably FPGA's would be a fine compliment to most amateur gear. The SDR (software defined radio) that Jose mentioned will be the best solution going forward for more exotic modems. These modems would be an integral part of the radio.
I was looking for a good way to test group delay, and was thinking of generating an FM signal with 3 to 5 KHz deviation and looking for an envelope at the output of the receiver. Does that sound ok? The signal generator is an HP 5640B. 73, Mark N5RFX >Another thing that I came across in my web searching was that amateur >equipment generally has group delays that make it difficult to even >employ some of the modems we have been discussing. 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/
