Research done by private research firms have addressed this problem. For medium length messages in the broadcast mode, they suggest heavy FEC. For longer messages they suggest less FEC and NAKs. For critical messages of any length they suggest FEC and ACKs.
For many receiving stations, they suggest medium to heavy FEC. Their research grant was for a national/international national command structure type message for many receivers. The length of their message was not revealed. The research done is considered intellectual property. They did find that the number of bits recovered from a single tone carrier that is generally used is less than what can easily be obtained. I do know that the computers they used were all of the single Intel P4 category. The mode(s) they used were all developed on common sound cards as well as special hardware soundcards. Walt/K5YFW -----Original Message----- From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] Sent: Thursday, August 24, 2006 9:13 AM To: digitalradio@yahoogroups.com Subject: Re: [digitalradio] The digital throughput challenge on HF [stuff deleted] If you want to "broadcast" a message from one to many, then the only practical alternative is to use a non-ARQ mode, typically with a large amount of FEC. While this is done on amateur frequencies for sending a bulletin, calling CQ, and having a roundtable, if your goal is to have accurate messaging, then I don't see any option other than a good ARQ system. 73, Rick, KV9U 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/
