Look at KA9Q's web site, especially http://www.ka9q.net/code/fec/, for FEC software.
73, John KD6OZH ----- Original Message ----- From: Rud Merriam To: digitalradio@yahoogroups.com Sent: Monday, October 22, 2007 05:13 UTC Subject: RE: [digitalradio] Re: OFDM Proposal Ed, I am looking into the possibilities of OFDM. Right now I am stumbling over how to modulate the sub channels using the IFFT. <g> Actually, I think it is done by putting equal values in the real and imaginary parts of a bin and then doing the IFFT but need to try it out. I am a big proponent of FEC feeling it is woefully underused in ham digital modes. If you ain't FEC'n; you ain't tryin'. More pragmatically if you don't need FEC then you are using more bandwidth or power than necessary. One form of FEC I am curious about is putting FEC on each symbol. It has been an awfully long time that I looked at the error correcting codes (ECC) that are used in computer memory so I do not recall the details. A little research should remedy that memory failure. But putting 2 bit detection with 1 bit correction on a byte wide symbol might be worth the effort. In other words, stand by while I play with this. I will keep the group updated either by direct results or questions. Rud Merriam K5RUD ARES AEC Montgomery County, TX http://TheHamNetwork.net -----Original Message----- From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Ed Hekman Sent: Sunday, October 21, 2007 11:55 PM To: digitalradio@yahoogroups.com Subject: [digitalradio] Re: OFDM Proposal Rud, I would really enjoy hearing some discussion on the use of OFDM on HF. I work on an OFDM project and have an understanding of how it works although I am not a system designer. I have also tried OFDM with HamPal (digital SSTV) and WinDRM (digital voice) and it seems to me that it offers a lot of potential for improving performance with HF multipath fading. To stimulate some discussion I would like to ask some questions for the experts in the field.
