I don't know if this info is much use but Skysweep Technologies bundle an OFDM (TX & RX) mode with their SkySweeper 5.12 package.
http://www.skysweep.com/skysweep.html The mode is called SkyOFDM and from their help file: "SkyOFDM is a state of art high speed modem based on the OFDM and turbo coding technologies. It offers several baud rates (300-9600 bps) and two different interleaving options (short and long). Also there are two bandwidth options: 2.0 and 2.6 kHz.The receiver should be set to the USB reception mode. The VHF/FM variant is not included in the SkySweeper Professional product." "The high baud rates of SkyOFDM are very sensitive to signal clipping, so please set the transmitted signal level carefully. The peak to average ratio (crest factor) is up to 10 dB depending the baud rate." I haven't used it though. 73 Sholto KE7HPV. ----- Original Message ----- From: "Rud Merriam" <[EMAIL PROTECTED]> To: <digitalradio@yahoogroups.com> Sent: Sunday, October 21, 2007 10:13 PM 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.
