--- KV9U <[EMAIL PROTECTED]> wrote: > I agree completely, Jose. > > However, all these things can (and often are done) > with other modes that > do not run as fast. The bandwidths are no > differerent than the wider > sound card modes at either 500 Hz for Pactor 2 or > closer to a voice > bandwidth such as Pactor 3 uses. And the Pactor > modes don't use > particulary unusual modulation schemes either and > 100 or 200 baud rates, > which while a bit fast for certain kinds of > conditions, seems to work > better than one would expect. > > So what are we doing wrong with existing sound card > modes? > > 73, > > Rick, KV9U
Well, about what´s being done the wrong way, I think I better pass it to the codesmiths. I am not completely clear about how the soundcard modes do it, but the success if Pactor is wrapping all those tricks together. Some of the modes use Reed Solomon codes, others use BCH, but I am not sure if any of them uses convolutional encoding with Viterbi decoding. One important point. If my memory does not betray me, I think Pactor uses DPSK, which does better passing by the ionosphere. Seems to be easier to take account of the phase jumps than of the absolute phase. I used at times packet at 1200 baud on 28, 21 and 14 MHz, and it worked in order of decreasing success on the lower frequencies....but it managed to work on 14MHz quite well at times. Multipath is the deciding factor in the link. If just one path is open, it may work, if there is multipath, better hold back to lower speeds. What surprises me (and I have never been able to test it personally) is that in Indonesia, some hams have used 1200 baud DPSK satellite modes succesfully on 40 meters. Once again, DPSK does the trick. It would be interesting to read about what and why the programmers have chosen their options while creating new sound card modes. 73 de Jose, CO2JA __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com 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/
