--- KV9U <[EMAIL PROTECTED]> wrote: > Hola Jose, > > I think that Paul, K9PS attempted to do this at one > time, but was not > able to finish it. He has developed ARQ criteria > that was the used to > help develop PSKmail. I thought that MT-63 could > handle multi-path quite > well, but I still prefer MFSK16 for difficult > conditions.
I agree....MT63 flies on 20...but gets nailed to the ground on 40, simply does not get thru. I believe the signalling rate is too high for the lower bands. Olivia works really well, better than MFSK16. Something that should not be forgotten is that Pactor II/III also uses FEC as convolutional encoding and maximum likelihood (Viterbi) decoding. And it DOES work, if you can recover a frame from errors, in spite of the FEC overhead, is still more efficient than repeating the whole frame, the usual behavior in traditional packet. Nevertheless, ARQ is necessary to insure error free reception. If the BER is not good enough, simply disconnect the link. Maybe only one modulation scheme (Layer One stuff) is not good enough for all situations, and different bands or propagation conditions may require different solutions. SCS boxes do it with different levels of PSK (BPSK, QPSK, 8PSK) and the number of carriers, from 2 to 16, and it does work. Even when you do not make a carbon copy, those ideas DO WORK. > While I can understand the reason for moving most of > the messaging to > the internet due to the congestion we would > otherwise have with HF > forwarding. We still need some kind of HF forwarding > for emergency use > when other systems are not operational. It seems to > me that it must have > a full character set. Certainly, and not only for emergencies. HF radio may not be that speedy, but certainly has more coverage than Internet...it requires no wires. > And in order to insure that such systems are in > place at all times for > the inevitable emergency, it also has to have some > kind of practical use > or it won't be ready when you need it the most. Certainly. And something else. In packet I found a "esprit de corps" among hams that I find absent from other digital communications media. 73, 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/ <*> 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/
