I have been testing MT63 heavily for quite some time for use with psmail, but PSK63 outperforms it, so I am back with PSK63.
The biggest drawback (let alone the 2kHz bandwidth required) is the time it needs to gain sync. MT63 could have a life where larger blocks are sent (e.g. for PSKftp) but from experience in the last 12 month I know that the optimum block size is more in the 16 ... 64 byte arena, which excludes MT63 for use in HF ARQ. My measurements on 10 Mhz show that MT63 has 20% less errors than PSK63 on the same channel. The is not enough to offset the negative points. Moreover the biggest channel killer is the Pactor 2/3 QRM, not QRN or noise. 73, Rein PA0R > -----Ursprüngliche Nachricht----- > Von: digitalradio@yahoogroups.com > Gesendet: 08.09.06 03:53:18 > An: digitalradio@yahoogroups.com > Betreff: Re: [digitalradio] ARQ sound card modes > > 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. > > 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. > > 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. > > 73, > > Rick, KV9U > > > > Jose Amador wrote: > > >--- Patrick Lindecker <[EMAIL PROTECTED]> wrote: > > > > > > > >>Hello Rick, > >> > >>TKS for info. Perhaps, next year I will see if it is > >>possible to carry a synchronous ARQ mode (perhaps > >>Pactor 1 forced to 100 bauds) in Multipsk, under a > >>big PC XP. > >> > >>73 > >>Patrick > >> > >> > > > >I know that somebody I cannot remember is working on a > > > >wrapper for MT63 as layer one. > > > >On my tests on 40 meters, seemingly MT63 does not > >stand the multipath on the lower bands. On 20 it works > >great. > > > >Maybe some Olivia variant could be good with a wrapper > >for the lower bands. Olivis is rugged, but > >sloooowww... > >Nevertheless, my KPC-2 received many packets on 40 m > >that it could not decode....the LEDs blinked and the > >TNC output was nil on 40 at 300 bauds. A slow, steady > >flow is far better than a quicker signalling rate with > >many failed frames. > > > >I see a need for substitute Layer One alternatives. > > > >Really, the performance of Layer One established in > >1982 sucks, a single failed bit trashes a frame. > > > >For some time Pactor and its variants has been a good > >substitute, but the high costs of the SCS boxes makes > >them unaffordable for many. Forwarding thruput is 10 > >times better, and even quasi-QRP operation (25 watts) > >becomes a workable option. > > > >After some time away from packet, I find that activity > >is inexistent. I don't know if a better Layer One > >could revive HF forwarding, but certainly, better > >alternatives are required for FBB and JNOS. I have > >been a BBS sysop since 1993. > > > >I tried a keyboard to keyboard QSO using PAX and it > >did better than 300 baud packet on 40 meters using > >Multipsk. I believe that some sort of a driver for FBB > >and JNOS would be a good thing, both for Windows and > >Linux....maybe even MSDOS...you don't need much of a > >computer to run a fairly decent radio only BBS under > >MSDOS...we have one here in Havana. > > > >Possibly many BBS's are doing internet forwarding > >among them, but that is not an option for many BBS's > >without an internet link. The revival of HF forwarding > >would be a good thing on those less fortunate cases. > > > >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 > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > 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 > > > > > > > > > -- http://pa0r.blogspirit.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! 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