The Winlink 2000 promoter brings up B2F from time to time with the claim that this is what makes their system have the extra efficiency. But apparently this is a bit overstated.
Is it possible to use more compression in the current keyboard modes or is Varicode about as good as can be expected? Varicode doesn't come close to a 2:1 compression, does it? Modes such as Pactor use many different enhancements so that when you put it all together, you have a superior mode. The one area that Pactor may fall down is that the baud rate is too high for some conditions and at those times other modes might work better that have slower baud rates and a similar modulation scheme. However, I still can not understand why Pactor modes work as fast as they do compared with non-ARQ sound card modes. Ignoring the issue of errors, one would think that a non ARQ mode would always run faster than an ARQ mode. Since any modulation scheme you can do in a discrete box should be able to be done with computer DSP/soundcards why is there such a discrepancy? 73, Rick, KV9U Jose A. Amador wrote: >I am afraid it is as Rein says. > >FBB, which uses B1F compression (hope I remember right) does not >compress the sysop keyboard, but just the BBS traffic. > >JNOS has a compressed ttylink mode that uses LZW and has never worked >for me (compile errors), but which might provide an edge. > >PTC-II boxes can do Huffman and some other sort of limited compression >on the fly, but only has english and german Huffman tables. It is NOT >used on BBS FWD. > >73 de Jose, CO2JA > >---- > >KV9U wrote: > > >>Rein, >> >>I am not clear on this. The B2F compression is used with Winlink 2000. I >>am not sure what it really is other than a compression scheme to nearly >>double plain text throughput and is some kind of adaptation to the >>protocols that were adopted by FBB such as B1F. >> >>Shouldn't this work with even short data packets? >> >>If you were doing some keyboarding with an ARQ mode that was running at >>100 baud, like Pactor, (but could drop down according the conditions ... >>unlike Pactor), and even if you used a cycle of 2 or 3 seconds >>transmitting and .6 seconds open for ACK or NAK, wouldn't this still >>work reasonably well with a throughput faster than most can keyboard? >>And by using the B2F compression, and doubling the throughput, get >>further enhancements? >> >>73, >> >>Rick, KV9U >> >> >> >>Rein Couperus wrote: >> >> >> >>>>Unfortunately this won't work. BZ2 compression is based on 'redundancy' in >>>>a message. There is hardly any redundancy in short messages as used in >>>>k-to-k. >>>> >>>>The only way you can do that is by using context-based compression, like >>>>the 'context based huffman' compression in pskmail, which reaches >>>>compression factors of 1 ... 50 : 1. >>>> >>>>Rein PA0R >>>> >>>>(by the way, it is open source). >>>> >>>> >>>> >>>> >>>> >>R >> Announce your digital presence via our DX Cluster telnet://cluster.dynalias.org Our other groups: http://groups.yahoo.com/group/dxlist/ http://groups.yahoo.com/group/themixwgroup http://groups.yahoo.com/group/contesting http://groups.yahoo.com/group/wnyar http://groups.yahoo.com/group/Omnibus97 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/
