I meant to bring up Q15X25 since this was going to be "the" solution for HF packet a number of years ago but no one really knew much about it and the only comments we ever heard was that it just did not work well.
And yet when you look at the modulation method and tones, it just seems like it would be a very good mode, even though some might criticize its width since it is always going to be operating at 2000 Hz bandwidth. Or can it vary the number of tones and BW? The raw speed is 2500 bps and so that seems very acceptable to me. The ARRL web site description says it is a KISS/AX.25 packet modem designed for AX.25 and TCP/IP. Since it uses 15 QPSK tones it has FEC and each tone is a reasonable 83.33 baud rate spaced at 125 Hz. The design is from non other than Pawel Jalocha who created a number of other modes including Olivia. Does anyone really have the definitive answer one what is or is not the truth about Q15X25? The 2FSK300 mode currently used has good speed for its bandwidth, if, and it is a big if, it has a frequency that has minimal Doppler and ISI and better than zero dB SNR. We know how fast PSK250 can work with NBEMS, again, if you have a perfect path, HI. 73, Rick, KV9U Mark Milburn wrote: > We have been talking about using Q15x25 but it turns out to be more talk than > doing so we haven't really done much. I think it's quite possible using FBB > or MSYS and then using MixW as the TNC. That way you have the error > correction of the bbs program and the ability to vary the Q15x25 for a wider > or more narrow transmission. > > Actually, I think 300 baud does quite well. Of course it is slow, but that > is a term relative to your expectations. It is now 2 PM here and I have > taken in over 20 messages and have forwarded 35 out today on 40 meters and > there are probably five or six more hours of forwarding time before the band > closes up between myself and my forwarding partners. That is pretty good, I > think. > > Mark >
