Thu, 18 Feb 1999 16:43:06 -0500
> >1. What means "stable" ?
> >2. I find it unfortunate that a linear TX is necessary,
> > since it's bad efficiency compared to switched
> > amplifiers. Is there a solution avoiding this ?
> >3. Is it better than AMTOR or RTTY at comparable
> > speeds/shifts?
> PSK31 is considerably better than RTTY and has about the same speed in terms
> of words per minute as it uses variable length coding for the alphabet to
> improve coding efficiency. AMTOR is only RTTY with error detection added,
> at twice the baud rate. Both these modes are very wide for LF use, not as
> good as PSK31, and if not used with a linear transmitter will generate
> splatter that goes outside the band edges.
> By stable, I mean the frequency shifts caused by ionospheric propagation.
> In use, PSK31 shows a phase display and at night on skywave paths on 3.5 and
> 7 MHz the phase wandering due to reflections can be seen. Whilst '31 is OK
> on all but polar paths with an active sun the 8 and 1 baud modes are
> unlikely to travel far. The much reduced phase / frequency shift at the
> lower LF frequency should support the lower modes - but until I have someone
> to experiment with ie with an EVM we won't know !!!
> ANdy G4JNT