John, et al:
> About QRSS, DFCW es 7 freq . I find qrss to be very effective. I
> believe DFCW is even more effective than QRSS because you can send info
much
> faster for the same signal to noise ratio. This makes sense because
although
> it takes same time to send a dot but the dashes are 3 times faster. It
does
> take up more spectrum space than QRSS but the greater efficiency will
either
> get the info across faster during condx of QSB or the transmitter can go
> double the dot length and get the info across in the same time as QRSS for
3
> db improvement in received SNR.
> The &FSK however takes up 3 times more spectrum space es I dont see
any
> benefit in speed/SNR improvement
After last night, I think I'm with you on this one. The DFCW mode is my
favorite, thus far. With 7FSK, my brain has trouble with all of the stuff on
the screen. There were a lot of extra dots and short lines mixed in with it
yesterday, and I don't think I could have ever properly decoded the signal.
The situation was more noise-free the night before, and I got the M0BMU id's
without too much trouble. The visually-decoded modes depend heavily on your
mind's pattern recognition capability. I think the 7FSK stuff exceeds that,
especially in the presence of noise.
On the other hand, what I saw of Steve Olney's Wajina (sp?) mode last summer
was impressive, though I didn't have the information to decode it at the
time. Hopefully, he'll be able to do more with it when the U.S. Lowfer guys
turn into Hifers next summer.
Regarding spectrum space, we've got a nice efficiency demo going in the U.S.
at present, with three stations sending QRSS60 id's on 0.5 Hz spacing on
182.200 kHz. It's been fascinating to watch the propagation each night. And
there's room for more in the screen.
John Andrews, W1TAG
