"Mike Blake" wrote in message
gy.com...
Where are the Q15x25 QSOs going on. I have MixW, which should work this
mode, but I am not aware of ever hearing it on the HF bands. Is this a
VHF/UHF only mode?
It's intended for HF, but works great on VHF/UHF too. Operating freqs listed
in the pages that follow.
http://home.att.net/~ronchap/q15x25modes/q15x25.htm
http://sharon.pi8zaa.ampr.org/mirror...25/Q15X25.html
There is also a Yahoo group named "Q15x25" that is a great source of info on
operating this digital mode.
Briefly: Q15x25 uses 15 PSK streams at 88.xxx baud each, theoretically
giving you around 2500 baud. That's where the 15 and 25 in the name come
from. It butts right up against the legal limits of bandwidth, but doesn't
cross those limits and is so it legal, despite doubts that some have
expressed in the past.
Q15x25 operates exactly like packet. It's a connected mode, and if a frame
gets through at all, it gets through intact. From what I can tell, the most
popular activity among Q15x25 enthusiasts is to swap JPEG images on the air,
kind of like SSTV but with error-correction so the pics always come through
clean.
There are versions for Linux and Winders.
My on the air experience with Q15x25 is that it works great when you have
clear spectrum, but under noisy conditions is no better or worse than 300
baud packet! - Except of course it takes up several times as much spectrum
to do so. Q15x25 will not pull out weak signals you can't hear or any of
that kind of stuff. On the other hand, under decent operating conditions it
can be pretty fast.
I also have discovered that by boosting the TXD up to 800-1000 MS or more,
you can conduct Q15x25 QSO's over a normal VHF voice repeater. A nice 2500
baud data transfer system for emergency use anywhere there is a voice
repeater... Admittedly not ideal, but still a big step up from nothing.
I remember reading a few weeks back that the author/authors of Q15x25 were
currently working on a new version, so it appears the mode is alive and
well, if not popular due to it's width. It really is hard to find a good
place to operate Q15x25 on busy freqs.
That's the problem with the wide modes, I guess. TANSTAAFL
Charles Brabham, N5PVL
Director: USPacket.Net
http://www.uspacket.net