Hi,
Not MY 3dB rule; just a pure application of Shannon's theorem (see the link to
K1JT page and consult WSJT ver3 manual at the last page)
Please also read what I said about speed, bandwith efficiency, and test
conditions...
By the way the mode can also do 500, 250hz and 125Hz BW, yes it is slow, but it
is the price to pay for the power gain.
Bandwidth versus power versus speed... Not my theory, unfortunately!
At equal RTTY BW ~250Hz (8/250) yes, it is abt 3times slower than TTY, but also
10dB more sensitive in a AWGN channel...still some 5dB benefit. Did not do the
tests yet, but I am sure it's gonna be far more significative under a
"CCIR-poor" channel (due to FEC). Did not test all modes combinations but I
guess it is also possible to use 250/4 for some 180LPM and get around -13dB in
an AWGN
channel...
Please just look at the figures, and be open-minded! (and don't forget that
RTTY'ers are bandwidth wasters from PSK'ers point of view! - and what to say
about SSB'ers...;-)
Patrick
Curious CW-operator
PS: And I would be interested if you could tell me how to optimize the PSK
parameters to cope with a CCIR-poor channel... ;-) For RTTY under "flutter"
channel I actualy used MMTTY with "fluttered" preset...
And last but not least, you can easily reproduce the same tests on your own, and
publish your own conclusions - By the way please note that I did not emit any
opinion... just raw figures...
Re: [RTTY] Olivia's beauty...
from [tgstewart] [Permanent Link][Original]
To: rtty@contesting.com
Subject: Re: [RTTY] Olivia's beauty...
From: tgstewart@pepco.com
Date: Mon, 14 Mar 2005 10:54:36 -0500
List-post: <mailto:rtty@contesting.com>
Yuk! 1khz bandwidth? Just what we need...>5 times less signals per khz
than RTTY or 20 times? PSK....and it's slow. I would also guess that you
didnt optimize the software settings for either RTTY or PSK for the
special conditions listed below. Lessee... 5 times the bandwidth and 1/2
the speed....by your 3db rule, Olivia should be at least 10 db better than
RTTY.
Ty K3MM
f6irf@free.fr
Sent by: rtty-bounces@contesting.com
03/14/2005 08:26 AM
To
rtty@contesting.com
cc
Subject
[RTTY] Olivia's beauty...
I just published a few figures concerning "Olivia" measured performances
versus a few other CGM's (PSK, RTTY, MFSK16. etc...)
http://groups.yahoo.com/group/oliviadata/message/87
Patrick
F6IRF
PS if you have no idea of what Olivia is, here is where to start:
Olivia is a new MFSK mode designed by Pavel Jalocha SP9VRC.
http://homepage.sunrise.ch/mysunrise/jalocha/mfsk.html
Pavel's software is designed for Linux, but can run under Cygwin
Chris Watts VK3DNH has developped the windows interface.
A good tutorial is provided by N1SU http://n1su.us/olivia/
The software provides limited features, just what is stricly required for
mode experimention.
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