DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws;
  s=s1024; d=btopenworld.com;
  h=DKIM-Signature:X-Yahoo-Newman-Property:X-YMail-OSG:X-Yahoo-SMTP:Received:Message-ID:From:To:References:In-Reply-To:Subject:Date:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE;
  b=pTHkQuykJ2OvuZFNu8QPh+ea7uOkcCZ0PBWq9oEW+6XF0SVIDLGB885boIUzeyaHJVp3btEKI2iwz/7nDO340EBlMIKj7bPZaEAxQ63xKw7IvhnA7OkCWE3EEq7G2+DU+RMcEiGhWRxkDl/heDGUr0ohTvn7dj1N6i+YhgJ/suQ=  ;
Message-ID: <765A691C44ED49C0AC79EA930DE89D38@JimPC>
From: "James Moritz" <james.moritz@btopenworld.com>
To: <rsgb_lf_group@blacksheep.org>
References: <006201cce044$06c16f80$0401a8c0@xphd97xgq27nyf> <3A9A60CAE4EB4355A5B0A30CDA0F450A@JimPC> <AE79F5BD0B964D4CBF8E04AD01E73808@JimPC> <4F29028F.7070207@talktalk.net>
In-Reply-To: <4F29028F.7070207@talktalk.net>
Date: Wed, 1 Feb 2012 21:29:41 -0000
MIME-Version: 1.0
DomainKey-Status: good (testing) 
Subject: LF: Re: Opera v qrs evaluation
Content-Type: text/plain;
	format=flowed;
	charset="iso-8859-1";
	reply-type=response
Content-Transfer-Encoding: 7bit
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
X-AOL-SCOLL-URL_COUNT: 0  
X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m287.2 ; domain : btopenworld.com DKIM : fail  
x-aol-sid: 3039ac1dc1484f29af031171
X-AOL-IP: 195.171.43.25
X-AOL-SPF: domain : blacksheep.org SPF : none


Dear Eddie, LF Group,

> Was -31dB the limit of decoding for OPERA, ie could you take QRS3 to below 
> copy ability yet get decodes from OPERA even if not 100% of the time.

Overnight, your signal decoded 100% of the time with reported levels down 
to -32dB SNR, which seems consistent with G0NBD's -34dB minimum figure. This 
was intended just as a quick "sanity check"experiment - the off-air signal 
and noise levels are not usually stable enough to get better than a couple 
of dBs repeatability, so trying to locate the exact threshold at which Opera 
fails to decode would be long-winded. Rik ON7YD's approach will give more 
precise results.

But for a realistic simulation, some way of including the effects of QSB is 
important too, I think, especially for 500kHz modes intended for 
intermediate to long distances. This is certainly done with HF channel 
simulations when evaluating different modes. I expect modes such as Opera 
and WSPR are rather effective with the frequent deep fades that occur on 
500k, because of their FEC ability to decode correctly when a fairly large 
fraction of the transmitted symbols are lost in a fade. This is certainly a 
problem with using QRSS on this band.

>I am still searching for the reason for never a report on my QRS3

I guess there just isn't a large crowd of people listening on 500k, and you 
would have to be a very conscientious listener to report every signal every 
time, without being specifically requested to do so. That is certainly a big 
benefit of the automated reporting possible with Opera and WSPR. It may not 
give you the "Man Triumphant over the Aether" feeling after spending several 
hours in a shed with headphones clamped to your ears, but it is nice to know 
your PC is reporting every detectable signal while you are at work or tucked 
up in a nice warm bed ;-)

Cheers, Jim Moritz
73 de M0BMU