Robert,
Your points are well documented and certainly true, however, they apply to
the question of copying a weak signal in the presence of noise or
interference. The issue with the third order IMD (3OIMD) measurement is
that it is a measure of how many additional interfering signals the brain
may have to deal with under certain circumstances, particularly during
contests and pileups.
Thus a receiver with better 3OIMD performance will allow that skilled
operator to do a much better job of copying the weak signal than a receiver
with poor 3OIMD response.
73, Joel Hallas, W1ZR
Original Message:
-----------------
From: Robert & Linda McGraw K4TAX RMcGraw@Blomand.Net
Date: Tue, 02 Aug 2005 07:00:24 -0500
To: tentec@contesting.com
Subject: Re: [TenTec] Corsair vs. Orion (weak signal)
While the technical measurements of the various receivers do seem to show
certain ones to be better than others, what ever "better" implies, the
reports of being able to hear signals on one receiver and not another
leaves
out one important factor. The human brain coupled with the ears do allow
one to hear signals that are typically 6 dB to 10 dB below or down in the
noise. Also the human hearing has and adaptive feature that allows the
brain to disallow, on a short term basis, any unwanted signals received by
the ears.
In most cases it is observed that the skill of the operator exceeds or
greatly impacts the end performance results, regardless of the technical
merits of the equipment. These factors do not seem to be "weighted" with
regard to receiver performance. A factor that I personally observe has to
do with the quality of the audio chain, the character of the noise being
produced within the receiver and the artifacts of any digital processing.
73
Bob, K4TAX
----- Original Message -----
From: "NJ0IP" <Rick@DJ0IP.de>
To: "'Discussion of Ten-Tec Equipment'" <tentec@contesting.com>
Sent: Monday, August 01, 2005 11:30 PM
Subject: Re: [TenTec] Corsair vs. Orion (weak signal)
> Tnx John. I'm familiar with those figures, but several people here have
> been making some strong claims of hearing stuff on the Corsair which they
> can't hear on the newer rigs. I'm just trying to get a better
> understanding
> of how that is possible and then of course would like to know if their
> claim
> includes Orion.
>
> So far no one has replied except you.
>
> 73
> Rick
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