On Friday 11 February 2005 10:33 am, Joe Montierth wrote:
> Second, I see this 3 dB thing bantered about as the
> smallest change that can be heard. I think this is
> wrong, due to personal experience, and talking to
> others. Most CW ops will tell you that when someone
> changes power by 3 dB, that it will make a good
> difference on the RX end, when the signal is in the
> noise.
Being a weak signal CW operator I can tell you that ONE dB
(or less) can make the difference between a contact and no
contact.... if you don't think so, you have not spent
several years working EME!
But getting back to FM and repeaters... I have seen a lot
of this 3 dB is / is not significant debate over the years.
Maybe it depends on what you are trying to do. I would
agree 3 dB is not noticeable or barely noticeable if the
signal is already well out of the noise. However, in areas
where you are trying to push repeater coverage from a given
site to the limits, 3 dB is significant on the outer
fringes and in the problem areas. I say this from personal
experience. I have seen 3 dB change in repeater power or
antenna gain make a significant and consistent improvement
in fringe/weak areas. It can be enough to make the
difference between the repeater being usable or not... I
call that significant.
Paul N1BUG
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