Paul Kelley wrote:
> 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
Another thing to think about-the 3 dB power change ISN'T what you're
hearing. To really compare apples to apples, you have to measure the
sound output (SPL) change that the 3 dB change creates...%cP
--
Jim Barbour
WD8CHL
(yikes)
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