Dick Carroll; wrote:
Mike Coslo wrote:
Floyd Davidson wrote:
Mike Coslo wrote:
Dick Carroll; wrote:
Floyd Davidson wrote:
some snippage
You increase the SNR, regardless of the bandwidth, by increasing the
signal level DICK.
Well, so much for your technical knowledge if THAT"S all you know
about it. Any experienced
ham, even without ANY tech schooling whatever, knows better than that.
As a dilletante, I realize that in any ratio, there are two
numbers.
Actually, there are three (bandwidth, signal, and noise) which
are related to channel capacity by the following formula
Capacity = Bandwidth * Log2 ( 1 + Signal/Noise )
The debate is over comparing *efficiency* of different modes (CW
and PSK-31), and hence the channel capacity for such a
comparison, must be normalized.
Reducing the Bandwidth parameter does decrease the observed SNR
in the channel, but the Capacity is not increased because the
actual noise power per Hz is unchanged.
So while it is quite possible to make the s/n ratio larger by
increasing the signal, it is equally possible, and sometimes much
better to increase the s/n ratio by lowering the noise. Sometimes it
is the *only* option available.
However, what has to change is the noise power per Hz, and
reducing the bandwidth does not change that.
Seems like narrowing the bandwidth might just do that!
Increasing the signal power has the desired effect. There are
other ways to accomplish that, of course. Reduction of noise by
any means other than reducing the bandwidth (switching from an
omni directional antenna to a directional antenna, for example)
will have the desired effect.
Okay. What we have here is two separate arguments IMO. Everyone is
right
Aw, Mike, don't mess up Floyd and Carl's playhouse. They're doing their
darndest to
trash an old CW fan, and you're spoiling it!
Ah tries ma best, tha knows!
In fact, their argument, which is correct as much as I've heard of it,
seems to me to be the *reason* why your argument is correct.
Ohhh, now I gave myself a headache.
- Mike KB3EIA -
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