Quick question - Noise margin and SNR

Possibly a stupid question Do noise margin and SNR mean exactly the same
thing? And if so are there any other words which mean the same thing I
should know of?

Thanks

Dan

On 23-Mar-2006, "Daniel" <(E-Mail Removed)> wrote:

> Possibly a stupid question Do noise margin and SNR mean exactly the same
> thing? And if so are there any other words which mean the same thing I
> should know of?

AFAIK - You can measure noise in the absense of a
signal, and you can measure the signal, thus determine
the SNR. SNR is a measurable quantity.

OTOH Noise margin as generally used means how
much the signal has to be greater than the noise
for a system to work, or acceptably work.
So, for instance, for satellite television, a better
LNB by contributing less noise, will give a
less picture noise, as will a better receiver front
end if it contributes less noise than a competitors
product. The noise margin is therefore subjective,
what you are prepared to accept, and equipment
subject, how good the equipment copes with a
not perfect signal. So noise margin has to be
qualified it is not a simple measureable ratio.

So no, they are not EXACTLY the same.

See: http://en.wikipedia.org/wiki/Signal-to-noise_ratio

73's de Phill H.