On Mon, 7 Nov 2005 21:44:11 +0000 (UTC), Dave wrote:

Matt Beard wrote:

Lobster wrote:

Need a new TV aerial; I note Screwfix sell different models for 'strong'
and 'weak' signal areas. AFAIK we're in a fairly OK area, but my
question is, is there any disadvantage in fitting the 'weak signal' type
if it might not be necessary? Otherwise it's clearly not worth even
considering paying two quid less for the 'strong' variety?

David

Aerials for weak areas have greater gain, this means that you get more
signal, but you also get more noise.

Not true.

Antenna gain is noiseless. You only get noise when you introduce
amplification using electronics.

I will be happy to be proved wrong though :-)

Dave

Well the answer is yes and no.

Any in and noise will be subject to extra boosting, but so what - in band
noise is not somethug yoiu cabdo anything about anyway.

No extra noise will be added of course, other than by the actual resistance
of the antenna and its drop cable...

So depending on how you interepret 'get more noise' the answer can be yes
or no, buit with the addendum that it matters not a sod anyway.

The idea of an antenna is to do two things

- get as much signal into the first amplification stage as possible so that
the input signal is well above the amplification noise floor.

- provide much greater gain for the wanted signal than other unwanted ones,
so as to reduce ghosting and out of band interference.

n very high signal areas and with digital setups there is no point in going
beyind a certain point on the first count =- either you have an adequacy of
signal or you don't. If you don't you get pixellation and/or a loss of
signal altogether.

Likewise with digital the finer nuances of tuning the antenna for rejection
of multipath off fixed objecst (as opposed to aircraft) are uncesseary: As
long as te reflections are about 10-20dB less than the main signal, the
digital decoder is likely to ignore them.

This makes the issue of a digital aerial pretty simple. You simply need to
get a good strong signal and provided its not _totally _being interfered
with it will decode well.

All teh thiungs that are releavnt in an analogue aerial - ghosting, narrow
beam, etc, overoading of te front end etc - are almost completely
irrelevant BELOW A CERTAIN :LEVEL. The digital takes care of all of it.

Increasing signal quality beyind what is required by sticking a ruddy great
array of whatever up a mile high pole is as useful as using red dye on your
CD's to get better sound quailty.

Use of high gain or narrow beam antennae is pretty spurious as is high
quality downlead. I've gt the best downlead there is, and I still get
pickup of sparking contacts in the house thermostats.,.

So don't get carried away with your digital aerial. Either your are one of
the 99% of peple who are withing decent range and you will simply connect
up and get a perfect signal, or you are one of the marginal one percent who
will need to spend money and care on an installation of some complexity.

Of course every rigger in the book will be telling you a load of bull****
and trying to sell you gold plated connectors, ultra expensive drop cables
and the biggest load of pigeon rooster he can find in his trade catalogues,
all at 100% markup, but that doesn't mean you NEED it.