GardenBanter.co.uk - View Single Post

04-11-2005, 01:58 AM

The message
from (Nick Maclaren) contains these words:
In article ,
Jaques d'Alltrades wrote:
/snip/
Line of site. If you don't line up your aerial correctly with the site
of the transmitter, you will not get good reception. Really!

It's line of *SIGHT* - nothing to do with the 'site' of the transmitter.
One aerial should be visible from the other. (FSVO visible)

Sorry. I should have said "THIS IS A JOKE".

Or not said "Really!"?

/snip/

I haven't looked into the digital signal technology in detail, but
it is very similar to tape recording technology as far as encoding
goes. And digital recording needs EITHER a significantly higher
bandwidth OR a significantly better signal to deliver the same
quality of analogue signal back.

The whole idea of digital is that it operates on a precise frequency -
as far as the generating and transmitting equipment will permit. It's
all about money - you can cram many more channels into the same area of
the radio spectrum. Being a series of pulses, as long as you can
separate them from background 'hash' a ver weak signal will suffice.

Grrk. You can transmit only a constant signal (i.e. containing no
information) on a precise frequency. Digital transmission actually
uses a MUCH wider frequency range than analogue! Seriously.

Digital is what it says, and encodes by strings of minute pulses, and
the bandwidth is very narrow. AM can also be transmitted on a very
precise wavelength. Only FM requires a lot of bandwith to wriggle about
in because it's the frequency changes which carry the information.

HOWEVER, your other point is correct. You can separate transmissions
on different frequencies rather better and, provided that you can
recognise enough bits, strength is irrelevant. But that isn't quite
the same thing as we were talking about ....

/snip/

However, with modern equipment the actual losses in conversion of audio
from analogue to digital and vice-versa are miniscule. The limiting
factors are the clipping and compression used in the digital conversion,
and the retranslation of the received data.

No, that misses the point here. If you need to force the converted
signal through a narrow 'channel' (digital or analogue), you lose
information. Inevitably. You can do the conversion near-perfectly,
but a bounded analogue bandwidth needs an infinite digital one and
conversely. The conversion isn't the problem.

The problem is what is done to save money, not what it is possible to do
to retain quality.

Don't get me going about digital radio either...

Don't get me going about analogue tape storage of computer data ....

And don't get me going about CDs...

--
Rusty
horrid dot squeak snailything zetnet point co full-stop uk
http://www.users.zetnet.co.uk/hi-fi/