75 ohm terminals.

Jim Lesurf wrote:

snip

For me, the test for Horizon was to listen with the display off - so
making it into a radio programme. Did this mean I felt I was missing
info or relief that I was avoiding flashing lights trying to distract
me? The result was the tendency to be bored and realise that a Radio
4 programme that gave info at this rate would stretch 5 mins of
content over an hour!

Indeed. It can be enlightening/depressing to look at the transcript of a
'Horizon' or similar programme. The information contained in a scheduled
50-60 minutes fits onto a couple of sides of A4. Worth it if the pictures
add information which can't be transcribed into words - but they usually
don't anymore :-( .

André Coutanche

In article , André Coutanche
wrote:
Jim Lesurf wrote:

snip

For me, the test for Horizon was to listen with the display off - so
making it into a radio programme. Did this mean I felt I was missing
info or relief that I was avoiding flashing lights trying to distract
me? The result was the tendency to be bored and realise that a Radio 4
programme that gave info at this rate would stretch 5 mins of content
over an hour!

Indeed. It can be enlightening/depressing to look at the transcript of a
'Horizon' or similar programme. The information contained in a
scheduled 50-60 minutes fits onto a couple of sides of A4. Worth it if
the pictures add information which can't be transcribed into words -
but they usually don't anymore :-( .

The last phrase is the frustrating point so far as I am concerned. For
presenting science and technology TV *should* have the advantage of

A) Letting you see who is speaking, thus making it easier for them to
communicate and enthuse.

B) Let you see what they are actually talking about

C) Diagrams and graphics (and even math) that can do "picture worth
thousand words" and convey loads of info.

Alas, whilst (A) may be catered for. In recent years (B) and (C) seem to be
displaced by 'graphics' that seem just to be aimed at distracting or
impressing the viewer with all the 'fancy camerawork'. The usual suspects -
wobbly-cam, over-saturation, wild zooms and pans and blurry shots of
distant car light.

The equivalent on on-science programmes seems to be 'presenter driving
along a road in their land-rover'. Perhaps with some playing and jumping
with the camera time-rate.

i.e. no real info. Just distractions and 'look how bored the cameraman
was'.

To set against this, some other programmes do much better. e.g. the recent
'Victorian Pharmacy' showing Mike Bullivant producing various chemicals,
etc. i.e. actually showing someone doing something.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
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Audio Misc http://www.audiomisc.co.uk/index.html

On 11 Aug, 09:58, Jim Lesurf wrote:

It refers to the 'inherent' behaviour of a length of the cable. Imagine a
*very* long length of cable. Now apply a voltage (potential difference)
between the wires at one end. This extracts some charge from one wire and
shoves it onto the other. (This is necessary for the wires to now have
different potentials.) This movement of charge, and the change in voltage
between the wires now 'ripples along the wires' at the speed of light.

The result is that a given applied voltage induces a current, and both
ripple out along the wires of the cable.

For any particular cable a given voltage will set up a specific amount of
current. The ratio gives you the 'characteristic impedance' of the cable.

If you now connect a load *with that resistance* at the other end of the
cable it will 'match' the cable. So when the voltage and current reach the
load, the voltage causes the load to demand the same amount of current as
now is flowing along the cable at the load. Result: All the conveyed energy
is 'eaten' by the load.

However if the load has the wrong impedance (i.e. not the same value as the
cable's) that won't work correctly. Some of the energy arriving at the load
'bounces' and is returned to the source. (In this case the antenna.) The
system then doesn't work properly.


Jim - thanks very much for that explanation, very helpful indeed!

Cheers,

David Paste

On Mon, 16 Aug 2010 16:08:05 +0100, Jim Lesurf
wrote:

The last phrase is the frustrating point so far as I am concerned. For
presenting science and technology TV *should* have the advantage of

A) Letting you see who is speaking, thus making it easier for them to
communicate and enthuse.

B) Let you see what they are actually talking about

C) Diagrams and graphics (and even math) that can do "picture worth
thousand words" and convey loads of info.

Alas, whilst (A) may be catered for. In recent years (B) and (C) seem to be
displaced by 'graphics' that seem just to be aimed at distracting or
impressing the viewer with all the 'fancy camerawork'. The usual suspects -
wobbly-cam, over-saturation, wild zooms and pans and blurry shots of
distant car light.

You forgot the explosions