In article 4740a423@qaanaaq, Andy Hall scribeth
thus
On 2007-11-18 19:42:18 +0000, Alan said:

In message , Terry D
wrote
Sorry if this is an inappropriate group for my posting, but I know there are
some very knowledgeable people out there.

I have an 8" LCD Evesham TV (analogue signal), which I watch at my desk
whilst working on my computer. The TV works fine with a small set-top
aerial (normally blu-tacked to the top of one of my printers!). However,
when I want to watch channel 4, I have to move the aerial down by about one
foot so I can achieve decent reception - all other channels are fine. Why
should this be? It doesn't really worry me (except when I want to watch
Countdown) but is there a technical explanation for this? The TV on the
ground floor of my house.


With analogue each of the channels are on a different frequency.
Obstructions within the room can affect these frequencies in different
ways. If you have any electronic equipment operating close to the
aerial the interference can swamp the signal you want.

For example, interference from dodgy lightbulbs.



There have been odd instances of fluorescent lighting affecting signals
in the 400 odd MHz area but very unlikely in this instance, more a
problem with multipath with indoor aerials...
--
Tony Sayer