TV recpetion - analogue

[Terry D]

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.

Terry D.

[Alan]

In message , Terry D wrote

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.

Indoor aerials are not usual regarded as a reliable means of collecting your TV signals :)

[Andy Hall]

For example, interference from dodgy lightbulbs.

[tony sayer]

In article , Terry D scribeth thus

Simple.. Their on different frequencies and chances are that what is known as multipath is happening this is where some signals take different paths to get to the aerial and sometimes they cancel out or add together.

[tony sayer]

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...

[Andy Champ]

x-posted to uk.tech.broadcast - Helpful lot. (Except they are about to prove me wrong on that...) I think you'll get asked where you are.

Andy

[Paul Martin]

It's caused by standing waves in the reflections from inside the house.

That's one reason why rooftop aerials are always preferred over set top aerials.

[The Natural Philosopher]

So you get better reflections from trees, power lines and aircraft.. ;-)

[Derek Geldard]

Sod's law innit.

DG