Why is ITV, Ch4 and Five etc such a poor signal

[craig3000]

It's really frustrating me, I have a TV adapter on my PC with the coaxial cables going through a surge protector. BBC is also strong no matter what however if I move the cable ITV, CH4 + 5 etc are always v.sensitive.

The cable is only single shielded from what I can tell, I had it working fine but had to move the cables, I shortened one of them thinking it would improve due to shorter length and therefore less crap to interfere with BUT just made it worse .

The cables where they are now are not only short 50cm combined but there not near any plugs or cables so as far as I'm concerned there is no interference, ariel on roof is fine, other tv's work.

Would a double shielded cable even make a difference.

 

[craig3000]

I've ordered 2x Belkin Pro Dual shielded cables, (need to because using a surge protector in between), at the moment of I only got a braided cable so braid + foil should help significantly also the aerial ends will have been factory made rather than me fiddling with them I suppose, fingers crossed was only £3.28 including delivery.

I just find it strange how even though I know for a fact it's the cable, BBC will work 100% whereas the others won't.