What you are seeing is one of the two problems that are well know about the "MPEG-2" system that is used to encode digital TV.
Because of the way the system works, horizontal movement across a crowd requires a disproportionate large amount of data to encode.
Because the bandwidth on Freeview is so limited, and as most broadcasters have decided to have more channels rather than better quality pictures, on most channels the bandwidth is so limited that the effect you see, a blurry mass of blocks is visible.
The sceptical will say that this is simply an excuse to sell you HDTV equipment and channel packages.
The other problem you will see is when strobe effects are used - this will often look like very large black and white boxes.
If these effects trouble you, do not go out and buy yourself a massive TV as they will be simply much clearer to you.
I have a 32 element digital TV aerial fitted on a mast on the roof. On normal digital channels (NON-HD) the picture is fine, but as soon as I try and watch in HD I get "blocking" on the picture, which at times makes watching in HD impossible. Do you have to have a special kind of aerial to watch Freeview HD? - and if so what is it. We use the Sandy heathtransmitter.
Rex Eady: No, and aerial is an aerial. It isn't specifically designed for receiving analogue, digital, high definition or whatever, but it is the frequency of the signals in question which dictate its design.
If this has only started to happen recently then be aware that there are engineering works going on at Sandy Heath.
For BBC One HD check that you are tuned to Sandy Heath on UHF channel 21 (474MHz). Observe the strength and quality when it's good and when it's not so good.
I am at NG228FE. HD channel 58 from Waltham has all but dissapeared It has been reliable since it started but now the signal condition quality is just above zero. Certainly can't use the programme guide to effect a recording as it is likely that it will result in a blank screen. Have tried a manual retuned but to no avail.
Is it the weather ?
Strange that the Orange mobile phone signal has weakened too.
Hi,re comments on blocking,this isnt what you're led to believe,This is delibrate noise added to persuade
you to purchase the high end stuff,its called Expander noise,used in vhs videos for copying reasons,what
happens is a diode connected to the power lines creates noise which can be modified by the manufacter,to
create what they want.So when you watch football,you see like a ghost trailing behind.