[mythtv-users] vga2scart interlacing on UK Channel 4

Andy Burns fedora at adslpipe.co.uk
Mon May 21 14:10:30 UTC 2007


On 21/05/2007 12:24, Mike Perkins wrote:


> Been following the above thread with interest. Am in the UK, but have 
> seen none of the above effects. Yes, my setup's not perfect, but I don't 
> have problems on certain muxes such as are described.
> 
> Couple of thoughts. First, is this problem restricted to one or a small 
> number of transmitters? It may be that the particular multiplex has less 
> signal strength/more channels crammed in/other engineering reason.

MUX-A is certainly a bit cramped, most streams in it are compressed to
an inch of their lives, it is also on 64QAM, but then so it MUX-2 and i
don't have problems with that, it is often transmitted at lower power
from a given transmitter than other muxes.

> Second, if the problem is not area-sensitive, are the affected users 
> using good quality digital-certified aerials? Some of the older designs 
> were tailored to the specific analog channels assigned to the selected 
> transmitter, which is why channel5(analog) reception can be so bad 
> (nearest available slot for it was out of band for the aerial to 
> handle). These older aerials may not be suitable for digital viewing 
> under all conditions.

My aerial is a new log-periodic, which is wideband, with flat frequency
response across the whole TV band, if anything I get lower BER on MUX-A
than on MUX-1

> Thirdly, any vegetation in the way between you and the mast? I have a 
> band of trees behind my house between me and Hannington. I have noticed 
> that the signal strength has gone down as the leaves have come out - 
> still acceptable, but we get a few more artifacts now (the bloody 
> woodpigeons jumping up and down on the aerial don't help, either!). May 
> explain why this has arisen recently and did not happen previously.

No trees, but this doesn't seem like a signal issue, some content of
that mux is upsetting the backend.





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