On Thu, 26 Jul 2007 23:31:48 GMT, "Arfa Daily"
wrote:

It's all very well saying that compression artifacts are a product of
available bandwidth, but that bandwidth is much limited with terrestrial
digital,


Both terrestrial broadcast, as well as satellite uplinks are 6MHz wide
STANDARD channel slots and transponder slots. That was one of the rules
of the game back when all this started.

So, on "terrestrial", one can expect the best picture, as it is "single
channel per carrier" (SCPC), whereas a satellite uplink from a service
provider is going to be a "multiple channel per carrier" (MCPC)
implementation, in 99.9999% of the cases.

Artifacts are a product of bit error rate. If the bit error rate of
your reception in zero, you WILL get ALL of the data.

The other source of artifacts are pre transmission compression.

In the old MCPC setup, only 6 or 10 channels per carrier could be
pumped, and it was an MPEG-2 compression schema and a 480i schema.

Now, they put up to 12 channels per carrier (per transponder) into the
uplink for 24 or 64 channels per transponder total.

With HDTV, much more data per frame needs to be dealt with. FEC is
your friend.