[opendtv] Re: ITV calling for temporary spectrum for transition to HDTV

Craig Birkmaier wrote:

> My guess is that they would use the new multiplex to develop
> an HDTV service using higher power and more advanced modulation
> techniques to increase the total bit rate for the multiplex.

Agreed. The multiplexes they have now are good for 15.6 Mb/s or so. If
they go to 64-QAM, they will be able to increase that to 22 Mb/s,
assuming they want to go with the SFN idea (still 2/3 FEC, but reducing
the GI to 1/8).

> Then, when enough people had purchased upgraded receivers they
> would convert the other four multiplexes and give back the
> loaner. With the higher bitrate in each multiplex they would
> then be able to offer a mix of SDTV and HDTV channels.

Agreed.

They seem to offer typically 4 or 5 program streams per multiplex now,
maybe occasionally 6. So if they went up to 64-QAM, kept the SD channels
as MPEG-2 compression, and avoided simulcasting, they could set aside
about 11 Mb/s for one HDTV program in each multiplex. Or they could
apply H.264 to all their programs, and get a few more b/s for the HD
channel. Maybe enough for two HD channels per multiplex.

Bert
 
 
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