[opendtv] Re: Kennard and Powell to the rescue
- From: "Bob Miller" <robmxa@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Mon, 12 Jan 2009 12:44:38 -0500
Within one year of the transition broadcasters themselves will be
asking for a better modulation.
Bob Miller
On Mon, Jan 12, 2009 at 10:14 AM, Manfredi, Albert E
<albert.e.manfredi@xxxxxxxxxx> wrote:
> Tom Barry wrote:
>
>> To me it seems equally likely because of 8vsb multipath that
>> you will need 1/4 rate FEC instead of 1/2 rate. And that more
>> or less delivers only half the usable payload, pretty much
>> eliminating even mobile AVC video if you started with only 1
>> mbps out of an ATSC stream.
>
> It would be nice to have the C/N margin requirements for the different
> modes spelled out in A/153, however I would like to point out that some
> applications of M/H could have more to do with compensating for lower
> transmit power than more multipath, depending how it gets put to use.
>
> John Shutt complained years ago that there's no way for a broadcaster to
> reach its audience when it needs to cut its power for maintenance
> reasons. This could be a way, and 1/2 rate would likely be just fine for
> this application.
>
> Anyway, Part 2, Table 6.1, says that if you want 1/4 rate for the entire
> robust stream, you need to take 1.8 Mb/s of the 19.39 Mb/s in order to
> provide one 312 Kb/s robust channel. That's still not unreasonable.
>
> Or, if you insist on taking 0.917 Mb/s only from the 19.39 Mb/s, 154.6
> Mb/s of 1/4 rate robust stream. That's probably not good for anything
> but small screens.
>
> Bert
>
>
> ----------------------------------------------------------------------
> You can UNSUBSCRIBE from the OpenDTV list in two ways:
>
> - Using the UNSUBSCRIBE command in your user configuration settings at
> FreeLists.org
>
> - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
> unsubscribe in the subject line.
>
>
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:
- Using the UNSUBSCRIBE command in your user configuration settings at
FreeLists.org
- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
unsubscribe in the subject line.
Other related posts: