[opendtv] Re: ATSC Mobile DTV
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Mon, 5 Jan 2009 18:37:10 -0500
> 7. So, let's compare this to DVB-T HM. We don't know the C/N margins,
> so the comparison is not very meaningful, but let's look at this
> anyway. If we take a 4.58 Mb/s chunk out of the 19.39 Mb/s main
> channel, it can provide as much as 1.58 Mb/s of 1/2 rate robust
> channel, or half that much for 1/4 rate.
>
> In DVB-T, 6 MHz channels, a 1/2 rate QPSK HM channel provides about
> the same robust bit rate capacity, with C/N margin in gaussian
> channels of 8.9 dB, if you want the rest of the channel to be used
> in 64-QAM mode, comparable to the M/H case.
Ooops.
In DVB-T, the robust channel *is* ~4.5 Mb/s, which is more than you can
achieve with M/H per Table 6.1. And that takes up roughly 7.8 Mb/s of
the main channel (using 2/3 rate at 64-QAM).
M/H would take a similar 7.3 Mb/s of the main channel to offer 2.5 Mb/s
of 1/2 rate robust channel, so now we really need to know the C/N margin
at 1/2 rate to see how this compares.
Bert
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