[opendtv] Re: Price comparison
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: "OpenDTV (E-mail)" <opendtv@xxxxxxxxxxxxx>
- Date: Sat, 8 Jan 2005 17:49:19 -0500
Doug McDonald wrote:
> =
http://www.stmicroelectronics.com/stonline/press/news/year2004/p1492p.htm=
>
> Indeed! Read this:
>
> " The STV0361 can manage signals containing such
> echoes by synchronizing up to 260 microseconds
> outside the guard interval. Doppler shifted signals,
> seen in mobile applications or where an echo is
> received from a moving object, are detected and
> processed in accordance with NorDig requirements,
> using adaptive channel correction in both time and
> frequency."
>
> Note tha phrase "time and frequency", and "260
> microseconds outside the guard interval".
>
> This just as I have been predicting: a convergence
> of methods from ATSC decoders into DVB-T ones.
I did notice that business about "outside the guard
interval," and the even more obvious reference to the
fact that they're incorporating a hefty equalizer in
their DVB-T design as well.
This means that in principle, barring the legacy
problems this would cause, DVB-T could rely more on
equalizers and less on guard intervals for robust
reception, which means they could tune transmitters
to the smallest 1/32 GI, and they could therefore
closely match the spectral efficiency of 8-VSB.
It would be interesting to see how the much slower
symbols in COFDM, but transmitted in extremely small
frequency bands, would affect the overall robustness
of a COFDM scheme which relies on equalization more
than GI.
> And yes, the price difference is very small ...
> expecially since it gains the receiver the
> equivalent of a 3 dB S/N advantage over COFDM.
This is another intriguing aspect of this
convergence in design. If the COFDM receivers use
8-VSB style equalizers, in principle the transmitters
could (barring the legacy) stop transmitting those
multiple usuppressed carrier which receivers now use
as pilots. Which would improve the C/N margin issue
and also bring COFDM and 8-VSB closer in performance.
How interesting.
Bert
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