[opendtv] Re: News: Single-frequency network proposed for over-the-air transmission in New York City
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Wed, 5 Sep 2007 16:14:05 -0400
Al Limberg wrote:
> Mark's point is well made. The deterministic trellis reset
> (DTR) tool in the A-VSB kit is what is needed to run an SFN in
> 8VSB.
Yes, he made a good point. If all that's needed is the DTR, then
existing receivers should be compatible *and* there will be no loss of
spectral efficiency. Which would be quite an accomplishment for
implementing SFNs, which otherwise usually involve increasing GI and FEC
compared with single-stick configurations.
Maybe we'll see that practical 8-VSB SFNs do mandate tower
synchronization, as opposed to using passive techniques more easily
accomplished with COFDM (where you can simply increase the GI to get the
required echo tolerance, and forego active synchronization). But en
revanche, as the French say, you get to retain spectral efficiency in
the process.
Hmmm. All reminiscent of past discussions on this topic, in pre-A-VSB
times.
Bert
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