[opendtv] A-VSB results

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Wed, 8 Nov 2006 12:38:55 -0500

Thanks for posting the presentation slides, Craig.


My take-away on the performance improvements achieved is that use of a
diversity antenna is very beneficial, especially so for mobile
environments. Also, turbo codes make use of the supplemental training
sequences (SRS) unnecessary unless you're really wanting to move fast.
Meaning, just use one or the other technique, not both together, unless
you need reception at speeds at or above 176 mph, or unless you want to
increase spectral efficiency at such speeds.

Use of SRS reduces the total payload by less than using turbo codes, and
the SRS technique is backward compatible. Which means, legacy receivers
will work, at reduced bit rate, even though they won't be made more
robust. However, I think the message is that the turbo code method (STS)
is more effective at lowering C/N margins. But I didn't see numbers for
the SRS technique by itself.

Also, I don't know if this buys much, but using the 4-symbol Data
Segment Sync exactly the same way as the SRS, for improved training in
rapidly shifting echo, should buy the equivalent of at least 1/2 byte's
worth of SRS, no? And perhaps more, given that these are 2-VSB symbols?

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