[opendtv] Re: PAL
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Fri, 15 Dec 2006 17:07:14 -0500
Al Limberg wrote:
> Interestingly, the Chinese also seem to have been oblivious
> to the power of repetitive PN sequences to generate channel
> impulse response using a simple PN match filter. So, their
> LG coaches may well be in the dark on the subject.
The Chinese, in two of three training sequence options, seem to use a
partial repetition of the PN sequence. In one case, a 255 symbol
sequence, and in the other, a 511 symbol sequence, like the one in ATSC.
"PN420 and PN945 are made up of a complete M-sequence of length 255 and
length 511, respectively and with their respective cyclical extensions
as pre-ambles and post-ambles, while PN595 is made up of the first 595
symbols of an M-sequence of length 1023 and it has no cyclical
characteristic."
I'm not sure how this might be done, but if these extensions help,
couldn't we repurpose the three unused (as far as I know) PN63 sequences
now in the ATSC training segment? Would it help to create an extension
to the PN511 sequence?
Bert
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