[opendtv] Re: With CFP, Air Test, ATSC 3.0 Off And Running | TVNewsCheck.com

  • From: "Tom McMahon" <tlm@xxxxxxxxxx>
  • To: "OpenDTV" <opendtv@xxxxxxxxxxxxx>
  • Date: Sat, 30 Mar 2013 23:35:08 +0000

I cannot speak for DVB of course, but based on my experience as a DVB member, 
if there were a documented Commercial Requirement for an extension or 
corrigedum, and if there were DVB member support in order to extend the 
adoption of the DVB Standard into new markets, it could be done.
----

Tom McMahon
Del Rey
+1-310-717-7208 Mobile
TLM@xxxxxxxxxx
WWW.DelRey.Com
WWW.LinkedIn.Com/in/McMahonTV


-----Original Message-----
From: Albert Manfredi <albert.e.manfredi@xxxxxxxxxx>
Sender: opendtv-bounce@xxxxxxxxxxxxx
Date: Sat, 30 Mar 2013 19:15:13 
To: opendtv@xxxxxxxxxxxxx<opendtv@xxxxxxxxxxxxx>
Reply-To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: With CFP, Air Test, ATSC 3.0 Off And Running | 
TVNewsCheck.com

Allen Limberg wrote:

> One way to reduce PAPR is to use 128QAM and 512QAM with
> cruciform symbol constellations rather than 64QAM and
> 256QAM with square symbol constellations. The 128QAM and
> 512QAM can be used with single-time retransmission to get
> back AWGN performance. Single-time retransmission (used
> by DVB-T2 in their rotated constellation option)
> overcomes burst noise and long drop-outs in received
> signal strength. If circular FFT is rotated one half
> revolution as between two transmissions, deep selective
> fading is overcome, too.

Thought-provoking as always, Al. So as always, everything comes at a price. I 
looked up these cross constellations, and it seems that because you cannot 
achieve a case where each adjacent constellation point differs always by only 
one bit, from any given point on the constellation, as you can achieve with 
square constellations, this increases the bit error rate.

Got to do more digging into these trades. But it does appear like Mark Aitken 
can indeed fine-tune what DVB-T2 has standardized, to tweak the coverage.

Bert                                       
 
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