[opendtv] Re: Seeing Ghosts on a Single Frequency Network

  • From: "John Shutt" <shuttj@xxxxxxxxx>
  • To: "OpenDTV" <opendtv@xxxxxxxxxxxxx>
  • Date: Tue, 8 Feb 2011 21:09:49 -0500
----- Original Message ----- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx> 


Not sure why you would "checkerboard" two SFNs on two different
frequencies. You mean, for example, up and down the East Coast? Every
other city uses the same frequency SFN? That still means you're trying to
cover a market with the SFN. And in order to cover something that's not a
straight line, I think you need four frequencies, whether it's marketwide
SFNs or MFNs.



I was responding to your comment:
"Qualcomm needed to provide coverage over a very large area with just Ch 55. They had no choice but to use an SFN. But look at the complexity of their network, and look at the lack of coverage area, compared to what they could have done with a checkerboard of frequencies." 

You used the term checkerboard, not me, so what do YOU mean by
"checkerboard.?"

It seems to me that if you're going to tie up 12 MHz of bandwidth using a
checkerboard network, you may as well just use all 12 MHz in a synchronized
SFN, using long echo tolerant guard intervals, symbol rates, and forward
error correction, so that your net bit payload in the 12 MHz wide channel is
the same as you would get on any one 6 MHz channel in the checkerboard.

As a bonus, you make the signal more receivable even when well within the
city grade contour of the closest transmitter.

John




----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:
- Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org 
- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word 
unsubscribe in the subject line.

Other related posts:

  1. Home
  2. opendtv
  3. Archive
  4. 02-2011