Craig Birkmaier wrote: > I don't think we are talking about systems that use a dense > mesh like cellular telephony. The synchronized main > transmitters will do the major portion of the work, using a > fraction of the power now assigned for ATSC transmission. I'm glad that Ian spoke up, to put things in perspective. And it's interesting to see that Craig can agree with Ian and yet disagree with me. There must be something either in what Ian described, or in what I've been describing, that isn't getting across. The dense mesh of towers would be required to create the sharp contour you keep advocating. Of course, if you give up on that idea, then everything becomes more reasonable. To create the sharp contour, you need lots of low power sticks at the edges. And it is specifically at the edges of the coverage area that your small sticks are the most problematic, *if* they are on the same channel as the main transmitter. So the idea of using small sticks to create your fine contour is exactly what won't work well. The practical reality of lowering the power of the big stick and then expecting small sticks at the edge to provide service to the market area fringes is that you'll have to resort of translators. Otherwise, even with the best of SFNs, you'll create areas of very bad reception. This is even with synchronization. The reason is the large distance between towers and the variability of signal propagation caused by all manner of factors, including terrain and weather. You'd just be asking for persistent coverage problems, especially toward the fringe. Of course, using on-channel gap fillers within the coverage pattern of the big stick will be easier to implement. And for 8-VSB, the lower the power of the gap fillers the better, as the CRC demoed in Ottawa back in 2003. > The on-channel repeater infrastructure will be unique to each > market based on topography, terrain blocking, and location of > pockets of population. Even here, we are probably talking > about "tens" not "hundreds" or"thousands" of repeaters. That's a completely different matter. Filling in where there are holes in coverage is an obvious application of OCRs, but has nothing to do with creating the sharp contours you advocate. Bert ---------------------------------------------------------------------- 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.