Craig Birkmaier wrote: > The coverage criteria was based on the same old > story - market-into-market interference. It had > almost nothing to do with equaling NTSC coverage, > other than the reality that you still have to > protect for interference into neighboring markets. Correct. Which means, it had a lot to do with coverage, and the constraints are the usual ones: preventing interference between adjacent markets. As always, context matters. So let's ask "as opposed to what?" If there are no clearly defined "guard zones" between markets, where no signal is required, then this interference issue will *always* emerge. Even with small sticks in SFNs. There are no dead zones between markets up and down the East Coast, for example. Less sparsely populated areas, sure. But they all belong to at least one market, if not two markets. It would be possible to create coverage, with some amount of realism, with smaller, lower power sticks, spread reasonably far apart. This requires synchronization between towers (that no COFDM country has adopted as a solution yet). But okay, let's postulate such a scheme. It can be done here as well as anywhere. If you want to avoid dead zones, as we must here, then adjacent markets won't be able to share frequencies. Even with the small stick approach. But the next market over can use those frequencies, *same as now*. An example might be Balt/Wash, Philadelphia, NYC. Baltimore and Washington overlap, and must do so. Many communities belong to both markets. The area between the Balt/Wash and Phila markets must also be covered completely. No justification for creating dead zones. Whether you deploy big or small sticks, this means that you can't use the same frequencies in Balt/Wash and Philadelphia. And many of those communities would belong to both Baltimore and Phildelphia markets anyway, legitimately, which further makes the point. So the question is, can the next major market over, NYC, use the same frequencies as Balt/Wash? NYC and Baltimore (and DC) use the same VHF frequencies (Channels 2, 4, 5, 7, 11). VHF being worst case, this shows that if you want to create continuous coverage, big sticks and smaller sticks don't make a huge difference in terms of frequency planning. It's coverage area without dead zones that creates the problem. We have big markets to cover here, and no wilderness areas between them. I'll agree that a more sharply defined coverage contour can reduce interference further away from the boundary zones between adjacent markets, But where it really *matters*, there is not a big difference. And the frequency plans would not be dramatically different. And *certainly* not if you stick to your idea of three or four towers only, per major market. That design wouldn't even create a particularly sharp contour. 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.