Tom Barry wrote: > I know little about SFN's. Are they supposed to also work from > a long distance away? Depends. Take the Berlin example. Two towers (three for a few of the channels) in a cluster, all within the GI. At long distance, they will generally appear as one single tower whose ERP is more or less the sum of the three. Actually, more "less" than "more." Those small area SFNs I believe are fairly safe. Because no receiver should ever see symbols coming from outside the GI, except perhaps in cases of unfortunate and loud echoes. Meaning, you use up the GI to accommodate the different towers, and now you add in a loud echo. Too bad! Paris has the "umbrella" configuration. One big stick, and three additional small sticks, all within the GI. In that case, a long distance away, the small sticks are inconsequential. But inside the SFN, reception may be easier. If you want to extend the SFN to a wide area, then you will create problems for receivers a good distance away from the forest of towers. The reason being, the receiver will almost certainly detect the signal from towers that are farther apart than the GI, at least some of the time, and this will vary with terrain, weather conditions etc. In a sense, Mark Schubin's reception conditions are very much like those of a SFN. A good receiver at that location will make use of all the various reflections just the same as if they had been separate small sticks. And he has no direct path to any transmitter, as far as I know. I think SFNs have always been hyped up way too much. And mostly because of vague descriptions. The devil is in the details. 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.