John Shutt wrote: > There is nothing that would prevent a chipset from making > a preliminary scan of the spectrum, note which channels > had a signal, even if it couldn't decode the bitstream, > and memorize those channels as a question mark or some such. My two boxes do something close to that. They scan and mark channels even if these aren't solid. Just detecting some kind of signal would give false positives, however, especially as long as we have NTSC out there. Or if white spaces are going to be used by other stuff. > Then the viewer would know that something was on those > frequencies, and could manually adjust the antenna for best > performance, allowing the chipset to then either decode the > VCT and add it to the active channel list, or let the viewer > erase that channel from the memory. The problem is really not so hard to deal with, if your receiver allows direct tuning to the *real* channel number. Before my first channel scan, I had downloaded a list of real channels used in our market. Then I did the auto-scan with each antenna. This maps the virtual channel in the box. Now you can go and see why the missing channels are not there. In some cases, I saw the signal trying to get past the threshold 15 dB C/N, and sometimes eventually making it. In other cases, the signal was way too weak. Examples back when were UPN and the local PBS affiliate. Both resolved themselves as they increased power or antenna height. If you're using an indoor antenna or antenna with rotor, it isn't so hard to try different orientations and see the effect on the signal monitor. BUT, you do need for the receiver to let you punch in the real channel number, because the virtual channel won't be mapped until you pick up that station. Both our STBs allow this. Other receivers might not. 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.