Frank Eory wrote: > C'mon Al, T/2 equalizers are as old as the hills. I studied them in college almost 2 decades ago and have built several in the intervening years. Not all 8-VSB receivers use symbol-spaced equalizers, as we discussed 5 years ago in the ATSC ad-hoc group. So naturally, not all of them have problems rejecting short-delay echoes. "Delay" never was and still is not a real "problem" for equalizers in ATSC receivers -- delay, aka equalizer tap spacing and total equalizer span, is just a matter of hardware... The T/2 tap spacing is old, but the methods previously used for adjusting the tap weights after data slicing (e.g. as described in Lee & Messerschmidt) under-sampled the "feedback" concerning tap weight adjustment. So, the performance advantages of T/2 equalizers over T equalizers, as measured for fixed tap weights, are not realized. The deficiency shows up with short-delay echoes. So, I believe USPAT 6,377,312 is instructive for most equalizer designers. Al Limberg --- [This E-mail scanned for viruses by Declude Virus] ---------------------------------------------------------------------- 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.