>digital comb filter Basically it's a video speed ADC, asic or dsp implementing the filter, followed by a DAC (or three - usually all the processing is done in digital after that, followed by a RGB treble DAC driving the CRT guns almost directly). Peter -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body