nolra@ux1.lbl.gov (Arlon Hunt) (02/14/89)
**************************************************************** To keep on friendly terms with the other users of this account, PLEASE SEND E-MAIL TO: noring%solgel.hepnet@lbl.gov NOT to the address where this posting originated from. Thankyou. **************************************************************** Does anybody out there in the land of Usenetia know anything about the use of a computer to digitally restore (that is, remove surface noise and enhance the sound) from 78 rpm recordings (my interest is in the jazz recordings of the 1920's and 30's, just so you know.) I know that many of the better 78 recordings of the 1920's and 30's have useful information out to 15 kHz, therefore good old analog filtering, which is the standard noise reduction technique, effectively removes this high frequency information, which is not desired. Thus the interest in computer restoration. Thanks, Jon Noring, LBL
macleod@drivax.DRI (MacLeod) (02/15/89)
Phase Linear had (has?) a technique where the system looks for energy above some figure - say 14 kHz - and assumes that it is a second harmonic of something. If it doesn't find energy at 7 kHz, it flushes the 14 kHz signal. You could work this in reverse to add harmonics to heavily-filtered input. Phase Linear was doing all this, as far as I know, with analog circuits. It should be a lot easier to do digitally, and a lot cleaner as well.
rusty@hodge.UUCP ( System Manager) (02/23/89)
In article <4284@drivax.DRI>, macleod@drivax.DRI (MacLeod) writes: > Phase Linear had (has?) a technique where the system looks for energy above > some figure - say 14 kHz - and assumes that it is a second harmonic of > something. If it doesn't find energy at 7 kHz, it flushes the 14 kHz signal. > You could work this in reverse to add harmonics to heavily-filtered input. Are you thinking of the 'Autocorelator' that they used to sell? It was also (mailnly) a multi-spectral noise gate (4 or 5 band, I believe). If so, note that Carver includes this same thing in some of their pre-amps. (Bob Carver *was* Phase Linear long ago). -- Rusty "No Bugs" Hodge, 1588 N. Batavia St. Orange, CA 92667 Tel (714) 974-6300 rusty@hodge.cts.com [uunet zardoz vdelta crash]!hodge!rusty FAX (714) 921-8038