Article View: comp.dsp
Article #1249Re: CD/DAT Pre-emphasis filter
From: Tim Channon
Date: Sun, 11 Oct 1992 17:32
Date: Sun, 11 Oct 1992 17:32
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> Does anybody know the characteristics of the pre-emphasis (and
> corresponding de-emphasis) filter used in CD (de-emphasis only) and DAT
> players to improve the signal-to-noise ratio of low-level high-frequency
> source material?
>
50us/15us (two time constants)
Very roughly and on _replay_ flat 0..3k, roll off 3k..10k, back to flat 10k..
limit. The phase response is pure analog so good luck.
The other possible standard applies to professional signals and is CCITT J17.
Rare but is used by NICAM.
The CD recommendation is _no_ emphasis.
Various cheap systems which can record jam emphasis on. This must be because
of the poor noise performance of the analog circuits prior to the A/D.
TC.
E-mail: tchannon@black.demon.co.uk or tchannon@cix.compulink.co.uk
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Path: arc1-ca.pugleaf.net!sparky!uunet!olivea!spool.mu.edu!agate!doc.ic.ac.uk!uknet!pavo.csi.cam.ac.uk!pipex!demon!black.demon.co.uk!tchannon From: tchannon@black.demon.co.uk (Tim Channon) Newsgroups: comp.dsp Subject: Re: CD/DAT Pre-emphasis filter Message-ID: <718849930snx@black.demon.co.uk> Date: 11 Oct 92 17:32:10 GMT References: <1992Oct9.193422.28914@bnr.ca> Sender: usenet@gate.demon.co.uk Organization: null Lines: 20 ReplyTo: tchannon@black.demon.co.uk X-Mailer: cppnews $Revision: 1.18 $