CD/DAT Pre-emphasis filter

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2 total messages Started by Michael Knappe Fri, 09 Oct 1992 19:34

#1229

Author: Michael Knappe
Date: Fri, 09 Oct 1992 19:34

10 lines
748 bytes

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? 

Thanks,

Michael Knappe
Bell-Northern Research
Ottawa, Canada

Re: CD/DAT Pre-emphasis filter

#1249

Author: Tim Channon
Date: Sun, 11 Oct 1992 17:32

21 lines
1327 bytes

> 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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