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Path: utzoo!linus!decvax!tektronix!orca!hammer!seifert
From: seifert@hammer.UUCP (Snoopy)
Newsgroups: net.video,net.analog
Subject: Re: MTS stereo decoder
Message-ID: <1811@hammer.UUCP>
Date: Wed, 12-Feb-86 12:48:33 EST
Article-I.D.: hammer.1811
Posted: Wed Feb 12 12:48:33 1986
Date-Received: Fri, 14-Feb-86 07:25:30 EST
References: <218@catnip.UUCP> <503@tekcbi.UUCP>
Reply-To: tekecs!doghouse.TEK!snoopy (Snoopy)
Organization: The Daisy Hill Puppy Farm
Lines: 23
Xref: linus net.video:2023 net.analog:682

Looking at the skiz in RE, there appears to be no place to put in
the proper dbx expansion.  Also, the 75us deemphases is applied
to the L and R outputs, not the L+R signal.

It appears that one might be able to leave off the 75us RCs,
regenerate the L+R and L-R signal, apply the 75us deemphases
to the R+L, apply the dbx expansion to the L-R, and then
get the L and R signals back again.  But this method would
involve a lot of extra and unnecessary processing.

Questions:  Is there a reasonable way to get at the L+R and L-R
signals?  (Presumably using a different chip)

What exactly does the dbx expansion involve?  Is it a straight
linear expansion?  What ratio?  Any deemphases required?

Also, audiophiles will want to upgrade the parts used.

Gee, if a software hacker like me can find all this wrong with their
design, I hate to think what a good analog person could find!

Snoopy
tektronix!tekecs!doghouse.TEK!snoopy