[BC] FM Stereo invention

[Cornelius Gould]

Willie..

Yes..and it is the reconstruction filter that does the "holding" that you
describe.  The switching decoder at the receive end will have to have a
lowpass filter in there somewhere (and it is usually in the form of the
de-emphasis circuit).

-C

On 2/19/07, WFIFeng at aol.com <WFIFeng at aol.com> wrote:
>
> In a message dated 02/19/2007 2:34:02 PM Eastern Standard Time,
> padrino at telos-systems.com writes:
>
> > What you're talking about is a simple sampling method. Not much
> different
> >  that what an A/D converter is doing at a base sampling rate. The theory
> is
> >  the same.
> >
> >  -Frank Foti
>
> Not exactly, tho... in a true sampling environment, the signal level is
> *held* until the next sample comes along. With the chopped 50/50 mpx, you
> have
> alternating levels. With a stereo signal with a large variation between
> channels,
> you'd have the level switching back and forth with a nearly 50% duty
> cycle.
> If, let's say, the L channel was silent, then you'd have the R being
> chopped
> on/off at that 50% duty cycle. It could be somewhat restored by a
> sample-and-hold
> ckt in the receiver, but that's starting to get more complex than
> practical.
> A low-pass filter would only tend to make the chopping less pronounced,
> but it
> would still be there. Making the filter too aggressive would sharply
> attenuate the highs.
>
> BTW, all- I'm just musing on this, I'm not really working on any projects,
> studies, debates, or anything like that. I do appreciate the discussion!
> It's
> very interesting! :)
>
> Willie...
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- Cornelius Gould
________________________________
"The significant problems we face cannot be solved at the same level of
thinking we were at when we created them."
- Albert Einstein (1879-1955)