"Cross connect" integrators?
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"Cross connect" integrators?

 
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Mark Todd
Guest
Posted: Sat Feb 05, 2005 9:42 pm    Post subject: "Cross connect" integrators? Reply with quote
I have a set of instructions for producing a device which includes the
following line:

"This low level signal (white noise) is fed through two
cross-connected integration stages (op-amp integrators) producing a
low frequency chaotic modulation signal."

Can anyone tell me how this "cross connection" is wired. My best guess
is to wire the output of each integrator to the input of the other
with their inverting inputs and outputs tied together.

It seems to be a strategy to derive second order modulation that does
not result in feedback. Why it produces a "low frequency" component
from white noise I do not understand.

I have never seen this done before, and the designer is no longer
contactable.

Any opinions on how and why this works would be most welcome.

Mark

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Tim Shoppa
Guest
Posted: Sat Feb 05, 2005 9:42 pm    Post subject: Re: "Cross connect" integrators? Reply with quote
Quote:
Can anyone tell me how this "cross connection" is wired.

Not from this distance. But a similar, easily mathematiically
described chaotic system (the Lorenz equation) is done with three
integrators at

http://frank.harvard.edu/~paulh/misc/lorenz.htm

In general to get chaoticity you need nonlinear terms.

Quote:
Why it produces a "low frequency" component
from white noise I do not understand.

Integration generally smooths things out... in the most general case an
RC integrator is also a low-pass filter.

Your description has words that are related to reality but without a
schematic I don't think you'll get anything definite.

Tim.
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Larry Brasfield
Guest
Posted: Sat Feb 05, 2005 9:42 pm    Post subject: Re: "Cross connect" integrators? Reply with quote
"Mark Todd" <marktodd@levin.com> wrote in message
news:j09a01du1nl23h6h7pov0cs1iccrvcsk7e@4ax.com...
Quote:
I have a set of instructions for producing a device which includes the
following line:

"This low level signal (white noise) is fed through two
cross-connected integration stages (op-amp integrators) producing a
low frequency chaotic modulation signal."

Can anyone tell me how this "cross connection" is wired. My best guess
is to wire the output of each integrator to the input of the other
with their inverting inputs and outputs tied together.

The outputs need not be tied together for them to be
"cross connected". But that term is not properly used
to denote a situation other than each output somehow
connected to the other's input.

Quote:
It seems to be a strategy to derive second order modulation that does
not result in feedback. Why it produces a "low frequency" component
from white noise I do not understand.

The integrators are likely creating a low-pass filter.

Quote:
I have never seen this done before, and the designer is no longer
contactable.

If you look for "state variable filters", (or "state variable active filters"),
you will see cross-connected integrators. For an example, see
http://www.maxim-ic.com/appnotes.cfm/appnote_number/1762
at about mid-page.

Quote:
Any opinions on how and why this works would be most welcome.

That would be more of a treatise than I'm good for at the moment.

Quote:
Mark
--

--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

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