CIC Interpolator block

Andy Luotto — Mon, 17 Dec 2007 14:05:54 -0500

Hi there
I am using the CIC Interpolator block (simulink) and it does not
appear to increase the sample rate at all. I am using this block to
feed a delta sigma digital DAC but I cannot make it working (a symptom
is that I cannot see any colour difference between input and output,
which should be expected if the block would increase the sample rate)
did anybody find this problem already?

thanks

Re: CIC Interpolator block

Andy Luotto — Mon, 17 Dec 2007 14:13:47 -0500

I am trying *both* passing the handler to the filter
Hcic = mfilt.cicinterpzerolat(Q,1,nr_stages, 16, 24);
and setting the paramenter manually, directly into the block

thanks

Re: CIC Interpolator block

Steve Conahan — Mon, 17 Dec 2007 18:08:36 -0500

"Andy Luotto" <andyluotto@excite.com> wrote in message
news:74183005-3d3d-4ea8-b1eb-6c5fc6d69be9@d4g2000prg.googlegroups.com...
> Hi there
> I am using the CIC Interpolator block (simulink) and it does not
> appear to increase the sample rate at all. I am using this block to
> feed a delta sigma digital DAC but I cannot make it working (a symptom
> is that I cannot see any colour difference between input and output,
> which should be expected if the block would increase the sample rate)
> did anybody find this problem already?
>
> thanks
>
"Andy Luotto" <andyluotto@excite.com> wrote in message
news:3b92d251-7762-4136-a673-7ce4de0d8572@d21g2000prf.googlegroups.com...
>I am trying *both* passing the handler to the filter
> Hcic = mfilt.cicinterpzerolat(Q,1,nr_stages, 16, 24);
> and setting the paramenter manually, directly into the block
>
> thanks
>

Hi Andy,

In the CIC Interpolation block dialog there is a parameter called "Framing"
that controls the behavior of the dimensions and sample times of the block
I/O ports as detailed below (the quoted text is from the documentation
reference page). Try changing the "Framing" parameter choice and see if you
get the expected (faster) output port sample time change instead of an
adjustment of the output port frame length.

http://www.mathworks.com/access/helpdesk/help/toolbox/dspblks/ref/cicinterpolation.html

"For frame-based operation, specify the method by which to implement the
interpolation; reduce the output frame rate, or reduce the output frame
size. This parameter cannot be set to Maintain input frame rate for
sample-based signals."

Cheers,
Steve Conahan
The MathWorks, Inc.

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