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Newbie noamchomsky
Newbie
3,904 Views
Registered: ‎03-06-2009

Crazy CIC Decimator Output

I am using CIC decimator from system generator. First, I developed a model in a separate file and tested it for different input data. Then i moved this model to a different file and a bigger model of complete transmitter and receiver, with almost the same input, the output of CIC decimator is not good. Instead of decimating and producing the same output as input (with of course less no. of samples), it is giving an output with very large negative values only. Please guide how can i correct this. The output of first case and second case are attached. The configuration of CIC decimator is as follows.

 

Stages: 5

Group Delay: 1

Decimator Ratio: 25

Input Q Format: 14.13

Output Q Format: 34.9

 

The snapshots' description is as follows.

 

case1.jpg: good one

case2.jpg: ugly one

 

What possibly can be the problem. Please guide.

 

Best Regards,

 

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Newbie cdramuneer
Newbie
3,654 Views
Registered: ‎03-21-2009

Re: Crazy CIC Decimator Output

Hi

 

You should use FFT Spectrum scope to better visualise decimation of ur input if it comes right over there then you are done decimation is not always clear in Time domain(in scope)

 

Best of Luck

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