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how to design digital filter without addon tool kit

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Hi,

I want to design a bandpass filter. Original signal is in analog form,ADC is used to convert input into digital data n vice versa at the output end. How to do it in labview 8.5 without addon tool kit. secondly how to check the response of filter according to this digital data,because by default it gives IMPULSE response,so how its going to deal with digital data...

Thanks !! 

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For a bandpass filter you may cascade a lowpass and highpass filter. See this paged http://en.wikipedia.org/wiki/Digital_filter. Also do a search for digital filters on www.ni.com. For the paged filter response , just take the Fourier transform of the digital filter impulse response. See picture. 

By the way If you ask nice I may send you some 'feed-backward' coefficients and  'feed-forward' coefficients. Since they are calculated in labview

Message Edited by t06afre on 03-04-2009 02:16 PM


Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
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Hi,

Thanks for the valueable info. It really helped me. I have couple of doubts like, how to get a gain of 80 db with the bandpass filter also how can i give analog signal(sound wave) as an input to this filter.

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A 80 dB gain-> 80=20*log(output signal/input signal) Just do a multiplication after the filter function. Digital filter use an array as input. And for the sound wave you may use a sound card.


Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)
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hi,

thanks..it seems that doubts r never ending,n now the latest one is, by default we can check the impulse rsponse of a filter,but if i wish to give continuous digital data,how this can be done? 

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Solution
Accepted by topic author digu
In the impulse response 1 sample is greater than zero, the rest is zero. For the step response the values are zero before the step, and non zero after the step. To do this just make an array with the signal you want to use. But the array must be long enough to want cover your analysis in time domain. As an example. I am now working with digital phase sensitive detector. For this I am using a 20KHz sample rate, one the last stages is a 3 Hz 20 order lowpass filter. To test the step response of this filter I needed at least 12 seconds of data. So the array containing the data was holding  20000*12 samples


Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)
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hi..

Thanks alot fr ur help...Now the doubts r clear..till i find new ones,have a nice time !!

thanks once again. 

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Please mark which post of t06afre helps you as solution rather than marking your own post. Hope you understand.

 

Thanks,

Mathan

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