Butterworth filter and FFT filter

[MTINI]

1. I am developing my application by using filters. I would like to know what is the difference betwen Butterworh filter.VI and Butterworth filter PointBYPoint.vi and also the same quention for FFT filter.vi.

2. I call the Butterworth filter.vi directly and compare with one VI where somebody wrote the code by putting a formula in same vertion Labview. But the results are different for same testing input data? Why have this? I am sure the formula is correct.

Thanks.

[Aashish_M]

Hey Mtini,

For more information about point to point analysis please refer to Point-By-Point Analysis.

The Point By Point VIs are usually used to conveniently and efficiently process data a point at a time.

As part 2 of your question, you'll need to either provide some screen shots or the VI's itself.

Hopefully this helps!!

[Carvalho10]

Good afternoon. I wonder how to implement a low pass filter on my system. Which icon to use and where to put. Thank you.

[johnsold]

Please start a new thread rather than appending your question to a 5-year-old thread.

You will get more helpful answers if you provide specific information about your requirements: Frequency range of desired signal and any interferring signals, sampling rate, does the data come in continuously or in batches? What generates the signal? How many samples at a time? Specifications of the filter - type, cutoff frequency, passband ripple, stopband attenuation, and so on. What wil you be doing with the data after it is filtered?

Lynn

[Carvalho10]

I have a plate and Arduimu through this plate has data accelerations and angular velocities. So this board is engaged in a car, and the car will transmit noise to plate through vibrations. My goal is to reduce. My thought using low pass filter to cut high frequencies.

[HollyBerry]

The Filter ExpressVI can easily be configured for a low pass filter. Theres a link to the help documentation below. 

https://www.ni.com/docs/en-US/bundle/labview-api-ref/page/vi-lib/express/express-analysis/filterbloc...

[Carvalho10]

How can I put the icon of the low pass filter in my schedule below. Where do I fit in, for example on the block roll, pitch and yaw. So I view the graph with the input signal and then another graph with filtered signal.

[HollyBerry]

It looks like your datatype is double rather than array. The Filter Express VI is designed to accept an array of data. Therefore, you will need to use some sort of point by point filter. There is a great example on the example finder. Go to Help>>Find Examples. Then select Analyzing and Processing Signals>>Signal Processing>> PtByPt and Array Based Filter. 

[Carvalho10]

I'm trying to put this filter in my VI but not getting to. The error in Labview programming.

[HollyBerry]

Which filter did you use and how are you implementing it in your program? What error number and message are you receiving?