HOW TO PLOT FILTER CHARACTERISTIC CURVES

[fenny]

I  need to compare the curves of different order of filters, how can i plot out the filters curves in LV?

I 'm thinking allow a constant array pass through the filters and i would get the filter curve, but i got weird result. say, when i set it to be low pass,

the outcome looked like high pass curve.

[devchander]

could you give more info?

like the filter you are using , a sample of data you want to filter and also attach the VI you are using and a snapshot of what curve you are getting.

regards

Dev

[fenny]

I 'm writing thesis, I need to show the chracteristic response  curves of different filters( like Butterworth, Chebychev), just to show the difference!

I don't want really filter some data, and I don't want to plot the filter response curves from mathematic equations

that's what I mean.

attached is waht I tried, but the curves come out looking weird!

[Dennis_Knutson]

You're doing a thesis on how a filter responds to DC? That's the signal you're inputing to the filter functions.

[devchander]

Generate a signal using any function generation VI's present in Labview and feed it to filter by selecting suitable filter settings.

Basic function generator.VI should do the job.

regards

Dev

[LittleQ]

What you are doing is using the filter to process a step signal u(t), then the result is the step response, which is the time-domain characteristics of a filter.

According to what you have said, you want to plot the frequency response of a filter since you are expecting a highpass curve.

The frequency response of a filter is the frequency domain characteristics of a filter. You can get it through filtering a impulse signal which has a flat spectrum and then computing the filtered-signal's spectrum.

Attach a simple VI to illustrate it.