how to use mat-lab to filter the input data

Could I ask how to filter my 'input data'? I undertook my experimental work a few days ago. The data were put in the .txt. They are actual time signals. I don't know how to put these signals into the load pass filter? and how to compute the FFT of the signal and FRF of the signal? I am new to Matlab. I would be really grateful if someone can help me.

[Star Strider]

Start here:

1. fft
2. Practical Introduction to Digital Filtering

Answer 1

[Jan]

See:

• doc filter
• doc filtfilt
• doc butter (for a Butterworth filter)
• doc fft

The documentation of Matlab is excellent and really helpful. Start to read here. To choose a matching lowpass filter, an analysis of the noise is useful, because there is an infinite set of different low pass filters. Choosing filter parameters requires to know, what you consider as signal and what as noise.