The Neurophysiological Biomarker Toolbox (NBT)

# How to band-pass or high-pass filter a Signal in NBT

NBT provides two functions to filter your signals. These functions both uses a so-called finite-impulse response filter, and assume that you have the Mathwork's Signal processing toolbox installed.

If you want to design a different filter, please contribute the NBT code! First explore the code for the two functions nbt_filter_fir and nbt_filter_firHp

## Band-pass filtering

To band-pass filter a signal in NBT you can use the function nbt_filter_fir. E.g., to filter a Signal in the Alpha frequency band (8-13 Hz) write:

[FilteredSignalinAlphaBand] = nbt_filter_fir(Signal,8,13,SignalInfo.converted_sample_frequency,2/8);


## High-pass filtering

To high-pass filter a signal in NBT you can use the function nbt_filter_firHp. E.g., a 0.5 Hz high-pass filter.

[Data_filtered] = nbt_filter_firHp(Signal,0.5,SignalInfo.converted_sample_frequency,2/0.5)