viz_preprocessed_data.ipynb——Visualization issue

[Dream999999]

Hello, sorry to bother you. I recently encountered an issue while using the code in viz_preprocessed_data.ipynb for visualization. It seems that the setting for the value of N appears to be unreasonable. The function mentioned is supposed to generate data that meets the requirements for FFT input, so why is there a need to set N=30*fs? Could you explain the reasoning behind this setting?