'fir1' requires Signal Processing Toolbox.i don't how to debug it with this format.

b_lpf = fir1(64, 10*10^3/(Fs/2),'low'); % LPF (the cutoff freqency is at 10kHz in this case (i.e., -6dB reduction relative to the passband)

b_hpf = fir1(64, 0.5*10^3/(Fs/2),'high'); % HPF (the cutoff frequency is 1kHz (-6dB).

Answer 1

[Steven Lord]

The fir1 function is part of Signal Processing Toolbox. What the error message you paraphrased in the title of your question means is that if you don't have this toolbox installed and licensed, you cannot use this function. You can check if the toolbox is installed using the ver function.