Based on my understanding, it seems that you are attempting to process or filter a real-time signal obtained from Arduino. However, you are facing difficulties in achieving the same due to sampling rate values.
In the above code, uncomment the relevant code block to enable filtering. But if you're not aware of the sampling frequency (fs) of the ECG signal, try estimating it using the time elapsed between consecutive samples. Updating the code by including an estimation of the sampling frequency (fs):
current_time = toc;
prev_time = 0;
if init_time > 1
elapsed_time = current_time - prev_time;
fs = 1 / elapsed_time;
[b, a] = butter(4, fc/(fs/2),'bandpass');
end
prev_time = current_time;
The updated code has the variable (fs) to estimate the sampling frequency. After the first sample, the elapsed time between consecutive samples is computed using tic and toc functions. From the elapsed time, we can estimate the sampling frequency as “1 / elapsed_time”.
The filter coefficients are then updated based on the estimated sampling frequency. This allows you to dynamically adjust the filter in real-time as the sampling frequency is estimated.
