In order to create a base band filter, you can follow the given steps:
STEP 1: Create a BPSK signal.
% Here I have created a BPSK signal variable 'bpsk_signal' using random binary data
% I have used 'randi' and 'repelem' functions for the same
data = randi([0 1], 1, 1000);
bpsk_signal = 2*data - 1;
bpsk_signal = repelem(bpsk_signal, 10);
% NOTE: This step is not required if you have a BPSk signal available.
STEP 2: Obtain a base band filter which would essentially be a low-pass filter.
% Here I am designing the low-pass filter using 'designfilt' function.
% I have added example parameters for reference. These can be changed
% according to specific use-case.
baseband_filt = designfilt('lowpassfir', 'PassbandFrequency', 50, ...
'StopbandFrequency', 70, 'PassbandRipple', 1, ...
'StopbandAttenuation', 60, 'SampleRate', 1000);
% 'fvtool' function helps in visualizing the magnitude response of the filter
fvtool(baseband_filt)
STEP 3: Filter the signal using the filter created.
% Use the 'filter' function to obtained the 'filtered_signal'
filtered_signal = filter(baseband_filt, bpsk_signal);
You can further plot the signals to observe the difference between original and filtered BPSK signal.
You can refer to the following Mathworks documentations to know more about these functions:
Hope this helps solve your query. Thanks.
