MATLAB: Plot +1 +1 -1 -1 rectangular pulse

evenplot rect

Hi,
I would like to ask for advice to help me to plot the rectangular pulse having +1 +1 -1 -1 in amplitude. Before, I plot with +1 -1 +1 -1, and this is fine because I use remainder, so it goes by odd and even. However, I don't know how to plot it with +1 +1 -1 -1 code. Can anyone please advice me on this? Below is my code;
for m = 0:Npulses
    if  rem(m,2) == 0 %i is even
        Tx1 = exp(1j*pi*gamma*(t-m*PRI).^2);
        W=ones(size(t));
        W(t<m*PRI)=0; 
        W(t>(m*PRI+tau))=0; 
        s1 = Tx1.*W+s1;
      else
          Tx2 = -exp(1j*pi*gamma*(t-m*PRI).^2);%
          W=ones(size(t));
          W(t<m*PRI)=0;
          W(t>(m*PRI+tau))=0;
          s1 = Tx2.*W+s1;
      end
end
where Npulses is number of pulses and PRI is Pulse Repetitive Interval.

Best Answer

Previously the pattern was repeating after every 2 occasions (+1 -1)(+1 -1). So, you used rem function with respect to 2. Now the pattern has to repeat after every 4 occasions (+1 +1 -1 -1)(+1 +1 -1 -1). So, let us use rem function with respect to 4. I think the changes as done below will suffice your requirement.
for m = 0:Npulses
  if  rem(m,4) == 0 | rem(m,4) == 1  %1st and 2nd term
        Tx1 = exp(1j*pi*gamma*(t-m*PRI).^2);
        W=ones(size(t));
        W(t<m*PRI)=0; 
        W(t>(m*PRI+tau))=0; 
        s1 = Tx1.*W+s1;
      else
          Tx2 = -exp(1j*pi*gamma*(t-m*PRI).^2);
          W=ones(size(t));
          W(t<m*PRI)=0;
          W(t>(m*PRI+tau))=0;
          s1 = Tx2.*W+s1;
      end
end
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