Change the phase difference between in-phase and quad-phase of a coherent receiver: 180 out of phase is obtained instead of 90 degrees.

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Clementine Chevalier 2019-11-6

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https://ww2.mathworks.cn/matlabcentral/answers/489574-change-the-phase-difference-between-in-phase-and-quad-phase-of-a-coherent-receiver-180-out-of-phase

编辑： Clementine Chevalier 2019-11-6

Hi everyone,

I am trying to model a coherent-on-receive receiver to compare its performances to an Hilbert transform. The problem is that the phase difference between in-phase and quad-phase is of 180° instead of 90° and I don't know how to change it.

My code is the following:

fs = 1e4;
t = 0:1/fs:1; 
x=cos(2*pi*t);
yh = hilbert(x);
receiver = phased.ReceiverPreamp('Gain',4,'NoiseFigure',60,'SampleRate',fs,'PhaseNoiseInputPort',true,'NoiseComplexity', 'Complex');
yr = receiver(x,1);
subplot(2,1,1)
plot(t,real(yh),t,imag(yh))
xlim([0 1])
legend('real','imaginary')
title('Hilbert transform')
subplot(2,1,2)
plot(t,real(yr),t,imag(yr))
xlim([0 1])
xlabel('Time (s)')
legend('real','imaginary')
title('Coherent Receiver')