題組內容

6. Consider a double sideband system with quadrature multiplexing (QM) which simultaneously sends two messages \( m_{1}(t) \) and \( m_{2}(t) \) through \( \cos 2\pi f_{c}t \) and \( \sin 2\pi f_{c}t \), respectively. The transmitted signal is given by $$x(t) = A[m_1(t) \cos 2\pi f_c t + m_2(t) \sin 2\pi f_c t].$$

(b)(10%) Now, assume that there is a phase error \( \theta \) but still no noise, i.e., the receiver believes the phase is \( 2\pi f_{c}t + \theta \). Run your demodulator again and explain what you observe.