Experiment: coherent and non-coherent demodulators.

Demodulator (or detector) can be either non-coherent, such as the envelope detector of AM, or coherent, such as the product detector of DSB. Write MATLAB programs to implement both of them. Hand in your source code, and plots which compare the demodulate outputs with the original message signals.

Let the message signal be cos(2fmt) with fm = 400Hz, the carrier wave be cos(2fct) with fc = 3000Hz. You may use t = 0 : 1/16000 : 0.06 to simulate a sampling frequency of 16kHz, in which case the FIR lowpass filter can be designed by B=fir2(32,[0 0.1 0.1 1],[1 1 0 0]) with lowpass cutoff frequency 16000 2 0.1 = 800Hz.

You need to first generate an AM (or DSB) signal, and then simulate the function of an ideal diode (or mixer), and then pass the results through the low-pass filter. To simulate the ideal diode, just let all negative input values to be zero at the output. The filter output will be the demodulated message signal.

I'm new to matlab, and am unfamiliar with the language. If you would be willing to upload your code so I could run through it it would be greatly appreciated :)