A signal 𝑥(𝑡) has a bandwidth 2𝐵 about a carrier frequency of 𝑓𝑐 = 2 GHz as shown in Figure (a) below. In order to demodulate this signal

Q. A signal 𝑥(𝑡) has a bandwidth 2𝐵 about a carrier frequency of 𝑓_𝑐 = 2 GHz as shown in Figure (a) below. In order to demodulate this signal, it is first mixed (multiplied) with a local oscillator of frequency 𝑓_𝐿𝑂 = 1.5 GHz, and then passed through an ideal low-pass filter (LPF) with a cut-off frequency of 2.8 GHz. The output of the LPF is sent to a digitizer ADC with a sampling rate of 1.6 GHz as shown in Figure (b) below. The maximum value of 𝐵 so that the signal 𝑥(𝑡) can be reconstructed from its samples according to the Nyquist sampling theorem is        MHz.

Ans: 300

Sol:

2B ≤ 0.6 GHz
B = 0.3 GHz
B_max = 0.3 GHz
= 300 MHz