Question

A complex signal has a bandwidth of 400 kHz. What is the minimum sampling

rate for this signal? Consider the scenario for both low pass and band pass signal.​

Answer 1

Consider the bandpass signal x(t)=xI(t)cos(2πfct)-xQ(t)sin(2πfct), where xI(t) and xQ(t) are lowpass signals, each with a bandwidth of W≪fc. This bandpass signal passes through a channel, which introduces no amplitude distortion but has a linear phase. However, if we assume the linear equation in (3.82c) does not pass through origin, we then have:

(3.105)β(f)=-2πftg+C=-2πftg-2πfc(tp-tg)

where tp is known as the phase delay or carrier delay and tg is known as the group delay or envelope delay.