Communication Systems - Engineering

Q1:

A signal m(t) with bandwidth 500 Hz is first multiplied by a signal g(t) where . The resulting signal is then passes through an ideal low pass filter with bandwidth 1 kHz the output of the low pass filter would be

A δ(t)

B m(t)

C 0

D m(t) δ(t)

ANS:B - m(t)

Multiplication in time domain is equivalent to convolution. According to the property of impulse signal, convolution of a signal m(t) with δ(t) is signal itself. m(t) x g(t) m(t).