GATE-2018 (24) :Wyllie – Time average equation

GATE-2014

45. An 80Hz seismic signal is sampled at a rate of 100 samples/sec. What will be its aliased period (in seconds) in the sampled signal ?

A) 30                          

B) 10                            

C) 0.1                     

D) 0.05

Solution:

R (Sampling rate)= 100 samples/second

f_s (Sampling frequency) = 80 Hz

f_a =aliased frequency

f_a=| R*n – f_s|

n=1

f_a = |100 – 80|

f_a = 20 Hz

aliased period = 1 / aliased frequency

                       = 1 / 20

                       = 0.05 seconds