Answer Happy

(a) Define a non-stationary signal and give an example of one. (f) Describe the algorithmic steps required to compute the Short- Time Fourier Transform. Specify the differences and uses of Narrowband and Wideband Spectrograms. (g) Two ships are entering a harbour at two different speeds. Ship A approaches at 2 m/s while ship B approaches at 1.5 m/s. What is the minimum number of pulses that a harbour based collision avoidance radar working at a carrier frequency of 2 GHz and a PRF of 800 Hz should use to discriminate, in Doppler, the two ships? (h) Ship A stops and it starts rocking. The tip of the mast of ship A oscillates at 0.5 Hz due to the rocking of the ship. The amplitude of the oscillation is 2 m. It is monitored by the harbour radar that extracts its micro-Doppler signature. Write an expression for the micro-Doppler signature from the tip of the mast of the ship when the oscillation is parallel to the radar line-of sight and sketch the micro-Doppler signature for 2 periods of the oscillation.