Question B3 a) b) c) The data received by a radar system is recorded in Table B3 below. k x(k) 0 -0.73 2 3 1 -0.72 0.86 0.85 Table B3: Signal data 4 -0.57 Estimate the spectrum of the signal at a quarter of the sampling frequency using a minimum variance spectral estimate. Use a 2-coefficient finite impulse response (FIR) filter for the estimate. (8) Estimate the spectrum of the signal at a quarter of the sampling frequency using a second order autoregressive (AR) estimate. Without doing the calculations, describe in detail how you would use the amplitude and phase estimation (APES) algorithm to determine whether there is a sine wave of a quarter of the sampling frequency present in this data. Be specific about what equations you would use, how you would use them and the order in which you would use them. Also indicate which parts of your answers to parts (a) and (b) above would be useful in doing such a calculation. (8)