5.7. A CW radar uses linear frequency modulation to determine both range and range rate. The radar wavelength is λ = 3cm, and the fre- quency sweep is Af = 200KHz. Let to = 20ms. (a) Calculate the mean Doppler shift; (b) Compute fou and fbd corresponding to a target at range R = 350Km which is approaching the radar with radial velocity of 250m/s.