Page 149 - Fundamentals of Radar Signal Processing
P. 149

(2.89)

               so that (Gleiser, 1979; DiFranco and Rubin, 2004; Peebles, 1998)







                                                                                                       (2.90)

               If the transmitted waveform is a standard RF pulse




                                                                                                       (2.91)

               where A(t) is the pulse envelope, the received echo waveform will be













                                                                                                       (2.92)


                     Inspection  of Eq.  (2.92)  reveals  several  characteristics  of  the  received

               signal. Its frequency is α F  Hz.  The change in frequency is the Doppler shift
                                                t
                                             v
               F :
                 D




                                                                                                       (2.93)

               The Doppler shift is positive for approaching targets (v > 0) and negative for
               receding targets as expected. The phase of the received signal is decreased by






                                                                                                       (2.94)

                     The  waveform  is  scaled  in  time  by  the  factor α .  For  example,  for  an
                                                                                  v
               approaching target, α  > 1 and a transmitted pulse is shortened by a factor of α              v
                                        v
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