| 摘 要： | In this paper,we discuss the backscattering wave of sonar,radar and sodar in moving medium,which is anon-stationary stochastic process even if its energy attenuation is compensated.The evolutionary spectra are agood approach to describe it,both the non-stationary factor A_t(ω) and the characteristic width B_L aresignificant.When the time interval corresponding to the volume element of the scatterers is smaller than B_L,we can suppose that the power spectrum displays a single hump characteristic,and when it is larger than B_L,we may use the power spectrum which displays a bi-hump characteristics.The transmitted signal which hasslow varing ambiguity function can reduce the effect of A_t,(ω).
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