EVOLUTIONARY SPECTRA OF BACKSCATTERING WAVE IN MOVING MEDIUM

In this paper, we discuss the backscatte,ring wave of sonar, radar and sodar in moving medium, which is a non-stationary stochastic process even if its energy attenuation is compensating. The use of evolutionary spectra is a good approach to describe it, while both the non-stationary factor A_t(ω) and the characteristic width B_L are significant. When the time interval corresponding to the volume element of the scatters is smaller than B_L, we can suppose that the power spectrum displays a single hump characteristic, and when it is greater than B_L, we may use the power spectrum which displays a bi-hump characteristic. The transmitted signal which has slow varying ambiguity function can reduce the ffect of A_t(ω).