Patent Document ID: 20070129910
Application ID: 10549199
Patent Flag: 0

Claim One:
1. A method for measuring flow layer velocities using correlation velocity measuring sonar, the method comprising steps of (1) Select transmit code for acoustic pulses; (2) According to the transmit code, transmit acoustic pulses into fluid medium, and receive echo signals backscattered by flow layers; (3) Demodulate and filter the echo signals of flow layer, and calculate the data temporal and spatial correlation function matrix of flow layer; (4) Extract the data matrix for fitting from the data temporal and spatial correlation function matrix derived from the step (3); (5) set a search range of the unknown parameter ensemble ={ V x , V y , σ vx , σ vy , γ}, wherein V x , V y are average values of relative velocities of flow layer in x, y directions respectively, σ vx , σ vy are standard deviations of velocities in x, y directions, γ is width factor; (6) Fit the data matrix for fitting derived from the step (4) with a theoretical function in the search range of the unknown parameter ensemble ; the theoretical function being φ ⁡ ( τ , ϑ , d ) = C ⁢ { exp ⁡ ( γβ θ ) - ζ 2 2 ⁡ [ θ e 2 2 ⁢ π ⁢ 1 ⁢ F ⁢ ⁢ 1 ⁢ ( 2 ; 1 ; β θ ) - cos ⁢ ⁢ 2 ⁢ ( α 3 - α 2 ) ⁢ B 2 2 ⁢ θ e 4 8 ⁢ π 2 ⁢ F 1 1 ⁡ ( 3 ; 3 ; β θ ) ] } wherein, C is a constant, τ is time delay, d is a distance between receive elements of the sonar array, 1 F 1 (·) is Kummer function, β θ = - β 2 2 ⁢ θ e / 4 ⁢ π , ⁢ β 2 = ω 0 c ⁢ ( ( τ ⁢ V _ x + d x ) 2 + ( τ ⁢ V _ y + d y ) 2 ) 1 / 2 , ξ 2 = ω 0 ⁢ τ c ⁢ ( σ vx 2 + θ vy 2 ) 1 / 2 , ⁢ α 2 = tg - 1 ⁢ τ ⁢ V _ y + d y τ ⁢ ⁢ V x + d x , α 3 = tg - 1 ⁢ σ vy σ yx , θ e 2 = 1 2 ⁢ θ b 2 ⁢ θ c 2 θ b 2 + θ c 2 ; wherein ω 0 is the central frequency of the transmit signal, c the velocity of sound, dx and dy is components of d in x direction and y direction respectively, and θ b and θ c are transmit beam width and receive beam width respectively; (7) Cooperate the velocity of vessel relative to the bottom with the average values of the relative velocities { V x , V y ,} according to the fitting result derived from the step (6) to attain the absolute velocities of flow layer.