Patent ID: 6859659

Claim:
An apparatus for measuring the velocity of a moving object or a collection of moving objects, the apparatus comprising: a generator for generating pulses of excitation signals, an emitting transducer for transforming said excitation signals into a beam of wave energy and for emitting said wave energy in a predetermined direction of propagation, a receiving transducer for receiving signals from said moving object or objects generated by interaction with said wave energy emitted from said emitting transducer, wherein said emitting transducer and said receiving transducer having respective sensitivities which in combination give a resulting sensitivity oscillating spatially in a direction transverse to said direction of propagation, wherein the velocity component transverse to the beam is estimated using v x = d x 2 ⁢ π ⁢ ⁢ k2T prf ⁢ arctan ⁡ ( 𝒥 ⁢ { R 1 ⁡ ( k ) } ⁢ ℛ ⁢ { R 2 ⁡ ( k ) } + 𝒥 ⁢ { R 2 ⁡ ( k ) } ⁢ ℛ ⁢ { R 1 ⁡ ( k ) } ℛ ⁢ { R 1 ⁡ ( k ) } ⁢ ℛ ⁢ { R 2 ⁡ ( k ) } - 𝒥 ⁢ { R 1 ⁡ ( k ) } ⁢ 𝒥 ⁢ { R 2 ⁡ ( k ) } ) ( 36 ) as an estimator, and the axial velocity component along the beam is estimated using v z = c 2 ⁢ π ⁢ ⁢ k4T prf ⁢ f 0 ⁢ arctan ⁡ ( 𝒥 ⁢ { R 1 ⁡ ( k ) } ⁢ ℛ ⁢ { R 2 ⁡ ( k ) } - 𝒥 ⁢ { R 2 ⁡ ( k ) } ⁢ ℛ ⁢ { R 1 ⁡ ( k ) } ℛ ⁢ { R 1 ⁡ ( k ) } ⁢ ℛ ⁢ { R 2 ⁡ ( k ) } + 𝒥 ⁢ { R 1 ⁡ ( k ) } ⁢ 𝒥 ⁢ { R 2 ⁡ ( k ) } ) ( 37 ) as an estimator, where ℑ{R(k)} denotes the imaginary part of the complex autocorrelation and ℑ{R(k)} the real part, and where R 1 (k) is the complex lag k autocorrelation value for the signal r 1 (i) given by r 1 (i)= r sq ( i )+ jr sqh ( i ) (38) where r sq (i) is the received and sampled spatial quadrature field and r sqh (i) is the spatial Hilbert transform of r sq (i) and R 2 (1) is the complex lag one autocorrelation value for the signal r 2 (i) given by r 2 ( i )= r sq ( i )− jr sqh ( i ), (39) where i denotes the pulse-echo line number, c is the speed of the wave energy, f 0 is the center frequency of the emitted wave energy, d x is a period of the lateral oscillation of the sensitivity, and T prf is the time between pulse emissions.