Patent ID: 7319636

Claim:
A method for computing a pressure signal gradient, comprising: recording a plurality of pressure signals at a first receiver and a second receiver, wherein the first receiver and the second receiver are disposed within a cluster; computing a calibration filter by minimizing a cost function φ(k x , ω) as a function of angular frequency, wherein φ ⁡ ( k x , ω ) = - 1 2 ⁢ ⁢ ρ ⁢ ⁢ ω ⁢ ( ( 1 ⅈ ⁢ ⁢ Δ ⁢ ⁢ z + k z ) ⁢ P ~ 1 + 1 ⅈ ⁢ ⁢ Δ ⁢ ⁢ z ⁢ G ⁡ ( ω ) ⁢ ⁢ P ~ 2 ) , where G(ω) represents the calibration filter, φ(k x , ω) represents a cost function, ρ represents the density of water, ω represents the angular frequency, {tilde over (P)} 1 represents the recorded pressure signals at the first receiver, {tilde over (P)} 2 represents the recorded pressure signals at the second receiver, Δz represents a vertical distance separating the first receiver from the second receiver, and k z represents an absolute value of a vertical wave number; and storing the calibration filter to memory.