Array compensating beamformer

• US 4,980,870 A
• Filed: 06/10/1988
• Issued: 12/25/1990
• Est. Priority Date: 06/10/1988
• Status: Expired due to Fees

• Current Assignee: ThermoTrex Corp. (Thermo Fisher Scientific Incorporated)
• Original Assignee: ThermoTrex Corp. (Thermo Fisher Scientific Incorporated)
• Inventors: Johnson, Paul A., Newman, Edward G., Spivey, Brett A.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Pihulic, Daniel T.
• Application Number:
  US07/204,753
• Time in Patent Office: 928 Days
• Field of Search: 367/103, 367/105, 367/12, 367/118, 367/119, 367/121, 367/125, 367/129, 342/154, 342/157, 342/368, 342/371, 342/373, 342/377, 342/380, 342/383, 364/724.17, 364/724.19
• US Class Current: 367/121
• CPC Class Codes: G01S 3/48 the waves arriving at the antennas being continuous or intermittent and the phase difference of signals derived therefrom being measured

Abstract

A compensating beamformer which requires orders of magnitude fewer calculations that prior art methods. A compensating beamformer is provided which comprises a plurality of sensing elements and a plurality of analog-to-digital converters, for converting incoming analog signals to digital form. Digital signals from at least four such elements are used to compute phase angle information which is combined to form a matrix of input data in the frequency domain. An unweighted steering vector is determined to sample data from the target direction. A corrector matrix is calculated based on input data from sensing elements. That corrector matrix along with its inverse, which is determined recursively, is used in combination with the unweighted steering vector to determine an optimal steering vector. The input data in the frequency domain are then multiplied by the optimal steering vector to obtain signals in the directions of interest. In preferred embodiments of this invention these calculations are repeated systolically to provide optimal steering vector updates on an essentially real-time basis.

Claims

1. An array beamformer comprising:

a plurality of sensing elements adapted to receive incoming signals and for transforming said incoming signals into a plurality of electrical analog signals,

a converting means for receiving said plurality of said electrical analog signals from said corresponding plurality of sensing elements and for converting said plurality of electrical analog signals into a plurality of digital signals,

a phase computing means for receiving said digital signals from said converting means, for computing therewith phase angle for of said digital signals from said converting means and adding the phase angles in such a way as to produce a matrix of input data, x(ω

_m) in the frequency domain,

space="preserve" listing-type="equation">x.sub.m,k =x.sub.k (ω

.sub.m)

a direction determination means for determining an unweighted steering vector, d=e^jω

τ

,

a correction determination means for determining for each d a corrector R(ω

_m) where R_ij (ω

_m)=<

x_ik (ω

_m) x_jk *(ω

_m)>

where <

>

denotes an approximation of average value,

a recursive determination means for determining the inverse of R_m, that is R_m^-1, recursively,

an optimal steering vector determination means for determining the optimal steering vector w_mpk where w_mpk =(d_mp R_mk^-1)/(d_mp R_mk^-1 d_mp^H)_ij, and

a signal estimator means for estimating in any direction p, time k and frequency m a signal, s_mpk where said signal s_mpk is estimated by s=wx.

2. The beamformer array of claim 1 wherein said plurality of sensing elements are a plurality of acoustic sensing elements.

3. The beamformer array of claim 2 wherein said plurality of acoustic sensing elements is a number of sensing elements >

500.

4. A process for detecting a source of acoustic or electromagnetic waves amid noise and interference comprising the steps of:

detecting incoming wave signals

converting said incoming wave signal to a plurality of electrical analog signals,

converting said analog signals into a plurality of digital signals,

computing the phase of said digital signals and combining said signals with said phase to obtain a matrix of input data in the frequency domain,

computing an unweighted steering vector, d=eⁱω

t,

determining a corrector, R(ω

) to maximize the signal to noise and interference ratio,

making a recursive determination of the inverse of R(ω

), R(ω

)^-1,

determining an optimal steering vector w using d and R(ω

)^-1, and

describing said wave as a function of direction, frequency and time based on said w and said matrix of input data in the frequency domain.

5. The process of claim 4 wherein an acoustic income wave signals are detected using a plurality of acoustic detectors.