Antenna formed of a plurality of acoustic pick-ups
First Claim
1. A method of providing an acoustic antenna formed from M discrete acoustic transducers having output signals respectively subjected to filters processing g(f)=(g1 (f), . . . , gM (f)) wherein the method comprises:
- a step for maximizing a directivity factor which depends on (1) the modules A(f)-(α
1H (f)α
1 (f) of the signals that are emitted by a near-field source and respectively received by said transducers, and (2) the modules d2 (f) of signals that are emitted by a perturbing source and respectively received by said transducers, said directivity factor being given by;
##EQU25## where A(f) is a matrix equal to;
space="preserve" listing-type="equation">A(f)=a.sub.1.sup.H (f)a.sub.1 (f)and, where D(f) is equal to;
##EQU26## said maximizing step comprising a linear unit gain for the signal emitted by the near field source given by the following relation;
space="preserve" listing-type="equation">g(f)a.sub.1.sup.H (f)=e.sup.-j2π
fτ
where τ
is a constant representing a pure delay.
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Abstract
The output signals of the acoustic sensors of the antenna are subjected to a processing of the superdirective kind, with a constraint as regards the modulus and a non-linear constraint which fixes the incoherent noise reduction.
The theoretical formulation of these constraints being as follows ##EQU1## the first constraint signifying that the total transfer function is a pure delay τ, and the second constraint signifying that a limit is fixed for the incoherent noise reduction.
The antenna is provided to improve the near-field reception.
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Citations
11 Claims
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1. A method of providing an acoustic antenna formed from M discrete acoustic transducers having output signals respectively subjected to filters processing g(f)=(g1 (f), . . . , gM (f)) wherein the method comprises:
a step for maximizing a directivity factor which depends on (1) the modules A(f)-(α
1H (f)α
1 (f) of the signals that are emitted by a near-field source and respectively received by said transducers, and (2) the modules d2 (f) of signals that are emitted by a perturbing source and respectively received by said transducers, said directivity factor being given by;
##EQU25## where A(f) is a matrix equal to;
space="preserve" listing-type="equation">A(f)=a.sub.1.sup.H (f)a.sub.1 (f)and, where D(f) is equal to;
##EQU26## said maximizing step comprising a linear unit gain for the signal emitted by the near field source given by the following relation;
space="preserve" listing-type="equation">g(f)a.sub.1.sup.H (f)=e.sup.-j2π
fτwhere τ
is a constant representing a pure delay.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
Specification