Non-linear dynamic filtering device for the angular measuring of noise in a radar
First Claim
1. A circuit arrangement for improving the accuracy of angular measurements in an echo-type target-locating system with a first reception channel emitting a sum signal Σ
- , a second reception channel emitting a difference signal Δ
, and circuitry connected to said reception channels for deriving therefrom an angular-deviation signal ε and
a quadrature deviation signal ε
q respectively appearing on a first and a second output thereof, comprising;
first calculating means connected to said first reception channel and to said second output for generating a weighting function P(t) under the control of said sum signal Σ and
said quadrature deviation signal ε
q, said weighting function P(t) going to zero during periods in which the sum signal Σ
is low and the quadrature deviation signal ε
q is peaking;
second calculating means in cascade with said first calculating means for establishing a gain-control signal K(t) varying with said weighting function P(t); and
dynamic filter means connected to said second calculating means and to said first output for processing said angular-deviation signal ε
by multiplying same with said gain-control signal K(t) and subjecting the product to recursive filtering.
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Abstract
To improve the accuracy of angular measurements in a radar or sonar system by suppressing noise due to target glint, an angular-deviation signal ε derived from the output signals Σ and Δ of a sum channel and a difference channel is multiplied with a gain-control signal K(t) before being subjected to recursive filtering. Signal K(t) is obtained, also by recursive filtering, from a weighting function P(t) which goes to zero during periods when the measurement of the angular deviation is unreliable as determined from a low value of sum signal Σ and from a peaking of a quadrature deviation signal εq, function P(t) being proportional to the product Σn ·(S-|εq|) where the exponent n is at least equal to 1 and S is a predetermined threshold. The recursive filter processing the deviation signal ε has two cross-connected stages, both controlled by signal K(t), respectively emitting a corrected deviation measurement ε and an estimated time differential τdε/dt, τ being a delay introduced in a recursive loop of each stage. Prior to being multiplied with gain-control signal K(t), the deviation signal ε may be additively combined with an angular-orientation signal θr of a radar antenna to yield an angular value θc which can then be multiplied by a measured target distance D to provide a transverse-deviation signal d; in that case the two filter stages respectively emit a corrected deviation signal d and a target-velocity estimate v.
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Citations
10 Claims
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1. A circuit arrangement for improving the accuracy of angular measurements in an echo-type target-locating system with a first reception channel emitting a sum signal Σ
- , a second reception channel emitting a difference signal Δ
, and circuitry connected to said reception channels for deriving therefrom an angular-deviation signal ε and
a quadrature deviation signal ε
q respectively appearing on a first and a second output thereof, comprising;first calculating means connected to said first reception channel and to said second output for generating a weighting function P(t) under the control of said sum signal Σ and
said quadrature deviation signal ε
q, said weighting function P(t) going to zero during periods in which the sum signal Σ
is low and the quadrature deviation signal ε
q is peaking;second calculating means in cascade with said first calculating means for establishing a gain-control signal K(t) varying with said weighting function P(t); and dynamic filter means connected to said second calculating means and to said first output for processing said angular-deviation signal ε
by multiplying same with said gain-control signal K(t) and subjecting the product to recursive filtering. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- , a second reception channel emitting a difference signal Δ
Specification