Pri-staggered post-doppler adaptive monopulse processing for detection and location of a moving target in ground clutter

A method for reducing total jamming power in sum and difference beams, the jamming power associated with interfering signals within a received data signal, comprising:

• determining the product of a single sum and difference beam weight Wand the sum of the respective covariance matrices of the sum and difference beams, where the weight is constrained such that the first element is equal to 1 but otherwise having no constraint points on the antenna pattern, as shown in the following equation:
• J=WH(RΣΣ+RΔΔ)W−λ(δHW−1)
• where:
• (δHW−1) is a constraint point of the antenna weight and not of the antenna pattern;
• and
• determining overall sum and difference beams using the single beam weight W.

A method for determination of a monopulse ratio comprising:

• receiving a data signal and beamforming the signal to provide first sub-array sum and difference beams represented by the following equations:
• ∑ l ⁢ ( T x ) = cos ⁢ ( 2 ⁢ ⁢ π ⁢ ⁢ T x ⁢ Md 2 ⁢ ⁢ λ ) ⁢ α ⁢ ( T x ) Δ l ⁢ ( T x ) = sin ⁢ ( 2 ⁢ ⁢ π ⁢ ⁢ T x ⁢ Md 2 ⁢ ⁢ λ ) ⁢ α ⁢ ( T x )
• where α ⁢ ( T x ) = ⅇ j2 ⁢ ⁢ π ⁢ ⁢ T x ⁢ M - 1 ⁢ ⁢ d 2 ⁢ ⁢ λ ⁢ sin ⁢ ( 2 ⁢ ⁢ π ⁢ ⁢ T x ⁢ Md 4 ⁢ ⁢ λ ) sin ⁢ ( 2 ⁢ ⁢ π ⁢ ⁢ T x ⁢ d 2 ⁢ ⁢ λ )
• and λ is the wavelength, M is the number of columns within each sub-array, d is the distance between the columns, and Tx is the azimuth directional cosine;
• relating the first sub array sum and the difference beams to a plurality of sub array sum and difference beams using the following equations:
• ∑ n ⁢ ( T x ) = ⅇ j2 ⁢ ⁢ π ⁢ ⁢ T x ⁢ ( n - 1 ) ⁢ D λ ⁢ ∑ l ⁢ ( T x ) , n = 1 , 2 , … ⁢ ⁢ N Δ n ⁢ ( T x ) = ⅇ j2 ⁢ ⁢ π ⁢ ⁢ T x ⁢ ( n - 1 ) ⁢ D λ ⁢ Δ l ⁢ ( T x ) , n = 1 , 2 , … ⁢ ⁢ N
• where
• D is the spacing between the sub-arrays;
• determining a single sum and a difference weight using the following equations:
• W = ( R ΣΣ + R ΔΔ ) - 1 ⁢ δ ( δ H ⁢ ( R ΣΣ + R ΔΔ ) ) - 1 ⁢ δ
• where
• δH—is a unit vector with 1 as the first element and all other elements are 0;
• H—is a Hermitian notation including equating conjugate and transpose;
• RΣΣ:—is the covariance matrix measurement of the sum channels;
• RΔΔ—is the covariance matrix measurement of the difference channels;
• adaptively beam forming sum and difference beams to determine an overall sum and difference beam as shown in the following equations:
• Σ(Tx)=Σ1(Tx)−WΣ(1)Σ2(Tx)− . . . −WΣ(N−1)ΣN(Tx)
• Δ(Tx)=Δ1(Tx)−WΔ(1)Δ2(Tx)− . . . −WΔ(N−1)ΔN(Tx)
• calculating the monopulse ratio (mA) using the overall sum and difference beams using the following equations:
• m A = ⁢ Δ ⁡ ( T x ) Σ ⁡ ( T x ) = Δ 1 ⁡ ( T x ) - W Δ ⁡ ( 1 ) ⁢ Δ 2 ⁡ ( T x ) - … - W Δ ⁡ ( N - 1 ) ⁢ Δ N ⁡ ( T x ) Σ 1 ⁡ ( T x ) - W Σ ⁡ ( 1 ) ⁢ Σ 2 ⁡ ( T x ) - … - W Σ ⁡ ( N - 1 ) ⁢ Σ N ⁡ ( T x ) m A = ⁢ sin ⁡ ( 2 ⁢ π ⁢ ⁢ Tx ⁡ ( M - 1 2 ) ⁢ d λ ) ⁢ ( 1 - W Δ ⁡ ( 1 ) ⁢ ⅇ j2 ⁢ ⁢ π ⁢ ⁢ T x ⁢ D λ ⁢ ¨ - W ⁢ ⁢ Δ ⁡ ( n - 1 ) ⁢ ⅇ j ⁢ ⁢ 2 ⁢ π ⁢ ⁢ T x ⁢ ⁢ ( N - 1 ) ⁢ D λ ) cos ⁡ ( 2 ⁢ ⁢ π ⁢ ⁢ T x ⁡ ( M - 1 2 ) ⁢ d λ ) ⁢ ( 1 - W Σ ⁡ ( 1 ) ⁢ ⅇ j ⁢ ⁢ 2 ⁢ ⁢ π ⁢ ⁢ T x ⁢ D λ ⁢ ¨ - W Σ ⁡ ( n - 1 ) ⁢ ⅇ j ⁢ ⁢ 2 ⁢ ⁢ π ⁢ ⁢ T x ⁢ ⁢ ( N - 1 ) ⁢ D λ )
• wherein the monpulse ratio can be preserved as the following equation:
• m A = tan ⁢ ( 2 ⁢ π ⁢ ⁢ T x ⁢ M - 1 2 ) ⁢ d λ ) .

A method for radar detection and tracking of a target using monopulse ratio processing in a sub-array comprising:

• receiving a data signal;
• forming and staggering a plurality sum and difference beams using fixed beam forming;
• filtering the received staggered plurality of sum and difference beams to localize clutter and form a plurality of sub-array sum and difference beams for each velocity;
• and
• adaptively processing the plurality of sub-array sum and difference beams to cancel the localized clutter and form a plurality of final sub-array sum beams and a plurality of final sub-array difference beams for the sub array,
• said adaptive processing including the determination of a sum and difference beam weight where power associated with interfering signals within said data signal is equated to a product of the weight and the respective covariance matrices of the sum and difference beams in order to reduce jamming power within the sum and difference beams.

An apparatus for detection and tracking of a target using monopluse ratio processing comprising:

• an array comprised of a plurality of sub-arrays for receiving a signal containing data;
• each sub-array being comprised of a plurality of columns
• each sub-array receiving data signals;
• means for fixed beam forming of the received data signals;
• means for staggering the received data signals;
• a filter which filters and localizes clutter which is a component of said received data signals;
• an adaptive processor which takes the filter output and cancels the clutter;
• and
• a means for determining a sum and difference beam weight where the jamming power associated with interfering signals within the received data signals is equated to a product of the weight and the respective covariance matrices of the sum and difference beams.

A program storage device readable by a machine, tangibly embodying a program of instruction, executable by said machine to perform method steps for:

• receiving a data signal;
• forming and staggering a plurality sum and a plurality of difference beams using fixed beam forming;
• filtering the received staggered plurality of sum and difference beams to localize clutter in the plurality of sum and azimuth beams to form a plurality of final sub-array sum and a plurality of final sub array difference beams where each beam is representative of a velocity;
• adaptively processing the plurality of sub-array sum beams and the plurality of sub-array difference beams to cancel the localized clutter and form an overall sum beam and an overall difference beam;
• determining a sum and difference beam weight where power associated with interfering signals within said data signal is equated to a product of the weight and the respective covariance matrices of the sum and difference beams in order to reduce jamming power within the overall sum and difference beams.