Monopulse Angle Estimation Research Articles

Monopulse based DOA and polarization estimation with polarization sensitive arrays

In this paper, the vector sensor array (VSA) and the scalar sensor array (SSA) with polarization sensitivity (PS) are placed under the same framework of polarization sensitive arrays (PSAs), whose direction-dependent PS factor is larger than zero. This commonality of their PS factors enables both VSA and SSA to perform polarization estimation effectively. Based on this new PSA model, a generalized monopulse algorithm is proposed to jointly estimate direction-of-arrival (DOA) and polarization parameters, by expanding the existing monopulse angle estimation in spatial domain to both spatial and polarization domains. Both the DOA and polarization parameters can be effectively and efficiently estimated by comparing the outputs of the sum and spatial/polarized difference beams with only one snapshot. Then, closed-form expressions for joint DOA and polarization estimation error variances are derived and the polarization estimation variance is proved to decrease monotonically with the PS factor. Simulations are carried out on an X-band 5×5 planar array composed of microstrip patch antennas to demonstrate the effectiveness of the proposed algorithm.

Adaptive Polarization-Constrained Monopulse Approach for Dual-Polarization Array

In this letter, the problem of monopulse angle estimation error under mainlobe interference for dual- polarization array is investigated. The adaptive monopulse angle estimation considering cross polarization with array beam scanning is analyzed. To reduce the angle estimation error, an adaptive polarization-constrained monopulse approach based on combined constrained cross polarization and main polarization is proposed. The cross polarization of antenna and target signal is not regarded as a source of estimation error which needs to be suppressed in previous literature. Instead, it contributes to the angle estimation here. The proposed method could obtain accurate monopulse angle estimation while suppressing mainlobe interference. Simulation results verify the performance of the proposed method.

Four‐channel monopulse angle estimation for phased array radar with elliptical plane

Four‐channel monopulse angle estimation for phased array radar with elliptical plane

Dynamic mainlobe interference suppression method based on monopulse with gray model Kalman filter

The architecture and processing algorithm of mainlobe interference suppression method is described for nulling the signal from mainlobe electronic jammer and multiple sidelobe electronic jammers while maintaining monopulse angle estimation accuracy on the target. The existing mainlobe interference suppression method is based on monopulse Wiener filtering. However, the Wiener filtering is more suitable to remove static interference. Therefore, the authors present the dynamic mainlobe interference suppression method with Gray Model Kalman filter to resolve this problem. The simulations verify the proposed method.

Combined Constrained Adaptive Sum and Difference Beamforming in Monopulse Angle Estimation

Motivated by beam distortions in multiple interferences environment, we propose a novel combined constrained method for adaptive sum and difference beamforming in monopulse angle estimation. By optimizing the adaptive weights of sum and difference beams jointly, the restriction on the degree of freedom to determine the adaptive sum or difference weight is evenly distributed to all weights. The constraints of array gain and monopulse ratio curve are utilized to avoid beam distortion while nulling the interferences. Simulations of the proposed algorithm have been provided, which show a significant improvement in beamforming and angle estimation performance compared with the conventional constrained adaptive monopulse algorithm.

A Novel Monopulse Angle Estimation Method for Wideband LFM Radars.

Traditional monopulse angle estimations are mainly based on phase comparison and amplitude comparison methods, which are commonly adopted in narrowband radars. In modern radar systems, wideband radars are becoming more and more important, while the angle estimation for wideband signals is little studied in previous works. As noise in wideband radars has larger bandwidth than narrowband radars, the challenge lies in the accumulation of energy from the high resolution range profile (HRRP) of monopulse. In wideband radars, linear frequency modulated (LFM) signals are frequently utilized. In this paper, we investigate the monopulse angle estimation problem for wideband LFM signals. To accumulate the energy of the received echo signals from different scatterers of a target, we propose utilizing a cross-correlation operation, which can achieve a good performance in low signal-to-noise ratio (SNR) conditions. In the proposed algorithm, the problem of angle estimation is converted to estimating the frequency of the cross-correlation function (CCF). Experimental results demonstrate the similar performance of the proposed algorithm compared with the traditional amplitude comparison method. It means that the proposed method for angle estimation can be adopted. When adopting the proposed method, future radars may only need wideband signals for both tracking and imaging, which can greatly increase the data rate and strengthen the capability of anti-jamming. More importantly, the estimated angle will not become ambiguous under an arbitrary angle, which can significantly extend the estimated angle range in wideband radars.

Parallel Implementation of High Speed Mono-Pulse Angle Estimation Processor Based on Multi-IC Architecture

This paper proposes a kind of high speed mono-pulse sum-difference angle estimation hardware architecture. Sum-difference amplitude mono-pulse algorithm is implemented in the hardware which is composed of 4 chips of XC6VSX315T and three chips of TMS320C6678. This hardware structure has already been applied in engineering.

Combining sum-difference and auxiliary beams for adaptive monopulse in jamming

Only in the presence of sidelobe jamming (SLJ), can the conventional adaptive monopulse technique null the jamming effectively and maintain the monopulse angle estimation accuracy simultaneously. While mainlobe jamming (MLJ) exists, the mainlobe of adaptive pattern will subject to serious distortion, which results in a failure of detecting and tracking targets by monopulse technique. Therefore, a monopulse angle estimation algorithm based on combining sum-difference beam and auxiliary beam is presented. This algorithm utilizes both high gain difference beams and high gain auxiliary beams for cancelling the mainlobe jammer and multiple sidelobe jammers (SLJs) while keeping an adaptive monopulse ratio. Theoretical analysis and simulation results indicate that the serious invalidation of monopulse technique in MLJ and SLJs scenarios is resolved well, which improves the monopulse angle accuracy greatly. Furthermore, the proposed algorithm is of simple implementation and low computational complexity.

Complex Angle Measuring Method of Passive-Radar-Seeker

To overcome the shortcomings of the traditional passive-radar-seeker(PRS) for anti-decoy, a complex angle measuring method is proposed in this letter. The complex angle measuring method consists of monopulse angle and spatial spectrum estimation, two angle-measuring units. PRS can get the angle high-resolution features through the complex angle measuring method. So it is possible that PRS confronts decoy. Finally, the simulation results verify the feasibility and anti-decoy capacity of the complex angle-measuring method.

Missile-Target Information Acquisition of PRS in Confrontation Environment

To overcome the shortcomings of the traditional passive-radar-seeker (PRS) for anti-decoy, a complex angle measuring method is proposed in this letter. The complex angle measuring method consists of monopulse angle and spatial spectrum estimation, two angle-measuring units. PRS can get the angle high-resolution features through the complex angle measuring method. To improve the precision and the stabilization of the angle-measure in the active-decoying environment, a grey processing approach is proposed in this paper. The methods of removing gross error and parameter estimation based on the grey entropy definition are proposed in the paper. Using grey data processing approach based on the definitions of grey distance measure and grey relation entropy, eliminate singularity and retain random error. Finally, the simulation results verify the feasibility and anti-decoy capacity of the complex angle-measuring method, and the grey processing approach can improve the precision and stabilization of angle-measurer in active-decoying environment, and can improve the precision of anti-radiation missiles (ARM)<b>.</b>

Adaptive digital beamforming for angle estimation in jamming

A radar digital beamforming (DBF) architecture and processing algorithm is described for nulling the signal from a mainlobe electronic jammer and multiple sidelobe electronic jammers while maintaining monopulse angle estimation accuracy on the target. The architecture consists of a sidelobe jamming (SLJ) cancelling adaptive array (AA) followed by a mainlobe jamming (MLJ) canceller. A mainlobe maintenance (MLM) technique or constrained adaptation during the sidelobe cancellation process is imposed so that the results of the SLJ cancellation process do not distort the subsequent mainlobe cancellation process. The SLJ signals and the MLJ signals are thus cancelled sequentially in separate processes. This technique was developed for improving radar processing in determining the angular location of a target, and specifically for improving the monopulse technique by maintaining the accuracy of the target echo monopulse ratio in the presence of electronic jamming by adaptive suppression of the jamming signals before forming the monopulse sum and difference beams.

Accuracy of angle estimation with monopulse processing using two beams

Expressions are provided for the accuracy of monopulse angle estimation using two beams. It is shown that, if the signal angle is halfway between the angles of the beams, the Cramer-Rao lower bound (CRLB) for monopulse processing is almost as small as the CRLB obtained if the entire array of sensors is used. The monopulse CRLB is considerably poorer if the angle of the signal is equal to that of one of the two beams. The expressions in this correspondence are for a uniformly weighted linear array of M equally spaced sensors, for which N/spl ges/M beams are formed.

Optimum beamformers for monopulse angle estimation using overlapping subarrays

We here derive the optimum sum and difference beamformers for monopulse target localization using a linear array. The beamformers are constructed, treating as superelements two overlapping subarrays. Removing the common factor associated with the superelement pattern from the angle error function leads to a closed-form target angle estimator independent of any adaptive nulling performed. Performance analysis of the angle estimator is conducted, and a procedure is developed to construct the beamformers, which achieve the minimum estimation variance under Gaussian noise. It is shown that the optimum angle estimator using the maximum overlapping subarrays is efficient for a moderately high signal-noise ratio (SNR) and a small off-boresight angle. The proposed method can be easily modified to incorporate interference cancellation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>