In order to reduce data volume of carrier-free ultra-wideband (UWB) fuze's signal processing and improve fuze's instantaneity, a signal processing method for carrier-free UWB fuze based on wavelet transform is proposed in this study. Under least mean square error criterion, decompose the transmitted pulse and echo signal by wavelet transform firstly, then estimate the target's distance and velocity information on high level of wavelet decomposition, finally, generate detonator signal to drive the executive level. The simulation results show that this method can effectively estimate the distance and velocity of target, also it can reduce data volume of signal processing greatly without impacting the measurement which is good to the real-time processing and engineering applications.

Bistatic inverse synthetic aperture radar (ISAR) operates with spatially separated transmitting and receiving antennas. This study presents a method capable of generating deceptive images from a series of intercepted bistatic ISAR chirp pulses. It is demonstrated that deceptive false-target images will be induced by the under-sampled pulses which are retransmitted to a moving target and scattered by it under the principles of bistatic ISAR configuration. Additionally, the jamming idea is proved to be applicable based on the characteristics of the false-target images and the requirement of jamming power. A scattering model of Yak-42 plane with 330 point scatterers is adopted to verify the effectiveness of the jamming idea.

In this study, it is demonstrated that inhomogeneity observed in a variety of radar experimental data can be modelled as a finite mixture of Weibull densities. An algorithm for identifying the parameters of each Weibull component in the mixture is developed. The proposed mixture identification algorithm is then applied to three representative sets of radar experimental data, and the quality of the statistical fit is assessed using the p-value, which is estimated based on the Kolmogorov–Smirnoff distance. An application of the Weibull mixture identification algorithm to detect an extended ground target is demonstrated. It is shown that based on the proposed Weibull mixture model, an optimal constant false-alarm rate detector can be implemented even in the presence of inhomogeneity.

A technique for failure correction in time-modulated linear arrays is presented. Starting from the knowledge of the array elements with failures, the on–off behaviour of the switches at the other elements is properly reconfigured to radiate a pattern as close as possible to the ideal one in terms of pattern features. The array reconfiguration is carried out by solving an optimisation problem through the minimisation of a suitable cost function proportional to the mismatch between ideal and reconfigured pattern features. Representative results are reported and discussed to illustrate the effectiveness of the proposed approach as well as to assess the robustness to failures of time-modulated arrays thanks to their real-time reconfigurability.

This study addresses the problem of tracking acoustically a moving source in shallow water, which is challenged by multi-path sound propagation. A specific source of interest is an autonomous underwater vehicle with periodic sound transmissions. Given a simple horizontal linear receiving array, the authors develop a Bayesian tracking method based on measurements of signal arriving angle and difference of respective sonar transmission and receiving time intervals. To counter the multi-path effect and thus improve estimation accuracy of time differences, passive time reversal processing is exploited. Further, the unscented Kalman filter is adopted in tracking to handle nonlinearity in measurements. The proposed method is tested in simulations as well as an at-sea experiment, and the results validate the effectiveness of the developed approach.

Motion compensation is a key procedure in inverse synthetic aperture radar (ISAR) imaging. The authors regard the motion compensation as a multi-parameter estimation problem. Based on the designing structured Gram matrices optimisation method, a novel motion compensation method is presented. This method consists of two parts: the range alignment algorithm and the phase compensation algorithm. The former estimates the offset of each range profile by using a criterion, which makes correlations among all of the range profiles approaching to maximum values simultaneously. Also, the latter can extract phase errors by using the optimisation method to approach the ideal optimal matrix which is derived from analysis on the signal model. The measured data processing results show that the novel motion compensation method has strong robustness and high estimation accuracy.

For weak global positioning system signal, long coherent integration can improve the acquisition performance effectively, but the unknown data bits restrict the coherent integration interval within a data bit. Data bits estimation can extend coherent integration interval over multiple data bits with more Doppler frequency search bins. To lighten the calculation burden of data bit combinations searching, an iterative acquisition algorithm is presented based on ordering data bit combinations by Grey code. Modified block-accumulating coherent integration over extended interval (BACIX) algorithm is also presented, which has linear complexity and better performance than BACIX algorithm.

In this study, a new approach is presented to detect ground moving targets and estimate their motion parameters for high-resolution and wide-swath (HRWS) synthetic aperture radar (SAR) systems. First, the space-time adaptive processing is adopted for clutter suppression, followed by the traditional SAR imaging and constant-false-alarm-rate detection for obtaining the ambiguous images of ground moving targets. Then, the real targets can be distinguished from all the ambiguous ones based on the space relationship between ambiguous images. Finally, according to the shift amount of moving targets in azimuth, which can be obtained by utilising the range histories of moving targets, the motion parameter can be achieved. The spaceborne HRWS simulation data confirm the validity of the method.

Most global navigation satellite system (GNSS) receivers cannot work in high dynamic scenarios because of poor navigation satellite acquisition in these environments. Hence, inertial navigation system (INS) is used to aid the GNSS signal acquisition and improve the acquisition capability of the receivers. In INS-aided acquisition, the Doppler estimation accuracy, which has an effect on the acquisition performance, is largely dependent on the quality of the selected inertial measurement unit (IMU). However, the mathematical relation between the IMU errors and the Doppler estimation errors is yet to be determined. This relation is derived and the relation curves are provided. Owing to the insufficiency of the researches on high dynamic applications, such as missiles and aircrafts, a high dynamic scenario is designed and acquisition experiments with different grade IMU assists are performed. The results of these experiments verify that the INS aid can reduce local frequency search space and achieve fast acquisition. Moreover, the experiments also compare the acquisition capabilities of the receivers aided by different grade IMUs and verify the effect of the IMU quality on acquisition performances. Finally, according to these experimental results, a suitable IMU can be determined for the INS-aided acquisition.

This study presents the signal processing techniques applied on a 9.4/18.8 GHz harmonic radar, which is used to investigate behaviours of small insects such as bees, beetles and butterflies. It is still a challenge to achieve high accuracy and long detection range simultaneously in a harmonic pulse radar system. The authors combine the spread spectrum technology with the classic pulse harmonic radar system to overcome the dilemma between accuracy and detection range. The processing gain of the pseudo-random code from the spread spectrum technology is used to increase the sensitivity and makes the system able to detect the signal with the weak power strength below the system noise level. To eliminate the effect caused by the local leakage, the signal-processing method provided to cancel the leakage through applying the symmetric property of the autocorrelation function of the pseudo-random code. In the field tests, the proposed system achieves a 60 m detection range within 1 m ranging accuracy by using 1.75 W transmitting power corresponding to 40.430 dBW equivalent-isotropically radiated power (EIRP). It is estimated to extend to at least 900 m detection range by using a 3 kW transmitting power corresponding to 72.771 dBW EIRP.

In this study, the authors derive an explicit expression for Cramer–Rao lower bound (CRLB) on direction parameters with the antenna locations of a single point target in the far-field scenario for multiple-input multiple-output (MIMO) radar, firstly. Since there are two unknown nuisance parameters (target radar cross section and interference-plus-noise strength), the authors use the concentrated CRLB to simplify the analytical computation. Then, the authors derive two sets of necessary and sufficient geometrical constraints for direction estimation with both bistatic and monostatic MIMO radars. Then, the authors consider the bounds on the asymptotic normalised mean-square angular error (ANMSAE), which are useful measures in three-dimensional bearing estimation problems. The authors derive the expressions for ANMSAE in both bistatic and monostatic MIMO radars, and discuss them in terms of the antenna locations. The authors then show that the uncoupled geometrical conditions are also sufficient to ensure that ANMSAE is independent of azimuth. Finally, the authors extend those conditions to obtain two sets of geometry constraints for bistatic and monostatic MIMO radars, respectively, such as some kinds of symmetry on the geometry, that ensure the optimal performance is isotropic, that is, the ANMSAE bounds are independent of all direction parameters. In numerical examples section, the authors give several representative antenna geometries to illustrate the derived antenna geometry strategy.