Radio Frequency Interference (RFI) significantly degrades the quality of spaceborne Synthetic Aperture Radar (SAR) images, and RFI source localization is a crucial component SAR interference mitigation. Single-station, single-channel SAR, referred to as most common operational mode SAR. However, studies on for this system are limited, accuracy remains low. This paper presents method locating ground-based using echo data. First, matched filtering employed estimate range azimuth times...

Considering the estimation accuracy reduction of Frequency Difference Arrival (FDOA) caused by relative Doppler companding, a joint Time (TDOA), FDOA and differential rate method is proposed its Cramer-Rao low bound derived in this paper. Firstly, second-order ambiguity function utilized to reduce dimensionality estimate initial TDOA rate. Secondly, updated obtained using cross function, which companding compensated existing Thirdly, estimator. Theoretical analysis on variance shows that...

Considering the limited FDOA estimation performance for frequency-hopping signal, a coherent accumulation method is developed in this paper. The normalizes of every hopping pulse and then accumulates all these modified CAFs coherently. As result, it can enlarge accumulative time length improve resolution accuracy distinctly. Theoretical analysis simulation results finally show superior proposed accuracy.

Abstract The enlargement of the field view (FOV) a photoacoustic (PA) tomography (PAT) system and improvement its lateral resolution are often two conflicting goals. A rectangular focused transducer is proposed to solve this problem. An asymmetric geometry results in characteristics ultrasound (US) field. Both simulation experiments confirm that can improve FOV PAT systems simultaneously. US study has potential performance for practical biomedical applications.

Localization of radiant emitter is becoming a major aspect wireless technologies, with applications in logistics, surveillance, and emergency response. Single sensor passive localization for stationary addressed this paper. When transmit pulses, can obtain time arrival (TOA) even though the transmitted unknown as prior. In paper, we proposed novel algorithm using Second Difference Time Delay (SDTD) solve non-linear equations Levenberg-Marquardt (LM) algorithm. Simulations corroborate...

The passive localization using multiple sensors is considered for emitter transmitting pulse signals with unknown start transmission time and period. Time of arrival (TOA) a estimated at every sensor, it difficult to intercept all pulses during the observation in practice, as there maybe obstacle on line sight or signal too weak be detected, namely, incomplete measurements. In this paper, an algorithm based combination new second difference coherent delays (SDCTD) measurement traditional...

This paper focuses on passive emitter localization using moving sensors. The increase in observation time is beneficial to improve the accuracy, but it could cause deterioration of relative motion between and sensors, especially nonlinear motion. common algorithms typically have two steps: (1) parameter estimation (2) position determination, where parameters are assumed be constant, not applicable for long times. We proposed time-varying delay-based direct determination (DPD-TVD) method,...

The measurement accuracy of frequency difference arrival (FDOA) is usually determinant for emitters location system using rapidly moving receivers. classic technique expanding the integration time cross ambiguity function (CAF) to achieve better performance FDOA likely incur a significant computational burden especially wideband signals. In this paper, nonconsecutive short-time CAF's methods proposed with expansion root mean square (RMS) time, instead and factor estimation precision...

In source localization system, micro and nano satellites are often used as distributed network to complete the task. This paper proposed a rotating triangular tethered satellite formation which has fewer station maintenance costs superior reliability maintain geometry. Likewise, it can achieve high-resolution accuracy with short baseline resulted from itself. this paper, we investigate performance of by comparing traditional influences TDOA, FDOA RFDOA on also analyzed. Simulation experiment...

This paper proposes a blind classification method for multiple frequency hopping (FH) signals based on time of arrival (TOA) sequence, without the knowledge FH pattern and needing only single channel receiver. The obtains residue TOA sequence by plane transform, eliminates outliers values using erosion algorithm classifies pulses finally k-means clustering algorithm. Simulation results show that proposed is effective achieves good performance

Abstract The scattering of guided waves propagating through pipe bends is studied by means normal mode expansion. First, the bi-orthogonality relationship for modes in derived, based on which displacement and stress fields at interfaces between straight curved parts are expanded with both parts. Then, field continuity principle, problem regarded as an eigenproblem a transfer matrix, solution gives conversions interfaces. A case study presented low-frequency longitudinal incident bend, it...