Robust Direct position determination against sensor gain and phase errors with the use of calibration sources

Wireless Communications and Mobile Computing

Ren

et al. 2022

Self Cite

This paper proposes a direct position determination (DPD) method for a digital modulation signal based on time difference of arrival (TDOA) measurements. Unlike the two-step positioning process, the measurements are used to directly estimate the source position. Fully utilizing information in a transmitted waveform can improve the accuracy of source localization in a single-step method. Based on maximum likelihood (ML) estimates, when the digital modulation scheme is known to the location system, an alternating iterative DPD method is developed to locate the emitter. The objective function of the proposed algorithm takes into account the source position and transmitted symbol sequence, which makes it a mixed-integer optimization problem. In particular, ML sequence estimation is adopted and the complex envelope is restored using a genetic algorithm. Then, based on Newton’s method, an alternating iterative algorithm is proposed to update the position and symbol sequence results. Compared with the existing DPD method, the proposed algorithm gives more accurate location results for unknown waveforms. In addition, the proposed algorithm can reach the Cramér-Rao bound (CRB) for known signal waveforms, as verified using comprehensive simulations.

Section: Introductionmentioning

confidence: 99%

A Mixed-Integer Solution for TDOA Based Direct Positioning of Digital Modulation Signal

Yang

Wireless Communications and Mobile Computing

Ren

et al. 2022

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“…TDOA and FDOA) for each satellite are estimated separately and independently, and thus the constraint that the measurements correspond to the same transmitter position is ignored, leading to performance loss for the final localisation result. In contrast to the conventional two-step methods, direct position determination (DPD) [13][14][15][16][17][18][19][20] is a single-step localisation method which directly localises the transmitter from sensor outputs without computing the intermediate parameters and augments the position estimation by implicitly using the constraint that all measurements correspond to the same geolocation of the transmitter. Therefore, the location accuracy of DPD has shown to be significantly higher than that of the conventional two-step methods, especially under low signal-to-noise ratio (SNR) conditions.…”

Section: Introductionmentioning

confidence: 99%

Single‐step geolocation for a non‐circular source in the presence of satellite orbit perturbations

Yin

Nie³

et al. 2021

IET Signal Processing

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This study addresses the problem of geolocating a strictly non-circular source on the surface of Earth by a cluster of passive satellites. The known satellite positions and velocities are subject to random errors. The authors propose a single-step satellite geolocation algorithm that directly localises the transmitter from sensor outputs using the information of time delays and Doppler shifts but without explicitly estimating them. It exploits the non-circular property of signals and a priori information of satellite orbit error distribution to jointly calibrate orbit errors and determine the longitude and latitude of the transmitter based on the ellipsoidal Earth model, which integrates an alternating iteration scheme for the estimation of various unknowns instead of the exhaustive grid search. Additionally, a detailed Cramér-Rao bound (CRB) derivation is presented for the single-step satellite geolocation of a non-circular source on Earth with and without satellite orbit perturbations, and it is proved that these CRBs are lower than the associated CRBs for a circular source. The simulation results illustrate that the proposed method asymptotically attains the associated CRB, and shows greater performance robustness to signal-to-noise ratio (SNR) and satellite orbit errors compared with conventional twostep satellite geolocation approaches.

“…DPD directly exploits sensor outputs to localize target without estimating intermediate parameter. It outperforms traditional two-step methods especially for low signal-tonoise ratio (SNR) and/or limited signal samples [2,3].…”

Section: Introductionmentioning

confidence: 99%

Direct Position Determination with Single Sensor Based on Signal Periodicity

Mathematical Problems in Engineering

Gao

et al. 2021

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Due to practical limitations on size and cost, aerial vehicles generally cannot equip complicated sensors to form sensor array for target localization. In this paper, we investigate the direct position determination (DPD) of stationary source via single moving sensor. First, we analyze artificial signal structure and construct the DPD model with the frame periodicity of artificial signal. The model incorporates Doppler information extracted from both transformation frames and adjacent samples into target localization. Secondly, we consider the effect of oscillator instability and present an iterative solution for joint estimation of target location and phase noise caused by oscillator imperfection. The proposed technique fully exploits periodic structure of artificial wireless signal, which leads to significant enhancement in localization performance. Both theoretical analysis and simulations are presented to confirm its effectiveness.