Target location and height estimation via multipath signal and 2D array for sky-wave over-the-horizon radar

Abstract

In sky-wave over-the-horizon radar (OTHR), it is quite difficult to handle the issues of target location (ground range) and height (altitude) estimation due to their joint effect on group range. This work addresses the joint estimation of target location and height by the means of multipath propagation of OTHR signals and structure of a two-dimensional (2D) array. Usually, the multipath signal results from ionosphere propagation in OTHR and can be produced in multi-input-multi-output (MIMO) radar by transmitting signals of various carrier frequencies. A 2D array provides the potential of elevation resolution, which is related to ground and slant ranges. By the multi-quasi-parabolic (MQP) ionospheric model, we formulate the multipath propagation and signal model for the OTHR with a target at location r and height h. Moreover, the joint maximum-likelihood estimates (MLEs) of r and h are derived, and the joint Fisher information matrix (FIM) is calculated. With the so-obtained FIM, the estimability is analyzed; that is: r and h are estimable if and only if either a multipath signal or 2D array is available. The joint Cramér-Rao bound (CRB) is computed and discussed for accuracy improvement. Additionally, the estimability is also extended to the joint estimation of target location, height, and velocity.

Distributed Multistatic Sky-Wave Over-The-Horizon Radar Based on the Doppler Frequency for Marine Target Positioning

“…This paper compares the estimation performance of the proposed 2WLS positioning algorithm with the estimation algorithm WLS. Since the positioning performance of the 2WLS algorithm may be affected by the Doppler frequency error proposed in the article or the reflected ionospheric height error [25], this paper is divided into three cases, one is the positioning accuracy simulation based on the Doppler frequency error, the second is the positioning accuracy simulation based on the ionospheric height error [26], and the third is the positioning accuracy simulation based on the Doppler frequency error and the ionospheric height error [27]. In the simulation, all receiving stations perform the Doppler frequency measurement every 5 s, a total of 10 measurements are performed, and then, the algorithm in this paper is used to locate the target.…”

Distributed Multistatic Sky-Wave Over-the-Horizon Radar’s Positioning Algorithm for the Marine Target

“…In the DMOTHR, OTHR can usually cover surveillance areas outside the range of conventional line-of-sight radars due to the refraction and reflection of radio waves by the ionosphere [1,2], so it can effectively monitor low-altitude flying objects and marine ship targets [3]. However, the propagation of sky-wave signals in the ionosphere will generate multipath signals [4], which pose a challenge to achieve target positioning. e positioning performance of the DMOTHR is related to the ionospheric state.…”

“…rough the multipath propagation of the OTHR signal and the twodimensional (2D) array structure, the joint estimation of the target position and height is solved [4], but this paper is only applicable to the 2D situation, and the target position in the actual geodetic coordinates cannot be estimated. e hill climbing algorithm based on the weighted least square method is used to locate the target of the OTHR [5].…”

A Single-Step Method for Over-the-Horizon Geolocation Using Importance Sampling

“…Hereby, the well-known multiple signal classification (MUSIC) method [6] is usually used. In the second step, one kind of methods embeds the estimated azimuth and elevation angle measurements into the mathematical models of the ionosphere layers to obtain the location of the transmitter [7,8].…”