Feng Cheng

An Experimental Study of HF Passive Bistatic Radar Via Hybrid Sky-Surface Wave Mode

This paper presents a description of recent research and development in HF passive bistatic radar (HFPBR) based on DRM digital AM broadcasting at Wuhan University, China. First, preliminary evaluation of its detection performance with special focus on the hybrid sky-surface wave propagation mode is introduced. Then, DRM broadcasting signal analysis as a radar waveform and associated signal processing techniques are described, consisting of ambiguity function analysis, reference signal extraction, multipath clutter rejection, and target localization. Finally, the experimental system and experimental data analysis are provided. Initial results from field experiments show that DRM-based HFPBR with hybrid sky-surface wave is a promising system for wide area moving target detection and ocean remote sensing.

Computationally Efficient RF Interference Suppression Method With Closed-Form Maximum Likelihood Estimator for HF Surface Wave Over-The-Horizon Radars

Among all types of unwanted signals in high-frequency (HF) surface wave (HFSW) over-the-horizon (OTH) radars, radio-frequency interference (RFI) is dominant since HF band is shared by many radio services. In observation data, there are two types of common RFI. The most common one is the conventional RFI which presents vertical stripe paralleling to range axis in range-Doppler spectrum (RDS) and has been exhaustively reported by previous papers. Meanwhile, a new type of RFI characterized by sloping stripes (called RFISS) in RDS is also frequently observed. This work concentrates on the new RFISS and establishes a unified model for the above two types of RFI. Based on this generalized model, a time-domain RFI suppression algorithm is proposed here. Benefiting from a closed-form approximate maximum likelihood estimator, the proposed algorithm exhibits excellent performance and is computationally efficient. Its operational performance is evaluated using the field data recorded by experimental HFSW OTH radar of Wuhan University.

MIMO Passive Radar Tracking Under a Single Frequency Network

In conventional MIMO radars, transmitting waveforms are usually assumed to be mutually orthogonal. This is also the case for MIMO passive radar when the transmitters occupy non-overlapping frequency channels, such as the FM-based MIMO passive radar. For the single frequency network (SFN)-based MIMO passive radar (SMPR), all illuminators transmit the same content at the same frequency simultaneously, that makes the signal indistinguishable. Therefore, one has to solve the measurement-to-transmitter association herein in addition to the standard measurement-to-target association in conventional MIMO radars. This paper investigates the non-standard target tracking for SMPR. A novel approach is proposed to achieve real-time operation as well as nearly optimal performance. Simulation results show comparable performance to the case with known association. Moreover, the feasibility of the proposed approach is demonstrated using field experimental data.

Deghosting for target tracking in single frequency network based passive radar

Nowadays most of modern digital TV and broadcast systems adopt a novel network technology, namely single frequency network (SFN). In SFN the same data stream is broadcasted from multiple transmitters in the same frequency band. Thus SFN-based passive radar (SPR) could generate multiple simultaneous measurements from the same target, introducing a measurement-to-transmitter association ambiguity (MTAA). False association could lead to ghosts. In this paper, we present a solvability analysis for MTAA under 2-dimensional (2-D) space and well-separated targets case. The purpose of this solvability analysis is to obtain the simplest sufficient condition for resolving MTAA. Besides, an association hypothesis decision (AHD) method is proposed for deghosting. Numerical simulations demonstrate that AHD is an effective method against ghosts under the SPR scenario.

Noncooperative registration for multistatic passive radars

Multistatic passive radars localize targets by using multiple bistatic range measurements. Multistatic localization requires all range measurements to be unbiased. It is proved by real data processing that registration is an important topic to be addressed. Traditionally, atomic clocks or GPS are used to achieve unbiased measurements. However, these approaches are unattainable under the case of multistatic passive radars as the transmitters of opportunity are beyond control. This paper proposes a novel registration method using noncooperative targets. The global convergence and accuracy of the proposed algorithm are obtained analytically. Computer simulations and experimental data are used to verify that the proposed algorithm possesses a good global convergence behavior and the performance can approach the Craḿer-Rao bound (CRB).