Hengyu Ke

Experimental Research for CMMB-Based Passive Radar Under a Multipath Environment

China mobile multimedia broadcasting (CMMB) is a digital television standard that works in a single-frequency network (SFN) at the ultrahigh frequency band and adopts orthogonal frequency division multiplex modulation with a cyclic prefix (CP-OFDM). This paper investigates the practical feasibility of a CMMB-based passive radar (CPR) in the multipath propagation environment. First, several aspects involving system considerations induced by propagation conditions and radar signal characteristics are analyzed, including power budget, dynamic range requirement, clutter rejection metrics, and ambiguity function analysis. Then targeting the problems caused by multipath signals in the complex propagation environment and corresponding processing techniques are discussed, covering reference signal extraction and clutter rejection, as well as, tracking and localization. The highlight is clutter rejection with subcarrier-based spatial adaptive processing (SSAP), which is matched with the features of CP-OFDM. The applicability of SSAP under severe channel response spread mainly contributed by SFN is specially considered. Last, a description of the experiments and the CPR systems developed by Wuhan University is given, together with results from previous field trials for low-altitude aircraft and ship detection.

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.

Signal Detection in Clutter and Noise Using Well-Characterized Subspace

In scenarios involving persistent signal and clutter, where subspaces of clutter and signal of interest may be well characterized, the generalized likelihood ratio test (GLRT), also known as matched subspace detector, exploits only the component of signal that is linearly independent of the clutter subspace. This letter introduces a detector that augments the GLRT in such a situation by incorporating and capitalizing upon an assumption of homogeneous spread of clutter energy across the dimensions of whole clutter subspace. The receiving operator characteristic curves show how the advantage of proposed detector over GLRT with a heuristic weight choice.

HFPBR activity at Wuhan University: Multipath clutter processing and experimental results

The paper describes the results achieved at Wuhan University on DRM (Digital Radio Mondial)-based HF passive bistatic radar (HFPBR) in surface wave mode. First, the high clutter environment is introduced following the radar configuration. Then, an adaptive multipath clutter rejection technique based on the waveform properties of DRM signal is presented. Finally, the experimental setup of the all-digital active/passive integrated HF surface wave radar system of Wuhan University is described. The experimental results achieved using the system are shown, there including the demonstration of the effectiveness of the technique above and the sea-state sensing application of HFPBR.

River traffic monitoring with UHF passive bistatic radar in clutter-rich environment

Passive bistatic radar (PBR) systems, which using existing commercial signals as the illuminators of opportunity, is an emerging technology in new radar systems. In this paper we investigate the feasibility of using PBR for ship detection. The challenges caused by the complex propagation environment are first described. Then corresponding techniques are introduced to handle these problems. Preliminary experiment results using CMMB-based PBR are discussed, demonstrating the potential and prospects of using UHF PBR for river traffic control.