Dr. Yimin Zhang, Research Professor at the Center for Advanced Communications (CAC), Villanova University, has been awarded a total of $1.2 million from two different Department of Defense research agencies.

The Air Force Research Lab awarded a $450,000 contract “Signal Processing for Improved Moving Target Detection, Localization, and Tracking using Multi-Static Passive Radars,” for which Dr. Zhang is the Principal Investigator.

In recent years, multi-static passive radars (MPRs), which use signals of opportunity, have attracted significant interest, primarily because of their low-cost and covertness. The fact that passive radars do not emit signals also makes them the preferred choice when considering frequency spectrum congestion. MPR systems distinguish themselves from conventional active radars in a number of fronts, e.g., extremely narrow signal bandwidth, low signal power, bistatic operation, and availability of multiple transmitters. In addition, passive radars may operate in a single-frequency network (SFN), where identical waveforms are transmitted from multiple illuminators. Target detection, localization and tracking (DLT) can be applied to ground moving targets, possibly observed through the unmanned aerial vehicles (UAVs), as well as aerial targets, observed from a ground receiver. Both settings can be extended to a set of distributed receivers. The objective of this effort is to investigate: (a) time-frequency analysis for motion parameter estimation, multi-target tracking and ghost detection; (b) robust target localization in the presence of positioning errors of the radar receiver platform; and (c) non-uniform sparse azimuthal data sampling.

The Office of Naval Research awarded a $750,000 grant on “Co-Prime Frequency and Aperture Design for HF Surveillance, Wideband Radar Imaging, and Nonstationary Array Processing, ” for which Dr. Zhang serves as a co-Principal Investigator.

The research employs co-prime sampling and arrays to improve radar sensing and surveillance in both narrowband and wideband signal platforms. The main objective is threefold: (1) Increased aperture and improved spatial resolution, enabling separation between individual targets and clutter in both active and passive HF radars; (2) Combating ambiguity and providing unique answers to target location coordinates in active and passive wideband radar sensing under forced coarse sampling in time, frequency, and space. These constraints can be imposed by cost, fast acquisition time, and unavailability of specific frequencies and antenna locations; (3) Improving direction finding of sources of nonstationary signals, as emitters or reflectors of electromagnetic waves, by integrating co-prime arrays with joint time-frequency signal representations.