Anthony F. Martone

Detection of RF Electronics by Multitone Harmonic Radar

Multitone harmonic radar is presented. The radar transmits multiple closely-spaced tones and receives nonlinear mixing products as well as harmonics. Harmonic and multitone responses are recorded from commercially-available RF devices. An original method for discriminating between electronic targets, by receiving at least two nonlinear mixing products near a harmonic, is presented. Target detection is demonstrated experimentally for a novel pulsed two-tone harmonic radar. Experimental results are extrapolated to estimate radar design parameters to achieve a realistic standoff range.

Automatic through the wall detection of moving targets using low-frequency ultra-wideband radar

This paper presents a time-domain, Moving Target Indication (MTI) processing formulation for detecting slow-moving personnel behind walls. The proposed time-domain MTI processing formulation consists of change detection and automatic target recognition algorithms. We demonstrate the effectiveness of the MTI processing formulation using data collected by an impulse-based, low-frequency, ultra-wideband radar. In this paper, we describe our radar system and algorithms used for the automatic detection of moving personnel. We also analyze the false alarm and detection rate of four operational scenarios of personnel walking inside wood and cinderblock buildings.

Through-the-wall detection of slow-moving personnel

This paper presents a time-domain, Moving-Target-Indication (MTI) processing formulation for detecting slow-moving personnel behind walls. The proposed time-domain MTI processing formulation consists of change detection and tracking algorithms. We demonstrate the effectiveness of the MTI processing formulation using data collected by the Army Research Laboratorys (ARLs), Ultra-Wideband (UWB), Synchronous Impulse Reconstruction (SIRE) radar. During the collection of the data, the SIRE radar remains stationary and is positioned broadside to the wall and 38 degrees off the broadside position. We have collected data for multiple operational scenarios including: personnel walking inside wood and cinderblock structures, personnel walking in linear and non-linear trajectories, and multiple personnel walking within the building structure. We analyze the characteristics of moving target signatures for the multiple operational scenarios and describe the detection and tracking algorithms implemented to exploit them.

Recent MTI experiments using ARL's synchronous impulse reconstruction (SIRE) radar

The Army Research Laboratory (ARL) has recently developed the ground-based synchronous impulse reconstruction (SIRE) radar - a low-frequency radar capable of exploiting both a real antenna array and along-track integration techniques to increase the quality of processed imagery. We have already demonstrated the systems utility by imaging static scenes. In this paper we address the moving target indication (MTI) problem, and we demonstrate the impulse-based systems ability to both detect and locate slowly moving targets. We begin by briefly describing the SIRE system itself as well as the system configuration utilized in collecting the MTI data. Next we discuss the signal processing techniques employed to create the final MTI image. Finally, we present processed imagery illustrating the utility of the proposed method.

Gapped spectrum shaping for tandem-hopped radar/communications & cognitive sensing

A non-repeating FMCW waveform was recently developed and experimentally demonstrated to provide a feasible instantiation of FM noise radar. This emission scheme was subsequently examined in terms of the impact of both stationary and hopped spectral gaps with the prospect of enabling in-band interference avoidance for cognitive sensing and possibly tandem hopped radar/communications. Here this gap-hopped spectrum framework is further explored with regard to the relation between the shaping of spectral gaps and the associated time sidelobe response. Experimental loopback measurements are shown that provide a sense of how this form of emission would operate on a real system.

Passive sensing for adaptable radar bandwidth

A spectrum sharing technique is introduced that passively monitors the RF spectrum for sub-bands of high signal to interference plus noise ratios (SINR) within a constrained bandwidth of interest. The goal of the proposed technique is to allow the radar to maintain high levels of SINR within selected frequency sub-bands in a highly congested RF environment. A sub-band is selected for radar that maximizes SINR and minimizes the range resolution cell size, two conflicting objectives. In this paper, a spectrum sensing experiment is conducted to collect multiple frequency spectra that are processed by the proposed technique. It will be shown that the proposed technique identifies frequency sub-bands of high SINR while maintaining range resolution requirements.

Noncoherent Approach for Through-the-Wall Moving Target Indication

A moving target indication, noncoherent change detection algorithm is introduced to detect moving targets inside buildings. The proposed algorithm is designed to attenuate image artifacts observed in coherent change detection images by utilizing noncoherent change detection, a positive threshold operation, and sidelobe minimization. The proposed algorithm is compared with coherent change detection for three moving target scenarios. It is shown that the proposed algorithm significantly reduces imaging artifacts while preserving the moving target signature.

Moving target indication with non-linear radar

A new approach for detecting a particular class of moving targets is presented. This method exploits characteristics of specific non-linear targets to both eliminate moving objects that are not of interest and suppress stationary clutter. Details of the underlying physical phenomena are discussed, and the signal processing procedures leveraged by the non-linear radar system are outlined in detail.

Stepped-frequency nonlinear radar simulation

RF electronic targets cannot be detected by traditional linear radar because their radar cross sections are much smaller than that of nearby clutter. One technology that is capable of separating RF electronic targets from clutter, however, is nonlinear radar. Presented in this paper is a combination of stepped-frequency ultra-wideband radar with nonlinear detection. By stepping the transmit frequency across an ultra-wide bandwidth and recording the amplitude and phase of the harmonic return signal, a nonlinear frequency response of the radar environment is constructed. An inverse Fourier transform of this response reveals the range to a nonlinear target.

Incorporating hopped spectral gaps into nonrecurrent nonlinear FMCW radar emissions

The time-varying landscape of spectral congestion is driving the investigation into new forms of “spectrally aware” radar emissions based on passive sensing of the environment. The recent Pseudo-Random Optimized FMCW (PRO-FMCW) framework, which can be viewed as an instantiation of FM noise radar, generates a nonlinear FMCW waveform that does not repeat and is designed using spectrally shaped optimization to improve range sidelobe and spectral containment. Here, these concepts are combined to generate time-varying spectral gaps within the PRO-FMCW waveform to avoid in-band interference. The impact on radar range sidelobe performance is considered with regard to both static and time-varying spectral gaps.