Dmitriy Garmatyuk

Feasibility study of a multi-carrier dual-use imaging radar and communication system

The paper describes a modelling scenario aimed at exploring high-resolution imaging, communication and in-band coexistence with other signals potential of a multi-carrier radar/communication system based on ultra-wideband waveforms obtained via orthogonal frequency division multiplexing (OFDM). Imaging performance is simulated for a well-studied scenario of stripmap SAR, for which backprojection algorithm is used in image reconstruction. The case of two airborne platforms is considered and image data communication between the platforms is modelled. This feasibility study lays foundation for subsequent analysis of a multi-platform sensor network scenario based on novel ultra-wideband radar architectures.

Wideband OFDM system for radar and communications

This paper describes the design and architectural composition of a radar system built on OFDM platform. The radar signal is generated digitally by forming an arbitrary-length vector of OFDM sub-carrier amplitudes and translating it in analog format via 1000 Ms/s D/A conversion. The resultant baseband signal has a bandwidth of 500 MHz, and variable number and composition of sub-carriers, which may be changed on a pulse-to-pulse basis. The signal is upconverted to 7.5 GHz carrier frequency and emitted via small-form horn antenna. The receiver includes 1 Gs/s A/D converter and processing is performed in frequency domain. The system is currently configured for short-range applications (3–5 m) and can be used as radar or communication unit without any changes to hardware and with very minimal changes to software. Experimental results from high-resolution range profile imaging and broadband data communications are presented and discussed.

Multifunctional Software-Defined Radar Sensor and Data Communication System

Orthogonal frequency-division multiplexing (OFDM) signal coding and system architecture were implemented to achieve radar and data communication functionalities. The resultant system is a software-defined unit, which can be used for range measurements, radar imaging, and data communications. Range reconstructions were performed for ranges up to 4 m using trihedral corner reflectors with approximately 203 m of radar cross section at the carrier frequency; range resolution of approximately 0.3 m was demonstrated. Synthetic aperture radar (SAR) image of a single corner reflector was obtained; SAR signal processing specific to OFDM signals is presented. Data communication tests were performed in radar setup, where the signal was reflected by the same target and decoded as communication data; bit error rate of was achieved at 57 Mb/s. The system shows good promise as a multifunctional software-defined sensor which can be used in radar sensor networks.

Ultra-wideband continuous-wave random noise arc-SAR

A coherent ultra-wideband random noise radar system operating in the 1-2-GHz frequency range has been developed at the University of Nebraska. A unique signal processing procedure based on heterodyne correlation techniques preserves phase coherence within the system, thereby enabling it to be used for synthetic aperture radar (SAR) imaging. Data acquisition is performed using a rotating boom with antennas installed atop a van containing radar equipment. This setup facilitates a simple and low-cost mobile SAR implementation, best suited for short-range quasi-stripmap Arc-SAR imaging. The use of ultra-wideband signals provides reasonable resolution of the obtained imagery. The amplitude and the phase response of the system are used to form the frequency-domain target scattering profile matrix, which are then transformed into a SAR image. The paper discusses the theory of SAR imaging using random noise signals and presents a detailed description of the radar and experimental imagery obtained using this system.

ECCM capabilities of an ultrawideband bandlimited random noise imaging radar

Investigated here is high-resolution imaging of targets in noisy or unfriendly radar environments through a simulation analysis of the ultrawideband (UWB) continuous-wave (CW) bandlimited random noise waveform. The linear FM chirp signal was selected as a benchmark radar waveform for comparison purposes. Simulation of the recovery of various types of target reflectivity functions (TRFs) for these waveforms were performed and analyzed. In addition, electronic counter-countermeasure (ECCM) capabilities for both types of systems were investigated. The results are compared using the error between the interference (jamming)-free recovered TRF and the recovered TRF under noisy conditions as a function of the signal-to-interference/jamming ratio (SIR/SJR). Our analysis shows that noise waveforms possess better jamming immunity (of the order of 5-10 dB improvement over the linear FM chirp) due to the unique radar correlation processing in the receiver.

Simulated Imaging Performance of UWB SAR Based on OFDM

This paper concerns initial simulation study of an imaging radar system employing frequency division multiplexing as means of generating radar pulses. General architecture of OFDM communication system with realistic parameters was adopted and then modified to be used for synthetic aperture radar modeling. Arbitrary target function consisting of several point scatterers was used to test systems ability to produce imagery. At the conclusion of the study it was found that UWB OFDM imaging radar does, indeed, present certain benefits, such as dynamic spectrum allocation, anti-jamming potential through pulse diversity, possibility for dual use as a communication system-while also having a potential to produce high-resolution target images on par with other pulse-based UWB radars

Radar and data communication fusion with UWB-OFDM software-defined system

This paper describes the architecture, testing methodology and experimental results of the software-defined ultra-wideband system built at Miami University. To achieve broadband data communication capability, spectrum-efficient OFDM method of modulation was chosen. The radar functionality using the same OFDM-coded pulses was implemented as well, and tested in short-range experiments. The system operates in X-band with a total transmit bandwidth of 1 GHz. Range resolution of 0.30 meters and data communication capability at approximately 57 Mb/s were established and the system was shown to be able to operate in either mode without any hardware adjustments. This concept may prove extremely useful in high-resolution radar sensor network scenarios.

Cross-Range SAR Reconstruction With Multicarrier OFDM Signals

In this letter, we describe the performance of an efficient method of slow-time synthetic aperture radar (SAR) signal processing based on reconstruction via matched filtering of estimated phase history of ultra-wideband (UWB) orthogonal frequency division multiplexing (OFDM) radar signals. The method can be used in conjunction with fast-time matched filtering to form full 2-D SAR images. The novelty of the approach is in using all subcarrier data of an OFDM signal for phase estimation, which then allows for the direct and efficient phase history computation in a method akin to multichannel azimuthal SAR processing. This fact also makes the proposed UWB OFDM SAR cross-range reconstruction resilient to narrowband interference and jamming, as well as allows for good waveform diversity/spectral flexibility potential. Simulation results demonstrating cross-range profile reconstructions are presented and discussed.

Deception jamming modeling in radar sensor networks

In this paper we create a modeling scenario which includes an airborne imaging radar platform, receiving platform and an electronic countermeasure (ECM) platform whose goal is to introduce false target images. We also assume a high-resolution stripmap SAR model operating with several common types of UWB signals, as well as the newly proposed OFDM radar waveforms. OFDM-coded radar signals possess a viable quality of high pulse diversity potential, which can provide for robust performance in various jamming scenarios. In this paper, a method of jamming known as dasiadeceptionpsila is considered and a jammer model which aspires to generate false targets using intercepted radar signals is used. Two approaches to creating a radar signal by the jammer are considered: instantaneous frequency (IF) estimator and digital RF memory (DRFM)-based reproducer. In both cases, the jammer aims to create a copy of a valid target image - but located elsewhere in the observed target scene - via resending the radar signal at certain time intervals. Radar imaging simulation based on backprojection algorithm in presence of a deception jammer is performed for the cases of linear frequency modulated (LFM), short-pulse Gaussian, frequency-hopped (FH) and OFDM ultrawideband waveforms. The comparisons in ECCM performance of these signals are made based on the analysis of simulated imagery.

Real-Time UWB-OFDM Radar-Based Navigation in Unknown Terrain

We present a signal processing algorithm and simulation study for aerial navigation with an ultrawideband orthogonal frequency division multiplexed (UWB-OFDM) radar in Global Positioning System (GPS)-denied environments. Stationary scatterers are detected and tracked using an M/N detector and modified global nearest neighbor (GNN) tracker. The radar measurements to the scatterers are combined with inertial navigation system (INS) measurements in an extended Kalman filter (EKF) to compute the aircraft position. The estimation error of the proposed algorithm is analyzed through computer-based simulations with/without radar measurements from the scatterers and with varying signal-to-noise ratio (SNR).