Radar waveform diversity has received considerable attention in recent years due to increasing spectral congestion and the burgeoning capabilities of digital waveform generation. The promise of waveform diversity is far greater utilization of available degrees of freedom to enhance sensing performance and to even facilitate new operating modes. This tutorial provides an overview of this very broad topic, from the basic principles upon which it is founded to the myriad different areas being explored in research for practical sensing applications.

Overview of radar waveform diversity

Joint radar and communication (JRC) technology has become important for civil and military applications for decades. This paper introduces the concepts, characteristics and advantages of JRC technology, presenting the typical applications that have benefited from JRC technology currently and in the future. This paper explores the state-of-the-art of JRC in the levels of coexistence, cooperation, co-design and collaboration. Compared to previous surveys, this paper reviews the entire trends that drive the development of radar sensing and wireless communication using JRC. Specifically, we explore an open research issue on radar and communication operating with mutual benefits based on collaboration, which represents the fourth stage of JRC evolution. This paper provides useful perspectives for future researches of JRC technology.

Joint radar and communication: A survey

This paper describes a new technique for modeling and simulating the coherent returns from radar sea clutter, based on the compound K-distribution model for clutter amplitude statistics. Using observations of recorded Doppler spectra, a simple method is proposed for characterizing the temporal variations of the Doppler spectrum observed in a single-range cell. It is shown that simulations based on this model can reproduce the main statistical features observed in real measurements.

Modeling and Simulation of Coherent Sea Clutter

In this work, the authors present results for classification of different classes of targets (car, single and multiple people, bicycle) using automotive radar data and different neural networks. A fast implementation of radar algorithms for detection, tracking, and micro-Doppler extraction is proposed in conjunction with the automotive radar transceiver TEF810X and microcontroller unit SR32R274 manufactured by NXP Semiconductors. Three different types of neural networks are considered, namely a classic convolutional network, a residual network, and a combination of convolutional and recurrent network, for different classification problems across the four classes of targets recorded. Considerable accuracy (close to 100% in some cases) and low latency of the radar pre-processing prior to classification (∼0.55 s to produce a 0.5 s long spectrogram) are demonstrated in this study, and possible shortcomings and outstanding issues are discussed.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-rsn.2018.0103

Practical classification of different moving targets using automotive radar and deep neural networks

Passive Radar signifying the localisation of a target by radar measurements without using own controlled emissions has been discussed, tried, reinvented, and matured within the last 80 years. Its advantages, like covert operation and saving the costs of a transmitter, are obvious. Military as well as civilian interests combined with the advances in technological developments have recently boosted research on passive radar and passive radar systems are currently approaching the market. This tutorial shall give an overview of the history, development, and processing in passive radar and enable the interested reader to further investigate the subject exploiting the presented material together with the cited references.

Tutorial: Passive radar tutorial

The initial analysis of data collected during the airborne experiments has demonstrated airborne passive radar operation, using commercial FM radio signals as illuminators of opportunity, and these are believed to be the first results of this kind The results have highlighted several practical techniques for improving the system performance: using multiple perspectives, optimal illuminator modulation bandwidth, and multiple looks over time

Passive bistatic radar experiments from an airborne platform

Low-THz Radar, Lidar and Optical Imaging through Artificially Generated Fog

In this study, the authors investigate the application of the Doppler beam sharpening (DBS) technique for angular refinement to the emerging area of low-terahertz (THz) radar sensing. Ultimately this is to improve radar image quality in the azimuth plane to complement the excellent range resolution and thus improve object classification in low-THz radar imaging systems for autonomous platforms. The study explains the fundamental theory behind the process of DBS and describes the applicability of DBS to automotive sensing, indicating the potential for synthetic beamwidths of a fraction of a degree. Low-THz DBS was experimentally tested under controlled laboratory conditions, not only to accurately localised target objects in Cartesian space but also to provide unique object imaging at low-THz frequencies with wide azimuthal beamwidth antennas. It was shown that a stationary (i.e. non-scanned) wide beam antenna mounted on a moving platform can deliver imagery at least comparable to that produced by physical beamforming, be that steering arrays or narrow beam scanning antennas as in the experimental case presented.

Application of Doppler Beam Sharpening for Azimuth Refinement in Prospective Low-THz Automotive Radars

This paper demonstrates the feasibility and effectiveness of forward-scatter radar (FSR) target detection based on the signals of opportunity made available by standard radio and TV broadcast transmission stations. This passive FSR (P-FSR) operation is obtained by means of a simple and robust correlation process based on self-mixing. This is shown to be very effective in extracting the characteristic FSR modulation produced by airborne targets, from the signals received from frequency modulated, digital audio broadcasting, and digital video broadcasting transmitters of opportunity. Target detectability is discussed as a function of the carrier frequency, the target size, and its height at the baseline crossing. Experimental results are shown using a wide variety of sources of opportunity, target types, baselines, and receiver configurations. The target signatures obtained from the different illuminators are compared and ways of extracting the kinematic parameters of the aircraft are discussed. This validates the claimed effectiveness and robustness of the P-FSR with the presented processing scheme.

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Passive Multifrequency Forward-Scatter Radar Measurements of Airborne Targets Using Broadcasting Signals

In this paper we investigate the feasibility of using Passive Bistatic Radar, PBR, to provide security for a harbour area. There have been numerous publications on the suitability of passive radar for air surveillance applications. However, this paper focuses predominantly on maritime applications. We investigate the ability of passive radar to detect, track, and eventually manage, marine vessels (boats). The paper includes a case-study of the Livorno Harbour in Italy. Livorno has been chosen as it represents a busy maritime hub. Simulations are provided to determine the theoretical radar performance, which are then compared with experimental results from a DVB-T-based passive radar. It will be shown that passive radars represent a viable solution for harbour protection applications.

A.G. Stove

Papers

Passive bistatic radar experiments from an airborne platform

Low-THz Radar, Lidar and Optical Imaging through Artificially Generated Fog

Application of Doppler Beam Sharpening for Azimuth Refinement in Prospective Low-THz Automotive Radars

Passive Multifrequency Forward-Scatter Radar Measurements of Airborne Targets Using Broadcasting Signals

Passive Bistatic Radar (PBR) for harbour protection applications