Radar Review

How Radar Works: Start Learning About EW Here

2023-03-08T15:02:00.002+01:00

Lecture 19 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-03-12T17:31:00.001+01:00

This document contains slides from a lecture on electronic countermeasures (ECM) against radar systems. It discusses how ECM techniques like chaff, noise jamming and random pulses can be used to mask targets from radar detection by increasing clutter. It provides details on how chaff works, including its reflectivity properties and how it is dispensed. Examples are given of chaff masking an aircraft and deceiving trackers. The presentation also introduces how electronic counter-countermeasures (ECCM) can be used to counter ECM techniques.

radar-2009-a-19-electronic-counter-measures

Lecture 18 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-03-10T17:29:00.000+01:00

This document provides an overview of a lecture on synthetic aperture radar (SAR). It begins with an introduction to SAR, including why it was developed due to limitations of conventional radar for imaging. It then discusses the basics of SAR and how it forms images using signal processing to synthesize a large antenna aperture. The document outlines the rest of the lecture topics which will cover SAR image formation techniques, examples, applications, and a history of the evolution of SAR from its origins in the 1950s to current systems.

radar-2009-a-18-synthetic-aperture-radar

Lecture 17 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-03-08T17:27:00.000+01:00

This document provides an overview of radar transmitter and receiver systems. It begins with an introduction and block diagram of radar transmitters and receivers. The bulk of the document then focuses on different types of high power tube amplifiers used in radar transmitters, including klystrons, traveling wave tubes, crossed field amplifiers, and magnetrons. It also briefly discusses solid state RF power amplifiers. The document concludes with an outline of topics to be covered, including receivers and waveform generators, other transmitter and receiver subsystems, and radar receiver-transmitter architectures.

radar-2009-a-17-transmitters-and-receivers

Lecture 16 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-03-04T17:24:00.003+01:00

This document summarizes a lecture on parameter estimation and tracking. It discusses tracking processes like track association, initiation, maintenance through prediction and updating, and termination. Filtering techniques like the Kalman filter are presented as ways to estimate target position and velocity while accounting for noise and maneuvers. Examples of civilian and military target maneuvers are provided to illustrate the challenges of tracking.

radar-2009-a-16-parameter-estimation-and-tracking-part2

Lecture 15 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-03-02T17:23:00.003+01:00

The document discusses a lecture on parameter estimation and tracking in radar systems. It covers topics like observable estimation including range, angle, Doppler, and amplitude measurement accuracy. It also discusses single target tracking techniques such as amplitude monopulse, phase comparison monopulse, sequential lobing, and conical scanning. The outline indicates it will cover multiple target tracking and provide a summary. Diagrams are included to illustrate concepts like angular tracking error sources and Doppler estimation.

radar-2009-a-15-parameter-estimation-and-tracking-part-1

Lecture 14 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-02-28T17:20:00.002+01:00

This document provides an overview of a lecture on airborne pulse Doppler radar systems. It discusses different airborne radar missions including fighter/interceptor radars like those used on F-16s and F-35s, as well as airborne early warning radars like AWACS. It covers topics like airborne radar clutter, pulse Doppler modes using different PRFs, and examples of military radars and their specifications. The goal is to explain the considerations and techniques involved in airborne pulse Doppler radar system design and operation.

radar-2009-a-14-airborne-pulse-doppler-radar

Lecture 13 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-02-26T17:17:00.001+01:00

This document discusses Doppler filtering techniques for radar clutter rejection. It begins with an introduction to the problem of rejecting ground, sea, rain, and bird clutter for radar systems. It then covers pulse Doppler processing techniques including the use of burst waveforms and Doppler filter banks. It concludes with a discussion of implementations of Doppler filters and issues with airborne pulse Doppler radars.

radar-2009-a-13-clutter-rejection-doppler-filtering

Lecture 12 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-02-24T17:14:00.003+01:00

This document contains lecture slides about radar clutter rejection techniques. It discusses the history of moving target indication (MTI) and how digital technology has enabled more advanced processing. MTI uses Doppler filtering to suppress stationary clutter and detect moving targets. Early MTI employed crude subtraction of stored pulses. Modern digital implementations allow complex signal processing over many pulses for improved clutter cancellation.

radar-2009-a-12-clutter-rejection-basics-and-mti

Lecture 11 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-02-22T17:11:00.008+01:00

The document describes a lecture on radar waveforms and pulse compression. It introduces matched filters and how they are implemented by convolving a reflected echo with a time-reversed transmit pulse. This maximizes the signal-to-noise ratio. Pulse compression techniques like linear frequency modulation and phase coding are then discussed, which allow the use of longer pulses that increase energy while maintaining high range resolution. The goal is to reduce the high peak power needs of short pulses for applications like airborne radar.

radar-2009-a-11-waveforms-and-pulse-compression

Lecture 10 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-02-19T17:03:00.002+01:00

The first part of this lecture discusses radar clutter from unwanted objects like ground, sea, rain, and birds/insects. It provides examples of military radars for which clutter is an issue and outlines factors that affect ground clutter backscatter like terrain type, frequency, and depression angle. Median ground clutter strength values are shown for various terrain types and frequencies.

radar-2009-a-10-radar-clutter1

The second part of the lecture provides details on the attributes of rain clutter such as how it is affected by wavelength and circular polarization. Graphs are presented showing reflectivity of rain and its Doppler spectrum. Bird clutter properties around radar cross-section, velocity, and density are also covered. The document aims to explain the impact of various clutter sources on radar performance.

radar-2009-a-10-radar-clutter2pdf

Lecture 9 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-01-21T16:58:00.002+01:00

The document is a lecture on radar antennas and discusses various antenna scanning techniques. It begins with an overview of radar systems and the radar equation. It then covers antenna fundamentals and different types of mechanical, electronic and hybrid scanning antennas used in radar systems. The lecture outlines electronic scanning with phased arrays, including linear and planar array beamforming. It discusses controlling the array pattern through element excitation phases and amplitudes. Properties of linear arrays like beamwidth and sidelobes are also covered. The document provides examples of increasing array gain by adding more elements.

radar-2009-a-9-antennas-2

Lecture 8 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-01-20T16:56:00.002+01:00

This lecture provides an overview of radar antennas and scanning techniques. It begins with introductions to basic antenna concepts such as near and far field regions, electromagnetic field equations, polarization, and antenna gain. It then discusses reflector antennas, which use mechanical scanning to direct the antenna beam. The document outlines additional topics that will be covered, including phased array antennas, frequency scanning, and hybrid scanning methods. The goal is to provide an introduction to different types of radar antennas and how they are used to direct electromagnetic energy.

radar-2009-a-8-antennas-1

Lecture 7 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-01-19T16:47:00.020+01:00

The first part of this lecture provides an overview of radar cross section (RCS) and techniques for predicting a target's RCS through both measurement and theoretical calculation. It begins with definitions of RCS and factors affecting it. Examples of typical RCS values for different targets are given. Physical scattering mechanisms and contributors to a target's RCS are described. Both full-scale and scale model target measurement techniques are outlined. Theoretical prediction methods including geometrical optics, physical optics, and diffraction theories are introduced. Scaling laws for applying results from scale models to full-scale targets are also covered.

radar-2009-a-7-radar-cross-section-1

The second part of the lecture discusses various methods for calculating radar cross section (RCS), including the finite difference time domain method, method of moments, geometrical optics, physical optics, geometrical theory of diffraction, and physical theory of diffraction. It provides overviews and comparisons of each method, explaining their approaches and areas of applicability. The document also includes examples of RCS calculations and summaries of key points about specific methods.

radar-2009-a-7-radar-cross-section-2

Lecture 6 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-01-18T16:44:00.012+01:00

This document summarizes a lecture on radar signal detection. It discusses detecting signals in noise, the radar detection problem, basic target detection tests, and how detection performance is affected by factors like signal-to-noise ratio and number of integrated pulses. It outlines concepts like probability of detection, probability of false alarm, and the tradeoff between the two. Integration of multiple pulses can improve performance through coherent or non-coherent integration. Fluctuating targets are also addressed.

radar-2009-a-6-detection-of-signals-in-noise

Lecture 5 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-01-17T16:30:00.014+01:00

This document contains lecture slides about radar signal propagation through the atmosphere. It discusses various propagation effects including reflection from the Earth's surface, atmospheric refraction, multipath interference, and attenuation. It provides equations for calculating propagation losses and phase differences between direct and reflected signals. Examples are given of how propagation affects radar coverage and detection range for a shipborne surveillance radar system.

Lecture 5. Propagation effects

Lecture 4 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-01-16T16:30:00.005+01:00

Lecture 4 Radar equationfrom Forward2025

Lecture 3 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-01-15T16:29:00.003+01:00

Lecture 3 Review of signals systems and dspfrom Forward2025

Lecture 2 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-01-14T16:27:00.013+01:00

Lecture 2from Forward2025

Lecture 1 from the Radar System Engineering course by Dr. Robert O'Donnell.

2017-01-13T16:25:00.011+01:00

Lecture 1from Forward2025

A course in Radar System Engineering by Dr. Robert O'Donnell.

2017-01-12T16:02:00.121+01:00

The course was initially developed in 2000 for engineers and scientists with little radar experience. It covers core topics in radar fundamentals and subsystems over multiple lectures. The course has evolved significantly and now includes additional material on radar applications. It is intended to provide students a broad understanding of radar principles and issues.

source

The course contents

How the Radar System Works: Defence and Science

2016-05-04T09:51:00.009+02:00

Revealed: Pentagon’s Plan to Defeat Russian and Chinese Radar With A.I.

2016-03-02T15:05:00.001+01:00

Dave Majumdar,
February 29, 2016

The Pentagon’s Defense Advanced Research Projects Agency (DARPA) is working on a new generation of electronic warfare systems that are based on artificial intelligence (AI). If the program were to prove a success, the new A.I.-driven systems would provide the United States military a way to counter evermore-capable Russian and Chinese radars.

“One of our programs at DARPA is taking a whole new approach to this problem, this is an effort we refer to as cognitive electronic warfare,” DARPA director, Dr. Arati Prabhakar, told the House Armed Services Committee’s Subcommittee on Emerging Threats and Capabilities on February 24. “We’re using artificial intelligence to learn in real-time what the adversaries’ radar is doing and then on-the-fly create a new jamming profile. That whole process of sensing, learning and adapting is going on continually.”

Current generation aircraft—including the stealthy Lockheed Martin F-22 and F-35—have a preprogrammed databank of enemy radar signals and jamming profiles stored in a threat library. But if those warplanes encounter a signal that has not previously been encountered, the system registers the threat as unknown—which means the aircraft is vulnerable to that threat.

“Today, when out aircraft go out on their missions, they’re loaded up with a set of jamming profiles—these are specific frequencies and waveforms that they can transmit in order to jam and disrupt an adversaries’ radar to protect themselves,” Prabhakar said. “Sometimes when they go out today, they encounter a new kind of frequency or different waveform—one that they’re not programmed for, that’s not in their library, and in a time of conflict, that would leave them exposed.”

During peacetime, the Pentagon usually deploys a signals intelligence aircraft like the RC-135V/W Rivet Joint to collect data on a new waveform. That data is then sent to a laboratory to be analyzed so that a new jamming profile can be created. Those new jamming profiles are then incorporated into a jet’s—F-22, F-35, F/A-18 or any other fighter—operational flight program updates. “Eventually, months—sometimes years—later our aircraft finally get the protection that they need against this new kind of radar signal,” Prabhakar said.

In the years prior to the digital revolution when radar waveforms were rarely altered, that slow process might have been adequate. In the current era where a new waveform can be created very quickly with minor software tweaks, the current process leaves American forces vulnerable. “That slow moving world is now gone,” Prabhakar said. “It’s not that hard to modify a radar system today. If you think about, the same technologies that have brought communications and the Internet to billions of people around the world, those are the same technologies that people are now using to modify radars.”

It’s a problem that has cropped up in many different regions around the world, Pabhakar said. Right now, the only U.S. combat aircraft that have some capacity to analyze enemy waveforms in real time are the Northrop Grumman EA-6B Prowler—which is still serving with the Marines—and the Navy’s Boeing EA-18G Growler. While both the Growler and Prowler have pre-programmed onboard threat libraries, both jets carry electronic warfare officers (EWO). Those EWOs can recognize and analyze the unknown enemy waveforms and—based on their experience—figure out a way to jam them in real time to an extent. However, it’s far from perfect because it relies purely on the skills of an individual EWO.

If DARPA’s new AI-based electronic warfare system works, it would save the Pentagon time, money and potentially even save the lives of aircrew if they encounter a new enemy surface-to-air missile system or fighter radar. “So what all of that means is that our aircraft in the future won’t have to wait weeks, months to years, but in real time, in the battlespace, they’ll be able to adapt and jam this new radar threat that they get.”

Dave Majumdar is the new Defense Editor for the National Interest. You can follow him on Twitter: @DaveMajumdar.

Image: Wikimedia Commons/U.S. Navy.
Source

Principle of FMCW radar

2016-01-13T10:49:00.005+01:00

This document discusses the principles and signal processing techniques of Frequency-Modulated Continuous-Wave (FMCW) radars, focusing on linear FMCW radar for precipitation measurements. It explains the modulation process that enables ranging capabilities, Doppler frequency shifts related to moving targets, and provides an overview of the IDRA drizzle radar system developed at the Delft University of Technology. The document includes specific technical specifications and a block diagram of the radar system, emphasizing its applications in atmospheric remote sensing.

principle-of-fmcw-radarsfrom tobiasotto

Phase-Coded CW MIMO Radar Using ZCZ Sequence Sets

2015-06-03T10:01:00.004+02:00

H. Haderer, R. Feger, C. Pfeffer and A. Stelzer, "Millimeter-wave phase-coded CW MIMO radar using zero-correlation-zone sequence sets," 2015 IEEE MTT-S International Microwave Symposium, Phoenix, AZ, USA, 2015, pp. 1-4, doi: 10.1109/MWSYM.2015.7166858.

Abstract —We present a phase-coded continuous-wave (CW) multiple-input multiple-output (MIMO) radar approach based on code-division multiplexing. We use zero-correlation-zone (ZCZ) sequence sets to separate at the receivers signals from multiple transmitters. In particular, our approach uses equidistantly shifted almost-perfect autocorrelation sequences for efficient implementation. We carried out measurements using a software-defined radar platform with 16 MIMO channels to demonstrate the capability of the proposed approach.

keywords: {Antenna arrays; Radar cross-sections; Array signal processing; Multiplexing; Radar antennas; Fading; phase-coded CW radar; zero correlation sequence sets; APAS; MIMO; beamforming},

URL: IEEE Xplore link

Haderer, H.; Feger, R.; Stelzer, A., "A comparison of phase-coded CW radar modulation schemes for integrated radar sensors," Microwave Conference (EuMC), 2014 44th European , vol., no., pp.1896,1899, 6-9 Oct. 2014 doi: 10.1109/EuMC.2014.6986832

Abstract: For radar sensors, for example, automotive radar sensors based on integrated circuits, taking advantage of the growing capabilities of digital circuits is becoming of increasing interest. Currently used linear frequency-modulated continuous wave (FMCW) signals could be replaced with phase-coded ones. As a consequence, the codes used would become a significant design parameter. In our investigation, we applied three binary codes (binary m-sequence, almost perfect autocorrelation sequence, and Golay-complementary sequence), one two-valued code (Golomb's code), and one ternary sequence (Ipatov's ternary sequence) and used a linear FMCW signal for comparison. The codes were selected with a future realization of the radar system based on integrated circuits in mind. We provide brief instructions for generating each sequence. Finally, we demonstrate the performance of the phase-coded signals by means of measurements carried out with a SiGe-based RF IQ-transceiver.
keywords: {CW radar; Golay codes; sensors; FMCW signals; Golay complementary sequence; Golomb code; Ipatov ternary sequence; autocorrelation sequence; automotive radar sensors; binary m-sequence; digital circuits; integrated circuits; integrated radar sensors; linear FMCW signal; linear frequency modulated continuous wave; phase coded CW radar modulation scheme comparison; radar system; Correlation; Integrated circuits; Phase measurement; Polynomials; Radar cross-sections; Sensors},
URL: IEEE Xplore link

Lei Xu; Qilian Liang, "Zero Correlation Zone Sequence Pair Sets for MIMO Radar," Aerospace and Electronic Systems, IEEE Transactions on, vol.48, no.3, pp.2100,2113, JULY 2012 doi: 10.1109/TAES.2012.6237581

Abstract: Inspired by recent advances in multiple-input multiple-output (MIMO) radar, we apply orthogonal phase coded waveforms to MIMO radar system in order to gain better range resolution and target direction finding performance. We provide and investigate a generalized MIMO radar system model using orthogonal phase coded waveforms. In addition, we slightly modify the system model to improve the system performance. Accordingly, we propose the concept and the design methodology for a set of ternary phase coded waveforms that is the optimized punctured zero correlation zone (ZCZ) sequence-pair set (ZCZPS). We also study the MIMO radar ambiguity function of the system using phase coded waveforms, based on which we analyze the properties of our proposed phase coded waveforms which show that better range resolution could be achieved. In the end, we apply our proposed codes to the two MIMO radar system models and simulate their target direction finding performances. The simulation results show that the first MIMO radar system model could obtain ideal target direction finding performance when the number of transmit antennas is equal to the number of receive antennas. The second MIMO radar system model is more complicated but could improve the direction finding performance of the system.
keywords: {MIMO radar; antenna arrays; orthogonal codes; phase coding; receiving antennas; ZCZ-ZCZPS; direction finding performance; generalized MIMO radar system model; multiple-input multiple-output radar; orthogonal phase coded waveforms; receive antennas; ternary phase coded waveforms; zero correlation zone sequence pair sets; zero correlation zone sequence-pair set; Correlation; MIMO; MIMO radar; Radar antennas; Receiving antennas; Transmitting antennas},
URL: IEEE Xplore link