Pocket Radar Guide: Key facts, equations, and data

With the development of high speed digital processor and solid state power electronics, more flexible waveforms become feasible to achieve by modern radar systems. In fact, the choice of waveforms has a significant impact on the performance of radar systems. In this paper, we review the conventional radar waveform design as well as explore the new generation of waveforms via different theoretical methods, including the most recent wavelet based waveforms. It is shown that the waveform design supports the radar advancement for more intelligent and divergent applications. In this endeavor, radar waveform design plays an even more important role in reaching specific purposes, in addition to range and speed detections, and further improves the performance and application scopes of radar systems.

It is a very common custom to use extremely simple target models in specification for radar, radar system design, performance analysis, comparison, and evaluation. While the use of rudimentary models simplifies the work, their use can only result in ultimate disappointment of the radar user, severe illness in the course of the radar development and testing, followed by major surgery, and sometimes a premature death of the program. Consideration of the purposes of radar indicates that its functions are to detect/identify/track real-world targets, not paper targets. Problems in relating simple target models to real-world targets are treated for both aircraft and ballistic targets. Based on proper radar representation, simulation results and data from field performance tests, the inadequacy of simple target models is shown. A number of situations in the design and comparison of radars are given to further illustrate the problem. Special treatment is accorded to "average" radar cross section (RCS). Finally, recommendations are made for target models which more nearly approach the real world and permit an improvement in the design, evaluation, and analytical comparison of radars. It is shown that these models, while giving more valid results, are not necessarily complex and are achievable.

This paper presents a technique for assessing the performance of continuous wave Doppler radar systems for physiological sensing. The technique includes an artificial target for testing physiological sensing radar systems with motion analogous to human heart movement and software algorithms leveraging the capabilities of this target to simply test radar system performance. The mechanical target provides simple to complex patterns of motion that are stable and repeatable. Details of radar system performance can be assessed and the effects of configuration changes that might not appear with a human target can be observed when using this mechanical target.

The reliable prediction of RF system performance depends on the morphology of the tropospheric environment. For instance, the performance of systems, operating at frequencies above 10 GHz, are particularly affected by hydrometeor scattering and molecular resonance processes occurring in the moist and unstable sea surface air. In addition, the turbulent transport processes occurring near the sea surface have a major influence in predicting communication and radar system performance. Evaporation ducts arise from such processes near the sea surface and therefore their characterization require humidity gradient measurements which are difficult to obtain at low heights. Successful implementations of Parabolic Equation Modelling (PEM) for predicting propagation rely on knowing the refractive index at very low heights.

The radar system designer is constrained by limited budgets for resources such as cost, weight, prime power, and volume. Under these constraints, the designer attempts to maximize the radar system performance. After selecting the operating frequency band and the basic design approach, the primary way to improve radar performance is to increase the average radiated power (P) and the antenna aperture area (A). Search radar performance scales with the power-aperture product PA, track radar performance scales in proportion to PA/sup 2/, and fire control radar performance scales as PA/sup 3/ of PA/sup 4/. After allocating resources to all other sub-systems (e.g. computers and signal processors), the system designer must determine how to balance resource allocation between P and A. This analysis determines the optimal allocation of the critical resource that is exhausted before others. If the resource cost of P and A are linear and independent, the analysis shows that for a search radar the critical resource should be divided equally between P and A. For a track radar, one-third of the critical resource should be allocated to P and two-thirds to A. For a fire control radar, one-fourth or one-fifth of the critical resource should be allocated to P, with the remainder allocated to A. The analysis also provides results to optimally balance P and A in the case where the resource costs are non-linear functions. The appendix reviews the relationship between P, A, and radar performance.

The impact of the microwave technology on the performance of modern radar systems is outlined, together with the resulting design implications. The most advanced characteristics of the main microwave components are pointed out and proper use of combined technologies in complex subsystems as electronically scanned antennas, is shown to be essential in order to reach advanced performance and capabilities for new radars. Different types of antennas configuration are examined from the viewpoint of improvements required by the enhancement of radar characteristics. Similar considerations apply to other microwave radar subsystems. High degree of integration, use of advanced computer resource and techniques are shown to be fundamental in the design and development of advanced microwave components. Outstanding features of advanced radars, as 3D and multifunctional systems, are pointed out. The introduction of new capabilities envisaged or being introduced in radar systems has a deep impact on the requirements for microwave components. On the other hand, technological advancements, mainly in the area of Ga As technology, will make the achievements of these advanced performances more feasible.

During radar operation, changes in the radar cross section (RCS) of a target have an adverse effect on the radar detection performance. In particular, the RCS of a target with high maneuvering characteristics can be changed rapidly. Therefore, a precise prediction of the RCS change is essential for satisfactory radar detection performance. In this study, a modeling and simulation (M&S) tool was developed for the estimation of radar detection performance. The M&S tool comprises a radar model, target model, and wave propagation model. In particular, pre-obtained RCS simulation data were utilized to consider the effect of the RCS change of the target. Using the developed tool, the RCS based on the relative attitude is extracted from the RCS simulation data and the RCS processed data using the moving average method. The M&S model is verified by comparing the two test results with the radar received signal power. Consequently, we verified that when using the RCS manufacturing data, the signal power is more similar to the test data than the other RCS simulation methods. It is expected that the radar performance on the high-maneuvering target can be estimated using the developed M&S tool.

This study investigates the problem of low probability of intercept (LPI)-based distributed multiple-input multiple-output (MIMO) radar waveform design against barrage jamming in signal-dependent clutter and coloured noise. Given the priori knowledge of the extended target impulse response, signal-dependent clutter, barrage jamming signals and coloured noise, the LPI-based scheme for optimal radar waveform design is proposed to minimise the total power consumption of the MIMO radar system by optimising the transmitted waveforms of different transmitters with a predetermined mutual information (MI) constraint for target characterisation performance. Firstly, the MI between the received echoes from the target at each receiver and the target impulse response is derived as a practical metric to characterise the parameter estimation performance of a target. Then, the LPI-based distributed MIMO radar waveform design strategy is developed. The resulting radar waveform optimisation problem is convex and solved analytically, whose solutions represent the optimum power allocation for each transmitter in the MIMO radar system. With the aid of numerical simulations, it is illustrated that to minimise the total transmission power, the optimal waveform should match with the target, clutter, jamming and coloured noise. In addition, it is also demonstrated that the LPI performance of the MIMO radar system can be significantly improved by employing the proposed radar waveform design scheme.

CRRFNet: An adaptive traffic object detection method based on camera and radar radio frequency fusion

A discussion of various types of x-band airborne radars is presented together with their systematic development through the years to the present time. Starting with simple, low pulse-repetition frequency (PRF) radars for measuring radar-target range, airborne radar development proceeded with more sophisticated high PRF Doppler radars where radar-target range and range rate were measured simultaneously. The use of Doppler (frequency) in signal processing allowed the separation of moving from nonmoving targets (ground), enabling the detection of moving targets in the presence of ground clutter. More recent developments in waveform generation and selection has resulted in the development of medium PRF radars, whereby a greater degree of tactical flexibility in target detection is achieved by combining the desirable features of both low and high PRF radars. Part of the available literature gives an overview, together with a specific example of the design and performance of an airborne medium PRF radar. Here, however, the systematic evolution of these radars is emphasized and the necessary theoretical background is developed for their performance calculations. Modern day airborne radars may be equipped with all three modes of operation, low, medium, and high PRF, allowing the operator to utilize the mode best suited for the tactical encounter. Low PRF and high PRF radars have been described elsewhere and are given here primarily for the sake of completeness and for the necessary background for developing medium PRF radar equations. They are also needed for developing the reasons why medium PRF radars came into being.

This paper reviews the remote sensing of waves and turbulence in statically stable atmospheric layers, utilizing sodar and microwave radar echoes from the small-scale inhomogeneities in gaseous refractive index caused by localized fluctuations in temperature, humidity, and velocity. Scattering theory and sounding methodology are reviewed briefly, and the relative performance of typical radar and sodar systems compared. The main section of the paper takes the form of a summary and discussion of experimental progress since 1969, showing how the echo patterns obtained may be applied to the interpretation of multiple layering, gravity waves, internal fronts and the details of dynamic instability and the genesis of turbulence in stably stratified shear layers. In addition, methods for the measurement of the intensity of the small-scale (∼ λ/2) variability of wind, temperature and water vapor from the observed radar or sodar echo intensities, and the use of Doppler techniques for the measurement of mean velocity and turbulence are discussed.

The design and operation of synthetic aperture radars require compatible sets of hundreds of quantities. Compatibility is achieved when these quantities satisfy constraints arising from physics, geometry etc. In the aggregate these quantities and constraints form a logical model of the radar. In practice the logical model is distributed over multiple people, documents and software modules thereby becoming fragmented. Fragmentation gives rise to inconsistencies and errors. The SAR Inference Engine addresses the fragmentation problem by implementing the logical model of a Sandia synthetic aperture radar in a form that is intended to be usable from system design to mission planning to actual operation of the radar. These diverse contexts require extreme flexibility that is achieved by employing the constraint programming paradigm.

“Trade Policy Reviews" analyse the trade policies and practices of each member of the WTO. The reviews consist of three parts: an independent report by the WTO Secretariat, a report by the government, and the concluding remarks by the Chair of the WTO’s Trade Policy Review Body. The opening section - "key trade facts" - provides a visual overview of the WTO member's major exports/imports, main export destinations, origins for its imports and other key data. This edition looks into the trade practices of Qatar.

“Trade Policy Reviews" analyse the trade policies and practices of each member of the WTO. The reviews consist of three parts: an independent report by the WTO Secretariat, a report by the government, and the concluding remarks by the Chair of the WTO’s Trade Policy Review Body. The opening section - "key trade facts" - provides a visual overview of the WTO member's major exports/imports, main export destinations, origins for its imports and other key data. This edition looks into the trade practices of Georgia.

“Trade Policy Reviews” analyse the trade policies and practices of each member of the WTO. The reviews consist of three parts: an independent report by the WTO Secretariat, a report by the government, and the concluding remarks by the Chair of the WTO’s Trade Policy Review Body. The opening section - “key trade facts” - provides a visual overview of the WTO member's major exports/imports, main export destinations, origins for its imports and other key data. This edition looks into the trade practices of Honduras.