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In this letter, we report initial experimental results which provide the foundation for low-terahertz (low-THz) radar imagery for outdoor unstructured scenarios as expected in automotive sensing. The requirements and specifications for a low-THz single imaging radar sensor are briefly outlined. The imaging capabilities of frequency-modulated continuous-wave (FMCW) radar operating at 150 GHz are discussed. A comparison of experimental images of on-road and off- road scenarios made by a 150-GHz FMCW radar and a reference 30-GHz stepped-frequency radar is implemented, and their performance is analyzed.

We propose a fast method of ultrawideband (UWB) radar imaging that can be applied to a moving target, having in mind such application as concealed weapon detection. We demonstrate the performance of the proposed method using simulations and measurements with static and moving targets. We also compare the computational complexity of the proposed method with that of a conventional method to clarify the feasibility of applying the proposed method to the intended real-time systems.

The 2007 Decadal Survey for the National Aeronautics and Space Administration recommended an Aerosol/Cloud/Ecosystems (ACE) mission with a new advanced cloud profiling radar. In this letter, we describe ACERAD, a radar design that could meet the goals for the ACE mission. ACERAD has 35 GHz (Ka-band) and 94 GHz (W-band) channels. It would scan at Ka-band and be nadir looking at W-band. The scanning antenna geometry is a classical Dragonian illuminated by a feed array; a reduced-size prototype of the antenna has been successfully fabricated and tested. ACERAD also uses a quasi-optical transmission line at W-band for low-loss routing of the signal from the transmitter to the antenna and from the antenna to the receiver. This letter briefly describes the ACERAD instrument design and test results for some of the major technologies needed for ACERAD implementation.

An ultrawideband (UWB) multistatic radar system, typically composed of one transmitter and several receivers, is a promising solution for tracking intruders moving inside a surveillance area. In this paper, the Hough transform is used to find the time-of-arrival (TOA) curves of the targets in the scan versus propagation time image for impulse-radio UWB multistatic radars. In order to parametrize these curves, which associate target TOAs over scan time, a straight-line constant-velocity mobility model is assumed for the target, providing a reasonable computational complexity and data storage requirement. The performance of our approach is verified by experimental measurements for a single target scenario in an indoor environment, where a dense clutter is observed. We show that the target TOA points can be well discriminated from false alarms and associated over scan time, forming the target TOA curves. These TOA curves can be estimated with a good accuracy, even though the target is missed at some points. In practice, before applying our TOA association algorithm, we have to remove the unwanted clutter. Because the conventional empty-room method generates too many false alarms due to shadowing effects in indoor environments, we also develop a modified empty-room clutter removal technique and we show that it can considerably reduce the number of false alarms.

A prototype high-resolution (1 km, 5 min) multiradar 3D gridded reflectivity product, including a suite of derived 2D vertical column products, has been developed for the Single European Skies Air Traffic Management Research program. As part of this, a new method for mapping radar data to grid points is being used, based on the concept of a binary space partitioning (BSP) tree that treats radar data as a set of points in a 3D point cloud. This allows the resulting analysis to be based on a complete picture of the nearby data from overlapping radars and can easily adapt to irregular grid configurations. This method is used with a Barnes successive corrections technique to retrieve finescale features while avoiding problems of undersmoothing in data-sparse regions. This has been tested using 3D domains enclosing the terminal maneuvering areas surrounding Paris, France, and London, United Kingdom, and using reflectivity plan position indicator scan data from the French and U.K. operational networks, encoded using the standard European Operational Programme for the Exchange of Weather Radar Information (OPERA) Data Information Model format. Quantitative intercomparisons between the new method, in various configurations; a high-resolution version of an existing method, in operational use at Météo-France; and a method that was developed by the National Oceanic and Atmospheric Administration for use with the Weather Surveillance Radar-1998 Doppler radar network, have been done using simulated radar scans derived from 3D synthetic radar reflectivity fields in stratiform and convective regimes.

Multifunction phased array radar (MPAR) is a multiagency initiative to investigate the feasibility of replacing the aircraft surveillance and weather radar fleets in the US with a network of phased array radars based on a single, scalable architecture. The Federal Aviation Administration and the National Atmospheric and Oceanic Administration have been collaborating on MPAR risk reduction, which focuses on reducing cost, ensuring that the technology could accomplish all the missions within radar timelines, and developing dual polarization (dual pol) capability. The agencies have completed siting, cost, spectrum, dual pol, and back end studies, among others; have developed three dual pol architectures; and are building operational arrays to demonstrate that the technology can meet the basic needs of the agencies.

A novel methodology is introduced for processing and presenting polarimetric data collected by weather surveillance radars. It involves azimuthal averaging of radar reflectivity Z, differential reflectivity ZDR, cross-correlation coefficient ρhv, and differential phase ΦDP at high antenna elevation, and presenting resulting quasi-vertical profiles (QVPs) in a height-versus-time format. Multiple examples of QVPs retrieved from the data collected by S-, C-, and X-band dual-polarization radars at elevations ranging from 6.4° to 28° illustrate advantages of the QVP technique. The benefits include an ability to examine the temporal evolution of microphysical processes governing precipitation production and to compare polarimetric data obtained from the scanning surveillance weather radars with observations made by vertically looking remote sensors, such as wind profilers, lidars, radiometers, cloud radars, and radars operating on spaceborne and airborne platforms. Continuous monitoring of the melting layer and the layer of dendritic growth with high vertical resolution, and the possible opportunity to discriminate between the processes of snow aggregation and riming, constitute other potential benefits of the suggested methodology.

Using an experimental coherent high-resolution X-band radar, we show that micro-Doppler signatures from one or more walking persons can be retrieved off the radar line of sight in a realistic urban environment. The off-sightline objects are illuminated by the radar wave multipath wall reflections. Velocity–time diagrams are created for specific walking targets using the short-time Fourier transform. Two scenarios are studied, with one and two persons, respectively, walking along a closed path.

This article introduces a new algorithm for obtaining a three-dimensional (3-D) radar coverage area, which enables the calculation of a radar coverage area, as well as a viewshed of the area. Its primary use is in the visualization of wireless communication systems and land mobile radio services. The algorithm also takes into account some environmental factors that affect the wave propagation, such as the refraction of waves, reflection from a rough surface, and the curvature of the earth. The algorithm is now operational in the province of Tehran, Iran.

The next generation of spaceborne synthetic aperture radar (SAR) remote sensing systems will emphasize on high-resolution and wide-coverage imaging. For these design goals, digital beamforming (DBF) in elevation is a promising candidate. DBF-SAR can provide global monitoring capacity for the continuous observation of a highly dynamic and rapidly changing world with high spatial resolution and short repeat intervals. A spaceborne experiment regarding a real complex scene and real spaceborne wave propagation channel effects remains a necessary step to complete the experimental verification of this advanced technique. Fortunately, the spaceborne–stationary bistatic configuration offers a potential chance to validate the advanced technique. The aforementioned experiment can be considered as a test bed for the development and implementation of DBF radar techniques applicable to Earth observation science and planetary measurements. The DBF experiment based on spaceborne–stationary bistatic configuration with TerraSAR-X as an illuminator has been successfully conducted in June 2013 by the Department of Space Microwave Remote Sensing System, Institute of Electronics, Chinese Academy of Sciences.

This paper develops an odometry algorithm for unmanned air vehicles (UAVs) based solely on radar measurements. The radar return from stationary ground-based scatterers is used to create a range-compressed image, which can be used to estimate the relative motion of the UAV. The Hough transform is used to extract scatterer features from the range-compressed image and to solve the data association problem. The estimated relative motion of the aircraft based on radar return is then fused with inertial measurement unit data in an extended Kalman filter. Radar data collected during actual flight tests are compared to truth data as estimated using a global positioning system sensor to demonstrate the effectiveness of the algorithm. Robustness properties of the algorithm are explored using simulation studies.

The introduction of photonics in microwave systems is setting new paradigms in radar architectures, providing new features potentially improving the surveillance effectiveness. In particular, photonics is enabling a new generation of the multiband radars able to manage multiple coherent radar signals at different frequencies simultaneously, with high and frequency-independent quality, enabling multispectral imaging for advanced surveillance systems. In fact, thanks to its high stability and huge bandwidth, photonics matches the urgent requirements of the performance and flexibility of the next-generation software-defined radar architectures, and it guarantees system compactness, thanks to the use of a single shared transceiver for multiband operations and to the potentials for photonic integration, which also promises reduced power consumption. In this paper, we present the first field trial, in a maritime scenario, of a fully coherent multiband radar enabled by the use of photonics. The paper reviews the basic concepts exploited for the photonic generation and the detection of the radar signals, and describes the extension to the multiband operation. We present details on the implementation and testing of a dual-band coherent radar system, discussing the potentials for a software-defined radio approach. Moreover, the results obtained after a simple digital data fusion are discussed, highlighting the capability of the coherent photonics-based multiband radars in exploiting the extended observation bandwidth for improving the system detection resolution with minimum computational costs.

In this paper, a detailed description of the roadmap to transform four individual CODAR SeaSonde high-frequency (HF) radars into an integrated HF radar network operated by Puertos del Estado (Madrid, Spain) is provided. To assess the maturation process into a fully operational status, the system must evolve via an implementation of phased approaches, including: homogenization of maintenance practices, quality control checks in real time, standardization of data access, and development of customized visualization tools. Additionally, continuous validation works with independent in situ sensors are required to provide upper bounds on both radial and total radar current measurement accuracies. Consistent correlation coefficients and uncertainty values emerge in the range of 0.31–0.81 and 8–22 cm/s, respectively, for the remotely estimated velocities. Complementarily, a dedicated online website has been developed to operationally monitor radar system health in real time. This automated quality control application analyzes a number of diagnose parameters to obtain estimates of their standard ranges and evaluate radar site performance according to them. Abrupt changes, gradual degradation, and/or failure problems can be easily detected, triggering alerts for troubleshooting. Once a good performance of HF radar systems is ensured, 2-D surface current maps are used for a broad range of practical applications, i.e., search-and-rescue operations, oil spill response, or the rigorous skill assessment of an operational ocean forecasting system such as Iberia–Biscay–Ireland (IBI), implemented within the frame of the Copernicus Marine Environment Monitoring Service.

A unified and reconfigurable multifunctional transceiver for future integrated data-fusion services of radar sensing and radio communication (RadCom) is studied and developed in this paper. This proposed alternative of the state-of-the-art architectures presents an unprecedented integration of all radar sensing and RadCom functions together in a time-division platform. Furthermore, it is capable of offering a positioning function of both moving and static objects with an enhanced resolution in ranging in addition to providing a greater capability of data communication. The design and the performance incompatibilities between radar and radio systems are explored and investigated. A systematic top–bottom approach is presented, which involves the step-by-step methodology, building block design considerations, and the system level simulation. With the purpose of validating the proposed scheme, a low-frequency prototype around the FCC-commissioned dedicated short range communication (DSRC) band is developed, and its performance is evaluated. Since such a unified transceiver can find applications in intelligent transportation infrastructures, the system demonstrator is designed and examined according to the desired specifications of future automotive radar networks. Through various system level measurements, the proposed scheme has demonstrated attractive features in connection with both radar and radio functions. With the radar mode, the added ability of angle detection and the improved range resolution against the previously demonstrated version make the system suitable for driving assistance applications. With the radio mode, the system demonstrator has proved a great capability of communication at a data rate of 25 Mb/s.

The following paper introduces a novel scanning method for mapping and localization purposes in mobile robotics. Our method is based on a rotating monostatic radar network, which determines the positions of objects around the scanner via a continuously running lateration algorithm. The estimation of surfaces with ultrawideband radar networks has been studied experimentally in lab environments, especially with lateration, envelopes of spheres, and SEABED algorithms. But we do not see a link to the field of mapping and localization of mobile robots, where laser scanners are dominating. Indeed, only few research groups use radars for mapping and localization, but their applied sensor principle is based on a rotating focused radar beam. Consequently, only 2D radar scanners are known inside the robotic world and methods for 3D scanning with radars need to be investigated. This paper will derive the theoretical background of the sensor principle, which is based on a radar network on a rotating joint, and discuss its erroneous influences. We were performing first scans of standard geometries and deriving a model in order to compare theoretical and experimental measurement results. Furthermore, we present first mapping approaches and a simulation of a scanner with multiple sensors.

We investigate methods of co-existence between radar and communications systems. Each system typically considers the other system a source of interference. Consequently, the traditional solution is to isolate the two systems spectrally or spatially. By considering a cooperative radar and communications signaling scheme, we derive achievable bounds on performance for a receiver that observes communications and radar return in the same frequency allocation. We assume the radar and communications operations to be a single joint system. Bounds on performance of the joint system are measured in terms of data information rate for communications and a novel radar estimation information rate for the radar.

An island-wide high-frequency (HF) radar network was recently established for measuring coastal surface currents in Taiwan. This research attempts to extract ship echoes from the HF radar system's sea-returns. By applying a simple procedure to the cross-spectra series of the radar signals, an adaptive detection technique is used to build an adaptive threshold surface. The ship information thus derived is compared to that obtained by an automatic identification system. The capability of this procedure to detect vessels is demonstrated.

Frequency modulated continuous wave (FMCW) radar is widely adopted solution for low-cost, short to medium range sensing applications. However, a multistatic FMCW architecture suitable for meeting the low-cost requirement has yet to be developed. This paper introduces a new FMCW radar architecture that implements a novel technique of synchronizing nodes in a multistatic system, known as over-the-air deramping (OTAD). The architecture uses a dual-frequency design to simultaneously broadcast an FMCW waveform on a lower frequency channel directly to a receiver as a reference synchronization signal, and a higher frequency channel to illuminate the measurement scene. The target echo is deramped in hardware with the synchronization signal. OTAD allows for low-cost multistatic systems with fine range-resolution, and low peak power and sampling rate requirements. Furthermore, the approach avoids problems with direct signal interference. OTAD is shown to be a compelling solution for low-cost multistatic radar systems through the experimental measurements using a newly developed OTAD radar system.

Microwave remote sensing instruments detect and image physical phenomena such as brightness temperature and volume reflectivity. The spatial resolution of these measurements is limited by the physical properties of the instrument such as the antenna size, the spatial scan pattern, and temporal sampling. Analysis shows that common sampling schemes undersample the spatial information present at the antenna. Here, we address methods to better capture the spatial information available by applying the Nyquist–Shannon sampling theory to the spatial averaging and sampling of remote sensing data. The use of overlapping windows for spatial averaging rather than treating pixels independently improves the image fidelity while maintaining the system sensitivity. Additionally, the sensitivity to spatially small targets can be maximized by matching the window shape to the antenna pattern. The spatial imaging of scanning radiometers, radars, and phased-array systems is addressed. These principles are demonstrated with the theory and data from the National Aeronautics and Space Administration Goddard Space Flight Center's High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP) radar.

The "Scandinavian Triangle" is a unique trio of radars within the DATAR Project (Dynamics and Temperatures from the Arctic MLT (60–97km) region): Andenes MF radar (69°N, 16°E); Tromsø MF radar (70°N, 19°E) and Esrange "Meteor" radar (68°N, 21°E). The radar-spacings range from 125-270km, making it unique for studies of wind variability associated with small-scale waves, comparisons of large-scale waves measured over small spacings, and for comparisons of winds from different radar systems. As such it complements results from arrays having spacings of 25km and 500km that have been located near Saskatoon. Correlation analysis is used to demonstrate a speed bias (MF smaller than the Meteor) between the radar types, which varies with season and altitude. Annual climatologies for the year 2000 of mean winds, solar tides, planetary and gravity waves are presented, and show indications of significant spatial variability across the Triangle and of differences in wave characteristics from middle latitudes. Key words: Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides: instrument and techniques)

Respiration monitoring for apnea diagnosis and movement tracking for physical activity analysis are essential and valuable indicators of underlying medical conditions in senior health care. Compared with other health sensing technologies, radar has shown its advantages in terms of non-contact implementation, immunity to ambient light and temperature changes, hardware simplicity, and long range coverage. Among various radar types, frequency-shift keying (FSK) radar inherits the ability to measure respiration from Doppler radar, while also having the ability to track the absolute range of a moving target with much less bandwidth requirement than frequency modulated continuous wave (FMCW) radar and ultra-wideband (UWB) radar. Therefore, in this paper, an FSK radar system is employed for both remote respiration monitoring and absolute range tracking. Fundamental theory and operating principle of FSK system are detailed. Respiration monitoring and range tracking experiments of a human subject were performed in an indoor environment. Results are presented to demonstrate the practical feasibility of the FSK sensing technology being applied to single senior home care applications.

Radar systems are considered suitable sensors for detection of moving objects and motion-based tracking. Among various radar types, frequency-shift keying (FSK) radar are attractive for being able to track the absolute range of a moving target with little bandwidth requirement and free from surrounding background clutter interference. However, its maximum unambiguous range is limited due to the periodicity of the phase difference over 2n and it is inversely proportional to the frequency shift between two transmitted frequencies, while its measurement resolution is proportional to this frequency shift. Frequency modulated continuous wave (FMCW) radar has no range limitation on target tracking but occupies a large bandwidth. Therefore, in this paper, a hybrid FSK-FMCW system is proposed by using a short-time operating FMCW system with small bandwidth as reference to increase the FSK system maximum discernable range without losing measurement resolution. Range tracking experiment of a human subject was conducted and results are presented to demonstrate the performance of the proposed hybrid method.

This section is intended to outline the methods that are used to extract geophysical information from the different types of radar remote-sensing strategies that have been devised to date, for different applications ranging from atmospheric sounding of cloud and precipitation, to the estimation of near-surface wind, to estimating the flow rate of glaciers, to the characterization of subsurface permittivity. The intent is to provide here a well-rounded overview with sufficient details to appreciate the steps that require special attention in each case. A brief listing of the different radar-based observing systems deployed to date is also provided.

We propose a modification of the known method used to synthesize frequency time radio images in non-radiating radars and based on minimization of the r.m.s. deviation of the observation data vector from its linear model with an additional limitation imposed on the L1 norm of the vector of the evaluated amplitudes of two-dimensional signal distribution in the range of delays and Doppler frequencies. The essence of the modification is that instead of solving the problem of conditional minimization at a full array in the “time delay—Doppler frequency shift” coordinates, this problem is solved sequentially for the zeroth and a preset frequency shift. In combination with additional computational tricks, the proposed modification allows one to increase the computational efficiency of image formation by three orders of magnitude.

We review the basic concept of frequency-modulated continuous wave (FMCW) and describe how such a radar system can be used in a harmonic radar concept. It is argued that synthetic aperture radar (SAR) for FMCW harmonic radar can be implemented by carefully choosing the wavenumbers in the mixing part of the FMCW concept. It is also argued that the following SAR processing is an extension of conventional SAR processing when applied to a harmonic FMCW system.

The paper studies instantaneous Doppler signature extraction from within a very high frequency (VHF) band spectrogram presented by the authors in previous work. The context of the current method is long-range aircraft detection by VHF Doppler effect. The method proposed calculates bistatic radar (BR) cross-section (BRCS) profiles and the correlation between them for different types of aircraft. The analysis is based on data represented by automatic dependent surveillance-broadcast (ADS-B) trajectory collection and passive BR with TV station as an illuminator of opportunity. Throughout the analysis, ADS-B data on location of an aircraft were adjusted with the use of extracted Doppler shift information. Then, this ground truth information on location was used for proper evaluation of BRCS profiles and, finally, for validation of the extraction method. The method is able to classify common intercontinental aircraft by size class with 70% accuracy from a 100-km distance by using an illuminator of opportunity located 300 km away.

This letter summarizes the applications of adaptive pulse compression (APC) in example solid-state radars for different missions. The radar examples include an X-band PX-1000 ground radar for severe weather observation, a Ku-band airborne radar for near-surface precipitation measurement, and an X-band radar experiment for air traffic observation. Representative APC algorithms are compared in terms of target estimation performance. In order to achieve the benefits of APC in actual radars, some important tradeoffs and considerations such as waveform template, sampling scheme, and noise estimation are discussed.

Human activity recognition is an emerging technology for many security, surveillance, and health service applications utilizing wireless sensor networks (WSNs). However, the exploitation of radar in WSNs has been only recently made possible through the development of small, low-power, and low-cost wireless radar motes, such as the BumbleBee radar developed by the Samraksh Company. This letter explores the capacity of using the BumbleBee radar for indoor human activity classification based on micro-Doppler signatures. The electromagnetic measurements of the signal transmitted by the BumbleBee radar are made to fully characterize the sensor and its limitations. A database of the multiperspective micro-Doppler signatures measured from the BumbleBee radar is compiled to analyze the classification performance and limitations due to the dwell time and the aspect angle. Within the operational constraints delineated, it is shown that the BumbleBee radar can be used to discriminate between walking, running, and crawling, even under variable conditions.

This letter proposes a signal processing method of passive bistatic radar (PBR) exploiting an uncooperative radar as an illuminator. Compared with other opportunity illuminators, the transmitting signal of a radar usually has a better ambiguity function, which leads to a higher range resolution. Two channels are needed in PBR system. The reference channel is used to estimate radar signal parameters and reconstruct directly propagated signal. The surveillance channel is used to receive scattered wave. An array antenna and a simultaneous multibeam algorithm are necessary in the surveillance channel due to the flexible beam scanning of the uncooperative radar. The procedure of the proposed method is explained in detail, which is then followed by a field experiment. Preliminary results from the field experiment show that the proposed method can be applied to target angle and bistatic range measurement successfully.

In this letter, a novel algorithm for attitude measurement based on a 3-D electromagnetic model (3-D em-model) is proposed. The 3-D em-model is established offline based on the geometric structure of the target, and it can be used to predict the scattering features at different target attitudes. In order to measure the attitude of the air target, we design a bistatic step frequency radar system. The directions of the two radars' lines of sight (LOSs) relative to the target are acquired by matching the high-resolution range profiles (HRRPs) from the target echoes to the HRRPs generated from the 3-D em-model. Since the directions of two radars' LOSs relative to the Earth are already known, the absolute attitude of the target can be acquired. The innovative contributions of this letter are as follows: 1) A comprehensive theoretical analysis of air target attitude measurement based on its own 3-D em-model is proposed; 2) the method can be applied to different kinds of air targets such as aircraft, satellite, missile, etc.; 3) the proposed attitude measurement method does not require target motion model in advance; and 4) the proposed algorithm can be applied to any kind of step frequency waveforms. Experiments using both data predicted by a high-frequency electromagnetic code and data measured in the chamber verify the validity of the method.

Atmospheric refraction in the troposphere causes the propagation speed of electromagnetic signals to be less than the light speed. This creates a difference between the actual propagation path delay and the distance of the geometrical straight-line path, i.e., a quantity known as the tropospheric delay. As classical imaging algorithms for spaceborne synthetic aperture radar (SAR) do not take the tropospheric delay into account, imaging filters are designed based on the assumption of rectilinear propagation with the light speed. Therefore, a residual phase exists in imaging results, which affects focusing quality under the condition of high resolution. In order to compensate for the impact of tropospheric delay on focusing performance, this paper modifies the spaceborne SAR echo model and then proposes an imaging compensation algorithm. The key to this algorithm is to fit a range delay coefficient based on the European Geostationary Navigation Overlay Service model of zenith delay and Niell mapping function, which projects the zenith delay onto the looking direction. After range compensation, classical imaging, and azimuth compensation, which compose the proposed algorithm, the processed results are well focused.

Ultrawideband (UWB) synthetic aperture radar (SAR) as a tool for oil well perforation monitoring is experimentally investigated in this paper. Experiments are conducted on a lab prototype that emulates the small section of an oil well. Oil well perforations are scanned using the designed UWB radar system for different experimental conditions. High-resolution images in both down-range and cross-range are obtained by using UWB pulses and signal processing. High-quality images are constructed using SAR processing algorithm with the proposed modifications. Experiments are carried out for different perforation conditions such as open, partially clogged and fully clogged cases. It is shown by the experiments that the proposed radar technique and the data processing methods are capable of providing more revealing high-quality images. This approach can be applied effectively to monitor the oil well medium and detect well impairment locations.

The improvement in Maritime Situational Awareness, the capability of understanding events, circumstances, and activities within and impacting the maritime environment, is nowadays of paramount importance for safety and security. The integration of spaceborne synthetic aperture radar (SAR) data and automatic identification system (AIS) information has the appealing potential to provide a better picture of what is happening at sea by detecting vessels that are not reporting their positioning data or, on the other side, by validating ships detected in satellite imagery. In this letter, we propose a novel architecture that is able to increase the quality of SAR/AIS fusion by exploiting knowledge of historical vessel positioning information. Experimental results are presented, testing the algorithm in the specific area of Dover Strait using real SAR and AIS data.

An improved rain detection system has been developed using a marine radar. The rain detection system is composed of a Furuno 1932 Mark II marine radar (radar scanner and display units), a radar control circuit, a signal conditioning circuit, an analog to digital converter (ADC), and a computer with a graphical user interface (GUI). The combination of the microcontroller and optocoupler in the radar control circuit was able to replace the omnipad and pushbutton control and it was also employed to activate the radar and the sector blanket mode. The signal conditioning circuit along with the ADC and the clutter removal made the video and navigation signals from the display unit become ADC-counted rain data. By comparing the ADC-counted rain data of the Furuno marine radar with the reflectivity obtained by GMR X Band weather radar, it was found that the Furuno rain detection sensitivity only spans from 30-55 dBZ.

Traditionally, the phase content in single-channel synthetic aperture radar (SAR) imagery is discarded. This practice is justified by conventional radar resolution theory, which is a theory strictly relevant to point targets. The advent of high-resolution radars permits small targets previously considered to be points to be now treated as extended targets, in which case this theory is not strictly applicable. With this in mind, this paper offers a new insight into the relevance of phase in single-channel SAR imagery. The proposed approach builds on techniques from the fields of complex-valued and directional statistics. In doing so, three main contributions are presented, the first being a novel method for characterizing the phase content. Second, a new statistical model for the phase is considered, and then a set of 15 solely phase-based features are discussed. Our results are demonstrated on real-world SAR datasets for ground-truthed targets. The statistical significance of the information carried in the phase is clearly demonstrated. Furthermore, if applied to a dataset with higher resolution, the proposed techniques are expected to achieve even higher performance.

This paper provides qualitative and quantitative values for the received interference power at the antenna ports of automotive radars as well as the probability of their occurrence for actual and future, not yet measurable traffic scenarios on main roads. The influence of the environment, the road traffic behavior, and the radar penetration rate for a defined antenna configuration can be observed. The basis for the analyses are ray-tracing based simulations in order to achieve adequate predictions for the received power levels due to multipaths. The results show that for a radar penetration rate of 100%, the difference between the strongest overall incoherent received interference power level and the level that is received in 90% of the time is up to 7 dB, dependent on the antenna placement and the environment.

This letter proposes a design concept that can satisfy the requirements for weather observations with a multifunction polarimetric phased-array radar at about 1-min volume update time while meeting present aviation requirements.

Accurate radar remote sensing requires a radar system with high cross-polarization isolation, highly matched dual-polarization patterns, and low sidelobes. A cylindrical polarimetric phased-array radar (CPPAR), which has polarization purity and scan-invariant beam properties, has recently been introduced to the weather and air surveillance communities. To achieve low sidelobes and matched beams, pattern synthesis using an optimization method is presented. Results reported herein support the idea that CPPARs can be designed and implemented for accurate weather measurements. Furthermore, some uncertainty analysis is performed to show the effects of the amplitude and phase errors on the radiation patterns of the PAR.

Radars are among the best exponents of radio-frequency (RF)/microwave devices for remote sensing [1], [2]. Long-range radars have demonstrated outstanding potential not only for defense/security environments, such as the detection, location, and tracking of targets, but also on a plurality of civilian scenarios, such as meteorological/weather measurement tasks, imaging of the Earth's surface through synthetic aperture radar (SAR) techniques, monitoring of animal migrations, and many others [3]-[7].

This letter considers the feasibility of a simplified real-time imaging flow theoretically for frequency-modulated continuous-wave synthetic aperture radar (FMCW SAR). The simplified imaging flow is based on the range-Doppler algorithm, whereas the simplifications contain absolving the residual-video-phase correction and performing the second-order motion compensation ahead of the range cell migration correction (RCMC). During the analysis, the platform movement within the transmission of a sweep is considered. Moreover, the hardware technique, i.e., the enhanced direct memory access, is used to improve the efficiency of the bulk RCMC. Eventually, the simplified imaging flow is evaluated in terms of quality and efficiency by using real Ku-band FMCW SAR data. The results indicate that the simplified method could produce SAR imagery of high resolution (0.25 m × 0.25 m) in real time, with a speed-up factor of 2.77 comparing with the frequency scaling algorithm.

A conceptual radar platform design for detecting space debris down to 1 cm in diameter is presented for space situational awareness. Using known imaging algorithms, we show it is possible to overcome the problems associated with the typically small radar cross sections to yield a radar-attributable vector. Given the latter, the problem of matching the observation to a unique piece of debris is tackled independently of the imaging, or the detection, problem.

Frontal radar imaging of human activities may be useful in certain applications, such as through-wall surveillance, where cameras and x-ray sensors cannot be deployed. High-resolution radar images are currently obtained using electrically large antenna apertures operating at high frequencies. However, high frequencies are heavily attenuated by most walls. Also, the implementation of a radar with lots of array elements and associated data acquisition channels is costly and complex. In this paper, we propose methods to generate high-resolution Doppler-enhanced radar images of moving humans at low carrier frequencies with limited number of antenna elements. When a human moves, different body parts give rise to distinct Doppler returns. The key feature of our method is to dynamically resolve multiple body parts of the human across three dimensions: Doppler, azimuth, and elevation. The additional Doppler dimension allows us to relax the resolution requirements in terms of the carrier frequency and number of array elements across the other dimensions. We further reduce the number of array elements below the Nyquist limits by incorporating compressed sensing principles into two-dimensional beamforming because compressed sensing is particularly suited for solving certain types of under-resolved problems.We test our technique on simulated electromagnetic radar scattered data from a moving human for different radar configurations.We also study the robustness of the proposed technique to noise.

The time-varying, dispersion and non-stationary ionospheric characteristics cause the sky-wave radar echo spectra broaden and the layer-structure characteristics make the multimode and multipath propagation occur, which seriously affect the detection performance of the OTHR. Therefore, in this paper, using the ionospheric model provided by CCIR as reference and the data from the Hainan ionosonde, a dynamic ionospheric model is proposed to assess the detection performance of the sky-wave radar. We will study the detection performance of the sky-wave radar by the quality of the propagation path from three aspects. Firstly, the coverage of the sky-wave radar under the given ionospheric parameters and the working frequency is calculated. Secondly, whether the multimode phenomenon appeared in the propagation is considered. Thirdly, whether the multipath phenomenon occurred is studied. Then a program is developed to assess the radar detection capability based on the propagation path analysis, which can provide the working parameters for the sky-wave radar.

In this paper, we present a novel development of compact micropower ultrawideband (UWB) radar by integrating ultrashort balanced transmitter, sampling receiver, and antennas into a single package. The developed transmitter produces a pair of Gaussian pulses with 1 MHz of PRF, 400 ps of duration, and 8.3 V for peak-to-peak amplitude. The receiver down-converts microwave signals with a conversion gain of 3 dB over a 4.5-GHz bandwidth. The integrated UWB micropower radar system allows for the short-range detection with high range resolution and accuracy, thus enhance effectively the capability of target detection and classification. The high performances of such radar system for detecting objects are demonstrated through the real-field tests of various target scenes.

This paper presents a broadband and phaseless synthetic aperture radar (SAR) with efficient sampling. The design relies on a novel phaseless monostatic element comprising a transmitter and a receiver. This element, together with a computationally inexpensive algorithm, can retrieve the phase of the monostatic scattered field at all the working band except for two small safety margins at the lower and upper frequencies. Furthermore, the phase retrieval works independently of the transmitter/receiver position. Consequently, conventional approaches to reduce the number of monostatic acquisition points can be employed. Thus, the proposed strategy is suitable to implement either arrays that benefit from a reduced number of low-complexity elements or raster scan systems that benefit not only from the cost reduction of the scanning components but also from a remarkable speed-up due to the reduced number of acquisition points. Moreover, in contrast to other off-axis schemes, the proposed system does not require neither mechanical nor electrical phase shifting and, therefore, it can be directly adapted to a large number of frequency bands. The performance of the system is validated by simulation and measurement examples in the millimeter-wave band.

The field of wireless communications has benefited from multiple-input and multiple-output (MIMO) techniques. As researchers seek to apply MIMO (multistatic) techniques to radar and specifically to synthetic aperture radar (SAR), a key factor in determining MIMO application and performance is the level of correlation of signals from different receiver/transmitter pairs. The level of correlation determines whether a MIMO array falls into the category of a collocated array or a distributed array. The type of array dramatically affects which MIMO techniques may be performed and what advantages MIMO offers from conventional techniques. This paper presents models for calculating geometric correlation of multistatic SAR pixels using a ground-plane image formation. The models' results are compared to previous correlation models found in literature. A key result is that correlation depends on pixel resolution and not the number of individual scatterers. This paper concludes that most MIMO arrays operating on a single platform operate in the collocated regime.