Ground Radar System Research Articles

Application coherent processing of two frequency-spaced radar signals in target monitoring under conditions of relayed interference

The use of ground-based radar stations for space surveillance makes it possible to solve problem of detecting new and tracing previously known targets around the clock. The quality of operation ground-based radar station for space surveillance can be significantly reduced when solving problems of radar surveillance in complex phono-target and signal-interference environment. To improve effectiveness of radar surveillance it is advisable to carry out joint use of radar station for space surveillance, in particular as part of multi-position complex with possibility of joint coherent radar signal processing, including signals separated by frequency. It is necessary to develop models for evaluating effectiveness joint use of deferent-band radar stations for space surveillance when solving problems of radar surveillance in complex phono-target and signal-interference environment based on implementation of coherent processing two radar signals. The purpose of study is increase potential accuracy of radar measurements target trajectory parameters in conditions of relayed interference based on implementation of coherent processing two radar signals at ground radar systems for space surveillance. A model of target monitoring has been developed in system of two different-range radar stations for surveying space according to probabilistic indicator and dependences on linkage target trajectories were obtained based on implementation of coherent processing two radar signals in various conditions of signal-interference environment. The result of study can be used in evaluating effectiveness joint use of several radar stations for surveying space as part of multi-position radar systems when observing targets in conditions of noise and relayed interference.

Design and Implementation of Satellite ADS-B Receiver

With the rapid development of Chinese aviation industry, the amount of air flights has increased rapidly, and the traditional ground radar surveillance system has a limited geographic range, while the satellite ADS-B surveillance system has the advantages of all-time, all-weather, large-scale, and long-distance. It is an effective supplement to the aircraft ground monitoring system. This paper conducts research from the satellite ADS-B receiver system functions, technical indicators, hardware design, software design, structural design, etc., and establishes a test environment to prove that the satellite ADS_B receiver performance index design meets the technical requirements and has high application value.

Dependence between the accuracy of target designation to an onboard missile radar station and errors related to determination of the target and missile coordinates by a ground radar system

This article investigates the dependence between the accuracy of target designation issued by a ground radar system to an onboard radar station based on the measured target and missile coordinates and on the relative missile position (relative to the radar and the target). Simulation and calculation methods are proposed for estimating the accuracy of target designation in terms of the observation angle and the range and speed of the target taking into account both the errors in measuring the target and missile coordinates by a ground radar system and the relative position of the missile. The influence of the errors in measuring the target and missile coordinates and the relative position of the missile on the target designation accuracy is investigated. The problem of tracing the optimal trajectory of missile guidance to the target is formulated taking into account the errors of target designation to an onboard radar station and other factors.

Security-Enhanced Filter Design for Stochastic Systems under Malicious Attack via Smoothed Signal Model and Multiobjective Estimation Method

In this study, a novel security-enhanced filter (SEF) is proposed for the system state and malicious attack signal estimation of the stochastic jump-diffusion systems with the external disturbance, measurement noise and malicious attack signal on system and sensor. To efficiently estimate the system state and malicious attack signal by the traditional Luenberger-type filter, a novel smoothed signal model of malicious attack signals is embedded in the system model so that the attack signals in the augmented system do not corrupt the augmented states estimation of SEF again. For the optimal filtering robustness and security, the stochastic multi-objective (MO) $H_{2}/H_{\infty }$ SEF scheme is proposed to achieve optimal disturbance and noise filtering performance and the optimal security enhancement under malicious attack. By using the suboptimal method, the stochastic MO $H_{2}/H_{\infty }$ SEF design could be equivalently transformed to linear matrix inequalities (LMIs)-constrained multi-objective optimization problem (MOP). In the case of nonlinear stochastic system, the MO $H_{2}/H_{\infty }$ SEF design problem could be converted to a Hamilton-Jacobi inequalities (HJIs)-constrained MOP. In order to overcome the difficulty in solving the HJIs-constrained MOP, based on the global linearization technique, the HJIs-constrained MOP for SEF design of nonlinear stochastic systems could be transformed to an LMIs-constrained MOP. Further, an LMIs-constrained multi-objective evolution algorithm (MOEA) is proposed to efficiently solve the LMIs-constrained MOP for the design of SEF. Two simulation examples including the missile trajectory estimation problem by ground radar system under the malicious attack signals and estimation of netwoked-based mass spring system are given to validate the effectiveness of the proposed method.

Performance Analysis of 3D Localization for a Launch Vehicle Using TOA, AOA, and TDOA

In general, a ground telemetry station for a launch vehicle (LV) includes a tracking function only; therefore, position measurements for LV depend on received navigation data from on-board systems of LV or depend on estimated position from ground radar system in real time. At the first launch of the Korea Space Launch Vehicle-1 (KSLV-1) in August 2009, we observed anomalies in ‘pairing separation’ event. As a result, we failed to obtain stable navigation data of the LV. In addition, estimated positions from the radar station away 1000 km to the LV also included many errors due to low antenna elevation angle. The experiences of failure has led to needs for additional localization solutions in ship-born telemetry station deployed in the Pacific to cover ‘satellite separation’ event. Time of arrival (TOA), time difference of arrival (TDOA), and angle of arrival (AOA) are typical location techniques used for an emitting target. In this study, we analyze three localization methods: TOA–AOA, AOA–AOA, and TDOA–AOA for a LV using ground telemetry stations. When each ground station is synchronized to a GPS time, by comparing the time stamps of each receiver (Rx), TOA and TDOA equations can be obtained. In addition, AOA equations can be obtained from the monopulse tracking antenna of each station. By solving these equations, a three-dimensional (3D) target point can be obtained. We confirm localization performance of the proposed solution by comparing with an on-board GPS of 3rd KSLV-1 mission in January 2013.

3D Localization for Launch Vehicle Using Virtual TOA and AOA of Ground Stations

Generally, a ground telemetry station for a launch vehicle (LV) includes a tracking function only; therefore, position measurements for LV depend on received navigation data from on-board systems of LV or depend on estimated position from ground radar system in real time. Time of arrival (TOA) and angle of arrival (AOA) are typical location techniques for emitting targets. In this study, we propose a virtual on-board timer to estimate TOA for LV and verify its localization performance using Combined TOA and AOA localization method. For real time processing, the proposed virtual on-board timer should be created at space center and distributed to remote stations before lift-off of LV. By comparing the time stamp of the virtual on-board timer and received time, TOA and its corresponding slant range can be estimated. In order to combine the estimated TOA and AOA, we create sphere equations with the estimated range radius and vertical plane equations, to include unit vectors for the AOA direction. By solving these equations, a three-dimensional (3D) target point can be obtained. We confirm localization performance of the estimated TOA by comparing with an on-board GPS of 3rd KSLV-1 mission in January 2013.

Embedded Digital SISO Radar using Wireless Open Access Research Platform for Object Detection and RCS Measurement

Nowadays, the ground radar systems are mostly used for controlling airspace or making weather images. These systems consist of large antenna, a lot of the electronic equipment and very powerful computational unit. Smaller versions of these systems are often carried on the board of planes but still they are quite complex devices. Much simpler versions of the systems mentioned above but still using the same basic principles are small compact devices for measuring Target RCS or Target detection. In these applications, small size embedded SDR radar can be used. Then real time processing of a radar signal can also be much simpler. For the above mentioned simple applications, it is possible and reasonable to have small devices with low power consumption that perform real time correlation based processing. Typical today’s embedded FPGA based SDR solutions have enough computational performance and their electric input is also very low. Moreover, the dimensions of the processor boards are very compact and they can be easily integrated into very small cases. That’s why it is good to transfer radar signal processing algorithms to the embedded system. The recent development in the digital Radar is now molded in these SDR systems. Our motivation is to design a Spread Spectrum based digital SDR radar which is very small in size and may be a low cost solution where we can bypass all the huge instrumentation complexity. This type of solution is now popular for defense organizations, even can be used in human daily life.

Design of target state estimation algorithm with hybrid measurements

ÖZETBazı güdümlü füzelerde, hedefe dair bilgiler (pozisyon/hız/ivme), arayıcının henüz hedefe kilitlenmediği durumda çalıştırılan arasafha güdüm algoritmalarında kullanılmak üzere, yer sisteminde bulunan radar tarafından ölçülerek/hesaplanarak veribağı yoluyla füzeye iletilir. Veribağı iletiminin terminal fazda sürmesi durumunda, bu bilgiler aynı zamanda terminal fazda tanımlı ileri güdüm yöntemlerinin uygulanması ve güdüm performansının arttırılması için kullanılabilir. Bu çalışmada, arayıcı ve radar tarafından sağlanan farklı frekanslardaki ölçümler, Extended Kalman Filtresi tabanlı kestirim yöntemiyle tümleştirilmiştir. 3 boyutlu füzehedef kinematiğini yansıtan küresel koordinat sisteminde tanımlı sistem modelinde, hedefin ivmelenmediği varsayılmıştır. Bu çalışmanın sonucunda, hedefe kalan mesafe ve yaklaşma hızı kestirimi elde edilmiştir.

Update: Magnetic Field Sensors Could Help Halt Runway Crashes

Air-traffic control is a complex and high-stress business. Mistakes are not allowed. And it's not limited to directing planes for takeoff and landing - a job that's been memorably described as three-dimensional chess. It also includes keeping track of where planes are on the ground. According to safety watchdog Eurocontrol, in 2005 alone there were 600 occasions when people, cars, or planes crossed Europe's airport taxiways when they shouldn't have. In fact, the most deadly airline accident ever happened on the ground: in 1977, two 747 jumbo jets collided in the Canary Islands, killing 583 people. Most big airports have expensive ground-radar systems to keep track of where the hundreds of moving planes are on the sprawling tarmacs. But ground radar sometimes reflects off buildings and terminals, leaving small gaps in coverage. Smaller airports like the one in Thessaloniki, Greece, can't afford ground radar. Such blind spots on the ground at airports large and small have prompted European researchers to explore the use of fluctuations in the Earth's magnetic field to better pinpoint where planes are on busy taxiways. The results, researchers say, show that using US $150 sensors can fill in the blind spots.

Practical design of a high-power tuning-less W-band triplexer for ground radar surveillance systems

The design of a rectangular waveguide 95 GHz (W-band) triplexer for ground radar systems is presented. The triplexer comprises three in-line filters with inductive irises as coupling elements and a manifold formed by three T-junctions. In particular, the scheme proposed is aimed at handling large powers and reducing losses. The triplexer was assembled and measured, showing very good agreement with the simulated results.

Ion outflow and associated perpendicular heating in the cusp observed by Interball Auroral Probe and Fast Auroral Snapshot

The spatial properties of ionospheric ion outflows associated with perpendicular heating processes in the cusp are studied using a conjunction study from two satellites and ground radar systems. Low‐energy outflowing ions are measured in a wide longitudinal range, between 13,000 and 19,000 km in altitude, over the dayside polar cap by the Hyperboloid experiment aboard the Interball Auroral Probe (AP). These observations are related to conjugate convection field measurements by the Saskatoon‐Kapuskasing pair of the Super Dual Auroral Radar Network (SuperDARN). Data analysis suggests that outflowing ions originate from a wide magnetic local time range associated with both the dayside cusp region and the dayside cleft region. A direct cusp crossing by the Fast Auroral Snapshot (FAST) satellite at 2000‐km altitude shows a correlation between transverse ion heating in a thin latitudinal region (∼1.3°) and the presence of broadband extremely low frequency (BBELF) turbulence, in addition to more intense electrostatic waves near and just above the lower hybrid (LH) frequency. This event is unusual because on the basis of the statistical survey of Freja and FAST data, most of the ion‐heating events in the midaltitude auroral zone are correlated with enhanced emissions in the BBELF range. Furthermore, the electron population has energies that are too small to drive LH waves unstable. This event offers the opportunity to analyze the contribution of cusp magnetospheric ion injections to the heating of the ambient H+ and O+ ions. Kinetic instability calculations demonstrate that LH waves are destabilized by the ring distributions, which result from injections of high‐energy magnetosheath ions. Calculations show that a preheating mechanism by BBELF turbulence near the ion gyrofrequencies is also required so that LH heating is able to occur. The altitude dependence of the LH perpendicular heating is then analyzed by modeling the transport of the injected magnetospheric ions along magnetic field lines. It is shown that LH heating acts as an additional process from ∼2000 up to 10,000 km in altitude. In addition, trajectory calculations show that the low‐energy outflowing H+ and O+ ions observed along Interball AP orbit in the polar cap are heated inside the cusp at altitudes extending up to 15,000 km. These results are then assembled to construct a possible heating scenario inside the cusp for this data set. The contribution of the different energization mechanisms to the ion heating as a function of altitude is then discussed.

Regularized gaussian mixture models for effective short-term forecasting of rainfall patterns

In this paper, we report about the application of regularized Gaussian mixture models in the task of predicting rainfall patterns based on ground radar images. The mixture models are used to obtain a parametric estimate of the rainfall density distribution that permits prediction through linear extrapolation of the parameters. Regularization is introduced to ensure the identifiability of the parameters and the linear relationship needed for prediction. On a set of 6 independent image sequences we demonstrate that this type of regularization can indeed significantly improve the prediction performance. Short-term prediction of rainfall patterns is extremely important for meteorological and environmental reasons. The type of prediction described in this paper is being used in a commercial package based on a low-cost ground radar system designed to provide optimal in-flow forecasts for sewage treatment plants.

The Use of TRMM Precipitation Radar Observations in Determining Ground Radar Calibration Biases

Since the successful launch of the Tropical Rainfall Measuring Mission (TRMM) satellite, measurements of a wide variety of precipitating systems have been obtained with unprecedented detail from the first space-based radar [precipitation radar (PR)]. In this research, a methodology is developed that matches coincident PR and ground-based volume scanning weather radar observations in a common earth parallel three-dimensional Cartesian grid. The data matching is performed in a way that minimizes uncertainties associated with the type of weather seen by the radars, grid resolution, and differences in radar sensitivities, sampling volumes, viewing angles, and radar frequencies. The authors present comparisons of reflectivity observations from the PR and several U.S. weather surveillance Doppler radars (WSR-88D) as well as research radars from the TRMM field campaigns in Kwajalein Atoll and the Large Biosphere Atmospheric (LBA) Experiment. Correlation values above 0.8 are determined between PR and ground radar matched data for levels above the zero isotherm. The reflectivity difference statistics derived from the matched data reveal radar systems with systematic differences ranging from 1 2t o27 dB. The authors argue that the main candidate for systematic differences exceeding 1 to 1.5 dB is the ground radar system calibration bias. To verify this argument, the authors used PR comparisons against well-calibrated ground-based systems, which showed systematic differences consistently less than 1.5 dB. Temporal analysis of the PR versus ground radar systematic differences reveals radar sites with up to 4.5dB bias changes within periods of two to six months. Similar evaluation of the PR systematic difference against stable ground radar systems shows bias fluctuations of less than 0.8 dB. It is also shown that bias adjustment derived from the methodology can have significant impact on the hydrologic applications of ground-based radar measurements. The proposed scheme can be a useful tool for the systematic monitoring of ground radar biases and the studying of its effect.

Passive deployment of a tether between two bodies in orbit

The authors consider the problem of deployment in orbit of a small tether that can serve as a standard of length for calibration of both onboard and ground optical and radar tracking systems, as an integrated sensor of the force fields of planets, etc. A tether for two bodies is examined. Possible methods for compact placement of a tether in orbit in operating condition are discussed. The main method is that of use of the centrifugal forces resulting from imparting to the tether an initial angular velocity in its deployment from the spacecraft. Various methods for creating moments of friction forces in hinges are considered. Numerical modeling of the dynamic processes is carried out within the framework of the theory of systems of bodies. Problems associated with determination of the required initial angular velocity and of the “cone of departure” of the tether from the spacecraft are examined.

On Line Measurement of Grass Flow in the Field

At IMAG-DLO, a project is carried out for precision farming in grassland. A Mobile Weighting Unit (MWU) is used for the on-line weighting of the grass crop after mowing of the crop (Fig.1). Under the MWU (a modified Heston swath mower) a conveyer belt with a width of 1.2m is mounted. On the IMAG experimental farm in Duiven measurements are done to get information about the yield and distribution of the grass along the field. 8 test rows are measured and the results are stored on the computer on the MWU.A ground radar system is used for the exact positioning of the MWU in the row. In the future a D-GPS system will be tested for the accurate positioning in the field.

Application of SAR data to monitoring of earthquake disaster

Surface changes and displacement caused by the Hyogoken-nanbu earthquake on 17 January 1995 are detected using JERS-1 SAR images with interferometric radar technology. The SAR signal data covering the damaged area were contaminated by serious bright line noise caused by interference with a ground radar system. With a spectral filtering technique, the signal data were processed into clear images. Collapsed non-wooden buildings and guarys were detected by comparing pixel brightness between a pair of images before and after the earthquake. A phase interferogram of the two images shows 0.6 m surface displacement along the radar line-of-sight direction around Kobe City, while it is 1.1 meter in Awaji Island where epicenter is located.

Radar development to 1945

The beginnings of radar early history of radar in the US Navy German radar development history of Japanese radar development to 1945 who invented radar? the UK CH ground radar system UK airborne radar RDF and early IFF countermeasure receiver techniques German World War II anti-jamming techniques the post-war years and progress in absolute microwave measurements.

Contribution of explosion and future collision fragments to the orbital debris environment

The time evolution of the near-Earth man-made orbital debris environment modeled by numerical simulation is presented in this paper. The model starts with a data base of orbital debris objects which are tracked by the NORAD ground radar system. The current untrackable small objects are assumed to result from explosions and are predicted from data collected from a ground explosion experiment. Future collisions between Earth orbiting objects are handled by the Monte Carlo method to simulate the range of collision possibilities that may occur in the real world. The collision fragmentation process between debris objects is calculated using an empirical formula derived from a laboratory spacecraft impact experiment to obtain the number versus size distribution of the newly generated debris population. The evolution of the future space debris environment is compared with the natural meteoroid background for the relative spacecraft penetration hazard.