scholarly journals Probabilistic analysis of ambiguities in radar echo direction of arrival from meteors

2020 ◽  
Author(s):  
Daniel Kastinen ◽  
Johan Kero
Keyword(s):  
Bayesian Method ◽  
Direction Of Arrival ◽  
Radar System ◽  
Stable Region ◽  
Radar Signal ◽  
Ambient Atmosphere ◽  
Radar Systems ◽  
Mu Radar ◽  
Meteor Trail ◽  
The Antarctic

Abstract. Meteors and hard targets produce coherent radar echoes. If measured with an interferometric radar system, these echoes can be used to determine the position of the target through finding the Direction Of Arrival (DOA) of the incoming echo onto the radar. If the DOA of meteor trail plasma drifting with the ambient atmosphere is determined, the neutral wind at the observation altitude can be calculated. Specular meteor trail radars have become widespread scientific instruments to study atmospheric dynamics. Meteor head echo measurements also contribute to studies of the atmosphere as the meteoroid input of extraterrestrial material is relevant for a plethora of atmospheric phenomena. Depending on the spatial configuration of radar receiving antennas and their individual gain patterns, there may be an ambiguity problem when determining the DOA of an echo. Radars that are theoretically ambiguity free are known to still have ambiguities that depend on the total radar Signal to Noise Ratio (SNR). In this study we investigate robust methods which are easy to implement to determine the effect of ambiguities on any hard target DOA determination by interferometric radar systems. We apply these methods specifically to simulate four different radar systems measuring meteor head and trail echoes using the multiple signal classification (MUSIC) DOA determination algorithm. The four radar systems are the middle and upper atmosphere (MU) radar in Japan, a generic Jones 2.5λ specular meteor trail radar configuration, the Middle Atmosphere Alomar Radar System (MAARSY) radar in Norway and the The Program of the Antarctic Syowa Mesosphere Stratosphere Troposphere Incoherent Scatter (PANSY) radar in the Antarctic. We also examined a slightly perturbed Jones 2.5λ configuration used as a meteor trail echo receiver for the PANSY radar. All the results are derived from simulations and their purpose is to grant understanding of the behaviour of DOA determination. General results are: there may be a region of SNRs where ambiguities are relevant; Monte Carlo simulation determines this region and if it exists; the MUSIC function peak value is directly correlated with the ambiguous region; a Bayesian method is presented that may be able to analyse echoes from this region; the DOA of echoes with SNRs larger then this region are perfectly determined; the DOA of echoes with SNRs smaller then this region completely fail to be determined; the location of this region is shifted based on the total SNR versus the channel SNR in the direction of the target; asymmetric subgroups can cause ambiguities even for ambiguity free radars. For a DOA located at the zenith, the end of the ambiguous region is located at 17 dB SNR for the MU radar and 3 dB SNR for the PANSY radar. The Jones radars are usually used to measure specular trail echoes far from zenith. The ambiguous region for a DOA at 75.5° elevation and 0° azimuth ends at 12 dB SNR. Using the Bayesian method it may be possible to analyse echoes down to 4 dB SNR for the Jones configuration, given enough data points from the same target. The PANSY meteor trail echo receiver did not deviate significantly from the generic Jones configuration. The MAARSY radar could not resolve arbitrary DOAs sufficiently well to determine a stable region. However, if the DOA search is restricted to 70° elevation or above by assumption, stable DOA determination occurs above 15 dB SNR.

scholarly journals Probabilistic analysis of ambiguities in radar echo direction of arrival from meteors

2020 ◽  
Vol 13 (12) ◽  
pp. 6813-6835
Author(s):  
Daniel Kastinen ◽  
Johan Kero
Keyword(s):  
Bayesian Method ◽  
Middle Atmosphere ◽  
Direction Of Arrival ◽  
Radar System ◽  
Stable Region ◽  
Radar Signal ◽  
Radar Systems ◽  
Mu Radar ◽  
Meteor Trail ◽  
The Antarctic

Abstract. Meteors and hard targets produce coherent radar echoes. If measured with an interferometric radar system, these echoes can be used to determine the position of the target through finding the direction of arrival (DOA) of the incoming echo onto the radar. Depending on the spatial configuration of radar-receiving antennas and their individual gain patterns, there may be an ambiguity problem when determining the DOA of an echo. Radars that are theoretically ambiguity-free are known to still have ambiguities that depend on the total radar signal-to-noise ratio (SNR). In this study, we investigate robust methods which are easy to implement to determine the effect of ambiguities on any hard target DOA determination by interferometric radar systems. We apply these methods specifically to simulate four different radar systems measuring meteor head and trail echoes, using the multiple signal classification (MUSIC) DOA determination algorithm. The four radar systems are the Middle And Upper Atmosphere (MU) radar in Japan, a generic Jones 2.5λ specular meteor trail radar configuration, the Middle Atmosphere Alomar Radar System (MAARSY) radar in Norway and the Program of the Antarctic Syowa Mesosphere Stratosphere Troposphere Incoherent Scatter (PANSY) radar in the Antarctic. We also examined a slightly perturbed Jones 2.5λ configuration used as a meteor trail echo receiver for the PANSY radar. All the results are derived from simulations, and their purpose is to grant understanding of the behaviour of DOA determination. General results are as follows: there may be a region of SNRs where ambiguities are relevant; Monte Carlo simulation determines this region and if it exists; the MUSIC function peak value is directly correlated with the ambiguous region; a Bayesian method is presented that may be able to analyse echoes from this region; the DOA of echoes with SNRs larger than this region are perfectly determined; the DOA of echoes with SNRs smaller than this region completely fail to be determined; the location of this region is shifted based on the total SNR versus the channel SNR in the direction of the target; and asymmetric subgroups can cause ambiguities, even for ambiguity-free radars. For a DOA located at the zenith, the end of the ambiguous region is located at 17 dB SNR for the MU radar and 3 dB SNR for the PANSY radar. The Jones radars are usually used to measure specular trail echoes far from zenith. The ambiguous region for a DOA at 75.5∘ elevation and 0∘ azimuth ends at 12 dB SNR. Using the Bayesian method, it may be possible to analyse echoes down to 4 dB SNR for the Jones configuration when given enough data points from the same target. The PANSY meteor trail echo receiver did not deviate significantly from the generic Jones configuration. The MAARSY radar could not resolve arbitrary DOAs sufficiently well enough to determine a stable region. However, if the DOA search is restricted to 70∘ elevation or above by assumption, stable DOA determination occurs above 15 dB SNR.

scholarly journals Broadband radar invisibility with time-dependent metasurfaces

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
V. Kozlov ◽  
D. Vovchuk ◽  
P. Ginzburg
Keyword(s):  
Signal Processing ◽  
Metal Plate ◽  
Primary Objective ◽  
Radar System ◽  
Radar Signal ◽  
Surveillance Systems ◽  
Radar Systems ◽  
Reliable Performance ◽  
Promising Solution ◽  
Radar Countermeasure

AbstractConcealing objects from interrogation has been a primary objective since the integration of radars into surveillance systems. Metamaterial-based invisibility cloaking, which was considered a promising solution, did not yet succeed in delivering reliable performance against real radar systems, mainly due to its narrow operational bandwidth. Here we propose an approach, which addresses the issue from a signal-processing standpoint and, as a result, is capable of coping with the vast majority of unclassified radar systems by exploiting vulnerabilities in their design. In particular, we demonstrate complete concealment of a 0.25 square meter moving metal plate from an investigating radar system, operating in a broad frequency range approaching 20% bandwidth around the carrier of 1.5 GHz. The key element of the radar countermeasure is a temporally modulated coating. This auxiliary structure is designed to dynamically and controllably adjust the reflected phase of the impinging radar signal, which acquires a user-defined Doppler shift. A special case of interest is imposing a frequency shift that compensates for the real Doppler signatures originating from the motion of the target. In this case the radar will consider the target static, even though it is moving. As a result, the reflected echo will be discarded by the clutter removal filter, which is an inherent part of any modern radar system that is designed to operate in real conditions. This signal-processing loophole allows rendering the target invisible to the radar even though it scatters electromagnetic radiation.

Methods of counteraction to means of electronic reconnaissance of the enemy during the operation of pulse-Doppler onboard radars of fighters for radiation

2021 ◽  
Author(s):  
A.V. Bogdanov ◽  
D.V. Zakomoldin ◽  
I.V. Kochetov ◽  
S.I. Akimov
Keyword(s):  
Radiation Power ◽  
Group Actions ◽  
Radar System ◽  
Radar Signal ◽  
Airborne Radar ◽  
Energy Potential ◽  
Advantages And Disadvantages ◽  
Radar Systems ◽  
Pulse Doppler ◽  
Technical Measures

The article proposes methods of counteraction to the enemy's electronic reconnaissance means, both for a duel situation and for group actions of fighters, analyzes their advantages and disadvantages, identifies limitations on their use. The physical meaning of these methods is to ensure the secrecy of the operation of on-board radar systems for radiation, due to the variation in the energy potential of the station, in particular, the time of coherent energy accumulation in narrow-band Doppler filters when receiving signals reflected from air targets and the radiation power of the transmitter of the on-board radar system when forming sounding radar signal packs. In the article, along with the methods of ensuring the secrecy of the operation of onboard radar systems of fighters, which make it possible to carry out technical measures only after radar contact with an air target equipped with electronic reconnaissance means, which leads to a decrease in their effectiveness, methods for controlling the secrecy of the operation of onboard radar systems of fighters are additionally given, allowing to provide stealth with a given probability in the dynamics of the approach of a fighter with its emitting airborne radar system with an air target, equipped with electronic reconnaissance means. In addition, it should be noted the method of managing the energy secrecy of airborne radar systems during group actions of fighters, within the framework of the development of which the possibility of summing up the powers emitted by the transmitters of the onboard radar systems of fighters when they work together for radiation in the position of conducting electronic reconnaissance is taken into account. Implementation of the developed methods will allow: to increase the survivability of fighters, and to an increase in this indicator, both the ensured secrecy of the operation of onboard radar systems of fighters for radiation and the implementation of the multi-position principle of building radar systems, given in the method of stealth control of the onboard radar system of fighters during group actions of fighters. to expand the combat capabilities of fighters, due to the fact that the covert operation of the onboard radar systems of fighters for radiation excludes the possibility of reconnaissance of the parameters of the sounding signal and, as a result, the possibility of setting active interference is excluded.

scholarly journals Broadband Radar Invisibility with Time-Dependent Metasurfaces

2021 ◽  
Author(s):  
Vitali Kozlov ◽  
Dmytro Vovchuk ◽  
Pavel Ginzburg
Keyword(s):  
Signal Processing ◽  
Metal Plate ◽  
Primary Objective ◽  
Radar System ◽  
Radar Signal ◽  
Surveillance Systems ◽  
Radar Systems ◽  
Reliable Performance ◽  
Promising Solution ◽  
Radar Countermeasure

Abstract Concealing objects from interrogation has been a primary objective since the integration of radars into surveillance systems. Metamaterial-based invisibility cloaking, which was considered a promising solution, did not yet succeed in delivering reliable performance against real radar systems, mainly due to its narrow operational bandwidth. Here we propose an approach, which addresses the issue from a signal-processing standpoint and, as a result, is capable of coping with the vast majority of unclassified radar systems by exploiting vulnerabilities in their design. In particular, we demonstrate complete concealment of a 0.25 square meter moving metal plate from an investigating radar system, operating in a broad frequency range approaching 20% bandwidth around the carrier of 1.5GHz. The key element of the radar countermeasure is a temporally modulated coating. This auxiliary structure is designed to dynamically and controllably adjust the reflected phase of the impinging radar signal, which acquires a user-defined Doppler shift. A special case of interest is imposing a frequency shift that compensates for the real Doppler signatures originating from the motion of the target. In this case the radar will consider the target static, even though it is moving. As a result, the reflected echo will be discarded by the clutter removal filter, which is an inherent part of any modern radar system that is designed to operate in real conditions. This signal-processing loophole allows rendering the target invisible to the radar even though it scatters electromagnetic radiation.

Automotive Radars

2017 ◽  
Author(s):  
Sujeet Patole ◽  
Murat Torlak ◽  
Dan Wang ◽  
Murtaza Ali
Keyword(s):  
Signal Processing ◽  
Pedestrian Detection ◽  
Radar Signal ◽  
Automotive Radar ◽  
Estimation Algorithms ◽  
Radar Systems ◽  
Starting Point ◽  
Processing Techniques ◽  
Automotive Radars ◽  
Signal Processing Techniques

Automotive radars, along with other sensors such as lidar, (which stands for “light detection and ranging”), ultrasound, and cameras, form the backbone of self-driving cars and advanced driver assistant systems (ADASs). These technological advancements are enabled by extremely complex systems with a long signal processing path from radars/sensors to the controller. Automotive radar systems are responsible for the detection of objects and obstacles, their position, and speed relative to the vehicle. The development of signal processing techniques along with progress in the millimeter- wave (mm-wave) semiconductor technology plays a key role in automotive radar systems. Various signal processing techniques have been developed to provide better resolution and estimation performance in all measurement dimensions: range, azimuth-elevation angles, and velocity of the targets surrounding the vehicles. This article summarizes various aspects of automotive radar signal processing techniques, including waveform design, possible radar architectures, estimation algorithms, implementation complexity-resolution trade-off, and adaptive processing for complex environments, as well as unique problems associated with automotive radars such as pedestrian detection. We believe that this review article will combine the several contributions scattered in the literature to serve as a primary starting point to new researchers and to give a bird’s-eye view to the existing research community.

A New Radar Signal Processing Architecture Based on Multi-Core Processor

2014 ◽  
Vol 556-562 ◽  
pp. 1618-1621
Author(s):  
Jia Liang Fan ◽  
Qiang Yang
Keyword(s):  
Signal Processing ◽  
Pulse Compression ◽  
Adaptive Beamforming ◽  
System Structure ◽  
Radar Signal ◽  
Radar Signal Processing ◽  
Test Results ◽  
Radar Systems ◽  
Multi Core Processor ◽  
Processing Architecture

Most radar systems based on the structure that contains many DSP chips. The system structure is always complex, and it is difficult to update. Nowadays, multi-core processor develops very fast. Compared with DSP chips, multi-core processor has better performance in signal processing field. In this paper, we present a signal processing architecture which based on multi-core processor. Pulse compression algorithms and PCI-E bus are discussed as two important technologies. Adaptive beamforming test results show that multi-core processor is able to achieve radar signal processing.

scholarly journals A Multiple Target Positioning and Tracking System Behind Brick-Concrete Walls Using Multiple Monostatic IR-UWB Radars

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 4033 ◽  
Author(s):  
Yoo ◽  
Wang ◽  
Seol ◽  
Lee ◽  
Chung ◽  
...  
Keyword(s):  
False Alarm ◽  
False Alarm Rate ◽  
Detection Rate ◽  
Tracking System ◽  
Radar System ◽  
Ultra Wideband ◽  
Radar Signal ◽  
High Detection Rate ◽  
Concrete Walls ◽  
Uwb Radar

Recognizing and tracking the targets located behind walls through impulse radio ultra-wideband (IR-UWB) radar provides a significant advantage, as the characteristics of the IR-UWB radar signal enable it to penetrate obstacles. In this study, we design a through-wall radar system to estimate and track multiple targets behind a wall. The radar signal received through the wall experiences distortion, such as attenuation and delay, and the characteristics of the wall are estimated to compensate the distance error. In addition, unlike general cases, it is difficult to maintain a high detection rate and low false alarm rate in this through-wall radar application due to the attenuation and distortion caused by the wall. In particular, the generally used delay-and-sum algorithm is significantly affected by the motion of targets and distortion caused by the wall, rendering it difficult to obtain a good performance. Thus, we propose a novel method, which calculates the likelihood that a target exists in a certain location through a detection process. Unlike the delay-and-sum algorithm, this method does not use the radar signal directly. Simulations and experiments are conducted in different cases to show the validity of our through-wall radar system. The results obtained by using the proposed algorithm as well as delay-and-sum and trilateration are compared in terms of the detection rate, false alarm rate, and positioning error.

scholarly journals Radar system with dedicated planar traveling wave antennas for elderly people monitoring

2020 ◽  
Vol 18 ◽  
pp. 97-110
Author(s):  
Sassan Schäfer ◽  
Simon Müller ◽  
Daniel Schmiech ◽  
Andreas R. Diewald
Keyword(s):  
Elderly People ◽  
Antenna Arrays ◽  
Traveling Wave ◽  
Radar System ◽  
Propagation Path ◽  
Design Parameters ◽  
Microstrip Technology ◽  
Actual Object ◽  
Radar Systems ◽  
24 Ghz

Abstract. Radar systems for contactless vital sign monitoring are well known and an actual object of research. These radar-based sensors could be used for monitoring of elderly people in their homes but also for detecting the activity of prisoners and to control electrical devices (light, audio, etc.) in smart living environments. Mostly these sensors are foreseen to be mounted on the ceiling in the middle of a room. In retirement homes the rooms are mostly rectangular and of standardized size. Furniture like beds and seating are found at the borders or the corners of the room. As the propagation path from the center of the room ceiling to the borders and corners of a room is 1.4 and 1.7 time longer the power reflected by people located there is 6 or even 10 dB lower than if located in the center of the room. Furthermore classical antennas in microstrip technology are strengthening radiation in broadside direction. Radar systems with only one single planar antenna must be mounted horizontally aligned when measuring in all directions. Thus an antenna pattern which is increasing radiation in the room corners and borders for compensation of free space loss is needed. In this contribution a specification of classical room sizes in retirement homes are given. A method for shaping the antenna gain in the E-plane by an one-dimensional series-fed traveling wave patch array and in the H-plane by an antenna feeding network for improvement of people detection in the room borders and corners is presented for a 24 GHz digital beamforming (DBF) radar system. The feeding network is a parallel-fed power divider for microstrip patch antennas at 24 GHz. Both approaches are explained in theory. The design parameters and the layout of the antennas are given. The simulation of the antenna arrays are executed with CST MWS. Simulations and measurements of the proposed antennas are compared to each other. Both antennas are used for the transmit and the receive channel either. The sensor topology of the radar system is explained. Furthermore the measurement results of the protoype are presented and discussed.

VARIATION OF METEOR ECHO RATES WITH RADAR SYSTEM PARAMETERS

1951 ◽  
Vol 29 (5) ◽  
pp. 403-426 ◽  
Author(s):  
D. W. R. McKinley
Keyword(s):  
Radio Wave ◽  
Wave Length ◽  
Radar System ◽  
Antenna Gain ◽  
Scattering Pattern ◽  
Magnitude Distribution ◽  
System Parameters ◽  
Transmitter Power ◽  
Meteor Trail ◽  
Strong Filter

Observations made with crossed-polarization radar system systems do not support the suggestion that the ionized meteor trail may act as a strong filter–polarizer of the incident radio wave. Experiments have been carried out to determine the variation of normal meteor echo rates with transmitter power, antenna gain, and radio wave length, and all confirm Lovell's scattering formula, provided that account is taken of the effective broadening of the scattering pattern of the meteor trail with increasing wave length. The limiting sensitivity of the 9.22 m. 200 kw. radar is determined to be about 9th magnitude. During a strong visual shower the observed increase in visual rates and low-power radar rates, compared to high-power radar rates, is explained by assuming that the magnitude distribution of the shower meteors differs from the normal nonshower distribution.

Machine Learning and Deep Learning Techniques for Colocated MIMO Radars: A Tutorial Overview

2021 ◽  
Author(s):  
ALESSANDRO DAVOLI ◽  
Giorgio Guerzoni ◽  
Giorgio Matteo Vitetta
Keyword(s):  
Machine Learning ◽  
Signal Processing ◽  
Deep Learning ◽  
Antenna Arrays ◽  
Research Work ◽  
Radar Signal ◽  
Open Problems ◽  
Technical Problems ◽  
Radar Systems ◽  
Learning Techniques

<p>Radars are expected to become the main sensors in various civilian applications, ranging from health-care monitoring to autonomous driving. Their success is mainly due to the availability of both low cost integrated devices, equipped with compact antenna arrays, and computationally efficient signal processing techniques. An increasingly important role in the field of radar signal processing is played by machine learning and deep learning techniques. Their use has been first taken into consideration in human gesture and motion recognition, and in various healthcare applications. More recently, their exploitation in object detection and localization has been also investigated. The research work accomplished in these areas has raised various technical problems that need to be carefully addressed before adopting the above mentioned techniques in real world radar systems. In this manuscript, a comprehensive overview of the machine learning and deep learning techniques currently being considered for their use in radar systems is provided. Moreover, some relevant open problems and current trends in this research area are analysed. Finally, various numerical results, based on both synthetically generated and experimental datasets, and referring to two different applications are illustrated. These allow readers to assess the efficacy of specific methods and to compare them in terms of accuracy and computational effort.</p>

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