Radar Sensor System Research Articles

Novel Anti-Deception Jamming Method by Measuring Phase Noise of Oscillators in LFMCW Tracking Radar Sensor Networks

In this paper, the effects of phase noise difference in receiving signals are introduced to discriminate targets. Oscillators and signal sources have their own phase noise levels and specific patterns. This property can be used for discriminating a real target from the airborne digital radio frequency memory (DRFM) in continuous wave tracking radar sensor networks with linear frequency modulation. A simulated signal made through complex circuits by DRFM has higher phase noise with different patterns. To investigate the phase noise level of oscillators, a system is provided to measure the phase noise. Then, the probability of detection ( $P_{D}$ ) and the probability of false alarm ( $P_{fa}$ ) can be achieved by defining an appropriate threshold to evaluate the performance of discriminating between real targets and DRFM targets. The phase noise powers are measured through the same sets of circuits and coherent time periods in various radar sensor systems. To control the amplitude fluctuation of the received signal, the normalization of signal phase power is defined in phase noise bandwidths. The likelihood ratio test is used for target discrimination by a threshold level to achieve the minimum $P_{fa}$ of target discrimination. The proposed method has a simple structure without any additional complexities, and is easily compatible with common radar systems. Two real DRFM systems are used to evaluate the performance of the proposed method in both the L-band and X-band frequencies. The presented results are investigated in different ranges, Doppler frequencies, signal-to-noise ratios, and signal-to-jammer ratios. The experimental results prove the capability of proposed method in radar sensor networks.

ALOS/PALSAR Data Evaluation for Land Use and Land Cover Mapping in the Amazon Region

In tropical biomes such as the Amazon, the cloud cover is frequent. The use of synthetic aperture radar (SAR) sensor systems is important to monitor and study these biomes because they can acquire data under cloud coverage. In this paper, an advanced land observing system phased array L-band synthetic aperture radar fine-beam dual (ALOS/PALSAR-FBD) image was evaluated for land use and land cover (LULC) classification of an Amazon test site. The features extracted from this image were also evaluated. To perform this task, a method for feature selection, considering the desired classes, was proposed. In order to better understand the applicability of this type of data in Brazilian Government projects (such as DETER-B and TerraClass), the results obtained with SAR images were compared with those from LANDSAT5/TM. The results show that the PALSAR-FBD image and the features selected are not suitable for the discrimination of densely forested classes. They presented, however, a good discrimination among the group of forested and agropastoral classes, as well as among nondensely forested classes (i.e., pastures, bare soil, and new regeneration). Therefore, these data present good applicability for mapping and monitoring of both deforestation and LULC and they can be used in the above mentioned projects. The classification of selected features, with eight classes of interest, achieved an increase of about 133% and 69% in the Kappa index (0.32) and an Overall Accuracy (0.54) regarding the PALSAR-FBD classification (0.136 and 0.322, respectively). This result shows the applicability of the proposed method. It is also expected that the features selected in this paper will improve the classification of similar study sites.

Modeling Radar Probability of Detection for a Randomly-Located Mover on an Arbitrary Road Network

The complexity of modern defense systems requires a holistic approach to modeling system performance. Reductionist methods fail to capture emergent behaviors and other complex behaviors characteristic of these systems. For sensor systems that include ground moving target indicator (GMTI) radar sensors, having a model for probability of detection is useful for simulating, analyzing, and evaluating system performance. To this end, this paper presents mathematical modeling of detection performance of a GMTI ground radar sensor system. Specifically, we define a detection scenario in which a single ground mover within the radar scan sector is randomly distributed on a road network according to traffic loading constraints. We perform mathematical modeling to generate a general truth expression for probability of ground mover detection over general road networks. We present special cases in which closed-form expressions for the probability of detection exist. We generate empirical detection results using Monte Carlo simulation with a GMTI radar simulation to validate the mathematical modeling.

잠수함 발사 탄도미사일 탐지를 위한 해상 센서플랫폼의 배치에 관한 연구

본 논문은 잠수함 발사 탄도미사일(SLBM) 탐지를 위한 해상 센서플랫폼의 배치에 관한 연구이다. 최근 북한은 SLBM의 수중 사출시험을 실시하였으며 이는 국제사회에 심각한 안보 위협이 되고 있다. 이러한 위협에 효과적으로 대응하기 위해 기동이 가능한 해상 센서플랫폼은 SLBM의 탐지 가능성이 높은 위치에 배치되어야 한다. 그러나 전형적인 레이더 센서체계의 최대탐지거리 특성은 표적의 비행궤적과 레이더 반사 단면적(RCS)에 따라 달라진다. 이러한 관점에서 본 연구는 SLBM의 전술적 특성에 따른 비행궤적을 분석하고, RCS를 계산하였다. 또한 센서 플랫폼의 위치에 따른 탐지 시간을 분석하여 효과적으로 SLBM을 탐지할 수 있는 해상 센서 플랫폼의 위치를 제시하였다. This paper describes deployment of a sea based sensor platform for the detection of a submarine launched ballistic missile (SLBM). Recently, North Korea successfully conducted the underwater launching test of the SLBM, which will seriously threaten the global security. To defend these threats successfully, a sensor platform of the ballistic missile defense (BMD) should be deployed in the area of high detection probability of the missile. The maximum detection range characteristics of the typical radar sensor system, however, depend on the radar cross section (RCS) and flight trajectories of the target. In this point of view, this work analyzed the flight trajectories based on the tactics and calculated the RCS of the SLBM. In addition, sea based sensor platform position is proposed from the analysis of the detection time.

BLASTDAR—A Large Radar Sensor Array System for Blast Furnace Burden Surface Imaging

In this paper, we present a radar sensor system for real-time blast furnace burden surface imaging inside a fully operative blast furnace, called BLASTDAR, the blast furnace radar. The designed frequency-modulated continuous-wave (FMCW) radar sensor array operates in the frequency band around 77 GHz and consists of several nonuniformly spaced receive and transmit antennas, making it a multiple-input multiple-output radar system with large aperture. Mechanical steering is replaced by digital array processing techniques. Off-the-shelf automotive-qualified multichannel monolithic microwave integrated circuits are used. By means of this configuration, a virtual antenna array with 256 elements was developed that guarantees the desired angular resolution of better than 3°, and a range resolution of about 15 cm. Based on the single-channel FMCW signal model, this paper will derive a multichannel signal model in combination with a digital beamforming approach and further advanced signal processing algorithms. The implementation of a simulation tool covering the whole design process is shown. Based on these simulation results, a system configuration is chosen and the obtained setup is defined and presented. A description of the manufactured cost-efficient radio frequency and baseband boards together with the housing design shows the practical implementation of the sensor. For the system calibration, two different methods are listed and compared regarding their performance. Verification measurements confirm the predicted performance of the developed sensor. Several measurements inside a fully operational blast furnace demonstrate the proper long-term functionality of the system, to the best of our knowledge, for the first time worldwide. It is in continuous operation since about two years in blast furnace #5 of voestalpine Stahl GmbH, Linz.

Fidelity Requirements for Effective Live-Virtual-Constructive Training of Navy F/A-18 Pilots

The Office of Naval Research (ONR) Live-Virtual-Constructive (LVC) training program seeks to safely integrate virtual tracks (display symbols that represent aircraft flown by pilots in simulators) and constructive tracks (symbols that represent computer-generated aircraft) into live F/A-18 E/F/G radar and cockpit sensor system displays to reduce resource demands and support new capability requirements in air combat training. In a preceding effort, the researchers identified a number of aircrew concerns about the design of LVC training technology and its potential effects on air combat training quality and realism. Based on these findings, the researchers conducted an exploratory survey to better establish and gauge LVC fidelity requirements. Thirty air combat training professionals completed the survey. The survey results, presented herein, will be used to guide LVC engineering decision-making and design trade-offs.

A Self-Calibrating Radar Sensor System for Measuring Vital Signs.

Vital signs (i.e., heartbeat and respiration) are crucial physiological signals that are useful in numerous medical applications. The process of measuring these signals should be simple, reliable, and comfortable for patients. In this paper, a noncontact self-calibrating vital signs monitoring system based on the Doppler radar is presented. The system hardware and software were designed with a four-tiered layer structure. To enable accurate vital signs measurement, baseband signals in the radar sensor were modeled and a framework for signal demodulation was proposed. Specifically, a signal model identification method was formulated into a quadratically constrained l1 minimization problem and solved using the upper bound and linear matrix inequality (LMI) relaxations. The performance of the proposed system was comprehensively evaluated using three experimental sets, and the results indicated that this system can be used to effectively measure human vital signs.

Evaluation of a Doppler radar sensor system for vital signs detection and activity monitoring in a radio-frequency shielded room

This study presents an evaluation of an advanced Doppler radar-based method for detection of vital signs, presence, and activity of a human subject in a test room with radar-signal reflecting aluminum-coated surfaces. Ten test subjects lay in four positions, and they sat in two locations in the room, both breathing normally and holding their breath. The mean ratios of the pulse rates determined from the radar signal and electrocardiography and respiration reference signals were 110% (respiration) and 99% (heartbeat), and the mean occupied and empty room radar signal variance ratios were 608 (breathing) and 20 (breath-hold). In a one-subject activity monitoring test, walking, standing and lying activities could be well separated from the radar signal. The results are promising and the proposed system seems to have potential to be used in position-independent health and activity monitoring of, for example, elderly people in care homes or intoxicated people in police custody.

Doppler Radar Motion Sensor With CMOS Digital DC-Tuning VGA and Inverter-Based Sigma-Delta Modulator

In most of the traditional miniature Doppler radar systems, ac coupling is adopted between the radio frequency front-end and baseband amplifier to block the dc offset due to clutter reflection. However, ac coupling causes distortion to low frequency signals and loses the dc information, which represents slowly changing or stationary moment of the target. A dc-coupled radar sensor system using a variable gain amplifier (VGA) with software-configured digital tuning architecture is presented in this paper to realize dc tuning and dc offset calibration. Furthermore, to process the output signals from the VGA, a novel low-voltage low-power inverter-based second-order sigma-delta modulator has been developed. The frequency of mechanical motion can be detected from the spectrum of the presented modulator output digital bit stream without a decimation filter, which can significantly reduce the cost and the power consumption. Furthermore, it can potentially detect the motion amplitude using the relative strength of the harmonics in the spectrum of the output digital bit steam. Experiments show that the presented digital dc-tuning VGA can completely relieve the radar sensor from circuit saturation and the inverter-based sigma-delta modulator can perform under low voltage and low power to accurately detect the movement frequency of the target without a decimation filter. Both the presented VGA and modulator show great potential for integrating a Doppler radar sensor system into a low-power high-accuracy single chip in the future.

Integrated Wireless Sensor Systems via Near-Space and Satellite Platforms: A Review

Due to extreme conditions, the near-space region is vastly underused and can be utilized for various scientific uses. The unconstrained orbital mechanism and low fuel consumption advantages for using synthetic aperture radar over the satellites and airplanes navigation systems make these conditions superior for a wide range of services, monitoring, earth observation, and sensing applications. The augmented integration within the existing global navigation system can help in measuring the direction-of-arrival, as well as collecting and distributing accurate location information. For wireless sensing applications, it can enable a new range of opportunities, a wide range of smart sensor applications as experimental platforms for deployment of new technologies. Here, we also examine the implementation of near-space platform (NSP) coverage and associated technologies. Then, a brief integration of communication and navigation services using NSP from a top-level system description of how to relay, associated complementary systems, including radar sensor systems, satellite systems, and terrestrial networks can be used.

Definition of adaptive detection threshold under employment of the generalised detector in radar sensor systems

An adaptive detection threshold under employment of the generalised detector (GD) in radar sensor systems is defined. GD is constructed in accordance with the generalised approach to signal processing in noise. To define the GD adaptive threshold based on the observed noise samples, the authors apply an appropriate noise power estimation technique. This study deals with an adaptive GD detection threshold definition as a function of the estimated noise power. Under investigations, they use two noise power estimation procedures. The first is the sliding window technique with the reference cells. The second procedure is based on the adaptive noise power estimation. Comparative analysis of simulation results demonstrates superiority by detection performance in favour of GD implementation in comparison with the well-known constant false alarm rate (CFAR) detectors, namely, cell averaging CFAR and ordered statistics CFAR detectors.

77-GHz Automotive Radar Sensor System With Antenna Integrated Package

In this paper, a 3-D integrated 77-GHz automotive radar front-end is presented. Embedded wafer level packaging (EMWLP) technology is proposed to eliminate the use of wire bonding, which not only introduces significant radio frequency loss, but also occupies large footprint for high-pin count die. The transceiver bare die is embedded in a reconfigured molded wafer with compression molding process. Double-sided multiple redistribution layers are formed to fan-out the transceiver input/output signals and through mold via is employed to realize the vertical interconnection. With these promising features, the EMWLP technology can be extended to a 3-D integration. A substrate integrated waveguide slot antenna is integrated on top of the EMWLP module and a lens is used to enhance the antenna directivity. The performance of the fully integrated radar front-end is tested and the measurement results show good package performance with RF loss around 5 dB for most of the samples. Temperature cycling reliability test was also performed by letting the fully integrated prototype goes through 1000 temperature cycles with JEDEC standard. The measured package loss spread across samples after 1000 cycles of TC test is about 13 dB, which is mainly due to the antenna warpage affecting the RF path's signal integrity.

Dual Super-Systolic Core for Real-Time Reconstructive Algorithms of High-Resolution Radar/SAR Imaging Systems

A high-speed dual super-systolic core for reconstructive signal processing (SP) operations consists of a double parallel systolic array (SA) machine in which each processing element of the array is also conceptualized as another SA in a bit-level fashion. In this study, we addressed the design of a high-speed dual super-systolic array (SSA) core for the enhancement/reconstruction of remote sensing (RS) imaging of radar/synthetic aperture radar (SAR) sensor systems. The selected reconstructive SP algorithms are efficiently transformed in their parallel representation and then, they are mapped into an efficient high performance embedded computing (HPEC) architecture in reconfigurable Xilinx field programmable gate array (FPGA) platforms. As an implementation test case, the proposed approach was aggregated in a HW/SW co-design scheme in order to solve the nonlinear ill-posed inverse problem of nonparametric estimation of the power spatial spectrum pattern (SSP) from a remotely sensed scene. We show how such dual SSA core, drastically reduces the computational load of complex RS regularization techniques achieving the required real-time operational mode.

Spatial Virtual Polarization Filter Design for Radar Sensor

As interferences are introduced from main-lobe direction which results in tar-get signal are masked by interference, traditional adaptive beam-forming can not suppress main-lobe interferences effectively. Polarization filtering is a main method to suppress the interference in radar and other sensor systems. Based on the spatial polarization characteristic (SPC) of antenna, a spatial virtual polarization filter (SVPF) is proposed by constructing polarization decomposition and polarization estimation of the received signal. A generalized construction method of SVPF is provided, the performance of the SVPF is given, and simulation results of the interference suppressing are illustrated. It is indicated that the proposed filter is a valid filtering technique for interference canceling. SVPF made single polarized radar own polarization information processing ability which improved radar working performance.

모노 펄스 레이더 센서용 직렬 급전 마이크로스트립 패치 배열 안테나 설계

In this paper, a method for simultaneously realizing the sum and difference patterns which are required in the monopulse radar sensor systems, is presented by using single taper array antenna with rectangular microstrip patches. The widths of patches are first determined by the voltage weights which are synthesized for the fundamental array factor patterns to be applied to the monopulse operation by using the sidelobe levels(SLLs) control technique. As the bi-directionally series-fed technique is applied and the lengths of connecting lines between patches are appropriately adjusted, the single array generates two phase-shifted beams which activates out-of-phase and in-phase ports of a hybrid coupler to synthesize the sum and difference patterns. The simulated results on the configuration designed at 9.5 GHz are compared with measured results showing the validity of the proposed method.

Using dual‐polarized ALOS PALSAR data for detecting new fronts of deforestation in the Brazilian Amazônia

This study shows the use of dual‐polarized L‐band Synthetic Aperture Radar (SAR) data acquired by the Advanced Land Observing Satellite (ALOS) Phased Array type L‐band Synthetic Aperture Radar sensor (PALSAR) system for differentiation between primary forest and new deforestation fronts. Results showed that the new deforested areas are not unequivocally detected in either of the single bands individually. Although most of the recent deforestation appears brighter than mature forests in the HH band, the identification of new deforestation using only this band depends on the stage of the clearing process. Then, the contribution of the HV band through a normalized difference index (NDI) is important for detection of the new deforested fronts. Results indicate that the method can be used as the basis for an operational programme to monitor deforestation in the Brazilian Amazônia.

Response of RF Networks to Transient Waveforms: Interference in Frequency-Hopped Communications

The long-tail transient responses of a bandpass network to pulsed and switched-tone stimuli are examined and a time-domain closed-form expression of the envelope response is developed. It is shown that the long-tail response leads to interference in frequency-hopping communication systems. Interference, and in particular co-site interference, can result in any radar, communication, or RF sensor system becoming exposed to unintentional pulsed RF signals. In the experimental study, 900-MHz Chebyshev bandpass filters are considered.

Vehicle Classification Based on the Radar Measurement of Height Profiles

The problem of classifying road vehicles according to vehicle type is considered. The proposed solution is based on using vehicle height and length and height profiles obtained by a microwave (MW) radar sensor. We show that if the radar sensor satisfies certain requirements, then a precise feature vector can be extracted, and simple deterministic algorithms can be applied to determine the vehicle class. Field trials using a spread-spectrum MW radar sensor system operating on these principles have been carried out. They confirm that accurate classification of a large number of vehicle classes can be reached

Frequency-tuning technique for remote detection of heartbeat and respiration using low-power double-sideband transmission in the ka-band

A Ka-band transceiver using low-power double-sideband transmission to detect human heartbeat and respiration signals is demonstrated. The Ka-band electromagnetic wave offers higher detection sensitivity on small movement due to its shorter wavelength. Indirect-conversion receiver architecture is chosen to reduce the dc offset and 1/f noise that can degrade the signal-to-noise ratio and detection accuracy. Furthermore, the double-sideband signals at the transmitter output can be in quadrature by choosing a proper frequency separation to relieve the severe null point problem that occurs at high frequency. As a result,the detection accuracy is significantly improved with low transmitted power. This radar sensor system achieves better than 80% detection accuracy at a distance of 2.0 m with a combined transmitted power of only 12.5 /spl mu/W in both sidebands.

Ultra-lightweight synthetic aperture radar based on a 35 GHz FMCW sensor concept and online raw data transmission

With the increasing number of small-size unmanned aerial vehicles (UAVs) for remote sensing, reconnaissance and surveillance applications, the demand for miniaturised and low weight synthetic aperture radar (SAR) sensor systems for these platforms has increased. Because of the extreme payload weight restrictions of unmanned platforms, size, weight and power (SWP) characteristics actually become dominating design drivers for UAV SAR developments. The author focuses on the development of a highly miniaturised SAR (MISAR) sensor that was especially designed for UAVs with stringent payload SWP constraints. The paper gives an overview of the design considerations for the MISAR sensor system. The realisation of the sensor is described and the results of test flights in fixed-wing aircraft, rotary-wing aircraft and in UAVs are presented.