Short-range Radar Research Articles

UWB Waveform for Automotive Short Range Radar

The use of UWB technology in radar applications enables the development of low cost radar systems with multiple applications in different areas. The main problem encountered when using UWB technology is the choice of the appropriate waveform for the intended application, i.e. the waveform that gives the best results in terms of accuracy and reliability while respecting the concept of simplicity of design and low cost. In this article, it is proposed to study certain types of waveforms used in the vehicular context, such as Gaussian pulses and orthogonal polynomials, in order to select the most appropriate waveform for UWB detection in road traffic. The choice of the waveform is based on the principle of correlation of each pulse with itself after its passage in the V2V channel which reflects the real environment, and it focuses on a measurement of the peak width of autocorrelation, which translates the similarity between the transmitted signal and its reference, in order to choose the one that gives the best performance in terms of precision and simplicity for the radar detection functionality. The simulation results allows seeing that the monocycle is the most suited waveform to the vehicular context thanks to its very fine autocorrelation peak, which allows better precision for the obstacle detection and classification function.

Coherent Measurements With MIMO Radar Networks of Incoherent FMCW Sensor Nodes

This work introduces a method for coherent multi-in multi-out (MIMO) processing over a network of frequency-modulated continuous wave (FMCW) radar sensor nodes with independent signal synthesis. The coherency between the bistatic channels is established algorithmically based on the frequency and phase-offset estimation from pairs of sensor nodes and subsequent least-squares estimation on the overdetermined equation system. For the chirp-sequence radar, the proposed processing allows range and speed measurements, as offsets are estimated and corrected for each individual ramp. The applicability of the method is demonstrated in a prototypical setup of a radar network with three sensor nodes comprising integrated 122-GHz transceivers. The obtained bistatic phase precisions of <; 0.1 rad approximately match those of the monostatic measurements of the same radar nodes. For a sequence of 30 ramps of 1-ms duration, this translates to ambiguous range precisions <; 10 μm and speed precision <; 1 mm/s. The absence of wired high-frequency links between the nodes makes the approach well suited for shortrange radar networks in cost-sensitive applications.

Quantum illumination with a generic Gaussian source

With the aim to loosen the entanglement requirements of quantum illumination, we study the performance of a family of Gaussian states at the transmitter, combined with an optimal and joint quantum measurement at the receiver. We find that maximal entanglement is not strictly necessary to achieve quantum advantage over the classical benchmark of a coherent-state transmitter, in both settings of symmetric and asymmetric hypothesis testing. While performing this quantum-classical comparison, we also investigate a suitable regime of parameters for potential short-range radar (or scanner) applications.

XÁC ĐỊNH GÓC MỞ TỐI ƯU TẠO LUỒNG MẢNH VĂNG SÁT THƯƠNG MỤC TIÊU KHI TÍNH TOÁN THIẾT KẾ NGÒI NỔ KHÔNG TIẾP XÚC

This paper presents the theoretical basis to determine the relative speed area of the ammunition -target. On that basis, the authors have proposed a method to determine the angle of the wave wings of the short range radar and the opening angle of the fragments beam to ensure that the target is in the observation area of the short range radar and fragments beam. The theoretical research paper’s results have shown that the systematic errors of the proximity fuse can be reduced to 83.33 percent when applying this research result.

Theory and methodology on safety braking of autonomous vehicles based on the friction characteristic of road surface

<p indent=0mm>Because of the direct contact between the tire and pavement, the skid resistance of asphalt pavement is a basic factor affecting the braking safety of autonomous vehicles. The road skid resistance mainly depends on the texture characteristics of the road surface. Considering the pavement friction characteristics, building a braking model of autonomous vehicles is an effective method to improve the braking safety of autonomous vehicles. In order to develop the safety braking method for autonomous vehicles based on the road surface friction characteristic, an automatic close-range photogrammetry system (ACRP system) was proposed and built based on the circle arranged three cameras close-range photogrammetry (CRP) technology to obtain the asphalt pavement surface texture accurately in real time. Automatic image acquisition and 3D reconstruction were achieved by the ACPR system. Sand patch testing method and laser scanning method (ZGScan) were applied to collect the on-site asphalt pavement texture comparing with the results of ACRP system. It shows the texture data obtained by ACPR system have relatively high accuracy and efficiency with recognition accuracy close to 0.02 mm. Then, the peak adhesion coefficients under different road conditions were calculated by considering the skid resistance contribution of the road surface texture. Based on CarSim/Simulink joint simulation, a braking model for autonomous vehicles was established. The characteristics of the autonomous vehicles during straight normal braking, emergency braking and driving on curved sections were analyzed. Then, the safety braking distance under different conditions was put forward. The research shows that the variation trends of friction coefficient curves under different pavement conditions (dry and wet pavement) are basically the same, which both decrease significantly with the increase of relative slipping ratio. When the speed exceeds <sc>40 km/h,</sc> the curve tends to be gentle, indicating that the actual contact area of the tire-road comes to a stable status when the speed is relatively high. Based on the tire hydroplaning model built by ABAQUS, the peak adhesion coefficient curves for different pavement conditions were obtained. It can be seen that the peak adhesion coefficient of the road surface is convex parabolic distribution at different driving speeds. Moreover, the peak adhesion coefficient gradually decreases as the speed increases. During normal braking, the vehicle should keep relatively low braking deceleration considering passenger comfort. As for emergency braking, autonomous vehicle should be equipped with professional short-range radar, long-range radar and high-definition camera to detect the environment surrounding the vehicle. On rainy days, the braking distance is averagely increased by about 45% compared to sunny days. When the braking distance between vehicles is large enough, it is recommended to brake with a braking force of <sc>4−6 MPa.</sc> Autonomous vehicles should keep a certain safe distance, which requires 1.1−1.2 times of the simulated average value of safety braking distance during the driving process on dry or wet pavement. As the radius of curved sections increases, the acceleration interference values under different road conditions basically reduce. When the radius is greater than or equal to<sc>100 m,</sc> the decrease rate of the acceleration interference value is more significant. In order to improve the braking comfort of the vehicles, the radius of the curved road should be controlled above <sc>100 m.</sc> In this paper, the safety strategies for autonomous vehicles considering pavement surface texture characteristics can provide references for the theoretical design of braking system and braking safety evaluation for autonomous vehicles.

Beam-steering radars at low cost

An inexpensive and compact short-range radar, which is capable of beam steering and operates at 330–500 GHz, can be used to detect heartbeat-induced chest motions through a person’s clothes.

Short-Range Radar Implemented with Ultrasound Sensor and PSoC5LP

Short-Range Radar Implemented with Ultrasound Sensor and PSoC5LP

Radar with increased angular resolution of objects in wide-angle scanning

The parameters of radar antenna systems constructed according to the traditional scheme with phase shifters inserted both in the transmitting and receiving antenna array with the radar in which signal processing is performed only on the receiving side are considered and compared in the paper. In the second case, an additional requirement of orthogonality of the radiated signals is imposed on the radiating system of the transmitter. The characteristics of the radar with three transmitters and four receivers are compared. Two variants of forming a virtual antenna array are considered. In the first case, the radiation of the linear regular antenna array is analyzed, in the second case the thinned one, but with the same number of emitters. We demonstrate that in the second case, it is possible to implement the radar with a better angular resolution. The features of using the radar as a short-range radar for vehicle security systems with a wide-angle view are elaborated. The possibility of false capture of the target is noted. The authors of the research suggest the unambiguous direction finding method.

A dynamic weighted algorithm for multiple radar fusion in an active protection system

The threat detection system based on short-range radars is an essential part of the active protection system (APS) of armored vehicles. The multi-radar data fusion problem is one of the crucial issues in the APS. Firstly, a general algorithm for multi-radar coordinates transformation is given. Then, based on the weighted fusion model and the trajectory characteristics of targets in the APS, a real-time dynamic weighting factor derivation algorithm is proposed. The algorithm is simulated in a dual-radar threat tracking and ballistic prediction scenario. The results prove the correctness and effectiveness of the algorithm.

Metamaterial Inspired Microstrip Offset Feed Truncated Antenna for Automotive Radar Application

A state-of-the-art design of microstrip offset feed truncated antenna for automotive radar applications operating at 24 GHz UWB band is proposed. The rectangular patch is truncated and ring shaped co directional complementary split ring resonator is imprinted on edge truncated rectangular patch to radiate in the short-range radar UWB band. The proposed antenna with Co-directional complementary split ring resonator antenna is having measurement of 5.1 x 4.65 x1.6 mm3 with operating frequency ranges from 24.6 to 30.3 GHz.This work comprises the thorough inquiries such as return loss, distribution of surface current, gain and radiation pattern. With the help of parametric analysis width of slit (z), width of feed (Wf) and length of feed (lf) the dimension of the proposed antenna is obtained. Simulation have shown decent fairness which proves the feasibility of the projected antenna for the automotive short-range RADAR application.

Super-Resolution Doppler Velocity Estimation by Kernel-Based Range–$\tau$ Point Conversions for UWB Short-Range Radars

Lower band ultrawideband (UWB) Doppler radar is promising for through-wall imaging, e.g., human body detection in rescue scenarios. The inherent problem with pulse-Doppler radar is the tradeoff between the Doppler velocity resolution and the resulting temporal resolution that makes it difficult to conduct real-time target tracking, because the separation of micro-Doppler velocities of the human body requires a higher Doppler velocity resolution. This problem is particularly severe for lower band UWB radar systems, which are required to attain a sufficient penetration depth in concrete material in the through-the-wall imaging scenario. Because UWB signals generally have large fractional bandwidths, the reflected pulse is located over a range gate along the slow-time direction; this is well known as the range walk problem. As a promising solution to this problem, this article newly introduces a technique for a super-resolution Doppler velocity estimation algorithm based on Gaussian kernel density estimation, which converts observed range– $\tau $ points to Doppler-associated ranges. In addition, this approach makes an important contribution for super-resolution range extraction with a compressed sensing (CS) filter, which is combined with the range-point migration (RPM) method for human body imaging associated with micro-Doppler components. 2-D or 3-D numerical simulations, including human body imaging scenario, demonstrate that the proposed method allows both accurate Doppler velocity estimation and human body imaging, which can be updated at the pulse-repetition interval.

A Mutiscale Residual Attention Network for Multitask Learning of Human Activity Using Radar Micro-Doppler Signatures

Short-range radar has become one of the latest sensor technologies for the Internet of Things (IoT), and it plays an increasingly vital role in IoT applications. As the essential task for various smart-sensing applications, radar-based human activity recognition and person identification have received more attention due to radar’s robustness to the environment and low power consumption. Activity recognition and person identification are generally treated as separate problems. However, designing different networks for these two tasks brings a high computational complexity and wastes of resources to some extent. Furthermore, there are some correlations in activity recognition and person identification tasks. In this work, we propose a multiscale residual attention network (MRA-Net) for joint activity recognition and person identification with radar micro-Doppler signatures. A fine-grained loss weight learning (FLWL) mechanism is presented for elaborating a multitask loss to optimize MRA-Net. In addition, we construct a new radar micro-Doppler dataset with dual labels of activity and identity. With the proposed model trained on this dataset, we demonstrate that our method achieves the state-of-the-art performance in both radar-based activity recognition and person identification tasks. The impact of the FLWL mechanism was further investigated, and ablation studies of the efficacy of each component in MRA-Net were also conducted.

Moving-target indication in ultra wideband radar

The article describes the principle of implementation of an UWB sounding signal for short range radar. The comparative analysis of UWB signals classification variants is made. A mathematical model of the formation of an ultrashort radio pulse from a video pulse is presented. The use of ultrashort radio pulses does not have difficulties in technical implementation and makes it possible to achieve high stability of the parameters of the sounding signal. The options for estimating speeds for UWB systems are considered. The method for moving-target indication and their separation from the underlying surface for UWB radars is proposed. The method uses coherent integration with subsequent spectral analysis based on Fast Fourier Transformation. Experimental studies of the proposed method of moving-target indication are made. The results of experiments prove the proposed method efficiency.

Масштабное физическое гидроакустическое моделирование РЛС с синтезированной апертурой малой дальности для БПЛА.

Масштабное физическое гидроакустическое моделирование РЛС с синтезированной апертурой малой дальности для БПЛА.

Six‐element dual polarized high‐gain MIMO antenna for multiband applications

AbstractA planar six‐elements, dual‐polarized, high‐gain, multiband antenna for diverse application is proposed in this manuscript. The proposed design consists of six radiating elements and a parasitic element on the top side of the structure. Each radiating element consists of overlapped ellipse with a line feeding technique. Iterations have been carried out on the number of antenna elements as well as on the spacing between the elements to get a minimum coupling between antenna elements. To compensate the coupling effect as well as to increase the impedance bandwidth, a ground plane structure has been modified with “L” shape structures. Fabricated prototype has an isolation less than −2 dB with highest gain of 6.7 dBi. Diversity in polarization is achieved by orienting antenna elements in vertical as well as in horizontal directions. A simple and compact design of antenna with good gain and less correlation coefficient makes an antenna useful for multiple input multiple output (MIMO) applications in the wireless communication systems. Simulation and measurement results validates the use of proposed structure in various applications like ISM, WLAN, Wi‐Fi, short range radar, and satellite applications.

Compact high gain half‐mode substrate integrated waveguide cavity antenna using hybrid mode

In this article, a compact fully planar high gain antenna based on half-mode substrate integrated waveguide (HMSIW) cavity is presented. The design uses a novel configuration of HMSIW cavity with high length to width ratio along with tapered open edge and a pair of slot stub. The high length to width ratio of the cavity helps to excite closely spaced multiple TEym10 cavity modes within comparatively smaller footprint due to use of the HMSIW cavity. These modes combine to give hybrid mode resonance in the cavity which helps to generate a narrow beam high gain radiation pattern of the antenna. The size of the proposed antenna is further reduced and a pair of slot stub is put along the sidewall of the cavity which helps to sustain similar hybrid mode field distribution within much smaller dimension. A size reduction of 76.7% is achieved in the proposed design configuration without degrading much of the gain performance. The proposed antenna resonates at 9.8 GHz with a gain of 7.9 dBi which is much higher than other reported HMSIW cavity antenna. The proposed antenna may find application in point to point communication, short range radar in X band.

Moving Target Localization Using Single-Station Dual-Frequency Radar in Asynchronous Mode

Dual-frequency radar is a preferred solution for moving target localization because of its low complexity and cost. Although several studies for dual-frequency radar are addressed in the literature, all of those methods are designed for the synchronous mode. In this letter, a new localization method based on phase compensation is proposed for dual-frequency radar in the asynchronous mode. Compared with the synchronous mode, the proposed method is suitable for most commercial short-range radars with the single local oscillator architecture and can provide a cost-effective solution. Moreover, both the theoretical variance and Cramer–Rao lower bound are derived for the performance analysis in the asynchronous mode. Computer simulations were conducted to verify the validity of the proposed method.

Multi-Target Tracking With Multiple 2D Range Scanners

We propose a novel efficient online method for tracking performers on stage. Most existing tracking methods have focused on using expensive, high-performing sensors, such as multilayer lidar sensors or high-resolution, short-range radars. Image sensor-based methods are not appropriate for tracking performers on stage because of challenging illumination conditions caused by lighting effects. In this paper, we introduce a robust multi-target tracking method based on the sensor fusing of two-dimensional distance sensors such as single-layer lidar sensors that have a relatively lower cost than the aforementioned types of sensors. In our method, measurements from each sensor are transformed into a reference coordinate system and objects are detected with those transformed measurements. Then, the object detections are used in generating or extending the trajectories of targets by detection-to-trajectory matching. In our experiments, we quantitatively evaluated the proposed method with a newly constructed dataset which consists of two scenarios simulating performances on stage. We collected the scan results of two single-layer lidar sensors and image frames captured by a camera sensor for each scenario. The experimental results show that the proposed method robustly tracks performers in challenging scenarios, in which the performers move abruptly and are densely located.

Short-Range Radar Based Real-Time Hand Gesture Recognition Using LSTM Encoder

Due to the development of short-range radar with high-resolution, the radar sensor has a high potential to be used in real human-computer interaction (HCI) applications. The radar sensor has advantages over optical cameras in that it is unaffected by illumination and it is able to detect the objects in an occluded environment. This paper proposes a hand gesture recognition system for a real-time application of HCI using 60 GHz frequency-modulated continuous wave (FMCW) radar, Soli, developed by Google. The overall system includes signal processing part that generates range-Doppler map (RDM) sequences without clutter and machine learning part including a long short-term memory (LSTM) encoder to learn the temporal characteristics of the RDM sequences. A set of data is collected from 10 participants for the experiment. The proposed hand gesture recognition system successfully distinguishes 10 gestures with a high classification accuracy of 99.10%. It also recognizes the gestures of a new participant with an accuracy of 98.48%.

Terahertz multi-beam antenna using photonic crystal waveguide and Luneburg lens

Recent years have seen the emergence of efficient, general-purpose terahertz photonic-crystal waveguides etched from high-resistivity silicon. Systems founded upon this platform will require antennas in order to interface with free-space fields. Multi-beam antennas are desirable to this end, as they are capable of interacting with a number of distinct directions simultaneously. Such functionality can be provided by Luneburg lenses, which we aim to incorporate with the terahertz photonic crystal waveguide. A Luneburg lens requires a precisely defined gradient-index, which we realize using effective medium techniques that are implemented with micro-scale etching of silicon. Thus, the photonic crystal waveguides can be integrated directly with the Luneburg lens and fabricated together from the same silicon wafer. In this way, we develop a planar Luneburg-lens antenna with a diameter of 17 mm and seven evenly spaced ports that cover a 120° field of view. Numerical and experimental characterization confirm that the antenna functions as intended over its operation bandwidth, which spans from 320 to 390 GHz. The Luneburg-lens antenna is subsequently deployed in a demonstration of terahertz communications over a short distance. The device may therefore find applications in terahertz communications, where multiple point-to-point links can be sustained by a given transceiver node. This form of terahertz beam control may also be useful for short-range radar that monitors several directions simultaneously.