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A Simplified Technique for Distance and Velocity Measurements of Multiple Moving Objects Using a Linear Frequency Modulated Signal
Abstract
In this paper, we propose a simplified algorithm for the unbiased estimation of range and the radial velocity of moving objects observed by a sensor with a frequency-modulated continuous wave signal. Linear frequency modulated signals and their different modifications are widely used in various microwave sensors for short- to medium-range measurements in automotive, safety, industrial, and other applications. Since the range (distance) to a detected object is measured as a beat frequency at the homodyne receiver output, the Doppler shift results in a biased measurement of the range. This phenomenon has been well known for a long time. The situation becomes more uncertain with an increase in the number of objects within the radar's field of view. There are many proposed techniques to solve this problem with one main technique adding a number of equations according to the number of detected objects in the hope of finding a single solution. We propose a simplifed system of those equations excluding all uncertainties from the hypothesis tree at the beginning of the procedure. When the performance of the signal processing hardware is limited, the simplicity of the algorithm increases in importance. The proposed technique is simple enough to be used on an embedded microprocessor. We performed an experiment involving a real microwave sensor to confirm a validity of the proposed algorithm.
... Different types of radars were used in target detection and classification applications. In particular, the Frequency Modulated Continuous Wave radars (FMCW) are the mostly adopted ones in different applicative field, and in particular in automotive applications [9]- [14], since they are able to simultaneously provide both range and velocity. Such an information can be obtained through different processing scheme, e.g., by using a 2D FFT technique [15]. ...
... Fig. 7 exemplifies this calculation when a single pedestrian is present in the scenario. Using (9) and (11) to measure the range and Doppler profiles works fine for a single target situation. However, applying (9) directly in a multi-target scenario leads to wrong range profile estimations. ...
... Using (9) and (11) to measure the range and Doppler profiles works fine for a single target situation. However, applying (9) directly in a multi-target scenario leads to wrong range profile estimations. This is because in the multi-target case it is always expected to have multiple peaks in the range spectrum that are coming from different targets. ...
A prototype of a radar system for classification of multiple targets passing through a road gate is presented in this paper. It allows to identify different types of targets, i.e., pedestrians, motorcycles, cars, and trucks. The developed system is based on a low-cost 24 GHz off-the-shelf FMCW radar, combined with an embedded Raspberry Pi PC for data acquisition and transmission to a remote processing PC, which take care of detection and classification. The processing chain relies upon a tracking algorithm to follow the targets during traversal, combined with a classification scheme based on support vector machines. The approach has been validated with experimental data acquired in different scenarios, showing good identification capabilities.
... They obtained the measurement by using the Doppler effect on the down-chirp and the up-chirp LFMWs. However, in a multi-target situation, these detection methods cannot get the correct values of distance and velocity because of the existence of false targets [24]. ...
The distance and velocity measurement can be obtained by the round-trip time and Doppler effect on the down-chirp and the up-chirp of the linear frequency-modulated waveform (LFMW), but false targets will appear in a multi-target situation, resulting in erroneous detection. Here, we report a photonics-assisted approach to realize unambiguous simultaneous distance and velocity measurement in multi-target situations utilizing a dual-band symmetrical triangular LFMW. Dual-band observation invariance is proposed, to effectively resolve the false targets. The de-chirped signals can be obtained from parallel de-chirping processing to the dual-band echoes. By measuring and calculating the beat frequencies of the de-chirped signals in the two frequency bands, the actual parameter measurements can be acquired according to the authenticity criterion. In the experiments, detections to three targets are performed, and the distance and velocities are acquired without false targets. The absolute measurement errors of the distance and the velocity are less than 9 mm and 0.16 m/s, respectively. These results show the feasibility of the proposed approach.
... CDL exploits both range-free and range-based methods to obtain a better estimation quality [11]. For the Doppler shift problem of moving objects during distance estimation, Lee proposed a simplified system to exclude all the uncertainties from the hypothesis tree [12]. In [2], a classical multidimensional scaling algorithm is generalized to account for measurement. ...
Distance estimation between sensor nodes is crucial to localization and object tracking in a wireless sensor network. The received signal strength indicator is widely used for wireless distance estimation, because of its advantages, including availability, low cost, flexibility, and so on. As is well known, RSSI measurement values are extremely susceptible to the surroundings, resulting in uncertain distance estimations. Without confidential information, the distance estimation results could not provide valuable priori information for follow-up processing methods and applications, such as localization, navigation, and guidance. In this paper, we propose a new uncertainty analysis method for RSSI-based distance estimation (UAM-RDE) to study the uncertainty propagation in RSSI-based distance estimations. In UAM-RDE, we explore the uncertainty propagation mechanism from the input to the output of the RSSI-based distance estimation, including uncertainty factor analysis, sensitivity analysis, propagation, and synthesis of uncertainty. The simulations and experimental results validate and demonstrate the feasibility of UAM-RDE.
... However, as the number of targets increases, otherwise as the number of f bu and f bd increases, the possible combination of the up and down beat frequency increases, the ghost-target problem becomes very difficult to solve. To differentiate the true target from the ghost one, sometimes the system adds additional chirp signals with different slope (± f c T/B) to the existing waveform [15][16][17]. This adds additional line with different slope in R-v plane as shown in Figure 4. ...
Recently, many automobiles adopt radar sensors to support advanced driver assistance system (ADAS) functions. As the number of vehicles with radar systems increases the probability of radar signal interference and the accompanying ghost target problems become serious. In this paper, we propose a novel algorithm where we deploy per-vehicle chirp sequence in a frequency modulated continuous wave (FMCW) radar to mitigate the vehicle-to-vehicle radar interference. We devise a chirp sequence set so that the slope of each vehicle’s chirp sequence does not overlap within the set. By assigning one of the chirp sequences to each vehicle, we mitigate the interference from the radar signals transmitted by the neighboring vehicles. We confirm the performance of the proposed method stochastically by computer simulation. The simulation results show that the detection and false alarm performance is improved significantly by the proposed method.
... Because the radar can clearly measure target range and the radial velocity simultaneously in multiple target situations, it is common to classify objects by analyzing velocity and range [29]- [31]. In [32], we studied how to classify objects more precisely based on velocity using an FMCW radar. ...
This paper discusses radar-based technologies that provide drivers with information about road curves under conditions in which optical sensors are unable to perform. The development of a task capable of estimating road curves has become a popular challenge since the commencement of the active development of advanced driver assistance systems and autonomous vehicles. Although the hardware implementation of a road curvature measurement system may have many variations, including cameras, we consider microwave sensors to be a reasonable alternative that offers many benefits. Road curvature measurement requires fast acquisition of the necessary data from a moving vehicle followed by efficient post-processing of the data to identify a sufficient number of reliable featured points in the local environment. These points would enable a hypothesis about the dimensions and shape of the probable road geometry to be built. Different studies attempted to solve this problem using specialized equipment and custom-built algorithms. Our solution is to use a commercially available radar and some pre-and post-processing algorithms for data conditioning and analysis to obtain reliable results in both day-and night-time environments and under various weather conditions in a relatively short time using a simplified approach based on circle-fitting algorithms. We confirmed the effectiveness of the proposed approach by conducting multiple road experiments with a commercially available microwave sensor. Considering that the road infrastructure is currently not optimized for road curvature measurements, the results we obtained with our proposed method (within 10%–17% of those on the actual map) are acceptable.
This paper deals with an intelligent mine periphery surveillance system, which has been developed by CSIR-Central Institute of Mining and Fuel Research, Dhanbad, India, as an aid for keeping constant vigilance on a selected area even in adverse weather conditions like foggy weather, rainy weather, dusty environment, etc. The developed system consists of a frequency modulated continuous wave radar, a pan-tilt camera, a wireless sensor network, a fast dedicated graphics processing unit, and a display unit. It can be spotting an unauthorized vehicle or person into the opencast mine area, thereby avoiding a threat to safety and security in the area. When an intrusion is detected, the system automatically gives an audio-visual warning at the intrusion site where the radar is installed as well as in the control room. The system has the facility to record the intrusion data as well as video footage with timestamp events in the form of a log. Further, the system has a long-range detection capability covering around 400 m distance with an integration facility using a dynamic wireless sensor network for deploying multiple systems to protect the extended periphery of an opencast mine. The field trial of this low-cost mine periphery surveillance system has been carried out at Tirap Opencast Coal Mine of North Eastern Coalfields in Margherita Area, Assam, India and it has proved its efficacy in preventing revenue loss due to illicit mining, unauthorized transportation of minerals, and ensuring safety and security of the mine to a great extent.
Synthetic aperture radar (SAR) installed on unmanned aerial vehicles (UAVs) has drawn increasing attention in the area of remote sensing due to its high spatial resolution and low energy consumption. However, due to the sensitivity toward atmospheric turbulences, strong motion errors can defocus the image in both azimuth and range directions. In this paper, based on symmetric triangular linear frequency modulation continuous microwave (STLFMCW) signals, a novel motion error estimation method is proposed. The core concept is to eliminate the effect of residual range cell migration (RCM) and investigate the motion parameters from azimuth phase history by range-frequency-domain interferometry between the up-ramp and down-ramp chirp sections. With preknowledge of the structural characteristics of the differential signal, we first obtain the high-order component, then estimate the quadratic term with an azimuth profile width minimization (APWM) algorithm on the basis of bisection search, and subsequently remove the linear part through phase gradient matching and joining. Consequently, the desired motion errors can be achieved purely based on raw data. Simulations demonstrate that our proposed algorithm can achieve high accuracy with or without standard prominent point targets. Experimental results on a W-band UAV SAR system in strip-map mode indicate that this approach also outperforms other existing postprocessing autofocus methods.
This paper deals with a periphery surveillance system, which has been developed and deployed by CSIR-Central Institute of Mining and Fuel Research, Dhanbad, India as an aid for keeping constant vigilance on a selected area even in adverse weather conditions like foggy weather, rainy weather, dusty environment, etc. The developed system consists of a frequency modulated continuous wave radar with 400 m range, a pan-tilt-camera, a wireless sensor network, a fast dedicated graphics processing unit, and a display unit. It is capable of controlling illegal mining, theft of minerals, and ensuring safety and security of the mine to a great extent. When an intrusion is detected, the system automatically gives audio-visual warning at the intrusion site where the radar is installed as well as in the control room. The system has the facility to record the intrusion data and video footage with timestamp events in the form of log.
Frequency modulated continuous wave (FMCW) radar is widely adopted solution for low-cost, short to medium range sensing applications. However, a multistatic FMCW architecture suitable for meeting the low-cost requirement has yet to be developed. This paper introduces a new FMCW radar architecture that implements a novel technique of synchronising nodes in a multistatic system, known as over-the-air deramping (OTAD). The architecture uses a dual-frequency design to simultaneously broadcast an FMCW waveform on a lower frequency channel directly to a receiver as a reference synchronisation signal, and a higher frequency channel to illuminate the measurement scene. The target echo is deramped in hardware with the synchronisation signal. OTAD allows for low-cost multistatic systems with fine range-resolution, and low peak power and sampling rate requirements. Furthermore, the approach avoids problems with direct signal interference. OTAD is shown to be a compelling solution for low-cost multistatic radar systems through experimental measurements using a newly developed OTAD radar system.
In this contribution a novel measuring concept for mass flow determination of pneumatic conveyed particles is presented. Therefore, the so-called pseudo transmission measurement concept was adapted for the simultaneous determination of volume fraction and particle flow velocity within a pneumatic conveying tube. The application of two ultra wideband 80-GHz FMCW radar systems increases the measuring accuracy and is used for measurements on a continuous particle flow. Therefore, an experimental pneumatic conveying system is introduced. Flow simulations of the conveying pipe and 3-D electromagnetic simulations of the measurement method illustrate the flow behavior inside the conveying tube and the RF-measuring performance, respectively. Measurement results concerning the volume fraction determination as well as the velocity determination will be presented and discussed in detail.
Chirp or frequency-modulated continuous-wave (FMCW) radar is a very well-known method for range applications. Using the current technology, conventional FMCW radar for W-band waves requires the use of expensive microwave mixers and low noise amplifiers (LNA). A uniquely simple and inexpensive solution is presented using very inexpensive glow discharge detectors (GDDs). The use of GDDs enables direct beating between the electric field of the target signal and the reference signal eliminating the requirement for expensive millimeter wave mixers, sources, and LNAs. This unique solution to FMCW radar is proven to be capable of determining range to target, and creating 3-D radar images. In this paper, a proof of concept of chirp/FMCW radar detection using a GDD in the W-band regime is demonstrated experimentally. The GDD chirp radar system has the following advantages: 1) much simpler realization in short range applications; 2) rigid, room temperature operation; 3) sub-microsecond response time; 4) large dynamic range; and 5) immunity to high-power radiation.
This paper describes a millimeter-wave sensor that is able to detect pedestrians, thereby reducing the likelihood of human road injuries or fatalities. The sensor consists of a transmit/receive channel module, operating in the millimeter-wave range (W-band) using frequency-modulated-continuous-wave mode. The laboratory prototypes of the sensor have been designed and tested in real-life environment. An analysis of system performance and experiments conducted has indicated a high-resolution, detection ability of both adults and children at a distance of up to 100–150 m.
Millimeter Wave (MMW) radars are currently used as range measuring devices in applications such as automotive driving aids (Langer and Jochem, 1996), (Rohling and Mende, 1996), the mapping of mines (Brooker et al., 2005) and autonomous field robotics (Brooker, 2001), (Langer, 1996). This recent interest is largely due to the advantages MMW radars offer over other range measuring sensors, as their performance is less affected by dust, fog, rain or snow and ambient lighting conditions. MMW radars can provide received signal strength values, at all discrete range intervals, within the working range of the radar (Clark and Durrant-Whyte, 1997), (Scheding et al., 2002). The received power versus range spectra hence contain useful range to target information, but are also corrupted by noise. User defined stochastic algorithms can then be implemented, which exploit this rich data to improve object detection and mapping performance. This is in contrast to many other range measuring devices which typically internally threshold received signals, to provide single hard decisions only, on the estimated range to objects (Mullane, 2007). This paper addresses the issues of predicting the power-range spectra from MMW radars which use the Frequency Modulated Continuous Wave (FMCW) range estimation technique. This is important for two reasons. First, in automotive and autonomous robotic applications, such sensors are used in conjunction with vehicle navigation and map state estimation filters. This is so that (typically uncertain) vehicle motion knowledge can be optimally fused with the noisy sensor information, to infer estimates of the state of interest (typically, the vehicle's pose (position and orientation) and/or information of the surrounding object locations). Hence, it is essential that predicted power versus range spectra can be computed, to apply a Bayesian recursive estimation framework, based on previous measurements, and uncertain vehicle motion information. Second, it-
is extremely useful to be able to simulate MMW radar data, given certain environmental configurations. This aids the development of reliable object detection algorithms, based on theoretical sensor and noise models, which can then be applied more effectively to real MMW radar data.
Many practical frequency-modulated continuous-wave (FMCW) radars utilize consecutive upchirps and/or downchirps of the same ramp slope to extract the desired range and velocity information of the targets. In this contribution it is demonstrated that consecutive ramp sequences provide only little more information compared to a non-consecutive sequence, but lead to a huge calculation complexity. Additional significant information on the target states for a non-consecutive sequence is gained by using the ramp slope as a design parameter. The ramp sequence distributed over a certain period is temporally aligned to a given point in time. State estimation is done by minimizing a cost function. A significant advantage of a cost function approach is that ghost targets are suppressed directly. For test purposes a 77-GHz FMCW radar prototype is used in an automotive environment.
In traffic environment, conventional FMCW radar with triangular transmit waveform may bring out many false targets in multi-target situations and result in a high false alarm rate. An improved FMCW waveform and multi-target detection algorithm for vehicular applications is presented. The designed waveform in each small cycle is composed of two-segment: LFM section and constant frequency section. They have the same duration, yet in two adjacent small cycles the two LFM slopes are opposite sign and different size. Then the two adjacent LFM bandwidths are unequal. Within a determinate frequency range, the constant frequencies are modulated by a unique PN code sequence for different automotive radar in a big period. Corresponding to the improved waveform, which combines the advantages of both FSK and FMCW formats, a judgment algorithm is used in the continuous small cycle to further eliminate the false targets. The combination of unambiguous ranges and relative velocities can confirm and cancel most false targets in two adjacent small cycles.
A Frequency Modulated Continuous Wave (FMCW) radar using only in-phase channel is advantageous for automotive applications. In this radar, it is necessary to search the pairs of beat frequencies in an up-chirp mode and a down-chirp mode to measure the distances and the velocity of multiple targets similarly to a FMCW radar with both of in-phase and quadrature-phase channel However the number of combinations to search the pairs is larger than that for the FMCW radar with both of in-phase and quadrature-phase channel. Therefore: false targets by mistaking the combination of these pairs increase. In this paper, we propose a novel measurement algorithm to reduce the false targets. We extract only the beat frequencies of the relatively moving targets using the differential frequency power spectrum of the up-chirp mode and the down-chirp mode. We can reduce the number of selected incorrect pairs by separating the stationary targets and the moving targets. We have conducted some simulations to confirm the capability of the proposed measurement algorithm. It was shown that the false tar get appearance probability is reduced without significant deterioration of the target detection probability.
For all radar applications it is required to measure the target range R and radial velocity vr simultaneously and unambiguously with high accuracy and resolution even in multi target situations. In this paper, a new radar waveform is proposed, which is based on a chirp sequence. In the considered case, each chirp signal has a very short duration Tchirp. Therefore, the measured beat frequency fB is dominated by the target range R and is less influenced by the radial velocity vr. However, the classical chirp sequence waveform suffers from possible ambiguities in the velocity measurement. It is, therefore, the objective of this paper to modify the classical chirp sequence based on an additional frequency modulation from chirp to chirp to get an unambiguous velocity measurement even in multi target situations.
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.
A low complexity range-azimuth frequencymodulated continuous-waveform (FMCW) radar sensor using joint angle and delay estimation method without singular value decomposition (SVD) and eigenvalue decomposition (EVD) is presented in this paper. Conventional joint angle and delay estimation techniques exploit the dual-shift-invariant structure of received signals through matrix decompositions, such as SVD and EVD, which increases the computational burden. The proposed method utilizes the dual-shift-invariant structure through matrix inversion and performs angle and delay estimation using extended one-dimensional pseudo-spectrum searching instead of two-dimensional pseudo-spectrum searching to reduce the computational complexity. We demonstrate the effectiveness of the proposed method through Monte-Carlo simulations. The proposed algorithm is also verified by processing real FMCW data collected in an anechoic chamber.
Short range radars can provide robust information about their surroundings under atmospheric disturbances, such as dust, rain, and snow, conditions under which most other sensing technologies fail. However, this information is corrupted by received power noise, resulting in false alarms, missed detections, and range/bearing uncertainty. The reduction of radar image noise, for human interpretation, as well as the optimal, automatic detection of objects, has been a focus of radar processing algorithms for many years. This paper combines the qualities of the well established binary integration detection method, which manipulates multiple images to improve detection within a static scene, and the noise reduction method of power spectral subtraction. The binary integration method is able to process multiple radar images to provide probability of detection estimates, which accompany each power value received by the radar. The spectral subtraction method then utilizes these probabilities of detection to form an adaptive estimate of the received noise power. This noise power is subtracted from the received power signals, to yield reduced noise radar images. These are compared with state-of-the-art noise reduction methods based on the Wiener filter and wavelet denoising techniques. The presented method exhibits a lower computational complexity than the benchmark approaches and achieves a higher reduction in the noise level. All of the methods are applied to real radar data obtained from a 94-GHz millimetre wave FMCW 2D scanning radar and to synthetic aperture radar data obtained from a publicly available data set.
In the last decade radar based driver assistance systems have increased the safety in all vehicle classes and get the access to mass market applications. Currently slow FMCW waveforms are the state of the art principle for automotive radar sensors at 24 GHz and 77 GHz. This contribution presents an innovative 77 GHz multi channel radar sensor, with the capability for fast FMCW PLL locked chirp modulations down to 10 μs. It gives a brief review on short FMCW chirp modulations and its processing. Furthermore the application of compressed sensing algorithms for r/v estimation is discussed and system simulations and measurements are presented.
Coherent radars have multiple applications; among them, they can obtain images of targets. Unfortunately, the image quality can be seriously compromised for highly maneuvering targets, since the commonly adopted stop-and-go assumption is no longer valid for them. An approximated conventional explicit model for the signal delay, being proportional to the time-dependent target range, is usually employed to evaluate the violation of the stop-and-go simplification in these scenarios. Nevertheless, even this model can lead to radar-based measurement inaccuracies for extreme situations; for example, those involving very fast relative dynamics between the platform and target or for radars exploiting long-time-pulse waveforms. In this paper, an implicit function is proposed as the exact model for the radar echo time delay. Solutions for the conventional and exact models in the case of first- and second-order range polynomials are provided, and pertinent comparisons between them are accomplished. The main conclusion of this paper is that the conventional model is generally a good approximation to the exact solutions, but there may be extreme cases for which it does not give insight into the real appearing effects. Thus, the application of the exact model for the derivation of the radar round-trip delay could enable the conception of advanced radar-sensor algorithms, which improve the image quality for highly maneuvering targets. Simulated results of 1-D range profiles for a linear frequency-modulated continuous-wave radar example are also presented for verification of the expounded analytical equations.
There are two kinds of FMCW waveform, which are slow-ramp FMCW and fast-ramp one. In some applications like automotive radar sensors, fast-ramp FMCW waveform is usually preferable for the improved target resolving capability in multi-target situation when compared with slow-ramp one. Usually fast-ramp FMCW waveform uses up or down chirps only. But, sometimes, the waveform has to be generated with up and down chirps alternatively due to hardware limitations. In this case, the computational load, memory usage and velocity ambiguity are increased due to the separated signal processing of up and down chirps. This paper proposes the signal processing method for the fast ramp FMCW waveform using both up and down chirps. The simulation and test results show the proposed new waveform and its signal processing method is acceptable for FMCW radar sensors with lower complexity.
In multi-target situations, typically triangular FMCW radar brings out false targets and degrades the radar performance. A novel transmitted waveform and multi-target detection algorithm for automotive applications is presented in this paper. The proposed waveform is composed of three segments: up ramp, flat frequency and down ramp in every small period. Especially, the flat frequencies are modulated by a unique PN code sequence within a determinate frequency range. The unambiguous relative velocities detected in the flat frequency segment can cancel some false targets initially. Corresponding to the waveform, which combines the advantages of both FSK and FMCW formats, a progressive judgment algorithm is used in the continuous small period to further eliminate the false targets.
For frequency modulate continuous wave radar, it is necessary and difficult to search the pairs of beat frequencies in an up-chirp mode and a down-chirp mode to measure range and velocity of multiple targets. However, the inherent problem of FMCW radar is multiple targets detection. False targets can appearance because of mistaking the combination of these beat frequencies. A novel waveform named double-slope symmetrical saw-tooth wave is proposed and its corresponding algorithm is also introduced to resolve the problem of multiple targets detection for automotive anti-collision radar. Computer simulation results and theoretical analysis prove that the method is effective and practical for multiple targets detection in intelligence transportation system.
In surveillance and security applications radar sensors can be used for scene imaging in environments with non-cooperative persons or objects. Beamforming techniques provide a solution for 2D or 3D radar imaging, but generally require a certain antenna aperture to obtain the required angular resolution. Looking at a scene simultaneously from different angles with multiple sensors can be advantageous in particular in enclosed scenarios, but raises the problem of associating radar measurements from individual sensors with the reflectors present in the scene. In this paper the use of Range-Doppler sensors that provide simultaneous range and velocity information for resolving the ambiguity associated with range-only measurements is demonstrated.
This paper presents the fundamentals, design, realization, and characterization of a state-of-the-art microwave (muW) based proximity sensor (PS) for position detection of stationary or moving targets in industrial applications. PS using established sensing technologies (inductive, capacitive, magnetic, optical, ultrasonic, etc.) have a large utilization range in rugged industrial environments and are able to fulfill the tough specific requirements. On the other hand, every version has specific weaknesses, which dramatically limit the application fields. Microwave technology is established in many sectors except for factory automation. In this study, we describe a prototype implementation of muW technology in an industrial PS for this field. The result represents an upgrade from the sensors based on the classical operating modes. The degree of novelty consists in the determination of the specifically addressed difficulties, new ideas, and the description of the original solutions to adapt the muW technology to PS demands. Basically, this paper refers to a binary version of the muW-PS. This version provides a switching output signal dependent on the relation between the actual distance and the programmed switching point. The majority of the gained facts are also usable for analog versions which convert the distance into an analog output signal.
The FMCW-radar-principle is widely used for short range radar systems. The basic idea for FMCW-radars is to generate a linear frequency ramp as transmit signal. There are too widely used principles for range-Doppler-processing: generation of ramps with different slopes and generation of a sequence of short ramps processed by a two-dimensional FFT. The developed ramp generation sequence also applies two-dimensional Fourier transforms, but allows to reduce the baseband bandwidth. The principle can be also regarded as an extension of a frequency stepped-CW-radar with intertwined ramps. In the following the method is derived for systems with and without I/Q-demodulator and first measurement results on a 24 GHz-system are presented. The waveform generator has been implemented on a FPGA.
A software-defined radar measurement system on the basis of a six-port receiver technique is proposed and described in this paper. The system makes use of a hybrid scheme of two performance-complementary operating modes, namely, frequency-modulated continuous-wave (FMCW) and two-tone continuous-wave signals. Generally, the FMCW-based measurement technique is deployed to give an approximate range value of target while the two-tone continuous-wave (CW)-based measurement technique can accurately determine the range that may, however, be ambiguous. The six-port circuit is used for the receiver as a precision phase detector in two-tone CW function and at the same time as a mixer in FMCW function. Various waveforms are generated in direct digital synthesizers and processed by different algorithms in a digital signal processor. The switching between the frequency-modulated CW and two-tone CW functions is controlled by software to improve the resolution and ensure a reliable operation. A system prototype is designed and made for a C-band demonstration. The Schottky diodes used as power detectors in the six-port are calibrated so that they can be used beyond the square-law region, thus allowing a higher power level and a better dynamic range. Measured results validate the proposed software-defined platform and accurate range results are confirmed.
He is currently Ph.D candidate in the School of Integrated Technology and Yonsei Institute of Convergence Technology, Yonsei University from 2012. His research area is development for microwave sensors
- Tae-Yun
Tae-Yun Lee received the B.S. degrees in Earth
System Science from Yonsei University, Seoul, Korea. He is currently Ph.D candidate in the School of
Integrated Technology and Yonsei Institute of Convergence Technology, Yonsei University from 2012.
His research area is development for microwave
sensors, Electromagnetic Wave Signal Processing,
and Inverse synthetic aperture radars.
FMCW Transceiver RS3400K/00 Data Sheet
- Fmcw Transceiver
A new method of multi-target detection for FMCW automotive radar
- Y Fan
- K Xiang
- J An
- X Bu
Y. Fan, K. Xiang, J. An, and X. Bu, "A new method of multi-target
detection for FMCW automotive radar," in Radar Conference 2013, IET
International, April 2013, pp. 1-4.
New radar waveform based on a chirp sequence
- H Rohling
- M Kronauge
H. Rohling and M. Kronauge, "New radar waveform based on a chirp
sequence," in Radar Conference (Radar), 2014 International, Oct 2014,
pp. 1-4.
Simulation and test results of triangular fast ramp FMCW waveform
- S Kim
- I Paek
- M Ka
S. Kim, I. Paek, and M. Ka, "Simulation and test results of triangular fast
ramp FMCW waveform," in Radar Conference (RADAR), 2013 IEEE,
April 2013, pp. 1-4.