The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Andreas Stelzer - One of the best experts on this subject based on the ideXlab platform.

  • a fast chirp mimo Radar system using beat frequency fdma with single sideband modulation
    International Microwave Symposium, 2020
    Co-Authors: Minh Nguyen, Reinhard Feger, Jonathan Bechter, Markus Pichlerscheder, Andreas Stelzer
    Abstract:

    In this paper, we investigate the feasibility of using a fast-chirp frequency-modulated Continuous-Wave Radar system in order to realize frequency-division multiple-access multiple-input multiple-output. The frequency shifting is implemented by single-sideband modulation for unambiguous range enhancement. Furthermore, we apply a binary mask to separate transmit signals at the receivers instead of using a bandpass filter. Measurements accomplished using a prototype Radar system with 3 transmit antennas and 4 receive antennas demonstrate the proposed approach.

  • in chirp fsk communication between cooperative 77 ghz Radar stations integrating variable power distribution between ranging and communication system
    International Journal of Microwave and Wireless Technologies, 2016
    Co-Authors: Werner Scheiblhofer, Stefan Scheiblhofer, Reinhard Feger, Andreas Haderer, Andreas Stelzer
    Abstract:

    We present the realization of a cooperative Radar system for ranging applications with integrated data-transmission capability. The simultaneous transmission is performed by the Radar-hardware without the necessity of additional components or an auxiliary data-link. Therefore, the data are directly embedded in the transmitted chirp of a frequency-modulated Continuous-Wave Radar sensor. A second station, acting as receiver, uses an identical, but unmodulated chirp for down-conversion. The resulting signal then is processed by a non-coherent demodulator setup, extracting the communication data. Measurement results from transmission of messages with different bit-rates are shown. By utilizing existing Radar-hardware a transmission rate of up to 256 kbps is possible, without the need of a dedicated transceiver. Additionally, a method to optimize the ranging results by variable distribution of the available signal power between distance-measurement and communication system is presented.

  • method to embed a data link on fmcw chirps for communication between cooperative 77 ghz Radar stations
    European Radar Conference, 2015
    Co-Authors: Werner Scheiblhofer, Reinhard Feger, Andreas Haderer, Andreas Stelzer
    Abstract:

    We present the realization of a cooperative Radar system for ranging applications with integrated data-transmission capability. The simultaneous transmission is performed by the Radar-hardware without the necessity of additional components or an auxiliary data-link. Therefore the data is directly embedded in the transmitted chirp of a frequency-modulated Continuous-Wave Radar-sensor. A second station, acting as receiver, uses an identical, but unmodulated chirp for down-conversion. The resulting signal then is processed by a noncoherent demodulator setup, extracting the communication data. Measurement results from transmission of messages with different bit-rates are shown. By utilizing existing Radar-hardware a transmission rate of up to 128 kbps is possible, without the need of a dedicated transceiver.

  • A 79-GHz Radar sensor in ltcc technology using grid array antennas
    IEEE Transactions on Microwave Theory and Techniques, 2013
    Co-Authors: Frank Bauer, Wolfgang Menzel, Xin Wang, Andreas Stelzer
    Abstract:

    Concept, design, and measurement results of a frequency-modulated Continuous-Wave Radar sensor in low-temperature co-fired ceramics (LTCC) technology is presented in this paper. The sensor operates in the frequency band between 77–81 GHz. As a key component of the system, wideband microstrip grid array antennas with a broadside beam are presented and discussed. The combination with a highly integrated feeding network and a four-channel transceiver chip based on SiGe technology results in a very compact LTCC RF frontend (23 mm $times$ 23 mm). To verify the feasibility of the concept, first Radar measurement results are presented.

  • Phase-error measurement and compensation in PLL frequency synthesizers for FMCW sensors - I: Context and application
    IEEE Transactions on Circuits and Systems I: Regular Papers, 2007
    Co-Authors: Markus Pichler, Peter Gulden, Claus Seisenberger, Andreas Stelzer, Martin Vossiek
    Abstract:

    The synthesis of linear frequency sweeps or chirps is required, among others, in frequency-modulated Continuous-Wave Radar systems for object position estimation. Low phase and frequency errors in sweeps with high bandwidth are a prerequisite for good accuracy and resolution, but, in certain applications where high measurement rates are desired, the additional demand for short sweep cycles has to be met. Transient phenomena in dynamic synthesizers as well as nonlinear system behavior usually cause unknown phase errors in the system output. For the class of phase-locked-loop (PLL)-based frequency synthesizers, a novel output phase-measurement method and dedicated circuitry are proposed that allow significant reduction of phase errors by adaptive input predistortion. The measurement procedure is implemented within the PLL control circuitry and does not require external equipment. The application of this method to PLL system identification and linearization of extremely short frequency sweeps is shown

Mehmet Rasit Yuce - One of the best experts on this subject based on the ideXlab platform.

  • Systolic Blood Pressure Estimation Using Wearable Radar and Photoplethysmogram Signals
    2019 IEEE International Conference on Systems Man and Cybernetics (SMC), 2019
    Co-Authors: Malikeh Pour Ebrahim, Jeanmichel Redoute, Fatemeh Heydari, Katie Walker, Mehmet Rasit Yuce
    Abstract:

    On-body Continuous Wave Radar (CWR) sensors, along with Photoplethysmogram (PPG) and Electrocardiogram (ECG) sensors, have been introduced to estimate blood pressure(BP) using time parameters as Pulse Arrival Time (PAT), Pre-ejection Period (PEP) and Pulse Transit Time (PTT) during different postures and exercises tasks. The Wavelet transform is applied to the signals to remove the noise components. The on-body CWR sensor and PPG sensor are placed on the sternum and left earlobe, respectively. The time parameters of 43 healthy subjects are collected in the different sitting, standing, and supine postures, and also for 26 healthy subjects in six different exercise tasks as handgrip, light, moderate and heavy bike exercise, and two recoveries. Two different regression methods are used to estimate BP from PTT and the results are compared with the estimated BP from PAT. The best Cumulative Error Percentage (

  • systolic time interval estimation using Continuous Wave Radar with on body antennas
    IEEE Journal of Biomedical and Health Informatics, 2018
    Co-Authors: Dilpreet Buxi, Evelien Hermeling, Marco Mercuri, Fabian Beutel, Roberto Garcia Van Der Westen, Tom Torfs, Jeanmichel Redoute, Mehmet Rasit Yuce
    Abstract:

    The estimation of systolic time intervals (STIs) is done using Continuous Wave (CW) Radar at 2.45 GHz with an on-body antenna. Motivation : In the state of the art, typically bioimpedance, heart sounds and/or ultrasound are used to measure STIs. All three methods suffer from insufficient accuracy of STI estimation due to various reasons. CW Radar is investigated for its ability to overcome the deficiencies in the state of the art. Methods : Ten healthy male subjects aged 25–45 were asked to lie down at a 30 $^{\circ }$ incline. Recordings of 60 s were taken without breathing and with paced breathing. Heart sounds, electrocardiogram, respiration, and impedance cardiogram were measured simultaneously as reference. The Radar antennas were placed at two positions on the chest. The antennas were placed directly on the body as well as with cotton textile in between. The beat to beat STIs have been determined from the reference signals as well as CW Radar signals. Results: The results indicate that CW Radar can be used to estimate STIs in ambulatory monitoring. Significance: The results pave way to a potentially more compact method of estimating STIs, which can be integrated into a wearable device.

  • blood pressure estimation using pulse transit time from bioimpedance and Continuous Wave Radar
    IEEE Transactions on Biomedical Engineering, 2017
    Co-Authors: Dilpreet Buxi, Jeanmichel Redout, Mehmet Rasit Yuce
    Abstract:

    Objective: We have developed and tested a new architecture for pulse transit time (PTT) estimation at the central arteries using electrical bioimpedance, electrocardiogram, and Continuous Wave Radar to estimate cuffless blood pressure. Methods: A transmitter and receiver antenna are placed at the sternum to acquire the arterial pulsation at the aortic arch. A four-electrode arrangement across the shoulders acquires arterial pulse across the carotid and subclavian arteries from bioimpedance as well as a bipolar lead I electrocardiogram. The PTT and pulse arrival times (PATs) are measured on six healthy male subjects during exercise on a bicycle ergometer. Using linear regression, the estimated PAT and PTT values are calibrated to the systolic and mean as well as diastolic blood pressure from an oscillometric device. Results: For all subjects, the Pearson correlation coefficients for PAT–SBP and PTT–SBP are −0.66 ( p = 0.001) and −0.48 ( p = 0.0029), respectively. Correlation coefficients for individual subjects ranged from −0.54 to −0.9 and −0.37 to −0.95, respectively. Conclusion: The proposed system architecture is promising in estimating cuffless arterial blood pressure at the central, proximal arteries, which obey the Moens–Korteweg equation more closely when compared to peripheral arteries. Significance: An important advantage of PTT from the carotid and subclavian arteries is that the PTT over the central elastic arteries is measured instead of the peripheral arteries, which potentially reduces the changes in PTT due to vasomotion. Furthermore, the sensors can be completely hidden under a patients clothes, making them more acceptable by the patient for ambulatory monitoring.

Eugin Hyun - One of the best experts on this subject based on the ideXlab platform.

  • doppler spectrum feature based human vehicle classification scheme using machine learning for an fmcw Radar sensor
    Sensors, 2020
    Co-Authors: Eugin Hyun
    Abstract:

    In this paper, we propose a Doppler-spectrum feature-based human–vehicle classification scheme for an FMCW (frequency-modulated Continuous Wave) Radar sensor. We introduce three novel features referred to as the scattering point count, scattering point difference, and magnitude difference rate features based on the characteristics of the Doppler spectrum in two successive frames. We also use an SVM (support vector machine) and BDT (binary decision tree) for training and validation of the three aforementioned features. We measured the signals using a 24-GHz FMCW Radar front-end module and a real-time data acquisition module and extracted three features from a walking human and a moving vehicle in the field. We then repeatedly measured the classification decision rate of the proposed algorithm using the SVM and BDT, finding that the average performance exceeded 99% and 96% for the walking human and the moving vehicle, respectively.

  • two step moving target detection algorithm for automotive 77 ghz fmcw Radar
    Vehicular Technology Conference, 2010
    Co-Authors: Eugin Hyun, Jonghun Lee
    Abstract:

    Today, 77GHz FMCW (Frequency Modulation Continuous Wave) Radar sensors are used for automotive applications. In typical automotive Radar, the target of interest is a moving target. Thus, to improve the detection probability and reduce the false alarm rate, an MTD(Moving Target Detection) algorithm should be required. This paper describes the proposed two-step MTD algorithm. The 1st MTD processing consists of a clutter cancellation step and a noise cancellation step. The two steps can cancel almost all clutter including stationary targets. However, clutter still remains among the interest beat frequencies detected during the 1st MTD and CFAR (Constant False Alarm) processing. Thus, in the 2nd MTD step, we remove the rest of the clutter with zero phase variation.

  • a meothod for multi target range and velocity detection in automotive fmcw Radar
    International Conference on Intelligent Transportation Systems, 2009
    Co-Authors: Eugin Hyun, Jonghun Lee
    Abstract:

    FMCW(Frequency Modulation Continuous Wave) Radar has many useful applications but a serious problems can occur in multi-target situations. Range-velocity processing should suppress so-called ghost targets and detect missing targets presented by beat frequency shift with Doppler frequency. In this paper, a new method is proposed for effective identification of the correct pairs of beat frequencies received from real targets.

Martin Vossiek - One of the best experts on this subject based on the ideXlab platform.

  • a millimeter Wave low power active backscatter tag for fmcw Radar systems
    IEEE Transactions on Microwave Theory and Techniques, 2013
    Co-Authors: Axel Strobel, Christian Carlowitz, Robert Wolf, Frank Ellinger, Martin Vossiek
    Abstract:

    In this paper, a fully integrated active backscatter transponder based on the switched injection-locked oscillator (SILO) principle for frequency-modulated Continuous-Wave Radar applications is presented. Furthermore, a method to characterize a SILO amplifier is extended and utilized to measure the system parameters of the presented backscatter tag that operates at 34.45 GHz. It is digitally tunable from 32.7 to 35.4 GHz and reaches an unpulsed output power of 5 dBm. Above injection power levels of $-\hbox{53 dBm}$ , the SILO tag responds phase coherent at its maximum output power. In system measurements, the SILO backscatter transponder was used to perform distance measurements at ranges from 0.7 to 11.5 m. A remarkably good mean distance measurement error of 7 cm with a standard deviation of 10 cm was achieved in a strong multipath environment. The single measurement precision is below 3 mm.

  • Phase-error measurement and compensation in PLL frequency synthesizers for FMCW sensors - I: Context and application
    IEEE Transactions on Circuits and Systems I: Regular Papers, 2007
    Co-Authors: Markus Pichler, Peter Gulden, Claus Seisenberger, Andreas Stelzer, Martin Vossiek
    Abstract:

    The synthesis of linear frequency sweeps or chirps is required, among others, in frequency-modulated Continuous-Wave Radar systems for object position estimation. Low phase and frequency errors in sweeps with high bandwidth are a prerequisite for good accuracy and resolution, but, in certain applications where high measurement rates are desired, the additional demand for short sweep cycles has to be met. Transient phenomena in dynamic synthesizers as well as nonlinear system behavior usually cause unknown phase errors in the system output. For the class of phase-locked-loop (PLL)-based frequency synthesizers, a novel output phase-measurement method and dedicated circuitry are proposed that allow significant reduction of phase errors by adaptive input predistortion. The measurement procedure is implemented within the PLL control circuitry and does not require external equipment. The application of this method to PLL system identification and linearization of extremely short frequency sweeps is shown

  • Method for high precision Radar distance measurement and synchronization of wireless units
    IEEE MTT-S International Microwave Symposium Digest, 2007
    Co-Authors: Sven Roehr, Martin Vossiek, Peter Gulden
    Abstract:

    In this paper we present a novel approach for high precision synchronization of wireless units. A concept similar to the standard FMCW (frequency-modulated Continuous Wave) Radar principle is used to estimate the offset in time and in frequency between two Radar units. It allows for a synchronization of both offsets significantly below 100 ps and 10 Hz, respectively. This highly accurate synchronization is used in a prototype system to measure the distance between wireless units similar to a secondary Radar. The prototype operates within the 5.8 GHz ISM-Band and uses a bandwidth of 150 MHz. With the setup presented the distance between two Radar units is measured with a standard deviation of less than 4 cm over a range of 250 m. The broadband measurement principle is robust towards multipath interference. It can be extended to other frequency bands and is well-suited for direct integration into communication channels.

  • influence of systematic frequency sweep non linearity on object distance estimation in fmcw fscw Radar systems
    European Microwave Conference, 2003
    Co-Authors: Markus Pichler, Peter Gulden, Andreas Stelzer, Martin Vossiek
    Abstract:

    The performance of frequency estimation procedures for sinusoidal signals in the presence of phase perturbations plays an important role in Continuous-Wave Radar systems for distance measurement, as it directly determines the ranging accuracy. For the most widely used frequency estimator, the fast Fourier transformation, the influence of deterministic deviations of the transmit signal from the ideal curve in FMCW/FSCW Radars is investigated, quantified and verified with measured Radar data.

Ke Wu - One of the best experts on this subject based on the ideXlab platform.

  • System Architecture and Signal Processing for Frequency-Modulated Continuous-Wave Radar Using Active Backscatter Tags
    IEEE Transactions on Signal Processing, 2018
    Co-Authors: Jian-feng Gu, Kuangda Wang, Ke Wu
    Abstract:

    In this paper, we study a frequency-modulated Continuous-Wave based radio-frequency identification system, which is composed of a reader with single transmitter and multiple receiving antennas as well as multiple active backscatter tags. In particular, our contribution is twofold in this paper. First, we construct a general architecture for achieving the functionality of wireless positioning based on the principle of the switched injection-locked oscillator (SILO). Unlike the previous SILO-based schemes, some limitations on the pulsed Waveform generated by the tags are overcome. In addition, only one reader set up with multiple receiving antennas is used to precisely localize tags based on the delay and direction-of-arrival estimates. Second, the developed algorithms make use of a shift invariant property among the baseband signal snapshots of intra- and/or intermodulation intervals, i.e., snapshots in one modulation period and/or sets of snapshots in multiple modulation periods. A new joint singular value decomposition based ESPRIT algorithm is developed for determining the number of multiple active tags and their positions by implementing the matrix reconstruction and stacking techniques. The proposed method has its basic foundation on the processing of received data with global fusion scheme. In this way, this method can improve the performance of parameter estimates in terms of accuracy and resolution without suffering from the pair matching problem. System simulations and experimental validations are carried out to verify the proposed system architecture associated with the signal processing technique.

  • 24 ghz frequency modulation Continuous Wave Radar front end system on substrate
    IEEE Transactions on Microwave Theory and Techniques, 2008
    Co-Authors: Zhaolong Li, Ke Wu
    Abstract:

    Design and implementation of a 24-GHz frequency-modulation Continuous-Wave Radar front-end system is presented and discussed, and its hybrid planar and Waveguide building blocks are fully integrated on one single substrate. A flexible and compact integration methodology on the basis of the substrate-integrated-circuits concept is deployed to design such a microWave front-end system-on-substrate. In this study, it is found that this surface-volume hybrid integration scheme not only enables the complete system integration of planar and nonplanar microWave circuits, but also combines respective advantages of such structures in connection with microstrip lines (planar) and Waveguides (nonplanar). Design strategies of the system building blocks including mixers, power dividers, and antenna arrays are discussed together along with the measured results. To verify the developed Radar prototype, laboratory-based target-range measurements are conducted.