The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform

Wenbo Wang - One of the best experts on this subject based on the ideXlab platform.

  • an lti model based study on Reflected Power canceler for fmcw radars
    IEEE Transactions on Microwave Theory and Techniques, 2018
    Co-Authors: Jinping Xu, Wenbo Wang
    Abstract:

    Frequency modulation continuous wave (FMCW) radar receivers generally suffer from transmitter leakage due to insufficient TX-to-RX isolation. One of the effective approaches to solving this problem is using Reflected Power cancelers (RPCs) that cancel the leakage from the transmitter adaptively. In this paper, a linear time invariant (LTI) model of the RPC is derived in order to carry out a comprehensive study of the mechanism of leakage cancelation and output noise performance for CW radar applications. Loop frequency responses for receiving signal, loop stability, and the influence of dc offset of IQ mixer are analyzed by a simplified transfer function. A detailed noise model of the RPC is established based on the LTI model to study the output noise components of the RPC under a large incident leakage, then the internal noise cancelation mechanism is elucidated. A prototype with its operating frequency range from 820 to 1020 MHz at UHF band is implemented. Measured loop frequency responses are in agreement with simulation results obtained with the proposed model. Furthermore, measured cancelation ratios for leakages of different ramp rates comply with the normalized Power gain at corresponding frequency offsets. The input-referred receiving noise of the RPC prototype is measured to be −155 dBm/Hz at 100-kHz offset under +10-dBm incident leakage Power. The proposed LTI model provides a useful tool for the design of high-performance RPC for FMCW systems in different application environments.

Edward A Keehr - One of the best experts on this subject based on the ideXlab platform.

  • a low cost high speed high resolution adaptively tunable microwave network for an sdr uhf rfid reader Reflected Power canceller
    International Conference on RFID, 2018
    Co-Authors: Edward A Keehr
    Abstract:

    A key problem with custom built and software-defined RFID reader architectures is that the large continuous-wave (CW) signal that must be transmitted during RFID tag reading must be concurrently processed by the RFID receive (RX) chain. Methods for handling this signal that are easily implemented in custom RFID reader ASICs are not typically inherently available in low-cost commercial off the shelf components. In this paper, a subranging digitally-tunable capacitor approach to Reflected Power cancellation in a low-cost software-defined RFID reader to address this issue is described. The key components of the proposed architecture cost under $4 in bulk and together consume less than 1mA quiescent current. The subranging aspect of the tunable microwave network providing the variable reflection coefficient reduces the residual cancellation error of the network by 30dB over the non-subranging case. The resulting network improves the TX leakage signal at the SDR ASIC RX input by 50dB over the uncancelled case and can be driven by an adaptive cancellation algorithm that converges in a median time of less than 10ms.

  • RFID - A low-cost, high-speed, high-resolution, adaptively tunable microwave network for an SDR UHF RFID reader Reflected Power canceller
    2018 IEEE International Conference on RFID (RFID), 2018
    Co-Authors: Edward A Keehr
    Abstract:

    A key problem with custom built and software-defined RFID reader architectures is that the large continuous-wave (CW) signal that must be transmitted during RFID tag reading must be concurrently processed by the RFID receive (RX) chain. Methods for handling this signal that are easily implemented in custom RFID reader ASICs are not typically inherently available in low-cost commercial off the shelf components. In this paper, a subranging digitally-tunable capacitor approach to Reflected Power cancellation in a low-cost software-defined RFID reader to address this issue is described. The key components of the proposed architecture cost under $4 in bulk and together consume less than 1mA quiescent current. The subranging aspect of the tunable microwave network providing the variable reflection coefficient reduces the residual cancellation error of the network by 30dB over the non-subranging case. The resulting network improves the TX leakage signal at the SDR ASIC RX input by 50dB over the uncancelled case and can be driven by an adaptive cancellation algorithm that converges in a median time of less than 10ms.

Yuanxun Wang - One of the best experts on this subject based on the ideXlab platform.

  • real time dsp for Reflected Power cancellation in fmcw radars
    Vehicular Technology Conference, 2004
    Co-Authors: Yuanxun Wang
    Abstract:

    A novel real-time DSP scheme is proposed for leakage cancellation in monostatic frequency modulated continuous wave (FMCW) radars. With the digital implementation, the proposed scheme shows a much more precise control of the leakage cancellation, compared to conventional analog implementation. Other advantages also include that the DC offset existing in analog mixers, affecting the cancellation performance, are eliminated. A radar test bed at 26 GHz has been built. The measurement results show more than 40 dB suppression in transmitter leakage, which proves the effectiveness of the proposed approach.

Ken Fong - One of the best experts on this subject based on the ideXlab platform.

  • system modeling and control of resonance frequency for an rf cavity using Reflected Power measurements
    International Conference on Advanced Intelligent Mechatronics, 2014
    Co-Authors: Ramona Leewe, M Moallem, Ken Fong
    Abstract:

    This paper presents a motion control system based on Reflected Power measurements to stabilize the natural resonance frequency of an RF cavity. Control of the natural resonance frequency of an RF cavity is essential for superconducting accelerator structures due to their high cavity sensitivity to internal and external vibrations and dependency on temperature changes. Due to the relatively high radio frequencies involved (MHz to GHz), direct measurement of the resonant frequency for real-time control is not possible with conventional microcontroller hardware. To address the control problem, this paper presents a nonlinear control scheme that relies on the measurement of the Reflected Power instead of the well-known phase comparison technique. The control scheme will be used in a motion control system to stabilize the resonance frequency of the cavity. The control algorithm is based on performance index minimization using the steepest descent method. A Lyapunov based stability analysis is presented that provides necessary conditions for closed-loop stability with the error reaching a bounded region in the state space of error dynamics. Simulations for the mechatronic system are presented to evaluate the performance of the proposed controller.

  • AIM - System modeling and control of resonance frequency for an RF cavity using Reflected Power measurements
    2014 IEEE ASME International Conference on Advanced Intelligent Mechatronics, 2014
    Co-Authors: Ramona Leewe, M Moallem, Ken Fong
    Abstract:

    This paper presents a motion control system based on Reflected Power measurements to stabilize the natural resonance frequency of an RF cavity. Control of the natural resonance frequency of an RF cavity is essential for superconducting accelerator structures due to their high cavity sensitivity to internal and external vibrations and dependency on temperature changes. Due to the relatively high radio frequencies involved (MHz to GHz), direct measurement of the resonant frequency for real-time control is not possible with conventional microcontroller hardware. To address the control problem, this paper presents a nonlinear control scheme that relies on the measurement of the Reflected Power instead of the well-known phase comparison technique. The control scheme will be used in a motion control system to stabilize the resonance frequency of the cavity. The control algorithm is based on performance index minimization using the steepest descent method. A Lyapunov based stability analysis is presented that provides necessary conditions for closed-loop stability with the error reaching a bounded region in the state space of error dynamics. Simulations for the mechatronic system are presented to evaluate the performance of the proposed controller.

  • control of rf cavity resonance frequency using Reflected Power measurements
    Conference of the Industrial Electronics Society, 2013
    Co-Authors: Ramona Leewe, M Moallem, Ken Fong
    Abstract:

    Control of the natural resonance frequency of an RF cavity is challenging due to the variations in the input frequency and the highly nonlinear dynamics involved. The drift of resonance frequency due to disturbances such as temperature variations has to be compensated using a sensor based feedback controller. Additionally, there are limited possibilities for measurement of relevant quantities such as the resonance frequency for the purpose of real-time control due to the extremely high frequencies involved. To address the control problem, this paper presents a nonlinear control scheme that relies on the measurement of Reflected Power. To this end, a mathematical dynamical model for the cavity is derived, based on which a feedback control scheme using the method of steepest descent is proposed. A Lyapunov stability analysis is presented for the closed-loop system. Simulations are presented to evaluate performance of the proposed controller.

  • IECON - Control of RF cavity resonance frequency using Reflected Power measurements
    IECON 2013 - 39th Annual Conference of the IEEE Industrial Electronics Society, 2013
    Co-Authors: Ramona Leewe, M Moallem, Ken Fong
    Abstract:

    Control of the natural resonance frequency of an RF cavity is challenging due to the variations in the input frequency and the highly nonlinear dynamics involved. The drift of resonance frequency due to disturbances such as temperature variations has to be compensated using a sensor based feedback controller. Additionally, there are limited possibilities for measurement of relevant quantities such as the resonance frequency for the purpose of real-time control due to the extremely high frequencies involved. To address the control problem, this paper presents a nonlinear control scheme that relies on the measurement of Reflected Power. To this end, a mathematical dynamical model for the cavity is derived, based on which a feedback control scheme using the method of steepest descent is proposed. A Lyapunov stability analysis is presented for the closed-loop system. Simulations are presented to evaluate performance of the proposed controller.

M Mokhtar - One of the best experts on this subject based on the ideXlab platform.