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Peter Willett - One of the best experts on this subject based on the ideXlab platform.

  • Reducing the Waveform Cross Correlation of MIMO Radar With Space #x2013;Time Coding
    IEEE Transactions on Signal Processing, 2010
    Co-Authors: X. Song, Shenghua Zhou, Peter Willett
    Abstract:

    Multiple-input-multiple-output (MIMO) radar is attractive for target detection, parameter identification, and target classification due to diversity of waveform and perspective. However, the mutual interference among the Waveforms may lead to performance degradation in resolving spatially close returns. In this paper, we consider the use of space-time coding (STC) to mitigate the waveform cross-correlation effects in MIMO radar. First, it turns out that a joint waveform optimization problem can be decoupled into a set of individual waveform design problems. Second, a number of monostatic Waveforms can be directly used in a MIMO radar system, which offers flexibility in waveform selection. We provide conditions for the elimination of waveform cross correlation, and discuss four kinds of space time codes. In addition, we also extend the model to partial waveform cross-correlation removal based on waveform set division. Numerical results demonstrate the effectiveness of STC in MIMO radar for waveform decorrelation.

  • Reducing the Waveform Cross Correlation of MIMO Radar With Space–Time Coding
    IEEE Transactions on Signal Processing, 2010
    Co-Authors: X. Song, Shengli Zhou, Peter Willett
    Abstract:

    Multiple-input-multiple-output (MIMO) radar is attractive for target detection, parameter identification, and target classification due to diversity of waveform and perspective. However, the mutual interference among the Waveforms may lead to performance degradation in resolving spatially close returns. In this paper, we consider the use of space-time coding (STC) to mitigate the waveform cross-correlation effects in MIMO radar. First, it turns out that a joint waveform optimization problem can be decoupled into a set of individual waveform design problems. Second, a number of monostatic Waveforms can be directly used in a MIMO radar system, which offers flexibility in waveform selection. We provide conditions for the elimination of waveform cross correlation, and discuss four kinds of space time codes. In addition, we also extend the model to partial waveform cross-correlation removal based on waveform set division. Numerical results demonstrate the effectiveness of STC in MIMO radar for waveform decorrelation.

X. Song - One of the best experts on this subject based on the ideXlab platform.

  • Reducing the Waveform Cross Correlation of MIMO Radar With Space #x2013;Time Coding
    IEEE Transactions on Signal Processing, 2010
    Co-Authors: X. Song, Shenghua Zhou, Peter Willett
    Abstract:

    Multiple-input-multiple-output (MIMO) radar is attractive for target detection, parameter identification, and target classification due to diversity of waveform and perspective. However, the mutual interference among the Waveforms may lead to performance degradation in resolving spatially close returns. In this paper, we consider the use of space-time coding (STC) to mitigate the waveform cross-correlation effects in MIMO radar. First, it turns out that a joint waveform optimization problem can be decoupled into a set of individual waveform design problems. Second, a number of monostatic Waveforms can be directly used in a MIMO radar system, which offers flexibility in waveform selection. We provide conditions for the elimination of waveform cross correlation, and discuss four kinds of space time codes. In addition, we also extend the model to partial waveform cross-correlation removal based on waveform set division. Numerical results demonstrate the effectiveness of STC in MIMO radar for waveform decorrelation.

  • Reducing the Waveform Cross Correlation of MIMO Radar With Space–Time Coding
    IEEE Transactions on Signal Processing, 2010
    Co-Authors: X. Song, Shengli Zhou, Peter Willett
    Abstract:

    Multiple-input-multiple-output (MIMO) radar is attractive for target detection, parameter identification, and target classification due to diversity of waveform and perspective. However, the mutual interference among the Waveforms may lead to performance degradation in resolving spatially close returns. In this paper, we consider the use of space-time coding (STC) to mitigate the waveform cross-correlation effects in MIMO radar. First, it turns out that a joint waveform optimization problem can be decoupled into a set of individual waveform design problems. Second, a number of monostatic Waveforms can be directly used in a MIMO radar system, which offers flexibility in waveform selection. We provide conditions for the elimination of waveform cross correlation, and discuss four kinds of space time codes. In addition, we also extend the model to partial waveform cross-correlation removal based on waveform set division. Numerical results demonstrate the effectiveness of STC in MIMO radar for waveform decorrelation.

Shigemitsu Okabe - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of breakdown characteristics of gas insulated switchgears for non standard lightning impulse Waveforms breakdown characteristics for non standard lightning impulse Waveforms associated with disconnector switching surges
    IEEE Transactions on Dielectrics and Electrical Insulation, 2008
    Co-Authors: Shigemitsu Okabe, S Yuasa, Shuhei Kaneko
    Abstract:

    To lower the insulation specifications (specifically, the lightning impulse withstand voltage) of a gas insulated switchgear (GIS) and thus cut the equipment cost while maintaining the high reliability of its insulation performance, it is necessary to define in an organized way the insulation characteristics for non-standard lightning impulse voltage Waveforms that represent actual surge Waveforms in the field and compare them with the characteristics for the standard lightning impulse waveform quantitatively. In the preceding paper, lightning surge Waveforms and disconnector switching surge Waveforms at UHV, 500 kV, and 275 kV substations were analyzed and five to six non-standard lightning surge Waveforms with basic frequencies of 0.6 to 5.0 MHz were identified. In this paper, the dielectric breakdown voltage - time characteristics were measured under several different conditions for the quasi-uniform SF6 gas gap that represents an insulation element of a GIS toward two kinds of non-standard lightning impulse Waveforms associated with disconnector switching surges. As a result, in the tested range, the dielectric breakdown values for non-standard lightning impulse Waveforms were higher than for the standard lightning impulse waveform by 6% to 36%.

  • Evaluation of Breakdown Characteristics of Gas Insulated Switchgears for Non-Standard Lightning Impulse Waveforms - Breakdown Characteristics for Non-Standard Lightning Impulse Waveforms Associated with Lightning Surges
    IEEE Transactions on Dielectrics and Electrical Insulation, 2008
    Co-Authors: Shigemitsu Okabe, S Yuasa, Shuhei Kaneko
    Abstract:

    To lower the insulation specifications (specifically, the lightning impulse withstand voltage) of a gas insulated switchgear (GIS) and thus cut the equipment cost while maintaining the high reliability of its insulation performance, it is necessary to define in an organized way the insulation characteristics for non-standard lightning impulse voltage Waveforms that represent actual surge Waveforms in the field and compare them with the characteristics for the standard lightning impulse waveform quantitatively. In the preceding paper, lightning surge Waveforms and disconnector switching surge Waveforms at UHV, 500 kV, and 275 kV substations were analyzed and five to six non-standard lightning surge Waveforms with basic frequencies of 0.6 to 5.0 MHz were identified. In this paper, the dielectric breakdown voltage - time characteristics were measured under several different conditions mainly for the quasi-uniform SF6 gas gaps that represent an insulation element of a GIS toward four kinds of non-standard lightning impulse Waveforms associated with lightning surges. As a result, in the tested range, the dielectric breakdown values for nonstandard lightning impulse Waveforms were higher than for the standard lightning impulse waveform by 3% to 32%.

  • Evaluation of breakdown characteristics of oil-immersed transformers under non-standard lightning impulse Waveforms - definition of non-standard lightning impulse Waveforms and insulation characteristics for Waveforms including pulses
    IEEE Transactions on Dielectrics and Electrical Insulation, 2007
    Co-Authors: Shigemitsu Okabe
    Abstract:

    To lower the insulation specifications (specifically, the lightning impulse withstand voltage) of oil-immersed transformers and thus cut the equipment cost while maintaining the high reliability in its insulation performance, it is necessary to grasp in an organized way the insulation characteristics under non-standard lightning impulse voltage Waveforms that represent actual surge Waveforms encountered in the field and compare them with the characteristics under the standard lightning impulse waveform quantitatively. As described in this paper, the first step in a series of study for the purpose above was taken by analyzing lightning surge Waveforms and restriking surge Waveforms such as disconnector switching surge Waveforms at UHV, 500 kV, and 275 kV substations and identifying four typical non-standard lightning impulse Waveforms with basic frequencies of 0.24 to 1.0 MHz. Then, two of these non-standard lightning impulse Waveforms, the single-pulse waveform which is the most basic type and the waveform with a pulse in the crest and a subsequent flat section, were used to measure the breakdown voltage and the partial discharge inception voltage while changing the parameters, on three models that represent the insulation elements of windings of oil-immersed transformers. Then, the resultant average breakdown voltages were evaluated in terms of the overvoltage durations, leading to a result of formulating them in a unified way. In the tested range, the dielectric breakdown values under non-standard lightning impulse Waveforms were higher, marking 52% at the maximum, than those under standard lightning impulse Waveforms in all the cases, suggesting a possibility of lowering the insulation specifications of an oil-immersed transformer

  • Evaluation of breakdown characteristics of gas insulated switchgears for non-standard lightning impulse Waveforms - analysis and generation circuit of non-standard lightning impulse Waveforms in actual field
    IEEE Transactions on Dielectrics and Electrical Insulation, 2007
    Co-Authors: Shigemitsu Okabe, S Yuasa, Shuhei Kaneko
    Abstract:

    To lower the insulation specifications (specifically, the lightning impulse withstand voltage) of a gas insulated switchgear (GIS) and thus cut the equipment cost while maintaining the high reliability of its insulation performance, it is necessary to define in an organized way the insulation characteristics for non-standard lightning impulse voltage Waveforms that represent actual surge Waveforms in the field and compare them with the characteristics for the standard lightning impulse waveform quantitatively. In this paper, first, lightning surge Waveforms and disconnector switching surge Waveforms at UHV, 500 kV, and 275 kV substations were analyzed and five non-standard lightning surge Waveforms with basic frequencies of 0.6 to 5.0 MHz were identified. Next, high-voltage circuits that generate these non-standard lightning surge Waveforms were designed and constituted using EMTP (electro magnetic transients program) based on a circuit with a gap, inductors, and resistors connected in series and resistors and capacitors connected in parallel. Further, circuits were actually constructed, to obtain voltage Waveforms approximately equal to those designed. Finally, the dielectric breakdown voltage-time characteristics were measured under several different conditions for the quasi-uniform SF6 gas gap that represents an insulation element of a GIS. As a result, it was found that, in the tested range, the dielectric breakdown values for non-standard lightning impulse Waveforms were higher than for the standard lightning impulse waveform by 6% to 32%

Shuhei Kaneko - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of breakdown characteristics of gas insulated switchgears for non standard lightning impulse Waveforms breakdown characteristics for non standard lightning impulse Waveforms associated with disconnector switching surges
    IEEE Transactions on Dielectrics and Electrical Insulation, 2008
    Co-Authors: Shigemitsu Okabe, S Yuasa, Shuhei Kaneko
    Abstract:

    To lower the insulation specifications (specifically, the lightning impulse withstand voltage) of a gas insulated switchgear (GIS) and thus cut the equipment cost while maintaining the high reliability of its insulation performance, it is necessary to define in an organized way the insulation characteristics for non-standard lightning impulse voltage Waveforms that represent actual surge Waveforms in the field and compare them with the characteristics for the standard lightning impulse waveform quantitatively. In the preceding paper, lightning surge Waveforms and disconnector switching surge Waveforms at UHV, 500 kV, and 275 kV substations were analyzed and five to six non-standard lightning surge Waveforms with basic frequencies of 0.6 to 5.0 MHz were identified. In this paper, the dielectric breakdown voltage - time characteristics were measured under several different conditions for the quasi-uniform SF6 gas gap that represents an insulation element of a GIS toward two kinds of non-standard lightning impulse Waveforms associated with disconnector switching surges. As a result, in the tested range, the dielectric breakdown values for non-standard lightning impulse Waveforms were higher than for the standard lightning impulse waveform by 6% to 36%.

  • Evaluation of Breakdown Characteristics of Gas Insulated Switchgears for Non-Standard Lightning Impulse Waveforms - Breakdown Characteristics for Non-Standard Lightning Impulse Waveforms Associated with Lightning Surges
    IEEE Transactions on Dielectrics and Electrical Insulation, 2008
    Co-Authors: Shigemitsu Okabe, S Yuasa, Shuhei Kaneko
    Abstract:

    To lower the insulation specifications (specifically, the lightning impulse withstand voltage) of a gas insulated switchgear (GIS) and thus cut the equipment cost while maintaining the high reliability of its insulation performance, it is necessary to define in an organized way the insulation characteristics for non-standard lightning impulse voltage Waveforms that represent actual surge Waveforms in the field and compare them with the characteristics for the standard lightning impulse waveform quantitatively. In the preceding paper, lightning surge Waveforms and disconnector switching surge Waveforms at UHV, 500 kV, and 275 kV substations were analyzed and five to six non-standard lightning surge Waveforms with basic frequencies of 0.6 to 5.0 MHz were identified. In this paper, the dielectric breakdown voltage - time characteristics were measured under several different conditions mainly for the quasi-uniform SF6 gas gaps that represent an insulation element of a GIS toward four kinds of non-standard lightning impulse Waveforms associated with lightning surges. As a result, in the tested range, the dielectric breakdown values for nonstandard lightning impulse Waveforms were higher than for the standard lightning impulse waveform by 3% to 32%.

  • Evaluation of breakdown characteristics of gas insulated switchgears for non-standard lightning impulse Waveforms - analysis and generation circuit of non-standard lightning impulse Waveforms in actual field
    IEEE Transactions on Dielectrics and Electrical Insulation, 2007
    Co-Authors: Shigemitsu Okabe, S Yuasa, Shuhei Kaneko
    Abstract:

    To lower the insulation specifications (specifically, the lightning impulse withstand voltage) of a gas insulated switchgear (GIS) and thus cut the equipment cost while maintaining the high reliability of its insulation performance, it is necessary to define in an organized way the insulation characteristics for non-standard lightning impulse voltage Waveforms that represent actual surge Waveforms in the field and compare them with the characteristics for the standard lightning impulse waveform quantitatively. In this paper, first, lightning surge Waveforms and disconnector switching surge Waveforms at UHV, 500 kV, and 275 kV substations were analyzed and five non-standard lightning surge Waveforms with basic frequencies of 0.6 to 5.0 MHz were identified. Next, high-voltage circuits that generate these non-standard lightning surge Waveforms were designed and constituted using EMTP (electro magnetic transients program) based on a circuit with a gap, inductors, and resistors connected in series and resistors and capacitors connected in parallel. Further, circuits were actually constructed, to obtain voltage Waveforms approximately equal to those designed. Finally, the dielectric breakdown voltage-time characteristics were measured under several different conditions for the quasi-uniform SF6 gas gap that represents an insulation element of a GIS. As a result, it was found that, in the tested range, the dielectric breakdown values for non-standard lightning impulse Waveforms were higher than for the standard lightning impulse waveform by 6% to 32%

David A. Hague - One of the best experts on this subject based on the ideXlab platform.

  • Target Resolution Properties of the Multi-Tone Sinusoidal Frequency Modulatedwaveform
    2018 IEEE Statistical Signal Processing Workshop (SSP), 2018
    Co-Authors: David A. Hague
    Abstract:

    The mainlobe width of a waveform's Ambiguity Function (AF) determines its ability to resolve multiple closely spaced targets in time-delay (range) and Doppler (range-rate). The contour of the AF's mainlobe is well approximated by a coupled ellipse known as the Ellipse Of Ambiguity (EOA) whose parameters can be directly calculated in closed form if the waveform's modulation function is known. The Multi-Tone Sinusoidal Frequency Modulated (MTSFM) waveform possesses a modulation function that is represented using a Fourier series expansion. These Fourier coefficients act as a set of tunable parameters that can be adjusted to synthesize Waveforms with desired properties. This paper derives closed form expressions for the EOA parameters of the MTSFM and demonstrates their mainlobe characteristics via simulation.

  • SSP - Target Resolution Properties of the Multi-Tone Sinusoidal Frequency Modulatedwaveform
    2018 IEEE Statistical Signal Processing Workshop (SSP), 2018
    Co-Authors: David A. Hague
    Abstract:

    The mainlobe width of a waveform’s Ambiguity Function (AF) determines its ability to resolve multiple closely spaced targets in time-delay (range) and Doppler (range-rate). The contour of the AF’s mainlobe is well approximated by a coupled ellipse known as the Ellipse Of Ambiguity (EOA) whose parameters can be directly calculated in closed form if the waveform’s modulation function is known. The Multi-Tone Sinusoidal Frequency Modulated (MTSFM) waveform possesses a modulation function that is represented using a Fourier series expansion. These Fourier coefficients act as a set of tunable parameters that can be adjusted to synthesize Waveforms with desired properties. This paper derives closed form expressions for the EOA parameters of the MTSFM and demonstrates their mainlobe characteristics via simulation.

  • The Generalized Sinusoidal Frequency-Modulated Waveform for Active Sonar
    IEEE Journal of Oceanic Engineering, 2017
    Co-Authors: David A. Hague, John R. Buck
    Abstract:

    Pulse compression (PC) active sonar Waveforms provide a significant improvement in range resolution over single-frequency sinusoidal Waveforms also known as continuous wave (CW) Waveforms. Since their inception in the 1940s, a wide variety of PC Waveforms have been designed using either frequency modulation (FM), phase coding, or frequency hopping to suite particular sonar applications. The sinusoidal FM (SFM) waveform modulates its instantaneous frequency (IF) by a sinusoid to achieve high Doppler sensitivity which also aids in suppressing reverberation. This allows the SFM waveform to resolve target velocities. While the SFM's resolution in range is inversely proportional to its bandwidth, the SFM's autocorrelation function (ACF) contains many large sidelobes. The periodicity of the SFM's IF creates these sidelobes and impairs the SFM's ability to clearly distinguish multiple targets in range. This paper describes a generalization of the SFM waveform, referred to as the generalized SFM (GSFM) waveform, which modifies the SFM's IF to resemble the time/voltage characteristic of an FM chirp waveform. As a result of this modification, the Doppler sensitivity of the SFM is preserved while substantially reducing the high range sidelobes, producing a waveform whose ambiguity function (AF) approaches a thumbtack shape. This paper focuses primarily on the properties of the GSFM's thumbtack AF shape and compares it to other well-known Waveforms with a similar AF shape. The GSFM waveform achieves zero range-Doppler coupling for single target measurements which in turn minimizes the variance in jointly estimating target range and velocity and optimizes resolution of multiple point targets in range and velocity. The GSFM's AF peak sidelobe levels, which determine the waveform's ability to detect weak targets in the presence of strong ones, are comparable to other well-established thumbtack AF Waveforms such as Costas or phase-coded Waveforms over a wide range of time-bandwidth product (TBP) values.