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Frequency modulation procedure is proposed to overcome the mode-mixing problem associated with the EMD method when processing signals with closely spaced frequencies. This procedure also provides the flexibility to start the reali...
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Frequency modulation procedure is proposed to overcome the mode-mixing problem associated with the EMD method when processing signals with closely spaced frequencies. This procedure also provides the flexibility to start the realization of IMFs either from the high frequency end as does the original EMD or from the low frequency end when the signal contains unwanted high frequency components. The EMD procedure, under the circumstances, may behave as high pass, low pass or band pass/stop filters. The proposed method, assisted by the Hilbert-Huang transform on the governing equations, identifies the instantaneous stiffness and damping coefficients as functions of vibration amplitude of a nonlinear system. The effectiveness of the proposed method is verified by numerical simulation.
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Based on the widely spread concept of instantaneous frequency (IF), we resumed the IF attractors (IFAs) method used for tonal components extraction from any given signal and we emphasized its essential advantages over traditional ...
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Based on the widely spread concept of instantaneous frequency (IF), we resumed the IF attractors (IFAs) method used for tonal components extraction from any given signal and we emphasized its essential advantages over traditional approaches by incorporating it into a popular application: the calculus of auditory masking threshold (AMT). Using MPEG1 Layer 1 psychoacoustic model, we propose to replace the classic algorithm for tonal/noise maskers identification with the IFAs method. The new approach proved a superior behavior regarding the accuracy estimation of tonal component confirmed by comparative tests. Also, we report notable AMT magnitude differences, between reference method and new approach.
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The paper presents effective algorithms for fast measurement and estimation of the unknown changing frequency and amplitude. The method for emulating coherent sampling with changing signal parameters by the interpolation of the DF...
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The paper presents effective algorithms for fast measurement and estimation of the unknown changing frequency and amplitude. The method for emulating coherent sampling with changing signal parameters by the interpolation of the DFT to estimate the frequency and amplitude of the particular component is described. An analysis of errors of the DFT coefficients caused by the frequency variation shows that the errors have two systematic contributions: the bias part due to the window spectrum main lobe and the long-range contribution. They can be both reduced with the interpolation. The optimum for reducing the time of measurement to two periods of the fundamental component and simultaneously reducing the influences of the harmonic components as possible can be the estimation with the two-point interpolation and the Hanning window.
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While spread spectrum systmes are robust to many types of interference. performance can be significantly degraded if the interfernece is strong enough, particularly for wideband interferences. In these situations, various signal s...
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While spread spectrum systmes are robust to many types of interference. performance can be significantly degraded if the interfernece is strong enough, particularly for wideband interferences. In these situations, various signal sprocesisng methods can be empolyed to remove, or excise, the jammer prior to despreading the received signal, resulting in enhanced perofrmnce. We investigate the effects of amplitude and frequency modulated (AM-FM) jam-mers on the performance of idrect sequence spread spectrum communication systems. We demonstrate that such jammers cuae significant degradation in bit-erro-rate with increasing AM on systmes designed to excise FM jammers only (e,e. systems ith fixed notch-width excison filters). We propose an adaptive techniqeu that utilzies the instatantaneous bandwidth of the jammer, in addition to its instantaneous frequencym, to filter widband AM-FM interfernece instantaneous power of the jammer. Simulations demosntrate additional improvement in system performance for the proposed adaptive technique compared to fixed nothc-width and fixed nothc-depth excision filters.
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摘要 :
While spread spectrum systmes are robust to many types of interference. performance can be significantly degraded if the interfernece is strong enough, particularly for wideband interferences. In these situations, various signal s...
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While spread spectrum systmes are robust to many types of interference. performance can be significantly degraded if the interfernece is strong enough, particularly for wideband interferences. In these situations, various signal sprocesisng methods can be empolyed to remove, or excise, the jammer prior to despreading the received signal, resulting in enhanced perofrmnce. We investigate the effects of amplitude and frequency modulated (AM-FM) jam-mers on the performance of idrect sequence spread spectrum communication systems. We demonstrate that such jammers cuae significant degradation in bit-erro-rate with increasing AM on systmes designed to excise FM jammers only (e,e. systems ith fixed notch-width excison filters). We propose an adaptive techniqeu that utilzies the instatantaneous bandwidth of the jammer, in addition to its instantaneous frequencym, to filter widband AM-FM interfernece instantaneous power of the jammer. Simulations demosntrate additional improvement in system performance for the proposed adaptive technique compared to fixed nothc-width and fixed nothc-depth excision filters.
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The paper describes an algorithm for estimating the pitch and formants’ center frequencies and bandwidths with the use of instantaneous complex frequency (ICF). ICF for each formant is computed from the analytic signal, obtained b...
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The paper describes an algorithm for estimating the pitch and formants’ center frequencies and bandwidths with the use of instantaneous complex frequency (ICF). ICF for each formant is computed from the analytic signal, obtained by filtering speech signal with a passband complex Hilbert filter, which additionally separates the analyzed formant from the speech signal.
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In heavy multipath scenarios such as urban canyons, the user code phase pseudorange error due to multipath fading can be as high as two meters even for the most sophisticated ranging signals such as Galileo E5 Alternate Binary-Off...
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In heavy multipath scenarios such as urban canyons, the user code phase pseudorange error due to multipath fading can be as high as two meters even for the most sophisticated ranging signals such as Galileo E5 Alternate Binary-Offset-Carrier A1tBOC (15,10). In this paper the author introduces methods to mitigate the code phase multipath by exploiting the frequency diversity which is inherent to the A1tBOC modulation used in Galileo E5 satellite navigation signals. A detailed analysis of the proposed method - called SCPC (Sideband Carrier Phase Combination) - is provided and its features are discussed.With the help of simulations and the signal collected from satellites, it is shown that the instantaneous code phase multipath error can be reduced to less than half a meter.
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In heavy multipath scenarios such as urban canyons, the user code phase pseudorange error due to multipath fading can be as high as two meters even for the most sophisticated ranging signals such as Galileo E5 Alternate Binary-Off...
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In heavy multipath scenarios such as urban canyons, the user code phase pseudorange error due to multipath fading can be as high as two meters even for the most sophisticated ranging signals such as Galileo E5 Alternate Binary-Offset-Carrier A1tBOC (15,10). In this paper the author introduces methods to mitigate the code phase multipath by exploiting the frequency diversity which is inherent to the A1tBOC modulation used in Galileo E5 satellite navigation signals. A detailed analysis of the proposed method - called SCPC (Sideband Carrier Phase Combination) - is provided and its features are discussed.With the help of simulations and the signal collected from satellites, it is shown that the instantaneous code phase multipath error can be reduced to less than half a meter.
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In this paper, a dual frequency ground-based monitor is developed to instantaneously detect orbit ephemeris faults in Ground Based Augmentation Systems (GBAS). Unlike current ephemeris monitors that each can only detect one type o...
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In this paper, a dual frequency ground-based monitor is developed to instantaneously detect orbit ephemeris faults in Ground Based Augmentation Systems (GBAS). Unlike current ephemeris monitors that each can only detect one type of ephemeris fault, the monitor designed here can detect all types of ephemeris fault. Ephemeris faults cause spatial gradients that can be detected using differential GPS measurements across spatially separated ground antennas. The new ephemeris monitor uses dual frequency carrier phase measurements and single frequency code phase measurements for fault detection. Analysis shows that the monitor can detect all hazardous ephemeris faults while meeting GBAS continuity and integrity risk requirements.
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摘要 :
In this paper, a dual frequency ground-based monitor is developed to instantaneously detect orbit ephemeris faults in Ground Based Augmentation Systems (GBAS). Unlike current ephemeris monitors that each can only detect one type o...
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In this paper, a dual frequency ground-based monitor is developed to instantaneously detect orbit ephemeris faults in Ground Based Augmentation Systems (GBAS). Unlike current ephemeris monitors that each can only detect one type of ephemeris fault, the monitor designed here can detect all types of ephemeris fault. Ephemeris faults cause spatial gradients that can be detected using differential GPS measurements across spatially separated ground antennas. The new ephemeris monitor uses dual frequency carrier phase measurements and single frequency code phase measurements for fault detection. Analysis shows that the monitor can detect all hazardous ephemeris faults while meeting GBAS continuity and integrity risk requirements.
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