Weak global navigation satellite system（GNSS） signal acquisition has been a limitation for high sensitivity GPS receivers. This paper modifies the traditional acquisition algorithms and proposes a new weak GNSS sign...Weak global navigation satellite system（GNSS） signal acquisition has been a limitation for high sensitivity GPS receivers. This paper modifies the traditional acquisition algorithms and proposes a new weak GNSS signal acquisition method using re-scaling and adaptive stochastic resonance（SR）. The adoption of classical SR is limited to low-frequency and periodic signals. Given that GNSS signal frequency is high and that the periodic feature of the GNSS signal is affected by the Doppler frequency shift, classical SR methods cannot be directly used to acquire GNSS signals. Therefore, the re-scaling technique is used in our study to expand its usage to high-frequency signals and adaptive control technique is used to gradually determine the Doppler shift effect in GNSS signal buried in strong noises. The effectiveness of our proposed method was verified by the simulations on GPS L1 signals. The simulation results indicate that the new algorithm based on SR can reach-181 d BW sensitivity with a very short data length of 1 ms.展开更多
Using the linear approximation method, we study a single-mode laser system driven by colored pump noise and quantum noise with coupling between the real and imaginary parts when the laser is operated well above thresh...Using the linear approximation method, we study a single-mode laser system driven by colored pump noise and quantum noise with coupling between the real and imaginary parts when the laser is operated well above threshold. The steady state mean intensity fluctuation C(0) and signal-to-noise ratio (SNR) are calculated. It is found that there is a maximum in SNR when there is a minimum in the fluctuation of laser system if the coupling coefficient between real and imaginary parts of the quantum noise equals zero.展开更多
Purpose-From many decades,bearings-only tracking(BOT)is the interested problem for researchers.This utilises nonlinear filtering methods for state estimation as there is only information about the target,i.e.bearing i...Purpose-From many decades,bearings-only tracking(BOT)is the interested problem for researchers.This utilises nonlinear filtering methods for state estimation as there is only information about the target,i.e.bearing is a nonlinear measurement.The measurement bearing is tangentially related to the target state vector.There are many nonlinear filtering algorithms developed so far in the literature.Design/methodology/approach-In this research work,the recently developed nonlinear filtering algorithm,i.e.shifted Rayleigh filter(SRF),is applied to BOT.Findings-The SRF is tested for two-dimensional BOT against various scenarios.The simulation results emphasise that the SRF performs well when compared to the standard nonlinear filtering algorithm,unscented Kalman filter(UKF).Originality/value-SRF utilises the nonlinearities present in the bearing measurement through the use of moment matching.The SRF is able to produce the solution in highly noisy environment,long ranges and high dimension tracking.展开更多
基金supported by the National Natural Science Foundation of China(61202078)
文摘Weak global navigation satellite system（GNSS） signal acquisition has been a limitation for high sensitivity GPS receivers. This paper modifies the traditional acquisition algorithms and proposes a new weak GNSS signal acquisition method using re-scaling and adaptive stochastic resonance（SR）. The adoption of classical SR is limited to low-frequency and periodic signals. Given that GNSS signal frequency is high and that the periodic feature of the GNSS signal is affected by the Doppler frequency shift, classical SR methods cannot be directly used to acquire GNSS signals. Therefore, the re-scaling technique is used in our study to expand its usage to high-frequency signals and adaptive control technique is used to gradually determine the Doppler shift effect in GNSS signal buried in strong noises. The effectiveness of our proposed method was verified by the simulations on GPS L1 signals. The simulation results indicate that the new algorithm based on SR can reach-181 d BW sensitivity with a very short data length of 1 ms.
基金This work was supported by the National Natural Science Foundation of China (No. 10275025)Emphases Item of Education Office of Hubei Province, China (No. 2003A001).
文摘Using the linear approximation method, we study a single-mode laser system driven by colored pump noise and quantum noise with coupling between the real and imaginary parts when the laser is operated well above threshold. The steady state mean intensity fluctuation C(0) and signal-to-noise ratio (SNR) are calculated. It is found that there is a maximum in SNR when there is a minimum in the fluctuation of laser system if the coupling coefficient between real and imaginary parts of the quantum noise equals zero.
文摘Purpose-From many decades,bearings-only tracking(BOT)is the interested problem for researchers.This utilises nonlinear filtering methods for state estimation as there is only information about the target,i.e.bearing is a nonlinear measurement.The measurement bearing is tangentially related to the target state vector.There are many nonlinear filtering algorithms developed so far in the literature.Design/methodology/approach-In this research work,the recently developed nonlinear filtering algorithm,i.e.shifted Rayleigh filter(SRF),is applied to BOT.Findings-The SRF is tested for two-dimensional BOT against various scenarios.The simulation results emphasise that the SRF performs well when compared to the standard nonlinear filtering algorithm,unscented Kalman filter(UKF).Originality/value-SRF utilises the nonlinearities present in the bearing measurement through the use of moment matching.The SRF is able to produce the solution in highly noisy environment,long ranges and high dimension tracking.
