Horizontal-Longitudinal Spatial Correlation of Acoustic Field with Deep Receiver in the Direct Zone in Deep Water

The horizontal-longitudinal correlation of acoustic field for the receiver near the bottom is analyzed by using nu- merical modeling. An approximate analytical solution of horizontal-longitudinal correlation coefficient is derived based on the ray method. Combining the characteristic of Lloyd＇s mirror interference pattern, the variability of acoustic field and its effect on horizontal-longitudinal spatial correlation are discussed. The theoretical pre- diction agrees well with the numerical results. Experimental results confirm the validity of analytical solution. Finally, the applicability of the analytical solution is summarized. The conclusion is beneficial for the design of bottom-moored array and the estimation of integral time for moving source localization.

Performance Analysis and Power Allocation for Cooperative SSK System with Receive Correlation in Rayleigh Fading Channel

In this paper,the performance analysis of cooperative space shift keying(SSK)system with dual hop amplify and forward(AF)in receive correlated Rayleigh channel is presented.By means of the performance analysis,a closed form approximate expression of the average bit error rate(BER)is derived for the performance evaluation.With this expression,in a high signal to noise ratio(SNR)region,a tight closed form asymptotic BER of the system is also derived.It can simplify the calculation of average BER and provide effective evaluation for asymptotic performance.By minimizing this asymptotic BER expression,a suboptimum power allocation(PA)scheme is developed,and the closed form PA coefficients are obtained.Simulation indicates that the suboptimal PA scheme outperforms the conventional equal PA scheme,and its performance is very close to that of the exhaustive search based optimal PA scheme but with low complexity.Moreover,the system performance under the spatially correlated channel is worse than that in spatially independent channel due to the effect of spatial correlation.

A novel satellite-equipped receiver for autonomous monitoring of GNSS navigation signal quality

Global navigation satellite system(GNSS) comes with potential unavoidable application risks such as the sudden distortion or failure of navigation signals because its satellites are generally operated until failure. In order to solve the problems associated with these risks, receiver autonomous integrity monitoring(RAIM) and ground-based signal quality monitoring stations are widely used. Although these technologies can protect the user from the risks, they are expensive and have limited region coverage. Autonomous monitoring of satellite signal quality is an effective method to eliminate these shortcomings of the RAIM and ground-based signal quality monitoring stations; thus, a new navigation signal quality monitoring receiver which can be equipped on the satellite platform of GNSS is proposed in this paper. Because this satellite-equipped receiver is tightly coupled with navigation payload, the system architecture and its preliminary design procedure are first introduced. In theory, code-tracking loop is able to provide accurate time delay estimation of received signals. However, because of the nonlinear characteristics of the navigation payload, the traditional code-tracking loop introduces errors. To eliminate these errors, the dummy massive parallel correlators(DMPC) technique is proposed. This technique can reconstruct the cross correlation function of a navigation signal with a high code phase resolution. Combining the DMPC and direct radio frequency(RF) sampling technology, the satellite-equipped receiver can calibrate the differential code bias(DCB) accurately. In the meantime, the abnormities and failures of navigation signal can also be monitored. Finally, the accuracy of DCB calibration and the performance of fault monitoring have been verified by practical test data and numerical simulation data, respectively. The results show that the accuracy of DCB calibration is less than 0.1 ns and the novel satellite-equipped receiver can monitor the signal quality effectively.