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There has been considerable recent interest in the positioning of autonomous underwater vehicles (AUVs). Underwater acoustic positioning system (UAPS) are usually used to determine position and speed of the moving target in water environment. Generally, moving target speed is estimated by derivative of the target position with traditional method. However, this approach relies heavily on accuracy of positioning. Thus, this paper presents a novel method for estimation of target speed with the UAPS only, especially with long baseline (LBL) acoustic positioning system. The method is made by estimating the Doppler frequency shift of the received signals and solving the set of linear equations. It could depend less on positioning accuracy than the traditional method. What’s more, it works well even though the moving target is subjected to acceleration or jerk. With simulations by MATLAB, it is shown that the method achieves very good performance.

The interoperability of global navigation satellite systems (GNSSs) has a significant impact on the service performance of GNSSs. To evaluate the GNSS interoperability, this paper creates an evaluation algorithm with such modules as space section, user section and environment section. The proposed algorithm evaluates the service performance with several common parameters, namely, the dilution of precision (DOP), navigation satellite system precision (NSSP), navigation satellite system integrity (NSSI), availability and continuity. The parameters of the algorithm could be configured based on the existing GNSS data or our self-developed data. Then, the proposed algorithm was applied to evaluate the service performance of three difference scenarios: Compass-only, Compass + GPS and Compass + GPS + Galileo. The results show that the combination of different GNSSs can greatly improve the service performance of GNSSs in both time and space.

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