The Design And Implementation Of Dual-mode Navigation Receiver Precision Timing System

With the rapid development of modern science and technology, all kinds of industry put forward higher requirements on the precision of time and frequency. And as the four major global navigation system is gradually mature and perfect, satellite timing technique because of its wide timing range and high precision is playing an important role in the field of timing. The working of a timing receiver is to receive satellite signals generated by the atomic clock, and output satellite timing signal (Second pulse) that is synchronous with the satellite clock provided for the use of other systems. At present the single GPS timing receiver occupy the most market, in order to improve the reliability of timing and prevent of excessive dependence on the GPS, this paper puts forward using a dual-mode system of BDS and GPS for timing.The focus of the thesis is to improve the precision of timing. analysis and research on the factors affected the accuracy of timing, and taking some corresponding measures to reduce the impact of these factors and improve the precision of timing. In timing receiver the key is to use the clock error to adjust the second pulse, so the accuracy of clock error directly affects the precision of timing. First of all, according to the principle of satellite timing and pseudo range equation, analysis of the impact of the various error sources for calculating clock error. Secondly, in order to further enhance the accuracy of clock difference and the second pulse adjusting precision, we adopt a kind of clock error calibration method based on phase-locked loop in this paper. Using the equation of calculating the clock difference as the phase discriminator, then the clock difference through a third order loop filter, using the filtered clock error to adjust the second pulse and get the local sampling instant, and feedback as the input of phase discriminator. Finally, in order to achieve timing receiver can into punctual mode when the satellite signal abnormalities, we put forward to establish a clock error forecast model using a set of clock difference data to achieve forecast during a short period of time, then use the prediction of data to adjust the second pulse, so the punctual timing signal is obtained. After the test, compared with using clock error of direct calculating to adjust the second pulse, the closed loop timing accuracy can increase nearly doubled, about50ns. In addition, AR (p) model can realize clock error forecast accuracy within5ns in a short period of time is validated by computer simulation.