In the modern information society, high-precision clocks are particularly important in the fields of electric power, communications, aviation, and finance, and have very strict objective requirements in terms of frequency accuracy. Currently, the technology of using GPS satellite clock sources to synchronize local clocks has become one of the mainstream methods for generating high-precision clocks at home and abroad. The core idea of this technology is to use the satellite clock to tame the local clock. Due to the development and application of 5G, the accuracy of the system's punctuality have higher requirements, Through analysis, it is found that the combination of BP neural network and PID control can be used to optimize the control of the constant temperature crystal oscillator and improve the precision of punctuality. Finally, the simulation results show that the method has a significant effect in improving the accuracy of punctuality.

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A geometric model for the Unmanned Aerial Vehicles (UAVs) is proposed in which horizontal maneuvers are made only by changing speed while keeping the flight direction constant. The calculating formulae for projected horizontal miss distance (HMD) and reserved time (Tau) to the closest point of approach are derived from the model according to the Galilean principle of relativity. The closed-form solution is presented to predict the separation to be achieved with a horizontal collision avoidance maneuver. The influence of speed change time and autopilot's response delay on the horizontal miss distance and reserved time are also calculated and analyzed. The simulation results indicate that the algorithm for conflict detection and resolution in the horizontal plane can predict not only the horizontal separation at the closest point of approach, but also the reserved time to get to the closest point of approach.

A new generation of traffic alert and collisionavoidance systems based on the Global Positioning System (GPS) and Automatic Dependent Surveillance Broadcast (ADS-B) is studied in this paper. Two horizontal escape maneuvers are proposed: One is to change speed but not flying direction, and the other is to change flying direction but not speed. The algorithms for conflict detection and collision avoidance are also presented. The relationships between turn angle, horizontal miss distance (HMD), and reserving time, as well as the relationships between speed, HMD, and reserving time, are calculated and analyzed. To effectively avoid collisions by horizontal escape maneuvers, the research results indicate that the speed of the host aircraft required to increase or decrease must be bounded within a speed range, and the angle of the host aircraft required to turn right or left must also be bounded within an angle range.Index Terms-Horizontal escape maneuvers, horizontal resolution advisory (RA), traffic alert and collision-avoidance system (TCAS).

A bstract-Taylor series expansion method based on TDOA (Time Difference of Arrival) is a typical location algorithm in cellular mobile telecommunication system, but its performance depends highly on the selection of initial position because of convergence problem. A new cooperative localization method based on conj ugate gradient and Taylor series expansion algorithms is presented to solve this problem. The convergence and computation efficiency are improved by using the result of conj ugate gradient method as the initial position in Taylor series expansion method. By comparing with those analogous algorithms, one is using the result of Chan algorithm, and the other is using the result of least square method, as the initial position in Taylor series expansion method, the computer simulation results indicate that the new algorithm has higher computation efficiency than that two analogous algorithms. Simulation results also show that the location accuracy and computation efficiency of the new algorithm can approach the performance obtained by Taylor series expansion method based on true position as the initial position.