Design And Implementation Of Variable-Rate RF Communication For Intersatellites

With the development of the micro-electronics and the micro-machines, especially technology of system on chip, material improvement was brought for the micromation of electron system and micromation of spacecraft was accelerated so as to accelerate the research of small satellite formation flying. More than one satellites worked together to complete a complex task which was usually accomplished by a bigger and more complex one. Small satellite formation flying needed high reliable communication, so it put forward higher demand for communication intersatellite. In our paper, the there's had designed a variable-rate communication method, where different communication rates were selected for variable distances among satellites, and this approach could adjust the frequency shift caused by Doppler effect, and implemented this arithmetic on a integrated electronic system (IES).Firstly, the there's designed and made a integrated electronic system (IES). According to the conception of micro spacecraft, as the experiment platform of the variable-rate communication, the integrated electronic system adopted SoC processors to integrate on-board computer and telemetering and telecontrol sub-system into one system. The core of was the RF chip nRF2401, and the software adopted the integrated processing of telemetering and telecontrol data and load data, in order to realize the integration of on-board computer and telemetering and telecontrol sub-system. The traditional problem that must be faced ,which cause the complicated converting form analog signal to digital signal or form digital signal to analog signal, has been solved by this method.Secondly, the there's analyzed communication link in the space and designed a variable-rate communication arithmetic and adjusted the frequency shift caused by Doppler effect, and implemented this method on IES. According to the theory of communication link in the space, the there's can know that the reliable of communication had a nearly relationship with the communication distance and the communication rate. Based on this theory, our method alerted the length of the signal through coding approach to adjust the communication rate, leading to the improvement of communication reliability. When the distance increased, the there's had to decrease the communication rate to ensure the reliable communication. In addition, a coding arithmetic was designed to compensate frequency shift caused by relative motion between satellites.Finally, aiming at the task that the there's had to realize the communication between satellite and earth station, the there's had designed earth station to ensure the communication. And the there's had to validate the variable-rate communication arithmetic. And the there's designed the communication plan to finish the variable-rate communication between satellite and earth station. In order to implement the communication, the there's established the communication protocols between satellite and earth station, and the there's established the interior communication protocols in earth station to make the earth station work well, and the there's we verified this method to establish a reliable earth station for the reach of variable-rate communication.