Research Of Variable-code-rate Inter-satellite Communication Based On Small-satellite Formation-flying System

Small satellites formation flying system has been paid more and more attention by the international aerospace fields because of its great advantages in reliability, cost, performance and other aspects, as well as a broad application prospects. Inter-satellite communication bears the mission of information interaction between two small satellites, whose quality, however, will be directly affected by the geometric parameters, motion parameters and communication system parameters. Therefore, this thesis mainly studies the methods to improve the reliability of inter-satellite communication under the circumstances of involving time-varying links and having low power requirements. The main contributions are summarized as follows:To begin with, based on the characters of the typical inner-satellite links and their impact factors, the inner-satellite links of (approximate) coplanar and non-coplanar orbits are analyzed to obtain the time-domain distribution of the maximum effective transmission rate. Under the constraints of low power consumption, an effective way with the variable code rate is proposed to improve the reliability of inner-satellite communication.Next, under the requirements of low power consumption and low computational complexity, a scheme depending on both the cyclic spectrum estimation and blind SNR estimation is proposed to obtain the accurate link characteristics information. Meanwhile, a digital multi-rate IF scheme is designed to improve the reliability and power utilization of inner-satellite communication. The appropriate modulation and synchronization modules are analyzed and then designed considering the communication condition and the low power consumption requirement of our system. Furthermore, a detailed analysis is carried out on the relationship between the carrier synchronization and symbol synchronization.Finally, the critical module of the digital IF scheme is introduced and further different rate-control instructions are provided to test and verify its effectiveness. In addition, the X-Band RF front-end circuits are further exploited to validate the performance of our variable-code-rate digital IF receiver.