Analysis of Interaction Between Navigation Payload and Constant Envelope Design of Navigation Signal

Abstract

Navigation signal design considers many factors, such as service requirements, in-heritance, compatibility and interoperability, and patent avoidance. The only consideration for the realization of navigation load is constant envelope. However, the constant envelope in current signal design is based on the assumption of unlimited bandwidth. In practice, satellite load cannot be realized. From the load point of view, there are two main types of loads on navigation satellites: one is linear devices, such as filters, which are mainly used to prevent aliasing, suppress mirror and extra-band radiation, prevent interference with other systems and achieve maximum useful power; the other is devices with non-linear effects, such as power amplifiers. In principle, linear devices before power amplifier can compensate in-band characteristics by analog and digital means, but power amplifier introduces more complex effects, which are related to multi-carrier, power ratio of signal components and constant envelope characteristics of signals. It is the common responsibility of load design and signal design to avoid or reduce the adverse effects caused by these practical devices. In this paper, the deterioration of Beidou navigation signal in navigation load is analyzed, and the influence of constant envelope deterioration of navigation signal near the saturation point of amplifier on signal quality is verified by simulation. By generating a navigation signal, it passes through a real L-band fixed amplifier. The test results show that the specific signal constant envelope design has little effect under the specific trans-mitting bandwidth condition.