操控中的一种半程载波捕获与跟踪方法

A Half-Way Carrier Acquisition and Tracking in Space Operation

摘要:

针对某低轨卫星的应答机载波锁定时间较短的问题,在分析应答机温度敏感特性基础上,讨论载波捕获与跟踪的时间约束,进而提出一种半程载波捕获与跟踪方法,即取消上行载波频率扫描,利用目标过顶前后的多普勒频移较小、输入信号较强的特点,实现应答机对载波的快速捕获与跟踪,尽可能拓宽上行遥控发令的可用时间窗口。测控结果表明,应答机温度具有短周期、长周期和长期变化规律,短周期为轨道周期,温度在地影期较高,在阳照区较低；长周期为年周期,冬至期间温度处于全年最高水平,夏至期间则最低；长期表现为逐年升温,平均每年增加约0.3°C；当应答机温度从25.9°C上升到26.2°C时,载波锁定时长由30s线性下降至0；使用半程载波捕获与跟踪方法后,上行链路可用遥控时间增加6s以上,便于应急或异常事件处理,为卫星延寿运行提供操控支持。

Abstract:

With respect to short carrier locking time from a transponder working in an LEO (Low Earth Orbit) satellite, details on constraints of carrier acquisition and tracking are discussed by analyzing the thermally sensitized characteristics of the transponder. A half-way carrier acquisition and tracking method is presented to cancel the frequency sweep process in the uplink. With low Doppler shifts and high signal power, the carrier can be rapidly acquired to extend the available telecommand window when the satellite is running over the zenith. The validated results have shown that the transponder temperature telemetry has an orbital period varies in which the temperature is low in the earth shadow and high in the sun, and has an annual period during which the temperature is low in summer and high in winter, and has a long term rise of 0.3°C each year. While the transponder temperature varies from 25.9°C to 26.2°C, the carrier locking time changes linearly between 30s and 0. With the presented method, more than 6s can be obtained to send orders in the uplink for emergent operations or anomalous event disposals to support the life extension of the payload.