基于1553B总线的卫星星时同步方法

Method of Satellite Time Synchronization Based on 1553B Bus

目前卫星的绝对时间由GPS提供,并通过总线广播的方式将时间信息码发送给各卫星载荷分系统,但各载荷收到时间信息进行相应的处理后都会有一定的延时,所以需要对卫星系统进行时间同步。卫星通常使用的星上时间同步方式为GPS秒脉冲和时间信息广播相结合的方法,但此方法需要占用一定的硬件资源。为了节省硬件资源,并保证卫星星时同步的精度,文章提出基于1553B总线卫星星时同步的方法,使用同步方式字命令和时间信息广播相配合,卫星载荷利用1553B总线控制芯片内部时间标记寄存器计时,计算软件处理延时,降低系统随机误差,进而实现星时同步。经过仿真和测试验证,表明该方法可以将系统时间同步随机误差降低到100?s。该方法采用软件实现,卫星无需提供GPS秒脉冲,节省硬件资源,降低成本,适用于时间同步要求精度高、未对载荷分系统提供GPS秒脉冲的卫星系统。

Presently, the absolute time of satellite is supplied by the Global Position System （GPS）, and the time information is sent to the payload subsystem through the bus in broadcast. Due to the time delay for the payloads to process the time information received, time synchronization is needed for satellite systems. The method combining the GPS second pulse with the time broadcast is widely used in time synchronization. However, this method needs to consume hardware resources. In order to save the hardware resources and ensure the accuracy of satellite time synchronization, a method is proposed for time synchronization on board, which is based on 1553B bus synchronize mode code and time broadcast. Using the time tag register in 1553B bus controller chip as payload time, the time delay is calculated by the software to reduce the random error and then to realize the time synchronization. The simulation and test results show that the system random error of time synchronization can be reduced to 100μs. As the method is realized by software without GPS second pulse, it is very suitable for the high-precision time system and the system without GPS pulse.