中继卫星的多类型数据帧均衡调制

Multi-Type Data Balance Modulation of Retranslator Satellite

跟踪与数据中继卫星系统(TDRSS)以其高覆盖率、大容量等优点成为航天领域的一个重点发展方向。在中继星上行数传中,地面站各分系统的图像、数据、话音等数据以数据帧的形式通过网络传输到地面站调制设备调制后按先到先调的原则顺序发送给中继星。中继卫星的星载接收机解调数据帧后根据不同的数据来源分发到独立的数据缓冲区以供后续处理。地面各分系统与调制器之间采用网络连接,某一分系统的网络传输速率波动会造成星载接收机解调该类数据的数据量突然增大和减少。由于星载接收机的后端缓冲区容量有限,解调数据量的突然增大和减少会使得星载接收机对应的缓冲区出现溢出与读空,进而造成该分系统数据帧的丢失与断档。提出了一种基于时间轮询的数据帧重排算法,在调制器的前端对来自网络的各分系统数据帧进行重新排序,完成了分系统数据帧的均衡调制发送,提高了数据帧周期平稳性,降低了对星载接收机端数据缓冲区的要求,该算法已经在具体工程中得到实际验证,具有灵活、安全、可靠的特点,在卫星通讯领域具有一定的参考价值。

TDRSS(Tracking and Data Relay Satellite System),for its high coverage,large capacity and other advantages,becomes an important development direction in aerospace field.The modulator in the earth station modulates and transmits data frames from each subsystem through the network to the retranslator satellite.The retranslator satellite demodulates data frames and distributes them to the different buffers according to the data source subsystem.However,the rate fluctuations of network would cause the receiver buffer overflow or buffer empty in the retranslator satellite.This article proposes a frame rearrangement algorithm based on time polling,which rearrangements data frames before they are modulated.This method can improve the period stability of data frame and reduce the requirements of data buffer in satellite receiver.This algorithm has the features of flexible configuration,security and reliability,and thus is of certain reference value in the field of satellite communication.