适用多种码速率的遥控副载波数字化解调设计

Remote sub-carrier digital demodulation for multiple code rates

摘要:

统一S波段测控体制采用相位调制技术实现遥控副载波的调制,星上应答机在实现S波段载波剥离后将遥控副载波送给星上遥控设备进行解调最终实现指令和数据的上注。遥控设备通常采用模拟电路实现解调,当输入不同码速率时均需要重新调试输入滤波器,并且当码速率较低时调试困难,滤波器及解调环路的工作参数更容易受环境温度影响,导致解调损失变高,跟踪解调环路易失锁。文章介绍了一种适应多种码速率的遥控副载波数字化解调方法。可以有效解决上述问题,减小解调损失,提高产品可靠性。文章中涉及到了数字化副载波跟踪环设计,数字化自动增益控制以及早迟路位同步恢复环路的设计方法,最后提出了两种提高产品可靠性的设计措施。本方法适用于采用FPGA工程实现,具有解调损失小,节省资源易实现以及可靠性高等优点。

Abstract:

Unified S-Band transponder tracks phase modulate carrier and exports remote sub-carrier which is psk signal. Remote control Unit receives sub-carrier and demodulates psk signal by analogy circuit. It is a hard work to debug a very small bandwidth band pass filter when the bitrate is very low also the parameter of band pass filter is changed when undergo large range temperature fluctuate. Once the designed parameter of filter is changed that may led to high loss of demodulation and easy to unlock.This paper presents a digital demodulation method which can avoid the shortcoming of anaglog circuit and improve the reliability of the product. The key technologies are digital carrier tracking, auto gain control and early-late bit synchronization. This method is suitable for the implementation of the project using the FPGA. It has the advantages of low demodulation loss, saving resources, easy realization and high reliability.