ETC系统中FM0软件解码的设计

摘要

Short distance communication in electronic toll collection(ETC) system requires high real time and reliability between OBU(on board unit) and RSU(road side unit). The frequency point of ETC system is 5.8 G and the wireless link is using FM0 encoding, because of it's easy to bit-synchronization extraction, the spectral bandwidth is narrow, the realizing circuit is uncomplicated, etc. According to the FM0 coding theory, this paper discusses achieving the FMO decoding by using C Language Programing and the STM32L0 Series low power consumption MCU of STMicroelectronics in the IAR Embedded System development environment. In the end, the feasibility of the FM0 soft decoding method is verified by using the oscilloscope, it only takes 30uS to decode one FM0 frame.%在电子不停车收费(Electronic Toll Collection,ETC)系统中车载单元(On Board Unit,OBU)与路侧单元(Road Side Unit,RSU)的短距离通信需要较高的实时性和可靠性,无线链路使用的是频点在5.8G的FM0编码,FM0编码其特点有便于位同步提取、频谱带宽较窄、实现电路简单等.针对ETC中的FM0编码,讨论了使用意法半导体公司的STM32L0系列低功耗单片机通过C语言在IAR编译环境下实现FM0解码,并使用示波器验证出该FM0软解码方法30uS内即可解出,实时性达到需求.