摘要
在专业网络音频传输系统中,由于晶振制造工艺、环境温度等因素导致主从节点音频时钟产生差异,引起系统失真率串升。而系统中以太网按照音频采样时钟的节拍来传输音频数据包。为此提出一种在物理层和MAC层的MII接口处进行音频采样时钟恢复的方案,同时设计相应的时钟调整算法进行晶振频率补偿,以提高主从节点音频时钟的同步性。在Xilinx FPGA平台上进行实际测试验证,结果表明,传输系统的失真度(包含模数和数模转换产生的失真)小于0.005%,长期运行的结果也表明了系统时钟同步的稳定性。
In the audio transmission system, clock out of sync led to system distortion rate increase. Ethernet package was transmitted at the audio sampling frequency. Based on this, a strategy used to recover audio sampling clock between physical layer and MAC layer was proposed. A Clock adjustment algorithm was designed to make frequency compensation of crystal and improve the synchronization between master and slave audio sampling clock. Test platform based on Xilinx＇s FPGA chip was developed. Preliminary tests were carried out on the platform.Test results show that the THD＋N （including THD＋N caused by A/D and D/A）was lower than 0.005 %.The long-running results also show the stability of clock synchronization in system.
出处
《电子技术应用》
北大核心
2010年第11期138-140,144,共4页
Application of Electronic Technique
