公开(公告)号：WO0128147A3

公开(公告)日：2001-08-30

申请号：PCT/US0028010

申请日：2000-10-09

Applicant: CONEXANT SYSTEMS INC

Inventor： BERNATH BRETT ALAN ,  BROOKS JOHN MILFORD ,  MEHTA MANOJ ,  GOLDENBERG YOAV PESACH

IPC: H04N21/2389 ,  H04N21/4385 ,  H04N21/8547 ,  H04N7/173

CPC classification number: H04N21/8547 ,  H04N21/2389 ,  H04N21/4385

Abstract: A system for synchronizing the upstream burst transmission in a cable system to a time specified by the cable head end is disclosed. The system includes a free running counter within a cable modem (CM) or network interface unit (NIU), along with logic to capture the value of this free running counter at the time a frame of MPEG-2 SYNC data arrives, to create a time tag stored in memory. A computer within the cable modem or network interface unit has access to the time tags in memory and the contents of a time synchronization message from the head end, also stored in memory. The computer contains a program to calculate the value of the local counter that corresponds to a time to transmit commanded by the cable system head end. The system includes logic within the CM or NIU to initiate an upstream burst transmission when the value of the local counter becomes equal to a calculated value, thus causing the cable modem to initiate its upstream burst transmission precisely at the time commanded by the head end.

Abstract translation: 公开了一种用于使电缆系统中的上游突发传输与电缆头端所指定的时间同步的系统。 该系统包括在电缆调制解调器（CM）或网络接口单元（NIU）内的自由运行计数器，以及在MPEG-2 SYNC数据帧到达时捕获该自由运行计数器的值的逻辑，以创建 时间标签存储在内存中。 有线调制解调器或网络接口单元内的计算机可以访问存储器中的时间标签以及来自头端的同时存储在存储器中的时间同步消息的内容。 计算机包含一个程序来计算本地计数器的值，该计数器对应于由有线系统前端发送的时间。 当本地计数器的值等于计算值时，系统包括CM或NIU内的逻辑以发起上行突发传输，从而使得线缆调制解调器精确地在头端命令的时间开始其上行突发传输。