mpeg网络系统监测simplified.pptVIP

* * * * * * 仪器上的 TR101 290测试 仪器上的字段间隔显示 右击SDT测试以 获取定时信息 PCR 漂移,偏置,不准确度,全抖动区间图形 DVB 模板举例 Pre-Record 检测需求 MPEG 码流结构及内容检查 MPEG 码流协议分析 DVB TR101290 实时监视实时差错记录，可定量察看传输码流的工作状况 时钟PCR分析 （技术检测） PCR ＿ OJ (全抖动) PCR ＿ AC (准确度) PCR ＿ FO (频率偏置) PCR 到达间隔 PSI/SI/PSIP/AREB SI 信息分析 用户设置的告警 触发记录 END Thanks * * * In order to decode MPEG compressed signals the decoder must be synchronised to the encoder. This is achieved using the Program Clock Reference (PCR). At the encoder a reference 27MHz clock drives a 42 bit counter which is periodically sampled. The resulting sample is embedded into the transport stream in the adaptation field. The decoder implements its own 27 MHz clock which in turn drives a counter which is sampled when a PCR is detected in the incoming transport stream. The difference between the last two received PCR values and the last two locally generated values gives an indication of whether the local 27MHz clock is synchronised to that at the encoder. * * * * * * * * * * * * * * * * The PAT measurements as defined in ETR 290 is actually composed of three independent measurements. The repetition rate should ensure that the PAT is repeated every 0.5s which allows rapid acquisition for a receiver. ETR 290 does not specify whether the repetition period refers to section repetition or PID repetition. A PAT cannot be scrambled, all IRDs have to be able to decode and interpret the PAT. PID 0 is reserved for the PAT. It is forbidden for anything other than a PAT to be multiplexed on to PID 0. The PMT tests are very similar to the PAT test. The definition of the repetition rate is that “sections with table_id 0x02 do not occur at least every 0.5s on the PID which is referred in the PAT”. Some multiplexers insert the PMT sections for all programs on a single PID which can lead to some differing results when the strict interpretation of the repetition rate for a section is applied. Each PID whic