Synchronization method and system for single frequency network digital broadcast television system

Abstract

The invention provides a synchronization method and a synchronization system for a single frequency network digital broadcast television system. The synchronization method comprises the following steps of: 1) in a central station, stamping a time stamp on each transport stream (TS) packet of TS program stream, wherein the time stamp records absolute stamping time; and 2) when each transmitting station receives each TS packet, calculating absolute transmitting time of the TS packet according to the time stamp of the TS packet and preset delay time, and transmitting the TS packet according to the absolute transmitting time by using each transmitting station, wherein the absolute transmitting time is the sum of the absolute stamping time of the TS packet recorded by the time stamp of the TS packet and the preset delay time. In addition, the invention provides a corresponding synchronization system. The method and the system can avoid error accumulation, improve synchronization reliability, ensure that the transmitting stations are easy and convenient to debug, and avoid asynchronization caused by packet loss, wrong packets and the like in an exciter, and are particularly suitable for a complex hybrid network and a remote distributed network.

Description

technical field [0001] The invention relates to the technical field of digital TV broadcast signal transmission, in particular, the invention relates to a synchronization method and system for a digital broadcast TV system of a single frequency network. Background technique [0002] At present, in the digital broadcast signal transmission system, the international standards for terrestrial digital TV broadcasting include DVB-T, ATSC-T, ISDT-T, etc., and China has also promulgated the terrestrial digital TV transmission standard GB20600-2006 with independent intellectual property rights (hereinafter Referred to as the national standard terrestrial digital TV standard), they can all realize single-frequency network transmission. The entire system of a single frequency network (SFN) only needs one frequency, and users do not need to change channels during mobile reception within the coverage of the network. Therefore, a single frequency network can save frequency resources comp...

AI Technical Summary

Problems solved by technology

However, TS streams inevitably have problems such as transmission jitter and bit errors in the actual transmission process, which leads to deviations in the time delays for each TS packet in the TS stream to reach each transmitting station, so it cannot be guaranteed that each TS packet Can launch synchronously

Moreover, since the existing technology can only use the second frame initialization packet for synchronization, the errors caused by transmission jitter and transmission errors in each TS packet per second may accumulate, which will cause more serious out-of-synchronization problems

Furthermore, because the second frame initialization packet itself also has problems such as transmission jitter and transmission errors, when the second frame initialization packet is delayed, it may cause the transmitting station to receive the SIP packet later than the local corresponding 1PPS rising edge+T delay_max At this moment, synchronization cannot be achieved, so in fact, the existing technology cannot achieve synchronization once per second

What's more serious is that the second frame initialization packet itself may have a transmission error problem, which may cause the transmitter to fail to receive the second frame initialization packet, which will lead to the complete destruction of the synchronization mechanism

[0006] (2) Difficulty in debugging

In a large network, due to the large number of sites and wide distribution, the transmission delay may exceed 1 second. Once the delay exceeds 1 second, the traditional method cannot achieve synchronization at all.

In addition, in a hybrid network with multiple transmission links, the above problems are also prone to occur, resulting in failure to achieve synchronization

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