SFN Data Stream Timestamping with 100 ns Precision
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Solution Overview
Problem
Current timestamping techniques in SFN networks lack sufficient precision, leading to increased complexity and cost in broadcasting, and are not optimal for ensuring synchronization across transmitters in DVB-T, DVB-H, and other digital broadcasting standards, particularly when inserting local or regional data streams.
Innovation Solution
A method that uses the time information from mega-frame initialization packets to timestamp data streams with a precision of 100 ns, utilizing two counters to accurately calculate timestamp values, ensuring synchronization and compliance with broadcasting standards without requiring significant architectural modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current timestamping techniques are used in SFN networks, then broadcasting can proceed with existing architectures, but timestamp precision is insufficient leading to synchronization issues
Solution Approach 1:
The patent applies preliminary action by pre-calculating and inserting timestamp values into TDT tables and MIP packets before transmission. The timestamping mechanism prepares reference time information in advance within the broadcast stream structure, allowing receivers to perform accurate time synchronization without requiring real-time timestamp calculation, thus achieving both high precision and reliability
Solution Approach 2:
The patent uses TDT tables and MIP packets as intermediary carriers to transmit timestamp information. These standardized broadcast structures act as mediators between the time reference source and the receivers, enabling precise timestamp transmission through existing SFN infrastructure without requiring direct time synchronization hardware at each transmitter
2Measurement precision
If higher timestamp precision is achieved, then synchronization accuracy improves, but system complexity and cost increase
Solution Approach 1:
The patent implements self-service by utilizing the existing broadcast stream structure (TDT tables and MIP packets) to carry timestamp information. The system serves its own synchronization needs using already-present data structures, eliminating the need for separate timestamping hardware or complex external synchronization systems, thus achieving high precision without increasing device complexity
Solution Approach 2:
The patent makes the existing TDT tables and MIP packets serve multiple functions: they continue to provide program timing information and service description while simultaneously carrying precise timestamp data for synchronization. This multi-functionality allows the system to achieve high timestamp precision without adding dedicated timestamping mechanisms, thereby avoiding increased system complexity
Data Source
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AI summary
The invention relates to a method for timestamping a data stream organised into consecutive packets which are in turn organised into at least one mega-frame, each mega-frame containing a mega-frame initialisation packet (MIP). According to the invention, such a method includes the following steps for each packet of said stream: determining the duration of the packet from a predetermined size of said packet and a predetermined flow of said given stream; if said packet is a packet conveying a time and date table (TDT table), obtaining a first piece of time information (UTC time) contained in said time and date table (TDT table); if said packet is the first packet of a mega-frame, obtaining a second piece of time information (STS) contained in a mega-frame initialisation packet (MIP) previously received; and timestamping said packet based on the duration of said packet and on said first and second pieces of time information.