Common-Wave Transmitter Clock Regulation for ATSC Time Synchronization
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Solution Overview
Problem
Existing methods for time synchronization in common-wave networks, such as those using the ATSC standard, often result in short-term signal interruptions due to inaccuracies in GPS-derived time references and system clocks, particularly when data transmission routes experience changes like Doppler effects, leading to incorrect delay settings in transmitters.
Innovation Solution
A regulating circuit in each high-frequency transmitter compares the actual transmission time with the setpoint transmission time, adjusting the system clock frequency to align the actual transmission time with the setpoint, allowing for automatic leveling of time displacements within the mHz range and adaptive adjustment of time delay for larger deviations, preventing signal interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS-derived time references and system clocks are used for synchronization, then time synchronization is achieved, but signal interruptions occur due to inaccuracies and Doppler effects
Solution Approach 1:
The patent implements a feedback mechanism where the actual transmission time is continuously compared with the setpoint transmission time, and the system clock frequency is automatically adjusted based on this comparison to eliminate time deviations and prevent signal interruptions
Solution Approach 2:
The system dynamically adjusts the system clock frequency in real-time based on the comparison between actual and setpoint transmission times, allowing the synchronization system to adapt to changing conditions such as Doppler effects and GPS reference inaccuracies
2Measurement precision
If delay times are recalculated to correct time deviations, then synchronization accuracy is improved, but signal interruptions occur during recalibration
Solution Approach 1:
Instead of recalculating delay times, the patent changes the system clock frequency parameter to achieve synchronization. This continuous adjustment of clock frequency avoids the signal interruptions that would occur during delay time recalibration while maintaining transmission time accuracy
3Device complexity
If freely-oscillating clock generators are used in transmitters, then device independence is achieved, but time synchronization drifts occur
Solution Approach 1:
The feedback mechanism continuously monitors the actual transmission time against the setpoint and adjusts the system clock frequency accordingly, enabling independently oscillating clock generators to maintain accurate synchronization without requiring complex centralized control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution ensures stable and continuous data transmission by regulating the system clock to match the setpoint transmission time, effectively preventing signal interruptions and maintaining network stability even with deviations up to ±10 ms, allowing for smooth operation without recalculating delay times.
Implementation Method 1
A regulating circuit in each high-frequency transmitter compares the actual transmission time with the setpoint transmission time, adjusting the system clock frequency to align the actual transmission time with the setpoint
Data Source
AI summary
An arrangement for synchronizing a transmission time of a digital data stream in individual high-frequency transmitters of a common-wave network operating according to an ATSC standard and transmitting identical data at an identical frequency. The stream generated in a master station is supplied to the transmitters as a periodic succession of data frames, and a setpoint transmission time is calculated in the transmitters from a synchronizing time stamp inserted into the data frames within the master station and from a time reference used in the master station and transmitters, while the transmission of the frames by the transmitter is determined by a system clock in the transmitters. The setpoint transmission time is compared with the actual transmission time determined by the clock, and the clock frequency is regulated by a regulating circuit so that the actual transmission time determined by the clock corresponds with the calculated setpoint transmission time.