PID PLL Clock Synchronization for MPEG Receiver Timing Drift
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Solution Overview
Problem
Existing communications systems face challenges in achieving sufficient synchronization between devices for audio and video playback, particularly in environments like motor vehicles, despite the use of standards like MPEG-2, due to timing discrepancies between transmitters and receivers.
Innovation Solution
A phase-locked loop (PLL) circuit with a proportional-integral-derivative (PID) controller is employed to synchronize the clocks of transmitter and receiver devices by producing error signals and correction signals, ensuring accurate timing alignment through a feedback loop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard communication system is used for transmitting audio-visual material, then basic transmission functionality is achieved, but timing synchronization between transmitter and receiver clocks deteriorates due to drift between audio and video components
Solution Approach 1:
The patent implements a feedback mechanism where the receiver clock is continuously compared with the transmitter clock, and timing errors are detected and fed back to adjust the receiver clock frequency. This closed-loop feedback system compensates for timing drift and maintains synchronization between audio and video components during transmission.
Solution Approach 2:
The patent dynamically adjusts the receiver clock frequency parameter based on detected timing errors. By changing the clock frequency parameter in real-time, the system compensates for synchronization drift and maintains accurate timing alignment between transmitted and received audio-visual signals.
2Adaptability or versatility
If wireless communication is used to connect devices for video playback, then flexibility and mobility are improved, but synchronization stability deteriorates due to timing drift between audio and video
Solution Approach 1:
The feedback mechanism continuously monitors timing synchronization over the wireless connection and adjusts the receiver clock accordingly. This ensures that even though the connection is wireless and potentially subject to variations, the timing synchronization between audio and video remains stable and drift-free.
Solution Approach 2:
The system dynamically adjusts the receiver clock frequency in real-time based on detected timing errors. This dynamic adaptation allows the system to maintain synchronization stability despite the variable nature of wireless communication, compensating for timing drift as it occurs.
3Productivity
If existing control systems are used with MPEG streams, then basic audio-visual transmission is achieved, but effective synchronization control deteriorates in environments like motor vehicles
Solution Approach 1:
The feedback mechanism continuously monitors timing synchronization during audio-visual playback and adjusts the receiver clock frequency to compensate for drift. This ensures reliable synchronization control even in challenging environments like motor vehicles where timing variations may occur during transmission and playback.
Data Source
AI summary
Various embodiments relate to a receiver and a timing circuit for synchronization between a transmitter clock of an MPEG stream and the local system clock of a receiver. The timing circuit may implement a phase-locked loop (PLL) circuit with a PID controller to produce a control signal based on the difference between the transmitter reference clock and the local system clock. Various embodiments may use clock differential signals and an accumulated error signal to produce proportional, integral, and derivative output components for a control signal. The control signal may control a signal generator that adjusts the frequency and/or phase of the local signal clock to lock with the transmitter reference clock. Various embodiments may also include an outlier filter to remove error signals outside a defined range and/or a programmable system clock to add precision to the generated local system clock.