FIFO Buffer PLL Data Synchronization for Audio Underflow
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional data synchronization methods, such as using a phase-locked loop (PLL), fail to effectively manage data transmission rates to prevent data underflow and overflow in scenarios like digital audio applications, where the receiving rate of a digital-to-analog converter (DAC) must match the transmission rate of a data source, especially during temporary transmission losses or errors.
Innovation Solution
A data synchronization apparatus comprising a FIFO buffer, control circuit, and PLL that adjusts the frequency of a master clock signal to match the receiving rate with the transmission rate, using FIFO and counter adjustment signals to prevent underflow and overflow, and incorporating a frequency counter to fine-tune the clock frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional PLL is used to match the receiving rate with the transmission rate, then the clock signal can be synchronized, but it cannot effectively prevent data underflow and overflow during transmission losses or errors
Solution Approach 1:
The FIFO buffer is configured in advance to store a predetermined number of data packets, creating a data reservoir that can absorb transmission fluctuations. This preliminary data storage capability allows the system to maintain operation during temporary transmission losses without requiring real-time rate adjustment
Solution Approach 2:
The system dynamically adjusts the receiving rate by controlling the master clock signal frequency based on FIFO buffer status. When the buffer is full, the receiving rate is reduced to prevent overflow; when the buffer is empty, the receiving rate is increased to prevent underflow, creating a responsive adaptive synchronization mechanism
2Speed
If the receiving rate of the DAC is made to match the transmission rate exactly, then synchronization is achieved, but the system cannot respond to temporary data unavailability or transmission errors
Solution Approach 1:
The FIFO buffer acts as a cushion between the data source and DAC, storing data in advance to protect against transmission interruptions. This cushion allows the DAC to continue receiving data at a steady rate even when the transmission rate fluctuates due to errors or losses
Solution Approach 2:
The system implements feedback control by monitoring the FIFO buffer's data level and using this information to adjust the master clock frequency. The control circuit detects buffer status and modifies the receiving rate accordingly, creating a closed-loop system that maintains reliable data flow
3Stability of the object's composition
If the receiving rate is adjusted gradually and steadily for acceptable audio quality, then audio performance is maintained, but the system responds slowly to transmission rate changes
Solution Approach 1:
The FIFO buffer serves as an intermediary element that decouples the data source and DAC, allowing independent operation at different rates. This intermediary absorbs the shock of rate changes, enabling gradual adjustment while maintaining overall system responsiveness through buffer status feedback
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
The apparatus ensures stable and gradual adjustment of the receiving rate, preventing data underflow and overflow, and maintaining acceptable audio quality by dynamically adjusting the master clock signal frequency based on FIFO and counter signals, even during transmission errors.
Implementation Method 1
a first-in first-out buffer (FIFO buffer) which receives and stores a plurality of data and provides a FIFO adjustment signal according to the number of the data stored in the FIFO buffer
Implementation Method 2
the PLL provides the master clock signal and adjusts the frequency of the master clock signal in response to a PLL adjustment signal
Data Source
AI summary
A data synchronization apparatus is provided. The data synchronization apparatus comprises a first-in first-out buffer (FIFO buffer), a control circuit and a phase-locked loop (PLL). The FIFO buffer receives and stores a plurality of data and provides a FIFO adjustment signal according to the number of the data stored in the FIFO buffer. The data stored in the FIFO buffer are sent out to an external device at a clock rate derived from a master clock signal. The control circuit provides a PLL adjustment signal according to the FIFO adjustment signal. The PLL provides the master clock signal and adjusts the frequency of the master clock signal in response to the PLL adjustment signal.