Asynchronous Sample Rate Conversion Using Digital Loop Timing Correction
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Solution Overview
Problem
Existing systems face challenges in accurately sampling signals at different rates without introducing artifacts, particularly when converting asynchronous sample rates, as they require expensive circuitry and are prone to errors due to latency and mismatched clock frequencies.
Innovation Solution
A method and circuit for asynchronous sample rate conversion using time domain interpolation, which generates an intermediate sample point to correct timing errors, allowing accurate representation of signals across different clock domains without introducing artifacts, by using a digital phase locked loop and modulo arithmetic to synchronize input and output rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If asynchronous sample rate conversion is performed using conventional methods, then signal conversion between different clock domains is achieved, but expensive circuitry and latency errors are introduced
Solution Approach 1:
The patent replaces complex hardware circuitry with a software-based solution running on a general-purpose processor. The sample rate conversion is achieved through digital signal processing algorithms rather than dedicated hardware circuits, eliminating the need for expensive specialized circuitry while maintaining signal integrity through software-controlled timing correction
Solution Approach 2:
The invention uses a general-purpose processor that can perform multiple functions, including sample rate conversion, rather than requiring dedicated hardware circuits for this specific task. This universal approach reduces overall system complexity and cost while maintaining the required functionality through software implementation
2Adaptability or versatility
If conventional sample rate conversion methods are used, then clock frequency mismatch is handled, but latency errors and artifacts are introduced
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors the timing of input samples and dynamically adjusts the interpolation process. By measuring actual arrival times of samples and comparing them against expected timing, the system generates correction factors that compensate for latency errors and maintain timing accuracy across different clock domains
Solution Approach 2:
The system performs preliminary timing analysis on incoming samples to predict and correct for latency errors before they affect the output. By calculating timing offsets in advance and pre-adjusting the interpolation parameters, the system prevents artifacts from being introduced during the conversion process
3Measurement precision
If timing error correction is applied to maintain signal integrity, then accuracy is improved, but additional processing complexity is introduced
Solution Approach 1:
The patent replaces complex hardware-based timing correction circuits with software algorithms running on a general-purpose processor. The timing error correction is achieved through digital signal processing techniques that calculate and apply corrections in software, reducing hardware complexity while maintaining or improving timing accuracy through more flexible and precise algorithms
Data Source
AI summary
Various embodiments perform sample rate conversion of a sample series at an input rate to an output rate. A version of the sample series is corrected with timing error information generated by a digital loop. The digital loop is locked to a first rate and clocked at a second rate.