Digital Sampling Rate Synchronization With Fractional Delay Filtering
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Solution Overview
Problem
Conventional methods for synchronizing sampling rates between wireless transmitters and receivers are limited by precision and require additional analog circuits, making them costly and inconvenient, especially in cases of asynchronous frequency-multiplexed signals.
Innovation Solution
A digital solution involving a timing control unit and a digital interpolator with a fractional delay filter, which estimates and corrects for timing offsets by adjusting the read pointer in a sample buffer to synchronize the receive sampling rate with the transmit sampling rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods for synchronizing sampling rates are used, then sampling rate synchronization is achieved, but precision is limited and additional analog circuits are required
Solution Approach 1:
The patent replaces conventional analog circuit-based sampling rate synchronization methods with a digital signal processing approach. A digital interpolator with fractional delay filter estimates timing offsets and adjusts the receive sampling rate in the digital domain, eliminating the need for additional analog circuits while achieving higher precision synchronization.
Solution Approach 2:
The patent changes the sampling rate parameter dynamically by estimating timing offsets and applying fractional delays through digital filtering. This allows precise adjustment of the receive sampling rate to match the transmit sampling rate without requiring fixed analog circuit configurations.
2Measurement precision
If digital solution with digital interpolator is used, then precision is improved and analog circuits are reduced, but device complexity in digital domain increases
Solution Approach 1:
The patent introduces a digital interpolator with fractional delay filter as an intermediary component between the ADC and demodulator. This intermediary estimates timing offsets and applies corrective delays, achieving high-precision synchronization while keeping the digital processing architecture modular and manageable.
Solution Approach 2:
The patent implements a feedback mechanism where the digital interpolator continuously estimates timing offsets between transmit and receive sampling rates, and dynamically adjusts the fractional delay to minimize synchronization errors. This closed-loop approach achieves high precision without requiring overly complex open-loop digital circuits.
3Measurement precision
If timing offset estimation is performed, then demodulation accuracy is improved, but processing time is increased
Solution Approach 1:
The patent performs timing offset estimation as a preliminary action before demodulation by analyzing the received signal to determine the fractional delay. This upfront estimation allows the digital interpolator to pre-correct sampling rate mismatches, ensuring accurate demodulation without requiring excessive processing time during the main demodulation operation.
Data Source
AI summary
Systems and methods are provided in which a wireless receiver can be configured to digitally synchronize a receive sampling rate to a transmit sampling rate, and may include a digital interpolator controlled by a timing control unit with a timing offset estimator. The timing control unit can be configured to calculate and output parameters to the digital interpolator. The digital interpolator can include a sample buffer followed by a fractional delay filter. Output parameters to the digital interpolator can include a fractional delay timing offset signal of the receiver relative to a transmitter timing signal and a buffer pointer control signal to control a position of the read pointer relative to a write pointer to compensate for subsample timing offset. The timing offset estimator can be configured to calculate and provide to the timing control unit a sampling period ratio control word and an instantaneous timing offset control word.