Wireless Clock Synchronization Phase Unwrapping
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Solution Overview
Problem
In medical imaging, particularly in MR and PET systems, accurate timestamp synchronization is crucial for image quality and time-of-flight precision, but wireless clock synchronization signals face ambiguities due to phase wrapping, especially with patient or environmental movements causing variable propagation delays.
Innovation Solution
A clocked electronic device with a wireless receiver and local oscillator uses a dual sideband modulated clock synchronization signal, determining a wrap count to unwrap the phase difference between carrier signals, ensuring accurate timestamp assignment and synchronization, even in the presence of phase wrapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a wireless clock synchronization signal is used to synchronize clocks in MR receive coils, then the ease of operation is improved, but the measurement precision deteriorates due to phase wrapping ambiguities
Solution Approach 1:
The synchronization signal is segmented into multiple frequency components (first and second carrier frequencies). By measuring phase differences at multiple frequencies, the system can resolve phase wrapping ambiguities that would prevent precise timestamp measurement while maintaining wireless operation
Solution Approach 2:
The system transitions from single-frequency phase measurement to multi-frequency phase difference measurement. This adds a frequency dimension to the measurement space, enabling the system to unwrap phases and achieve precise timestamp synchronization that would be impossible with single-frequency measurements alone
2Measurement precision
If the carrier frequency is increased to improve timestamp precision, then the measurement precision is improved, but the reliability deteriorates due to phase wrap occurrences
Solution Approach 1:
The system uses feedback from phase difference measurements at multiple frequencies to detect and correct phase wrapping. By comparing phase differences at different frequencies, the system can identify when wrapping has occurred and adjust measurements accordingly, maintaining both precision and reliability
Solution Approach 2:
The synchronization approach combines measurements from multiple frequency components into a composite measurement. This composite measurement strategy allows the system to achieve high timestamp precision while maintaining reliability by using the complementary information from different frequencies to resolve ambiguities
3Measurement precision
If continuous monitoring of wrapped phase is performed to unwrap phase accurately, then the measurement precision is improved, but the loss of time increases during communication interruptions
Solution Approach 1:
The system performs preliminary measurements at multiple frequencies to establish phase difference relationships before communication interruptions occur. This preliminary information allows the system to quickly resolve phase wrapping ambiguities after interruptions without requiring continuous monitoring, reducing time loss while maintaining precision
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 method provides robust and precise clock synchronization, reducing ambiguities and maintaining timestamp reliability, even during brief communication interruptions, with improved temporal resolution for medical imaging applications.
Implementation Method 1
a first propagation-delayed carrier signal and a second propagation-delayed carrier signal at respective first and second carrier frequencies separated by a frequency difference
Data Source
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AI summary
A clocked electronic device, such as a wireless magnetic resonance (MR) receive coil (20), comprises a wireless receiver or transceiver (30) configured to receive a propagation- delayed wireless clock synchronization signal (54) comprising first and second propagation- delayed carrier signals at respective first and second carrier frequencies separated by a frequency difference, a clock (60) comprising a local oscillator (62) driving a digital counter (64), and at least one electronic signal processing component (66) configured to perform clock synchronization. This includes determining a wrap count (k) from a phase difference (φ 1) between phases of the first and second propagation-delayed carrier signals, unwrapping a wrapped phase (φ 2,wrapped ) of the propagation-delayed wireless clock synchronization signal using the wrap count to generate an unwrapped phase (φ 2,wrapped ), and synchronizing the clock using the unwrapped phase.