Incoherent Clocking Across Clock Domains for Phase-Continuous Sampling
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Solution Overview
Problem
Existing incoherent clocking methods for radio telescope arrays suffer from beating effects due to harmonically related sampling frequencies, leading to phase discontinuities in the sampled waveform.
Innovation Solution
A method and system that utilize dual-port memory and Gray code to sample and transfer the tracer phase across digital clock domains, ensuring that the discrete-time waveform is always repetitively sampled at different phases, thereby preventing phase discontinuities, using a larger second clock frequency to read addresses and employing a round-trip phase measurement for precise frequency correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sampling is performed at harmonically related frequencies between remote and central clocks, then frequency synchronization is achieved, but phase discontinuities and beating effects occur in the sampled waveform
Solution Approach 1:
The patent introduces an intermediary frequency domain that is not harmonically related to either the remote or central clock frequencies. By sampling at this intermediate frequency, the system avoids the beating effects and phase discontinuities that occur when sampling at harmonically related frequencies, while still achieving accurate frequency measurement and synchronization through the dual-port memory phase comparison mechanism.
2Device complexity
If a single clock frequency is used for sampling, then system simplicity is maintained, but accurate frequency correction across different clock domains cannot be achieved
Solution Approach 1:
The patent segments the sampling process into multiple clock domains: a remote clock domain at the antenna, a central clock domain at the processing site, and an intermediate sampling frequency domain. This segmentation allows each domain to operate independently at its optimal frequency while the dual-port memory structure provides the mechanism to compare and correct phases across domains, achieving high precision frequency correction without requiring a single unified clock frequency.
Data Source
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AI summary
The present invention provides a method and system to correctly sample, at a central location, a signal at a second clock frequency from a remote antenna when the signal is at a first clock frequency. The present invention provides an improved method of incoherent clocking to correctly sample a signal from a remote antenna at a clock frequency of a central location, such as a central site of a radio telescope array. The signal contains a "tracer" which is related to the frequency of the remote antenna. The tracer phase is written into a dual-port memory at the first clock frequency and then read from the memory at the second clock frequency. The tracer phase is transferred across digital clock domains using Gray-doe methods so that phase coding errors do not occur.