Manchester Code Edge Detection Using Asynchronous Clock
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In signal transmission systems using Manchester codes, decoding without restoring the clock signal is challenging, especially in devices with limited mounting space, and existing methods like oversampling can lead to error accumulation, particularly with high data volumes.
Innovation Solution
A signal transmission and reception system that includes a Manchester coding circuit, a high-speed clock generation circuit, an edge detection circuit, and a signal detection circuit, which detects edges in specific time periods to accurately decode Manchester coded signals without needing to restore the clock signal, using a high-speed clock that is asynchronous with the transmission clock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clock recovery circuit such as PLL is used to restore the clock signal, then the transmission accuracy is improved, but the device complexity and mounting space requirements increase
Solution Approach 1:
The patent extracts the clock recovery function from the reception device by using the transmission device's clock signal directly for Manchester code decoding. The reception device only needs to capture edges during specific time periods without restoring the clock, thereby eliminating the need for complex clock recovery circuits like PLL while maintaining decoding accuracy.
Solution Approach 2:
Instead of restoring the clock signal at the reception device and then decoding the Manchester code, the patent inverts the approach by using the transmission device's clock signal to determine the correct time periods for edge detection. This reverses the conventional wisdom that clock recovery must occur at the reception end, allowing simpler reception device design.
2Device complexity
If oversampling is used to decode the Manchester coded transmission signal, then the clock restoration is avoided, but the transmission accuracy deteriorates due to error accumulation
Solution Approach 1:
The patent applies preliminary action by pre-determining the correct time periods for edge detection based on the transmission device's clock signal. Instead of using oversampling and then correcting errors, the system pre-establishes the exact windows (first period and second period) where edges should be captured, preventing errors from accumulating in the first place.
Solution Approach 2:
The patent replaces the mechanical oversampling process with a time-period-based edge detection mechanism. Instead of sampling the signal multiple times per clock cycle and using voting logic to determine bits, the system uses the known clock timing to directly identify the correct edges during predetermined periods, eliminating the error accumulation inherent in oversampling methods.
3Device complexity
If edges are detected using a high-speed clock asynchronous with the transmission clock, then the mounting space is reduced, but the detection precision may be compromised
Solution Approach 1:
The patent introduces the transmission device's clock signal as an intermediary to bridge the asynchronous high-speed clock and the Manchester coded transmission signal. This intermediary clock signal provides the timing reference needed to accurately determine which edges occur during the first and second time periods, enabling precise edge detection even when using an asynchronous high-speed clock for the actual detection process.
Data Source
AI summary
A signal transmission and reception system includes a transmission device configured to transmit a transmission signal, a reception device configured to receive the transmission signal, in which the transmission device includes a Manchester coding circuit that generates an encoded signal in which transmission data is converted into a Manchester code as a switching edge, as at least a part of the transmission signal on the basis of a transmission clock, and the reception device includes a high-speed clock generation circuit, an edge detection circuit configured to detect an edge of the transmission signal, and a signal detection circuit configured to detect the edge detected in a period sandwiched between a first elapsed time at which a first period has elapsed from a start point and a second elapsed time at which a second period longer than the first period has elapsed from the start point as the switching edge.