Manchester Signal Decoding Without PLL for Short Telegrams
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Solution Overview
Problem
Existing Manchester coding decoding methods face challenges in accurately processing short telegrams due to high susceptibility to interference and the need for phase-locked loops, which result in errors and delayed decoding of short signal sequences.
Innovation Solution
A decoding method that forms a moving data mean value and a sliding clock mean value for Manchester-coded signals, allowing for the derivation of a decoded data signal and clock signal without requiring a phase-locked loop, using comparators and logical operations to reconstruct the clock signal, enabling efficient processing of short telegrams with reduced settling times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a phase-locked loop is used to continuously adjust the sampling frequency, then the clock signal synchronization is improved, but the decoding of short telegrams is delayed due to settling time requirements
Solution Approach 1:
The patent extracts the clock signal recovery function from the phase-locked loop by directly sampling the input signal at its center point. This separates the clock recovery task from the complex PLL structure, eliminating the settling time requirement while maintaining synchronization accuracy.
Solution Approach 2:
The patent performs preliminary detection of signal edges to determine the precise center point of each bit period before sampling. This preliminary action enables accurate timing without requiring the gradual settling process of a PLL, allowing immediate decoding of short telegrams.
2Measurement precision
If the sampling frequency is tightly coupled to the transmission frequency, then decoding accuracy is improved, but the system becomes susceptible to frequency deviations and faults
Solution Approach 1:
The system uses the input signal itself to determine the sampling timing by detecting its edges and calculating the center point. This self-service approach eliminates the need for external frequency reference coupling, making the system immune to frequency deviations while maintaining accurate decoding.
3Object-affected harmful factors
If a moving average filter is used before phase-locked loop, then interference immunity is improved, but the complete decoding of short signal sequences remains impossible due to PLL synchronization delay
Solution Approach 1:
The patent removes the phase-locked loop from the signal processing chain entirely, replacing it with direct center-point sampling. This extraction eliminates the synchronization delay that prevents complete decoding of short signals, while the moving average filter continues to provide interference immunity.
Data Source
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AI summary
In a decoding device (4) for a Manchester-coded signal (1), it is proposed to use moving average images (9, 17, 28) to form at least one moving data average (10) and/or one moving clock average (18) with respect to different averaging times and to provide bimarous output signals as data signal 6 and/or clock signal (23) from these moving averages (10, 18, 29) by means of comparators (11, 19, 30) (Fig. 5).