DME Signal Decoding Circuit for RFI-Distorted Period Detection
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Solution Overview
Problem
Automotive electronic systems face challenges in decoding Differential Manchester Encoding (DME) signals due to radio frequency interference (RFI), which causes signal distortion and prevents the decoding mechanism from converging when only a comparison circuit is used.
Innovation Solution
A signal processor comprising a signal receiving circuit, a pre-processing circuit, a period acquisition circuit, and a decoding circuit that generates a square wave signal, captures multiple adjacent signal periods, and decodes based on time length and voltage value changes to correctly interpret DME signals despite RFI interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only a comparison circuit is used to receive and decode the signal, then the circuit complexity is reduced, but the decoding reliability deteriorates due to RFI causing signal distortion and preventing convergence
Solution Approach 1:
The signal processing function is divided into multiple independent circuits: signal receiving circuit, pre-processing circuit, period acquisition circuit, and decoding circuit. Each circuit handles a specific aspect of signal processing, allowing the system to maintain low overall complexity while achieving reliable decoding through specialized functional breakdown.
Solution Approach 2:
A pre-processing circuit is introduced as an intermediary between the signal receiving circuit and the decoding circuit. This intermediary circuit generates square wave signals and captures period information, mediating the effect of RFI before the signal reaches the decoding stage, thereby protecting the decoding reliability without significantly increasing overall system complexity.
2Measurement precision
If multiple signal periods are captured and decoded based on time length and voltage changes, then the measurement precision of signal interpretation is improved, but the device complexity increases due to additional circuits
Solution Approach 1:
The period acquisition circuit performs multiple functions: capturing signal periods, determining time lengths, counting voltage value changes, and identifying signal period groups. By making this single circuit multi-functional, the system achieves high measurement precision without proportionally increasing device complexity.
Solution Approach 2:
The pre-processing circuit performs preliminary actions by generating square wave signals and preparing period information before the decoding stage. This preliminary processing organizes the signal data in advance, enabling the decoding circuit to achieve high precision interpretation with simpler logic operations.
3Reliability
If RFI compensation is performed through multiple circuit stages, then the reliability against RFI is improved, but the loss of time increases due to additional processing steps
Solution Approach 1:
The signal processing proceeds continuously through the different circuit stages without interruption or reprocessing. The signal receiving circuit, pre-processing circuit, period acquisition circuit, and decoding circuit operate in a continuous pipeline, maintaining RFI protection while minimizing processing time delays.
Solution Approach 2:
The pre-processing circuit performs preliminary signal conditioning and the period acquisition circuit captures period information in advance, before the main decoding operation. This preliminary action prepares the signal data beforehand, reducing the time required for the actual decoding process while maintaining RFI compensation.
Data Source
AI summary
A signal processor includes a signal receiving circuit, a pre-processing circuit, a period acquisition circuit, and a decoding circuit. The signal receiving circuit is configured to receive an input signal. The pre-processing circuit is configured to generate a square wave signal according to the input signal. The period acquisition circuit is configured to capture several periods of the square wave signal. The several signal periods includes several signal period groups, and each of the several signal period groups includes at least two signal periods of the several signal periods. The at least two signal periods are adjacent to each other. The decoding circuit is coupled to the period acquisition circuit and is configured to perform decoding according to a time length and a number of times of voltage value change of the several signal period groups to obtain a decoding result.