Reception Circuit Correlation Timing for Preamble-Free Data Start Detection
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Solution Overview
Problem
Existing reception circuits are unable to detect the beginning of data in received signals that do not contain a preamble or unique word, and are incompatible with various coding systems, particularly those compliant with ISO/IEC14443 TypeA or TypeB.
Innovation Solution
A reception circuit that performs a correlation operation using a reference signal sliding one symbol relative to the received signal, with a delay portion to output a delayed signal and a detection portion to identify the beginning peak timing, allowing for data detection regardless of the presence of a preamble or unique word and across different coding systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a correlation operation is performed using specific unique words as a reference signal, then the beginning of data can be detected for received signals according to a specific code system, but the system cannot detect the beginning of data for received signals according to other code systems or without preambles
Solution Approach 1:
The reference signal is designed with a universal structure that can match various coding systems. By using a reference signal with a specific waveform pattern (high level during first half symbol period, low level during second half symbol period) and performing correlation operations with multiple delay versions, the system can detect data beginnings across different coding systems including ISO/IEC14443 TypeA and TypeB, without requiring specific preambles or unique words.
2Reliability
If the system uses specific unique words for data beginning detection, then detection can be performed for signals with those unique words, but the system becomes incompatible with card mode signals compliant with ISO/IEC14443 TypeA or TypeB that do not contain preambles
Solution Approach 1:
The system changes the parameter of the reference signal to accommodate different signal types. By adjusting the reference signal waveform and correlation operation parameters, the system can reliably detect data beginnings in signals with preambles, unique words, or no preambles at all, including ISO/IEC14443 TypeA and TypeB card mode signals.
3Productivity
If a correlation operation is performed while sliding one symbol of reference signal, then fast detection can be achieved, but the system requires precise timing synchronization
Solution Approach 1:
The system performs preliminary correlation operations with multiple delay versions of the reference signal before final detection. By pre-calculating correlations at different delay positions and identifying the maximum correlation value, the system achieves fast detection without requiring precise prior timing synchronization, as the delay portion systematically searches for the optimal alignment.
Data Source
AI summary
A reception circuit is provided which can detect the beginning of data regardless of a preamble or a unique word contained or not in a received signal and regardless of coding systems for received signals. The reception circuit includes a correlation operation portion that performs a correlation operation to generate a correlation signal while sliding one symbol of reference signal in relation to a received signal. The reference signal goes to a high level during a first half symbol period and goes to a low level during a second half symbol period. The reception circuit further includes: a delay portion that outputs a delay signal by delaying the received signal for a half symbol period in relation to the received signal; and a data beginning timing detection portion that detects a beginning peak timing for the correlation signal as a beginning timing of data contained in the delay signal.