Audio Signal Decoding With Dynamic Clock Sync for Card Readers
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Solution Overview
Problem
Portable electronic devices, such as smartphones, are not compatible with Manchester encoded data signals due to audio interface optimizations for voice communication, leading to signal distortion and failure in data decoding.
Innovation Solution
A method for dynamically decoding audio streams by adjusting the encoder and decoder clock frequencies, preprocessing signals to smooth noise, and identifying known start sequences to interpret data blocks, allowing for successful data interpretation without device adaptations, and enabling compatibility with various devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If audio interface optimizations for voice communication are applied, then sound quality is improved, but data signal interpretation fails
Solution Approach 1:
The patent introduces an intermediary preprocessing step between the audio interface and decoder. This preprocessing stage includes smoothing the received signal and detecting zero-crossing points to identify the actual clock frequency, thereby mediating between the optimized audio interface output and the data decoding requirement. This intermediary processing converts the distorted signal into a form that can be successfully decoded.
Solution Approach 2:
The patent dynamically adjusts the clock frequency parameter based on detected zero-crossing points in the signal. Instead of using a fixed clock frequency, the system measures the actual frequency from the distorted signal and adapts the decoding process accordingly. This parameter change allows the decoder to synchronize with the actual signal frequency despite audio interface distortions.
2Device complexity
If fixed clock frequency decoding is used, then decoder simplicity is maintained, but compatibility with different devices is lost
Solution Approach 1:
The patent transforms the static fixed clock frequency approach into a dynamic system that automatically adapts to different devices. The decoder measures the actual clock frequency from the received signal by detecting zero-crossing points and adjusts its operation accordingly. This dynamic adaptation enables compatibility with multiple device types without requiring complex device-specific configuration or multiple decoder variants.
3Measurement precision
If signal preprocessing is added, then decoding accuracy is improved, but processing time increases
Solution Approach 1:
The patent applies a targeted preprocessing approach rather than comprehensive signal processing. Specifically, it focuses on smoothing the signal and detecting zero-crossing points to determine clock frequency, rather than applying full-spectrum analysis or complex filtering. This partial action provides sufficient decoding accuracy while minimizing additional processing time.
Data Source
AI summary
The proposed technology generally relates the field of data transmission, in particular it relates to decoding an encoded data signal received at an audio interface of a portable electronic device, wherein the encoded data signal is encoded with an encoding scheme having an adjustable encoder clock frequency. The proposed method comprises pre-processing the received encoded data signal; scanning the received encoded data signal for a known start sequence and when a known start sequence is successfully detected then calculating an actual frequency based on the detected start sequence; interpreting, a data block succeeding the start sequence using the assessed actual frequency; and assessing whether to request adjustment of the adjustable encoder clock frequency based on the scanning and/or the interpretation. The proposed technology relates to a method performed in a portable communications device well as a corresponding device and computer program.