Cable Length Measurement Using Multi-Phase Sampling
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Solution Overview
Problem
Existing methods for measuring cable length in high-speed Ethernet communication systems, such as TDR and DSP-based echo response, suffer from unsatisfactory resolution due to low sampling rates, particularly in automotive environments where stringent electromagnetic interference requirements exist.
Innovation Solution
The method involves shifting sampling phases to generate reflection samples at a higher data rate, combining these samples to determine a delay parameter, and applying a matching filter to enhance signal-to-noise ratio, thereby improving measurement resolution and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TDR or DSP-based echo response methods are used to measure cable length, then the measurement can be performed in high-speed Ethernet communication systems, but the measurement resolution is unsatisfactory due to low sampling rates
Solution Approach 1:
The patent applies periodic action by transmitting multiple data symbols at different phases (e.g., 0°, 90°, 180°, 270°) periodically and combining their reflection samples. This periodic multi-phase transmission allows the system to achieve higher effective sampling rates equivalent to 4x the original symbol rate, thereby improving cable length measurement resolution without requiring a higher physical sampling rate
Solution Approach 2:
The patent merges reflection samples from multiple data symbols transmitted at different phases. By combining these samples constructively, the system generates a high-resolution cable length measurement that would normally require a much higher sampling rate. This merging technique allows low symbol rate systems to achieve measurement precision equivalent to high symbol rate systems
2Measurement precision
If the sampling rate is increased to improve measurement resolution, then the cable length measurement precision improves, but the data rate requirement increases
Solution Approach 1:
The patent uses periodic multi-phase data symbol transmission where data symbols are sent at different phases (0°, 90°, 180°, 270°) in a periodic sequence. This periodic approach allows the system to achieve 4x effective sampling rate for measurement purposes while maintaining the original low data symbol rate for actual data communication, thus improving measurement precision without increasing the data rate requirement
Solution Approach 2:
The patent segments the measurement process into multiple phases by transmitting data symbols at different phases separately and processing their reflections independently. Each phase's reflection sample contributes to the final high-resolution measurement, allowing the system to achieve high measurement precision through segmented processing rather than requiring a high overall data symbol rate
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly enhances the measurement resolution of cable length, achieving precision equivalent to higher data symbol rates and providing accurate length estimates even in low symbol rate environments, such as those found in automotive systems.
Implementation Method 1
a plurality of data symbols are transmitted at a first data rate via a wired data communication link
Implementation Method 2
a reflection signal is received from the wired data communication link
Data Source
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AI summary
Embodiments described herein provide a system for cable length measurement in a communication system. The system includes a transmitter, a receiver, a signal sampler and a cable length calculation unit. The transmitter is configured to transmit a plurality of data symbols at a first data rate via a wired data communication link, and the receiver is configured to receive a reflection signal. The signal sampler is configured to sample the received reflection signal using a phase shift number of shifting sampling phases to generate reflection samples, and combine the reflection samples with different sampling phases to generate a series of reflection samples corresponding to a second data rate higher than the first data rate. The cable length calculation unit is configured to determine a delay parameter from the series of reflection samples, and generate an estimate of a length of the data communication link.