Time-Varying Template for Ultrasonic Short-Range Detection
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Solution Overview
Problem
Existing ultrasonic ranging systems face challenges in effectively detecting objects at short distances due to echoes being partially or fully overlapped with the excitation period, leading to incomplete correlation with fixed-length receive templates.
Innovation Solution
A time-varying template generation system that adjusts the length of the receive template based on a time index from the start of the burst signal, allowing for better correlation with echoes that may be partially or fully within the listening period, and includes a time-varying gain amplifier to compensate for gain variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed-length receive template is used for correlation, then the system structure is simple, but the detection accuracy for short-distance objects deteriorates because echoes are partially or fully overlapped with the excitation period
Solution Approach 1:
The patent applies the dynamics principle by transitioning from a fixed-length receive template to a time-varying receive template whose length is dynamically adjusted based on the time index from the start of the burst signal. This allows the template to adapt to different echo durations, particularly for short-distance objects where echoes overlap with the excitation period, thereby improving detection accuracy without requiring complex additional hardware
Solution Approach 2:
The patent implements parameter changes by modifying the template length parameter as a function of time. The time-varying template generator adjusts the template length based on the time index, and the time-varying gain amplifier compensates for gain variations. This dynamic parameter adjustment enables accurate correlation for echoes of varying lengths while maintaining system simplicity
2Measurement precision
If the receive template length is increased to capture full echoes, then the correlation completeness improves, but the signal-to-noise ratio deteriorates due to including unnecessary excitation period data
Solution Approach 1:
The time-varying template dynamically adjusts its length to match the actual echo duration for each time index, capturing only the relevant echo portion without including unnecessary excitation period data. This dynamic adaptation ensures complete correlation for short-distance echoes while maintaining high signal-to-noise ratio by excluding irrelevant signals
Solution Approach 2:
The system performs preliminary action by pre-calculating and storing multiple template lengths corresponding to different time indices. When processing echoes, the appropriate template length is selected based on the time index, enabling optimal correlation without real-time complex calculations and maintaining high signal-to-noise ratio
3Measurement precision
If a time-varying template is used to improve short-distance detection, then the detection accuracy for near objects improves, but the processing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the template processing into discrete time-indexed segments, each with its own optimized template length. The time-varying template generator creates a sequence of templates for different time indices, and the correlator processes echoes using the appropriate segment. This segmentation approach improves short-distance detection accuracy while keeping processing complexity manageable through structured organization
Solution Approach 2:
The system performs preliminary action by pre-generating and storing templates for multiple time indices before actual echo processing. This pre-computation eliminates the need for complex real-time template generation during echo correlation, reducing processing complexity while maintaining high detection accuracy for short-distance objects
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
Improves the detection of short-range objects by ensuring that the receive template matches the length of the echo signal, enhancing the signal-to-noise ratio and accuracy of distance measurement.
Implementation Method 1
The transducers emit ultrasonic signals that reflect off nearby objects, if present, and sense the reflections
Implementation Method 2
The round-trip time of the ultrasonic signals is measured so that distance to the object can be determined
Implementation Method 3
correlator circuitry coupled to the time-varying template generation circuitry and configured to correlate a received transduced reflected signal with the time-varying coded receive template to produce a correlated signal
Implementation Method 4
A time-varying gain amplifier can be coupled to the correlator circuitry and configured to adjust the gain of the correlated circuitry in an amount that is based on the time index from the start of the burst signal
Data Source
AI summary
Ultrasonic ranging systems and methods that emit coded bursts and correlate transduced acoustical echoes of the bursts with a receive template characterizing a burst code to determine time-of-flight information use receive templates of time-variable length to improve short-range object detection. The template length is based on a time index measured from the start of the burst emission. The detection can account for a dead zone of transducer ringing following a burst. A time-variable gain that is also based on the time index can be applied to the correlated signal. The length and gain can be adjusted with reduced temporal frequency to reduce computation cost.