Multi-Valued Signal TOF Ranging for Low-Interference Detection
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Solution Overview
Problem
Conventional time of flight (TOF) ranging systems face limitations in signal interference, safety compliance, and accuracy due to high peak power pulses, leading to suboptimal signal-to-noise ratio (SNR) and interference from other devices.
Innovation Solution
A TOF ranging system utilizing multi-valued signals with low peak power and low average power, generating temporal pulses through correlation of transmitted and received signals, improving SNR and reducing interference, and enabling precise distance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high peak power pulses are used in conventional TOF ranging systems, then the transmission distance and signal detection capability are improved, but the signal interference and safety compliance issues worsen
Solution Approach 1:
The patent changes the signal parameter from high peak power to multi-valued low peak power signals. By using signals with multiple amplitude levels instead of binary high-power pulses, the system achieves better signal-to-noise ratio through correlation processing while maintaining lower peak power levels, thus improving measurement precision without generating harmful interference
Solution Approach 2:
The patent employs periodic modulation of the light signal with multi-valued amplitude levels. The modulated signal is transmitted periodically and correlated with the received signal to extract distance information, allowing continuous operation with improved detection capability while avoiding the harmful effects of high peak power pulses
2Length of stationary object
If high peak power pulses are used in conventional TOF ranging systems, then the transmission distance is improved, but the safety compliance and environmental interference worsen
Solution Approach 1:
The system changes from high peak power to multi-valued low peak power signals, achieving extended transmission distance through correlation processing of the modulated signals. The lower peak power reduces environmental interference and improves safety compliance while maintaining adequate transmission range through signal integration and correlation techniques
3Reliability
If multi-valued signals with low peak power are used, then the signal-to-noise ratio and safety compliance are improved, but the system complexity increases
Solution Approach 1:
The patent uses multi-valued amplitude modulation with correlation processing to achieve high signal-to-noise ratio with low peak power signals. The correlation operation integrates signal energy over time, improving reliability without requiring high peak power, while the added complexity is confined to the signal processing unit which performs the correlation calculation
4Object-generated harmful factors
If multi-valued signals with low peak power are used, then the interference from other devices is reduced, but the manufacturing complexity increases
Solution Approach 1:
The system employs multi-valued signal modulation with correlation detection to reduce interference from other devices. The lower peak power and spread spectrum characteristics of the multi-valued signals provide inherent interference rejection, while the manufacturing complexity is managed through integration of the signal processing functions in a unified processing unit
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
The system achieves improved SNR, reduced interference, and enhanced resolution, precision, and accuracy in distance measurement by minimizing interference from other devices and environmental factors.
Implementation Method 1
each emitting device being configured to emit a wave signal having modulated intensities or modulated amplitudes or modulated polarizations that are proportional to the corresponding delayed modulation signal
Implementation Method 2
the correlator being configured to correlate the time varying multi-valued modulation signal with the detected signal to generate an output signal which represents a round trip flight time from the array to the target point
Data Source
AI summary
A time of flight (TOF) ranging system includes multiple emitters, each emitting a signal whose intensity, amplitude or polarization is modulated by a corresponding delayed modulation signal. Each delayed modulation signal is a delayed version of a time varying multi-valued modulation signal, the amount of delay being determined by a spatial position of the emitter and direction of a target point on the target. The signal reflected by the target is correlated with the original modulation signal to generate an output having a peak representing the TOF to the target point. The same process is performed to detect other target points. Another TOF ranging system includes one emitter and multiple detectors; the signal from each detector is delayed in a similar manner and their sum is correlated with the original modulation signal to generate an output representing TOF. Yet another TOF ranging system includes multiple emitters and multiple detectors.