Multi-phase correlation vector synthesis for TOF ranging
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Solution Overview
Problem
Conventional Time-of-Flight (TOF) ranging systems face challenges in achieving high phase sensitivity and accuracy due to signal distortion and interference, particularly in 3D imaging applications, where the phase detection based on in-phase and quadrature-phase demodulation techniques is suboptimal under real-world noise conditions and multi-path interferences.
Innovation Solution
A novel multi-phase correlation and vector synthesis method that employs an arbitrary number of correlations, generating correlation vectors from multiple phase positions over one period of the transmitting signal, and synthesizes in-phase and quadrature-phase signals using zero-force synthesis to improve phase sensitivity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional I/Q demodulation or matched filter techniques are used for phase delay detection, then the system structure is simple and easy to implement, but the phase sensitivity and measurement precision are insufficient under real-world noise conditions and multi-path interferences
Solution Approach 1:
The patent divides the phase detection task into multiple independent correlation operations at different phase positions (0°, 90°, 180°, 270°). Each correlator processes a specific phase component separately, and the results are combined through vector synthesis. This segmentation allows each correlator to focus on a specific aspect of the signal, improving overall phase sensitivity while maintaining manageable complexity through modular architecture.
Solution Approach 2:
The patent combines the output correlation vectors from multiple correlators (at different phase positions) through vector synthesis to produce the final in-phase and quadrature-phase signals. This merging process integrates information from multiple phase references, enhancing the signal-to-noise ratio and improving phase detection precision beyond what a single correlator could achieve alone.
2Measurement precision
If only 4-phase correlations are used, then the device complexity is low, but the measurement error is large (±16.5 cm)
Solution Approach 1:
The patent transitions from traditional 2D I/Q demodulation to a multi-dimensional correlation approach by introducing multiple phase references (0°, 90°, 180°, 270°). This adds a temporal/dimensional aspect to the signal processing, allowing the system to capture more information about the phase delay across multiple reference points, thereby improving distance measurement accuracy to ±1.05 cm.
Solution Approach 2:
The patent uses multiple copies of the transmitted signal at different phase positions as reference signals for correlation. Instead of using a single reference signal, the system creates and processes multiple phase-shifted copies (sin(ωt), cos(ωt), -sin(ωt), -cos(ωt)), which provides redundant information that can be synthesized to improve measurement precision and reduce the impact of noise and interference.
3Reliability
If conventional correlators are used, then the implementation is straightforward, but the received signal distortion and interference cannot be sufficiently compensated
Solution Approach 1:
The patent employs feedback mechanisms through the correlation process, where the received signal is correlated with multiple phase-referenced copies of the transmitted signal. The correlation outputs are then fed back through vector synthesis to generate corrected in-phase and quadrature-phase signals. This feedback loop continuously refines the phase delay estimation, compensating for signal distortion and interference to improve detection reliability.
Solution Approach 2:
The patent changes the parameter of phase reference by using multiple phase-shifted versions of the transmitted signal (0°, 90°, 180°, 270°) instead of a single reference. This parameter variation allows the system to probe the received signal at different phase angles, enabling better characterization of the signal characteristics and improving the ability to compensate for distortion and interference through the correlation and synthesis processes.
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 reduces measurement errors, achieving a ±1.05 cm inherent error range compared to ±16.5 cm with conventional 4-phase correlations, and enables more accurate 3D imaging, sonar, and touchless pointer systems by ensuring linear phase delay variation with distance.
Implementation Method 1
correlations are performed between the received signal and the two orthogonal signal components of the transmitting signal
Implementation Method 2
The in-phase and quadrature-phase signal components are synthesized from the output correlation vectors of multi-phase correlators based on the principle of the zero-force synthesis method, which is a 1st order linear transformation
Implementation Method 3
In Time-of-Flight (TOF) ranging, the distance between the transmitter and the reflected object is calculated from the phase difference (or phase delay) between the transmitted and received signals
Implementation Method 4
The phase delay (Ø) of the received signal due to the flight time is calculated by taking the arc tangent of I/Q
Data Source
AI summary
A TOF ranging system based on a multi-phase correlation vector synthesis ranging method is presented. The method is a generalized expansion from conventional 2- or 4-phase correlations to arbitrary N-phase correlations in finding in-phase (I) and quadrature-phase (Q) signals of the reflected signal at the receiver, where N is an odd number greater than or equal to 3. The correlation vectors of the output of multi-phase correlators are processed by a zero-force synthesizer to produce optimal I and Q signals, from which the phase delay or ranging information is calculated. Embodiments disclose necessary components in realization of the method, such as half clock shifter, full clock shifter, dual edge reference pulse generator, and correlation integrator. The TOF ranging method enables the construction of finer and more accurate TOF systems like 3D imaging systems, 3D sonar imaging systems, or 3D touchless pointer systems.