Wireless Distance Measurement Using Phase Detection
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Solution Overview
Problem
Existing EM-based distance measurement systems face challenges in achieving high accuracy due to power limitations and oscillator synchronization issues, particularly in wireless environments, which hinder precise continuous wave phase measurement for applications like natural hazard monitoring.
Innovation Solution
The system employs active, cooperative responders with delay lines and omni-directional antennas, avoiding oscillator synchronization by using a pulse burst initialization process and phase measurement to achieve sub-centimeter resolution, and utilizes a priori knowledge of sensor-to-target distances to maintain accurate inter-sensor spacing, enabling fine range accuracy without distributed oscillator synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If distributed oscillator synchronization is used in wireless distance measurement systems, then measurement precision can be improved, but power consumption increases and system complexity increases
Solution Approach 1:
The patent extracts and removes the oscillator from the remote sensor node, eliminating the need for oscillator synchronization in wireless distributed systems. The master station generates the continuous wave signal and transmits it to the remote node, which only measures phase without generating its own oscillating signal, thereby reducing power consumption while maintaining measurement precision
Solution Approach 2:
The patent introduces a delay line as an intermediary component in the remote sensor node that introduces a known time delay to the received continuous wave signal. This delay line serves as a reference for phase measurement without requiring the remote node to have a synchronized oscillator, enabling accurate distance measurement with reduced power consumption
2Measurement precision
If distributed oscillator synchronization is used in wireless distance measurement systems, then measurement precision can be improved, but device complexity increases
Solution Approach 1:
The patent extracts and removes the oscillator from the remote sensor node, eliminating the need for oscillator synchronization in wireless distributed systems. The master station generates the continuous wave signal and transmits it to the remote node, which only measures phase without generating its own oscillating signal, thereby reducing power consumption while maintaining measurement precision
Solution Approach 2:
The remote sensor node performs self-service by measuring the phase of the received continuous wave signal against its own delayed version of the same signal. This self-referential measurement approach eliminates the need for external oscillator synchronization infrastructure, reducing system complexity while maintaining measurement accuracy
3Ease of operation
If conventional EM-based distance measurement techniques are used, then implementation is simpler, but measurement precision is insufficient for natural hazard monitoring
Solution Approach 1:
The patent employs continuous wave (CW) phase measurement where a continuous sinusoidal signal is transmitted from the master station to the remote node. This continuous signal allows for precise phase comparison and sub-centimeter distance measurement accuracy, improving upon conventional techniques while maintaining implementation feasibility through the use of standard wireless communication components
Solution Approach 2:
The patent changes the measurement parameter from time-of-flight to phase difference of continuous waves. By measuring the phase shift of a continuous sinusoidal signal rather than timing electromagnetic pulses, the system achieves sub-centimeter precision suitable for natural hazard monitoring while keeping the system relatively simple to implement using standard wireless communication hardware
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 allows for precise distance measurement with sub-centimeter resolution and reduces power consumption, overcoming traditional limitations in wireless environments, enabling reliable and accurate distance monitoring in hostile conditions.
Implementation Method 1
the travel time is measured by determining the phase delay experienced by the signal in being propagated along the propagation path
Implementation Method 2
a sine wave signal of known frequency, and the travel time is measured by determining the phase delay experienced by the signal in being propagated along the propagation path
Data Source
AI summary
A system and method for monitoring topological changes in a defined area. A grid of sensors is arranged in the area, with known distances between them. The sensors communicate wirelessly with a host computer, which individually addresses each sensor to instruct that sensor to be in an interrogate mode or responder mode. When a sensor is in interrogate mode, it measures distance from a neighboring sensor using radar (continuous wave phase difference) measurements. When a sensor is in responder mode, it receives, delays, and returns a signal received from a neighboring sensor.