Doppler-Compensated Ultrasonic Positioning System

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Solution Overview

Problem

Existing positioning systems using ultrasonic signals for mobile units face accuracy and reliability issues due to motion-induced phase changes, particularly in environments where the mobile receiver unit moves at speeds comparable to the signal speed, leading to challenges in correctly decoding transmitter-unit identifiers.

Innovation Solution

The system compensates for Doppler-induced phase deviations by adjusting the template or sampled data before cross-correlation, allowing for more accurate detection and decoding of transmitter-unit identifiers, thereby improving the accuracy of position determination in mobile receiver units.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the mobile receiver unit moves at speeds comparable to the signal speed, then the positioning system can operate in high-speed environments, but Doppler-induced phase changes cause accuracy degradation and decoding failures

Engineering Contradiction:
Improvemobile receiver unit speedVSAvoidposition determination accuracy
Core Design Contradiction:
SpeedVSMeasurement precision

Solution Approach 1:

The system performs preliminary analysis of the sampled data to determine the Doppler-induced phase deviation before performing cross-correlation. By detecting the phase deviation in advance and adjusting the template data accordingly, the system prepares for the high-speed movement effects beforehand, enabling accurate position determination even when the mobile receiver unit moves at speeds comparable to the signal speed

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system changes the phase parameter of the template data based on the determined Doppler-induced phase deviation. By adjusting the phase shifts within the template data to compensate for the Doppler effect, the system maintains measurement precision despite high-speed movement of the mobile receiver unit

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If Doppler-induced phase changes are not compensated, then the system operation is simple, but the decoding accuracy of transmitter-unit identifiers deteriorates

Engineering Contradiction:
Improvesignal processing complexityVSAvoididentifier decoding reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The system performs preliminary analysis of the sampled data to determine the Doppler-induced phase deviation before performing cross-correlation. By detecting the phase deviation in advance and adjusting the template data accordingly, the system prepares for the high-speed movement effects beforehand, enabling accurate position determination even when the mobile receiver unit moves at speeds comparable to the signal speed

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses the analyzed Doppler-induced phase deviation as feedback to adjust the template data before cross-correlation. This feedback mechanism ensures that the template data compensates for the Doppler effect, significantly improving the reliability of transmitter-unit identifier decoding in high-speed environments

Inventive Principle:
Principle #23Feedback

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 enhances the accuracy and reliability of position determination, especially in environments where the mobile receiver unit moves at speeds comparable to the signal speed, by effectively mitigating the effects of Doppler-induced phase changes, resulting in a higher rate of successful decoding of transmitter-unit identifiers.

Implementation Method 1

a plurality of transmitter units, each comprising a transmitter and configured to transmit a respective transmitter-unit identifier, phase-modulated on a carrier signal

Methodology Applied
Scientific EffectPhase modulation: Phase Modulation

Implementation Method 2

analyse the sampled data to determine a Doppler-induced phase deviation within the transmitter-unit-identifier-bearing portion of the sampled data

Methodology Applied
Scientific EffectDoppler effect: Doppler Effect

Data Source

PatentUS11662422B2Position determining system determining doppler-induced code phase deviation
Publication Date: 2023.05.30 SONITOR TECH AS
  • US11662422B2 patent drawing
  • US11662422B2 patent drawing
  • US11662422B2 patent drawing

AI summary

A system is provided for determining the position of a mobile receiver unit (7) in an environment (1). The system comprises a plurality of transmitter units (2, 3, 4, 5) which transmit a respective phase-modulated transmitter-unit identifier, a mobile receiver unit (7), arranged to receive a signal from a transmitter unit (2, 3, 4, 5), and a processing subsystem (205; 9). The processing subsystem (205; 9) is configured to sample received signals to generate sampled data, wherein the identifier spans a transmitter-unit-identifier-bearing portion of the sampled data, obtain template data corresponding to the identifier, analyse the sampled data to determine a Doppler-induced phase deviation, adjust the template or the sampled data to change one or more phase shifts by an amount depending on the determined deviation, cross-correlate the template with the sampled data, determine a time-of-arrival of the signal, decode the identifier from the sampled data, and use the time-of-arrival and the decoded identifier to determine information relating to the position