Terminal Positioning via RF-Ultrasound Time Difference Measurement

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Solution Overview

Problem

Conventional methods for determining the position and distance of objects using time of flight (TOF) and RF signal strength are inefficient, energy-intensive, and lack accuracy due to environmental interference, necessitating multiple base stations for averaging, which increases cost and reduces efficiency.

Innovation Solution

A system utilizing a target base station that transmits ultrasound signals and RF signals to determine the time difference and distance between a terminal and the base station, incorporating a processing engine to synchronize time and calculate distances based on time intervals and thresholds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional TOF method is used with multiple base stations for position determination, then position determination accuracy is improved, but determining time is prolonged and energy consumption increases

Engineering Contradiction:
Improveposition determination accuracyVSAvoiddetermining time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The base station pre-generates and stores multiple candidate position results with their corresponding time values before actual position determination is needed. When a position measurement is required, the system directly retrieves and compares these pre-calculated results based on time stamps, avoiding real-time iterative calculations and significantly reducing determination time while maintaining accuracy through selective choice of the most recent valid result

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Instead of requiring complete interactive signal exchanges with all base stations, the system uses partial measurement data from a subset of base stations to generate candidate positions. The position determination is achieved by selecting from these partial results based on time validity, reducing the total measurement time and energy consumption while still achieving accurate position determination

Inventive Principle:
Principle #16Partial or excessive action

2Device complexity

If conventional RF signal strength method is used for distance measurement, then distance determination is simplified, but measurement accuracy deteriorates due to environmental interference

Engineering Contradiction:
Improvemeasurement method complexityVSAvoiddistance measurement accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The system introduces an intermediary validation mechanism where multiple candidate distance measurements are first generated independently, then filtered and selected based on time consistency and validity criteria. This intermediary selection process eliminates measurements corrupted by environmental interference while preserving the simplicity of RF-based measurement, achieving both simplicity and accuracy

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system implements feedback through time-stamp validation and candidate result comparison. Each distance measurement is tagged with timing information and validated against expected time-of-flight ranges. Invalid results are fed back for rejection, while valid results are selected, creating a self-correcting measurement system that maintains accuracy without increasing operational complexity

Inventive Principle:
Principle #23Feedback

3Reliability

If multiple base stations are used for simultaneous distance measurement to ensure accuracy, then measurement reliability is improved, but system cost increases and efficiency decreases

Engineering Contradiction:
Improvemeasurement reliabilityVSAvoidnumber of base stations
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The base station pre-calculates and stores multiple candidate position results with validity indicators before actual use. This preliminary preparation allows the system to achieve reliable position determination by simply selecting the most recent valid candidate, eliminating the need for multiple base stations to operate simultaneously and reducing overall system complexity while maintaining measurement reliability

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system creates multiple candidate position copies from partial measurement data and selects the valid one based on time stamps. Instead of requiring multiple physical base stations to provide redundant measurements, virtual copies of position data are generated and validated computationally, achieving the same reliability effect with fewer physical components

Inventive Principle:
Principle #26Copying

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 position and distance determination efficiency and accuracy by reducing the need for multiple base stations, minimizing energy consumption, and enhancing precision through synchronized time intervals and threshold-based calculations.

Implementation Method 1

For position determination, a time of fight (TOF) method is commonly employed

Methodology Applied
Scientific EffectTime of flight: Time of Flight

Implementation Method 2

When measuring a distance between the object and the base station, RFID (Radio Frequency Identification), Bluetooth, WIFI, or other RF signals are commonly used

Methodology Applied
Scientific EffectRadio Frequency signal propagation: Electromagnetic Propulsion

Data Source

PatentEP3874773B1Systems and methods for determining position and distance of a terminal
Publication Date: 2025.11.05 ZHEJIANG DAHUA TECH CO LTD
  • EP3874773B1 patent drawingFigure 1
  • EP3874773B1 patent drawingFigure 2
  • EP3874773B1 patent drawingFigure 3

AI summary

Systems and methods for determining a time difference are provided in the present disclosure. The systems includes a first base station configured to receive a first signal transmitted from a terminal and receive a second signal from a second base station. The systems may also include the second base station configured to receive the first signal transmitted from the terminal, and transmit the second signal after receiving the first signal. The systems may further include at least one processor configured to determine a time duration between the first base station receiving the first signal and receiving the second signal and determine the time difference between a first time period of the first signal transmitted from the terminal to the first base station and a second time period of the first signal transmitted from the terminal to the second base station based on a third time period and the time duration.