Double threshold ultrasonic distance measurement technique and its application.

Area of Science:

• Instrumentation and Measurement
• Acoustics and Ultrasonics
• Signal Processing

Background:

• Accurate time-of-flight (TOF) measurement is crucial for ultrasonic applications.
• Existing TOF techniques face challenges with signal noise and real-time processing.
• Developing cost-effective and precise ultrasonic measurement systems is an ongoing need.

Purpose of the Study:

• To adapt and validate a double threshold method for accurate ultrasonic time-of-flight (TOF) measurement.
• To develop a robust system for ultrasonic distance and gas flow measurements.
• To demonstrate the method's effectiveness in noise suppression and temperature/pressure compensation.

Main Methods:

• Implementation of a double threshold method using hardware circuits and the TDC-GP21 timing chip.
• Development of high-precision temperature (10 mK) and pressure (0.01% accuracy) measurement modules.
• Experimental validation of the system for both ultrasonic distance and gas flow measurements.

Main Results:

• Achieved a time resolution of approximately 22 ps with effective noise suppression.
• Demonstrated low cost and ease of implementation for the double threshold method.
• Distance measurement yielded maximum absolute deviation of 0.69 mm (0.28% relative error) from 100-600 mm.
• Gas flow measurement showed maximum absolute deviation of 1.16% and 0.65% repeatability for 50-700 m³/h flow.

Conclusions:

• The double threshold method is a viable, low-cost solution for accurate ultrasonic TOF measurement.
• The developed system reliably measures distance and gas flow with high precision.
• The system's hardware requires no adjustment for use as a two-path ultrasonic gas flowmeter.