Ultrasonic ranging is mainly used for distance measurement of reversing reminders, construction sites, industrial sites, etc. Although the current ranging range can reach 100 meters, the measurement accuracy can often only reach the order of centimeters.
Due to the advantages of easy directional emission of ultrasonic waves, good directivity, easy control of strength, and no direct contact with the measured object, it is an ideal method for liquid height measurement. In precision liquid level measurement, it is necessary to achieve measurement accuracy of millimeter level, but at present, domestic integrated circuits for ultrasonic distance measurement only have measurement accuracy of centimeter level. By analyzing the causes of ultrasonic ranging errors, increasing the measurement time difference to the microsecond level, and using the LM92 temperature sensor to compensate for the sound wave propagation speed, our designed high-precision ultrasonic rangefinder can achieve millimeter-level measurement accuracy.
The ultrasonic ranging system uses the most modern signal processing technology, and the use of high-performance acoustic wave sensors has obtained reliable and accurate measurement results. While analog signal output and switch signal output, RS-232 and RS-485 interfaces allow users to connect the ultrasonic ranging system to the computer.
Through the device synchronization function, several ultrasonic ranging systems can work simultaneously. In this way, we can use the ultrasonic system array to measure the shape and structure of the object.
Measuring object
Almost all materials that can reflect sound waves can be measured, even those that absorb sound waves (such as fiber cotton or foam rubber, etc.) can be detected, but the maximum detection range will be shortened. Because the detection result is not affected by the shape of the object, the detection object can be solid, liquid or even powder.
Maximum detection distance
The maximum detection distance is determined by the number of ultrasonic waves returned from the measured object, and the number of reflected waves is determined by the size of the object, the surface structure and the angle with the ultrasonic beam. If the conditions are suitable, even very small objects, such as wires with a diameter of only 0.2 mm, can be detected. However, for any object, if the measurement conditions are different from the ideal conditions, it will affect the maximum measurement distance and measurement stability.
Ultrasonic emission angle
Ultrasonic emission angle refers to the attenuation range of sound waves up to 3dB. If the measurement target is very close, this limitation can also be ignored. If the maximum measurement distance is to be reached, the measured object should be located within the emission angle area.
Range
The measuring range is determined by the maximum and minimum measuring distance. If the measuring distance is too short, the conversion time of the ultrasonic pulse cannot be accurately measured.
Measuring frequency
Only when the ultrasonic reflection pulse is received, and after a certain delay, a new ultrasonic pulse will be emitted. Therefore, the measurement frequency of the ultrasonic ranging system with a long measuring distance is low, and the measurement frequency of an ultrasonic ranging system with a short measuring distance is high.
Minimum measuring distance, blind zone
The ultrasonic ranging system uses a single transducer to transmit and receive ultrasonic pulses. Because the transducer cannot perform two operations at the same time, an area is reserved in front of the ultrasonic ranging system, and objects in this area will not be detected. detected.
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