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The principle of ultrasonic ranging

Views: 0     Author: Site Editor     Publish Time: 2023-03-04      Origin: Site

The sound wave frequency that human ears can hear is 20HZ~20KHz. When the frequency is higher than 20KHz, the human ear cannot hear it. Therefore, we call the sound wave with a frequency higher than 20KHz "ultrasonic wave".

Ultrasound has a strong directivity and travels a long distance in the air. It will be reflected when encountering obstacles. Therefore, people often use ultrasonic wave for distance measurement.

The most commonly method of ultrasonic distance measurement is the echo detection method. The ultrasonic transmitter emits ultrasonic waves in a certain direction. At the same time as the emission, the timer starts timing. The ultrasonic receiver stops timing immediately when it receives the reflected ultrasonic waves. The propagation speed of ultrasonic waves in the air is 340m/s. According to the time recorded by the timer, the distance from the emission point to the obstacle surface can be calculated.

The main performance indicators of ultrasonic sensors include:

(1) Working frequency. The working frequency is the resonant frequency of the piezoelectric chip. When the frequency of the AC voltage applied to its two ends is equal to the resonant frequency of the chip, the output energy is the largest and the sensitivity is also the highest.

(2) Working temperature. Since the distance point of the piezoelectric material is generally relatively high, especially the ultrasonic probe for diagnosis uses a small power, so the working temperature is relatively low, and it can work for a long time without failure. The temperature of the ultrasonic probe used in medical treatment is relatively high, and a separate cooling device is required.

(3) Sensitivity. It mainly depends on the manufacturing chip itself, the electromechanical coupling coefficient is large, and the sensitivity is high.

With the rapid development of science and technology, it is not difficult for us to find the application of ultrasonic sensors. For example, the reversing radar uses ultrasonic waves to measure distance, so as to realize the function of parking and obstacle avoidance. Engineer from Manorshi recommend three ultrasonic sensors MSW-A1458H09TR, MSW-A1440H09TR, and MSW-A1840H12TR. They have good stability, high sensitivity and high precision, and have been It was well received by the market.