Main technical parameters of ultrasonic transducer

I. Ultrasonic Transducer

The ultrasonic transducer, also known as an ultrasonic converter, is an electroacoustic transducer that uses imported film chips and is suitable for distance measurement and level detection in air media. Due to the use of multilayer impedance matching, backing, and piezoelectric element with small frequency error in the transducer's focusing element, it has good time stability and temperature stability, no depolarization phenomenon, good passband characteristics, and the chip and acoustic transducer are unified in calculating the fundamental resonant frequency. The backing material formula has good vibration characteristics, giving the transducer a large bandwidth, high transmission and reception sensitivity, and a small pulse-echo duration, resulting in the maximum equivalent electromechanical coupling coefficient.

II. Main Technical Parameters of the Transducer

◇ Center Resonant Frequency: 40kHz±2kHz

◇ Static Capacitance: 3300P±300P

◇ Resonant Impedance: 120Ω±20Ω

◇ Bandwidth (-3dB): Δf-3dB≥2kHz

◇ Operating Voltage: 300～500VP-P

◇ Limit Voltage ≤1000VP-P

◇ Transmission Beam Angle: 60 degrees

◇ Operating Temperature: -40～+80℃

◇ Protection Level: IP65

III. Module Performance

1: Operating Voltage: DC5V;

2: Quiescent Current: Less than 2mA;

3: Output Signal: Level signal, high level 5V, low level 0V;

5: Sensing Angle: 60 degrees;

6: Detection Distance: 0.01 – 5.00 meters;

   7: High Precision: Up to 1mm

IV. Pin Connection Description

  (Pin definition observation direction: probe down, pins inward, from left to right)

1, GND and VCC are the power supply pins, and the module is powered by +5V;

2, The IN pin is the signal input pin of the module. The user inputs the control signal from this pin to drive the module to work. The control signal can be a square wave signal output from the microcontroller's IO port;

3, The OUT pin is the return signal output pin after the module receives the ultrasonic wave. This pin outputs a high level after the module is powered on. When the user sends a drive signal from the input pin, if the module receives the return ultrasonic wave, the OUT pin will be pulled low, outputting a low level;

4, The reserved pin is used for function expansion;

V. Working Principle

   The user inputs a 40KH square wave signal from the IN pin, that is, the user continuously sends high and low levels from the microcontroller's IO port to generate a square wave. The number of square waves is generally around 10. After sending, the user starts the timer and starts timing. At this time, the ultrasonic transmitting head starts to emit ultrasonic waves. When the emitted ultrasonic waves are reflected back by the obstacles in front, the reflected ultrasonic waves are received by the receiving probe. At this time, the OUT pin of the module will generate a transition from high level to low level. At this time, the user needs to stop timing. The user calculates the measured distance based on the timing time and the following formula:

Calculate the measured distance:

Measured distance = (time * speed of sound (340M/S)) / 2   `nbsp_tag

VI. Precautions

   1. The ultrasonic transmitting head emits a 60-degree ultrasonic beam outward, so there should be no other obstacles between the probe and the object being measured.

   2. The ultrasonic module measures the vertical distance between the object being measured and the probe. When measuring, keep the probe facing the object being measured.

   3. Ultrasonic measurement will be affected by environmental wind speed, temperature, etc.

VII. Possible Problems

   1. Due to the influence of the unevenness of the object being measured, the reflection angle, the environmental wind speed and temperature, and multiple reflections, the measurement data error may increase.

   2. Due to the inherent characteristics of the ultrasonic measurement blind zone, when the measurement position changes and the received data remains unchanged during close-range measurement, it means that the measurement blind zone has been entered.

   3. When the module measures distant objects, if no measurement data is returned, it may be beyond the measurement range or the measurement angle is incorrect. The measurement angle can be adjusted appropriately.

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