Views: 8 Author: Site Editor Publish Time: 2019-03-20 Origin: Site
Hardware circuit design
The square wave of 40 kHz transducer fishfinders ultrasonic sensor is programmed by the single chip , output by the P3.6 port, and then the ultrasonic transmitting probe is used to transmit the ultrasonic wave through the amplifying circuit. After the emitting ultrasonic wave is reflected back by the obstacle, the ultrasonic receiving head receives the signal, and sends it to the single-chip microcomputer through the detection amplification, integral shaping and a series of processing of the receiving circuit. The single-chip microcomputer of ultrasonic sensor transducer calculates the distance of the obstacle by using the propagation speed of the sound wave and the time interval from the transmission of the pulse to the reception of the reflected pulse, and is displayed by the single-chip microcomputer. The distance measuring device is composed of an ultrasonic sensor, a single chip microcomputer, a transmitting/receiving circuit and an LED display. The input end of the sensor is connected to the transmitting and receiving circuit, and the output end of the receiving circuit is connected with the single chip microcomputer, and the output end of the single chip is connected with the input end of the display circuit.
Ultrasonic transmitting and receiving circuit design:
Ultrasonic wave is a mechanical wave with a vibration frequency exceeding 20 kHz. It can travel in a straight line, and the direction of propagation is good. The distance of propagation is also far. When external ultrasonic sensor is transmitted in the medium, it encounters an obstacle on the reflecting surface incident on it. A reflected wave will be generated. Due to the above several characteristics of ultrasonic waves, ultrasonic waves are widely used in the measurement of object distance, thickness and the like.Moreover, the measurement of ultrasonic waves is an ideal non-contact ranging method. When the distance measurement is performed, the ultrasonic wave transmitter and receiver is installed on the same horizontal line complete the transmission and reception of the ultrasonic waves, and simultaneously start the timer to count. Firstly, the ultrasonic transmitting probe emits ultrasonic waves in the direction of reversing and simultaneously starts the timer. When the ultrasonic waves are in the air, they will be reflected back when they encounter obstacles. When the receiving probe ultrasonic transducers receive the reflected waves, it will give negative pulses. Go to the microcontroller to stop timing immediately. In this way, the timer can accurately record the time t(s) used for the round-trip propagation between the ultrasonic emission point and the obstacle. Since the ultrasonic wave propagates in the air at a normal temperature of about 340 m/s, the distance between the obstacle and the transmitting probe is: S = 340 × t / 2 = 170 × t.
Ultrasonic transmitting circuit design
The ultrasonic transmitting circuit is composed of an ultrasonic depth transducer and an ultrasonic amplifier. The ultrasonic probe converts the electrical signal into a mechanical wave, and the 40 kHz square wave pulse generated by the single chip needs to be amplified to drive the ultrasonic probe to transmit the ultrasonic wave. Therefore, the emission driving is actually a signal amplifying circuit. The chip performs signal amplification. The ultrasonic receiving circuit is designed to be attenuated during the propagation of ultrasonic waves in the air. If the distance is long, the ultrasonic signal received by the ultrasonic receiving circuit will be weak, so it is necessary to amplify the receiving signal. The multiples are also relatively large.
Ultrasound is a general term for mechanical waves whose frequency exceeds the limit of the human ear's auditory frequency. It can be transmitted in gases, liquids, and solids. The ultrasonic sensor is a sensor that is developed using the characteristics of ultrasonic waves. Ultrasonic sensors can be used in distance detection, flow measurement, metal flaw detection, etc. Therefore, ultrasonic testing is widely used in industrial, national defense, biomedical and other aspects.
A mud level transducer is a device or device that can sense a specified measured object and convert it into a usable signal according to a certain rule. Usually, it is measured as a non-electrical physical quantity, and the output signal is generally a power. It can serve as a extension of the human sensory organs and expand human access to information in the natural and productive fields in all aspects. In the middle of the 20th century, it was found that crystals of certain media (such as quartz crystals, potassium tartrate crystals, etc.) were able to generate higher power ultrasonic waves under the action of high voltage and narrow pulse. According to this, Ultrasonic sensors are capable of emitting, receiving, and analyzing sounds that are invisible to our ears. In the detection aspect, the ultrasonic sensor can perform functions such as ultrasonic ranging and ultrasonic flaw detection, and can be used for detecting submarine wrecks, enemy submarines, and displaying metal internal injuries. These can be applied to various technical fields such as industry, agriculture, light industry and medical care, and are closely related to our lives.
