5.1 Sonar Module
Ultrasonic sensors (also known as transceivers when they both send and receive, but more generally called transducers) work on a principle similar to radar or sonar which evaluate attributes of a target by interpreting the echoes from radio or sound waves respectively. Ultrasonic sensors generate high frequency sound waves and evaluate the echo which is received back by the sensor. Sensors calculate the time interval between sending the signal and receiving the echo to determine the distance to an object.
This technology can be used for measuring wind speed and direction (anemometer), tank or channel level, and speed through air or water. For measuring speed or direction a device uses multiple detectors and calculates the speed from the relative distances to particulates in the air or water.
Ultrasonic ranging module HC - SR04 provides 2cm - 400cm non-contact measurement function, the ranging accuracy can reach to 3mm. The modules includes ultrasonic transmitters, receiver and control circuit. The basic principle of work:
- Using IO trigger for at least 10us high level signal,
- The Module automatically sends eight 40 kHz and detect whether there is a pulse signal back.
- If the signal back, through high level , time of high output IO duration is
- the time from sending ultrasonic to returning.
- Test distance = (high level time×velocity of sound (340M/S) / 2
5.1.1 Electric Parameter
- Working Voltage DC-- 5 V
- Working Current --15mA
- Working Frequency-- 40Hz
- Max Range --4m
- Min Range --2cm
- Measuring Angle --15 degree
- Trigger Input Signal-- 10uS TTL pulse
- Echo Output Signal-- Input TTL lever signal and
5.1.2 Component Overview
- Resolution of 1 inch
- 20Hz reading rate
- 42kHz Ultrasonic sensor measures distance to objects
- RoHS Compliant
- Read from all 3 sensor outputs: Analog Voltage, Serial, Pulse Width
- Virtually no sensor dead zone, objects closer than 6 inches range as 6 inches
- Maximum Range of 254 inches (645 cm)
- Operates from 2.5-5.5V
- Low 2.0mA average current requirement
- Small, lightweight module
- Designed for easy integration into your project or product
- Our most popular indoor ultrasonic rangefinder
- Our low cost, all-around sensor that is excellent for many projects
Figure 24: Working Principle of Sonar
Figure 25: Ultra Sonic Sensor HC SR04