The JSN-SR04T Waterproof Ultrasonic Range Finder uses ultrasonic waves to detect the presence of and measure the distance to objects in front of it.  The V3.0 is the latest version of the module with additional measurement modes available over earlier versions.

PACKAGE INCLUDES:

• JSN-SR04T V3.0 Waterproof Ultrasonic Range Finder
• JSN-SR04T V3.0 Electronic Control Module

KEY FEATURES OF JSN-SR04T V3.0 WATERPROOF ULTRASONIC RANGE FINDER:

• 23 to 600 cm (9″ to 20 feet) detection range
• 40 kHz operation
• ±37.5 degree field of view
• 2.5 meter (8′) transducer cable
• 3.3 & 5V operation and logic compatible (see notes below about 3.3V operation)

The JSN-SR04T is very similar to the standard ultrasonic modules like the HC-SR04 with the exception that it uses a single waterproof transducer instead of two and it also provides more methods for interfacing to a microcontroller.

Because the transducer is waterproof, it can be used for indoor or outdoor sensing such as providing a car parking sensor, security alarm, obstacle avoidance or monitoring the water level is water storage tanks,

Like any ultrasonic sensor that depends on sound waves bounding off an object to detect it, it is able to detect hard objects quite well including the surface of calm water, but detection of soft fabrics or other sound absorbing material is less consistent and empirical testing may be required to determine suitability for a particular application.

Because these modules use sound waves for detection, they are not sensitive to light sources or optically reflective surfaces like IR can be.  In addition, because sound travels relatively slowly it is possible to measure the time that it takes for the sound to travel to the object and be echo’d back and therefore the distance to the object can be calculated with a fair amount of accuracy which can be quite handy.

The detection and measurement range is from 23 cm up to 600 cm which is about 9″ to 20 feet with a stated accuracy of 1cm.  The ultrasonic sound is pulsed at 40 kHz and is not audible to the human ear.

If an echo is not returned (no object detected), the module will timeout after a fixed delay.  This is required to prevent the module from hanging if there is no return echo.