A number of ultrasonic articles are already published here ... The acoustic emission frequency is 40kHz, and measuring angle is 45-75 degree. The module (sensor/control electronics) has the same four ...

The HC-SR04 ultrasonic range sensor is a pretty cool pre-wired module ... module is in the 2- to 400-cm range with a measuring angle of 15°. The ultrasonic distance measurement principle of the module ...