The Ultrasonic Sensor seems to be malfunctioning due to noise. What can be done to resolve it?Last Updated: September 16, 2018
Different countermeasures should be used depending on factors such as the path of noise entry, the frequency component, and the peak value. Typical examples are given below.
|Type of noise||Noise intrusion path and countermeasure|
|Before countermeasure||After countermeasure|
|Common mode noise
(Common noise applied between the mounting board and the +V and 0-V lines, respectively.)
|Noise enters from the noise source through the frame (metal).
||(1) Ground the inverter motor (to 100 Ω or less)
(2) Ground the noise source and the power supply (0-V side) through a capacitor (film capacitor, 0.22 μF, 630 V).
(3) Insert an insulator (plastic, rubber, etc.) between the Sensor and the mounting plate (metal).
(Ingress of high-frequency electromagnetic waves directly into Sensor, from power line, etc.)
|Noise propagates through the air from the noise source and directly enters the Sensor.
||Insert a shield (copper) plate between the Sensor and the noise source e.g., a switching power supply).
Separate the noise source and the Sensor to a distance where noise does not affect operation.
|Power line noise
(Ingress of electromagnetic induction from high-voltage wires and switching noise from the switching power supply)
|Noise enters from the power line.
||Insert a capacitor (e.g., a film capacitor), noise filter (e.g., ferrite core or insulated transformer), or varistor in the power line.