White Paper: Mechanical & Fluid Systems

Noise and Signal Distortion Considerations for Encoders in Motion Control Applications


An encoder is an electro-mechanical transducer that converts mechanical rotary motion into digital signals for the control of machinery. Encoders are used widely in motion control applications – everything from conveyor belts to observatory mirrors to windmills, and many, many more. The encoder produces a square wave signal as the shaft rotates. Speed, position, servo feedback, etc. can be determined through proper processing of this signal.

As the electrical signal leaves the encoder, it is “clean” of electrical noise. However, by the time the signal reaches its intended counter, PLC, etc., it may be degraded and may not be “clean” enough for the system to work properly. It is vital to ensure clarity of signal from your motion sensing devices to your controller because excessive electrical noise degrading the signal can lead to miscounts.

Electrical noise generated by AC power, electric motors, fluorescent lighting, relays, and many other sources can cause a plethora of problems in electrical systems. There are several options and installation considerations to take into account to ensure that your encoder’s signal is clean and electrical noise is mitigated. Encoders’ cables are an important consideration, with cable length, termination, and connections all playing a part in keeping a signal “clean.” There are also additional methods to reduce noise. This white paper will focus on strategies and ways to reduce noise and signal distortions to ensure the signal from your encoder remains clean and uncorrupted.

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