How To Measure Incremental Encoder Signals

A digital encoder is a device that senses mechanical motion and converts it into electronic pulses or digital codes.  You may not see what it actually looks like, but certainly you have encountered equipment and appliances that have such mechanisms installed.  A good example perhaps is the dial-type radio tuner that has a digital display.  There are two types of digital encoders, the absolute encoder and the incremental encoder.  However, what will be discussed here is how to measure the signals of the latter only. Because it uses only two sensors, this type of digital encoder is less expensive than the absolute ones.  Therefore, it is also more commonly found in the electronics market.

As a shaft encoder, this device allows any shift in position to be registered and converted into digital pulses. When the shaft turns, pulse trains are created in the two sensor channels. The relationship of the phase of the two signals presents the direction of the shaft’s rotation.  Therefore, if you must measure the signals of the relative encoder, which is how it is also called, you may only have to observe the direction and speed of the rotation.  The following are the ways an accurate measurement can be done.

  1. Instead of relying on just one interval of the shaft or mechanical motion, sample as many intervals as possible.  With more samples in hand, you should be able to find out the average measurement of the signals it produces by taking into account the number of pulses in every interval.
  2. You may also get the measurement by gauging the time difference in between pulse intervals.  However, this will require you to apply an external hardware first.  This will be used to produce interruptions in the normal encoder process.  With this connected, you can then begin to measure the time differences. 
  3. Rotary encoders testing instruments are available in many electronic shops.  You can buy one of these and use it to measure the signals produced by your encoder.  This is much simpler to do because all that it requires you to do is to connect it to the terminals of your encoder.  It has its own LCD display on which you view the measurement readings.
  4. Another method of measuring its signal is to take note of the position.  As a position encoder, the shifts of its position are recorded and translated into different frequencies of signals.  However, this may need another external hardware to provide you with accurate readings.

Among all these suggested steps, it is reading the pulse per revolution rate that is being constantly being considered.  The PPR has a corresponding signal strength and frequency.  Therefore, by considering this, you can have the measurement of the signals your incremental encoder produces. If it is under another sub-type such as a linear encoder, the same principles and processes may also be implemented except for that part where the position is being made the basis for the measurement.


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