Question

What is quadrature and 4X (4 times) quadrature encoding?

Answer

Quadrature is a description of the 90 degrees out of phase between channel A and B.

The rising edge to rising edge (referred as the Cycle) on channel A or B indicates that one set of bars or slits (on the internal encoder disk) have passed by the optical sensor. The quadrature state of channels A and B create four unique logic states. These four unique logic states are decoded to determine distance traveled and rotation direction.

4x counting usually refers to a counter which may be configured to recognize each quadrature state as a separate count. So with this in mind 250 ppr encoder would yield 1000 individual states or edges. A 250 ppr encoder will have 250 ppr for channel A and 250 ppr for channel B.

PPR, or pulses per revolution, is another term for "line count". A line on an encoder is the physical slit on the encoder's disc that allows an optical sensor to trigger from low to high.

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FAQ Subcategory: None

This item was last updated on 2017-12-01
Document ID: 822

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