What is Encoder Resolution?

Encoder resolution is a fundamental specification in motion control systems, representing the number of distinct positions or increments an encoder can measure within a single revolution (rotary) or a unit of distance (linear). It determines the smallest movement that a system can detect. High-resolution encoders are vital for applications requiring precision positioning, such as CNC machining, robotics, and medical imaging.

Understanding PPR vs. CPR

Many users often confuse PPR (Pulses Per Revolution) with CPR (Counts Per Revolution). PPR refers to the physical number of lines or pulses on the encoder disk. However, in quadrature encoders, the system can count both the rising and falling edges of two channels (A and B). This leads to different multiplication factors:

• X1 Decoding: Only one edge of channel A is counted.
• X2 Decoding: Rising and falling edges of channel A are counted.
• X4 Decoding: All edges of both channels A and B are counted, providing four times the resolution of the physical PPR.

How to Use This Calculator

To calculate your system's resolution, follow these steps:

1. Enter the PPR (Pulses Per Revolution) stated on your encoder's datasheet.
2. Select the Decoding Type. Most modern industrial controllers use X4 decoding.
3. Optional: Enter the Diameter of your drive wheel or the Pitch of your lead screw in millimeters to calculate linear resolution.
4. Click "Calculate" to see the angular and linear feedback values.

Why is Resolution Important?

Resolution directly impacts the smoothness of motor control and the accuracy of position tracking. However, it is important to distinguish between resolution and accuracy. While resolution is the smallest increment detectable, accuracy is how close the measured position is to the true position. A system can have high resolution but low accuracy due to mechanical errors or mounting issues.