A quadrature encoder is an incremental position sensor that outputs two square-wave signals (Channel A and Channel B) offset by
90 electrical degrees (a quarter cycle) out of phase.
How It Works
• Two Offset Channels: As a shaft or linear strip moves, Channel A and Channel B generate pulses as light passes through slots (optical), or via magnetic or capacitive sensing.
• Direction Detection: The phase lead/lag relationship determines direction. If Channel A changes state before Channel B, the system is moving in one direction (e.g., clockwise); if Channel B changes first, it is moving in the reverse direction.
• Speed and Position: The frequency of the pulses measures velocity, while a counter tracks total relative movement. An optional Index (Z) channel can provide a single reference pulse per revolution to reset or verify home position.
Resolution Multiplication (1x, 2x, 4x)
By reading the signal transitions (rising and falling edges) of both channels, a controller can multiply the base resolution:
• 1x (Single): Counts only one edge per cycle.
• 2x (Double): Counts both rising and falling edges of Channel A.
• 4x (Quadruple): Counts rising and falling edges of both Channel A and Channel B, multiplying the Pulses Per Revolution (PPR) by four.
Common Applications
• Motor Control: Tracking speed, commutation, and shaft positioning in robotics and industrial automation.
• User Interfaces: Rotary dials, volume knobs, and CNC jog wheels.
• Conveyors & Positioning: Measuring linear or rotational distance accurately.
Learn more about output behavior and decoding methods in the Dynapar Quadrature Encoders Guide or explore the fundamentals on Five Flute's Quadrature Encoder Overview.
Are you trying to interface a quadrature encoder with a microcontroller (like an Arduino or STM32), or looking for help with a specific resolution or part number?