This function is actually done external to the encoder by a counter or controller. Another method to increase resolution is interpolation or internal electronic subdivision of the encoder s base resolution. Typical multiplication factors obtained by interpolation are in the 2-20X range. Quadrature and interpolative methods can also be combined to further multiply the basic encoder resolution, but practical limits must be observed. An extremely high output of pulses could overwhelm the bandwidth of the control system.
Electronic interfaces are important if the encoder is to work properly with external controls.
Two common types of output interfaces open-collector and differential line driver are discussed in the main article. In addition, the robustness of the output signals must be assured through electrical isolation. Auxiliary products exist for this purpose. For an example of a new optical isolator module specifically for incremental encoders, see the July 2000 issue s product section . Encoder varieties, features, options Rotary encoders are made in a variety of styles.