The analog signals produced by sine encoders are sensitive to noise, but complementary signals (Sin-, Cos-, and Ref-) can provide some immunity to common mode noise. This technique is also used to mitigate noise in incremental encoders, although the analog signals of sine encoders are more susceptible to noise than the digital signals of incremental versions. To mitigate the effects of noise, sine encoders can use a technique referred to as differential signaling, in which two complementary signals are transmitted on each channel. But because the sine encoder’s analog sine waves are continuous - not step functions, like the digital square waves of incremental encoders - the signals themselves can be broken down, or interpolated, into very fine counts to provide extremely high position resolution. For incremental encoders, this requires counting both the rising and falling edges of both square waves per period. For sine encoders, this is done by counting the number of zero crossing of the waveform per period. Signals from a sine encoder (top) versus an incremental encoder (bottom).īoth incremental and sine encoders can use X4 encoding for a fourfold increase in resolution. This is why sine encoders are also referred to as “sine-cosine” encoders. When two sine waves are in quadrature, one is actually a cosine.
![layouteditor sin cos layouteditor sin cos](https://i.ytimg.com/vi/oRFr9DqKCdM/maxresdefault.jpg)
![layouteditor sin cos layouteditor sin cos](https://i.ytimg.com/vi/75xQCU9q5p4/maxresdefault.jpg)
Incremental encoders, on the other hand, provide position and direction information as a pair of quadrature digital square waves. This difference in output waveform allows sine encoders to supply significantly higher resolution than incremental encoders can achieve.
![layouteditor sin cos layouteditor sin cos](https://image.slidesharecdn.com/caccongthucluonggiacdayduchinhxac-130131035317-phpapp01/95/cac-cong-thuc-luong-giac-day-du-chinh-xac-2-638.jpg)
The primary difference between the two is that sine encoders supply position and direction information as 1 Volt peak-to-peak (1 Vpp) analog sine waves - typically termed “A” and “B” - in quadrature. Both devices measure either rotary or linear position changes and direction, and both are available with either optical or magnetic sensing technology. A sine encoder is similar to an incremental encoder in design and function.