altGurley Precision Instruments (Troy, NY) offers the R158 rotary incremental encoder that generates quadrature square waves at up to 1 million counts per revolution. It has an optional temperature range from -40 to 100 °C, and an optional radial/axial load of 60N/40N. A 1/4-cycle gated, once-per-rev index signal or full-cycle sinusoid index is standard. Output options include an RS-422 differential line driver, current-source analog waveforms, or voltage-source analog waveforms.