There are two azimuth encoders. ... The first plots show the encoder difference versus azimuth (.ps) ( .pdf) : . Top plot: The encoder difference (in encoder units) versus azimuth angle. ... Bottom plot: the same plot with the vertical scale in degrees rather than encoder counts (there are about 6935 encoder counts in a degree). There is a positive going bump in the encoder difference at az=160 degrees and a corresponding negative going bump 180 degrees away. ...