Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder

A method of dynamically adjusting gain and offset in an optical encoder, the method comprising:

• providing an encoder disk comprising a diffraction grating;
• illuminating the encoder disk with light;
• providing a detector structured to detect light diffracted from the diffraction grating and output a first fine count channel;
• calculating a first target gain and first target offset for the first fine count channel;
• and
• applying a correction to data sampled from the first fine count channel based on the first target gain and first target offset;
• wherein calculating the first target gain and the first target offset includes:
• determining a minimum value and maximum value in a set of data from the first fine count channel;
• calculating a moving average minimum based on the minimum value and minimum values from a plurality of prior sets of data from the first fine count channel;
• calculating a moving average maximum based on the maximum value and maximum values from the plurality of prior sets of data from the first fine count channel;
• calculating the first target gain according to the equation Gcal=(ave_maxA−ave_minA)/2, where Gcal is the first target gain, ave_maxA is the moving average maximum, and ave_minA is the moving average minimum;
• and
• calculating the first target offset according to the equation OFFSETcal=(ave_maxA+ave_minA)/2, where OFFSETcal is the first target offset.