Abstract: An electromagnetic tracking system includes an adjustable source of electricity, a magneto-resistive (MR) sensor coupled to the adjustable source of electricity and configured to couple to a device for tracking a position of the device, and a controller coupled to the adjustable source of electricity and the MR sensor to adjust an amount of electricity provided to the MR sensor by the adjustable source of electricity. The electromagnetic tracking system is configured to track MR sensors and coil-based sensors simultaneously using one or more input channels on the controller.