This disclosure relates generally to systems and methods for localizing a device relative to an instrument. A sensor of the instrument can be monitored for a change in signaling during a first transition of the device relative to the instrument. The sensor can further be monitored for another change in signaling provided by the sensor of the instrument in response to a second transition of the device relative to the instrument. A transition distance difference can be determined between the first transition and the second transition. A location of the device relative to the instrument can be determined based on a location of the instrument and the transition difference distance.
