Patent ID: 8725240

Claim:
A method comprising: causing current to flow between each of three or more sets of current-injecting electrodes on a first catheter inserted into an organ in a patient's body, the organ having a periphery; in response to current flow caused by each set of current injecting electrodes, measuring electric signals at each of multiple measuring electrodes on the first catheter and measuring an electrical signal at each of one or more measuring electrodes located on one or more additional catheters inserted into the organ in the patient's body; and determining the position of each of one or more of the measuring electrodes on the one or more additional catheters relative to the first catheter based on the measured signals for the measuring electrodes on the first catheter and the one or more additional catheters, the determination associating each measured signal with a homogeneous component that depends on the relative position of each signal measuring electrode with respect to each set of current injecting electrodes and an inhomogeneous component associated with the periphery of the organ.