Distortion suppression in electromagnetic tracking systems

An electromagnetic tracking system, comprising:

• a plurality of field transmitters;
• at least one receiver;
• a field controller operatively coupled to the plurality of field transmitters, and configured to cause a field transmitter of the plurality of field transmitters to transmit a set of electromagnetic signals, each electromagnetic signal of the set of electromagnetic signals having a frequency that is different than a frequency associated with each of the other electromagnetic signals of the set of electromagnetic signals, wherein each electromagnetic signal is a sinusoidal function comprising an amplitude and a frequency;
• and
• a signal processor configured to:
• receive, from the at least one receiver, a received field signal corresponding to each transmitted set of electromagnetic signals, wherein each received field signal comprises an undistorted field component and a distortion component;
• wherein the amplitudes and frequencies of the sinusoidal functions comprising each transmitted set of electromagnetic signals are selected such that the distortion component of each received field signal comprises a residual error arising from terms of at least a specified order in frequency;
• extract, from each received field signal, a plurality of field components corresponding to at least one of the plurality of field transmitters;
• and
• determine, based on the plurality of field components, location information associated with the medical device.

A method for tracking a catheter using an electromagnetic tracking system having a plurality of field transmitters and at least one receiver, the method comprising:

• transmitting, using a first field transmitter of the plurality of field transmitters, a first set of electromagnetic signals, each electromagnetic signal of the first set of electromagnetic signals having a frequency that is different than a frequency associated with each of the other electromagnetic signals of the first set of electromagnetic signals, wherein each electromagnetic signal of the first set of electromagnetic signals is a sinusoid corresponding to a first sum of sinusoidal functions, each of the sinusoidal functions of the first sum comprising an amplitude and a frequency;
• transmitting, using a second field transmitter of the plurality of field transmitters, a second set of electromagnetic signals, each electromagnetic signal of the second set of electromagnetic signals having a frequency that is different than a frequency associated with each of the other electromagnetic signals of the second set of electromagnetic signals, wherein the second set of electromagnetic signals corresponds to a second sum of sinusoidal functions, each of the sinusoidal functions of the second sum comprising an amplitude and a frequency;
• receiving, from the at least one receiver, a received field signal corresponding to the first and second sets of electromagnetic signals, wherein the received field signal comprises an undistorted field component and a distortion component;
• wherein the amplitudes and frequencies of the sinusoidal functions comprising the transmitted sets of electromagnetic signals are selected such that the distortion component of the received field signal comprises a residual error arising from terms of at least a specified order in frequency;
• deconvolving the received electromagnetic signal to extract a first field component and a second field component, the first and second field components corresponding, respectively, to the first and second field transmitters;
• and
• determining, based on the first and second field components, at least one of a position of the at least one receiver and a location of the at least one receiver.