Abstract: Electromagnetic tracking systems and methods for correcting hemispherical ambiguity are described. The system may include a single transmitter having three coils arranged in an industry-standard coil arrangement (ISCA). The tracking system may also contain a receiver having three coils arranged in an ISCA configuration, as well as a fourth coil having a different orientation then any of the other three coils of the receiver. The fourth coil may be used to determine the correct solution to the hemispherical ambiguity that can occur when tracking using two three-coil assemblies. Other embodiments are described.