Disclosed herein are various systems and methods for transmitting information using modulated magnetic fields. A system comprises a transmitter having a first magnetic field source for transmitting a first modulated magnetic field to a receiver for decoding and a field controller coupled to the first magnetic field source for controlling the first modulated magnetic field. The system can further include a receiver having a first magnetometer configured to detect the first modulated magnetic field produced by the first magnetic field source and a decoder coupled to the first magnetometer for interpreting the first modulated magnetic field.