Abstract: Embodiments described herein relate to a magnetic positioning system and method that allows the position of a receiver to be determined in environments containing conducting material such as concrete. A number of transmitters create modulated magnetic fields which are distorted as they propagate through the conducting materials. A finite difference time domain (FDTD) simulation of the environment is used to generate an accurate model of the fields within the environment. A receiver is used to measure the field strength of each transmitter. The receiver position is determined by evaluating the misfit between the received fields and the values in the FDTD model.

Abstract: There is provided a Through the Earth Emergency Radio (TER) method and apparatus for creating a communications link that can penetrate the earth or other thick, solid barriers. The communication link is used to connect mobile radios or other conventional wireless devices located below ground and on the surface. The through the earth communication link uses a multi-carrier modulation method that minimizes the impact of AC power line noise by locating each carrier between the harmonic frequencies of the AC power line noise.

Abstract: There is provided a Through the Earth Emergency Radio (TER) method and apparatus for creating a communications link that can penetrate the earth or other thick, solid barriers. The communication link is used to connect mobile radios or other conventional wireless devices located below ground and on the surface. The through the earth communication link uses a multi-carrier modulation method that minimizes the impact of AC power line noise by locating each carrier between the harmonic frequencies of the AC power line noise.

Abstract: The present invention provides an apparatus for portable through-the-earth radio (PTTER). The PTTER provides bidirectional voice and/or data communication between a surface radio and a portable radio. The PTTER also provides a transmit antenna having a primary loop and one or more secondary loops configured to increase the magnetic field produced by the primary loop. The PTTER also provides a transportable loop antenna that can be wound around a form for transportation. The PTTER also provides a receive antenna optimal for implementing noise cancellation. The PTTER also provides a navigation subsystem for detecting distance and direction to increase the effective range of the PTTER. The PTTER can be implemented in a backpack form factor.

Abstract: A system, method and apparatus for controlling buried devices by means of a very low frequency (VLF) modulated magnetic field capable of providing through-the-earth (TTE) communications. The system comprises a plurality of VLF transmission loop antennas positioned to cover a desired coverage area and configured to transmit a magneto-inductive signal to a desired operating depth. One or more VLF receivers are configured to receive one or more magneto-inductive signals from the one or more VLF transmission antennas. The VLF receivers are operatively connected to the buried devices, and configured to output a control signal thereto in response to the magneto-inductive signals. The plurality of VLF transmission loop antennas may be square or rectangular antennas positioned in an array to cover the desired coverage area, the VLF transmission loop antennas sized and sufficiently powered to transmit the magneto-inductive signal to the desired operating depth.

Abstract: There is provided a Very Low Frequency (VLF) transmit antenna system, method, and apparatus for creating a magnetic field at low frequencies suitable for communications through the earth or other thick, solid barriers. At least two loop antennas are arranged such that a magnetic field of each one of the at least two loop antennas passes through each remaining one of the at least two loop antennas, thereby closely coupling the at least two loop antennas. A full bridge Pulse Width Modulated transmitter is directly connected to each loop antenna for driving the latter. When a loop of a given loop antenna is broken and its magnetic field collapses, the transmitters connected to the remaining loop antennas increase the current in the remaining loops to maintain a constant magnetic field.

Abstract: There is provided a Very Low Frequency (VLF) transmit antenna system, method, and apparatus for creating a magnetic field at low frequencies suitable for communications through the earth or other thick, solid barriers. At least two loop antennas are arranged such that a magnetic field of each one of the at least two loop antennas passes through each remaining one of the at least two loop antennas, thereby closely coupling the at least two loop antennas. A full bridge Pulse Width Modulated transmitter is directly connected to each loop antenna for driving the latter. When a loop of a given loop antenna is broken and its magnetic field collapses, the transmitters connected to the remaining loop antennas increase the current in the remaining loops to maintain a constant magnetic field.