Patent ID: 7796943

Claim:
A communications system comprising: a plurality of sub-surface portable transceivers each including: a digital data source, a modulator coupled to the digital data source, a power amplifier coupled to the modulator and a loop antenna inductively coupled to the power amplifier; and, a base transceiver including: an electrically insulated ferrite core antenna for receiving magnetic signals, an electric di-pole antenna for receiving ambient noise, a noise canceller coupled to the insulated ferrite core antenna and electric dipole antenna and responsive to the electric-dipole antenna to filter noise from signals received via the insulated ferrite core antenna, wherein the noise canceller is configured to determine the electric component of the received ambient noise from the electric-dipole antenna representative of the magnetic component of the electromagnetic noise received from the insulated ferrite core antenna and cancel the noise from the signal received by the insulated ferrite core antenna, and a demodulator coupled to the noise canceller and a decoder coupled to the demodulator.