Through-the-earth emergency radio system
AssigneeVital Alert Communication Inc.
InventorsMichael James Roper, Peter Kwasniok, Vladimir Puzakov
Life of this patent
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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.
Claims27
A method of providing a Through-the-Earth (TTE) communication link, the method comprising:
- determining a fundamental frequency of an alternating current (AC) power line noise;
- inputting a data stream representing a text message, digitally coded voice or other data;
- performing an inverse Fourier transform on a block of N data and overhead symbols to create a single Inter-Harmonic Modulation (IHM) waveform containing N separate modulated carriers, where a frequency Mth carrier Fm=(M+0.5)*Fac, where M is a positive integer with a range of 1 to N and Fac is a fundamental AC frequency, wherein N is a positive integer;
- converting the waveform to at least one pulse-width-modulation (PWM) signal;
- controlling an output from a PWM transmitter connected to one or more loop transmit antennas using the at least one PWM signal;
- and
- transmitting a signal comprising the N separate modulated carriers to a receiver.
A method of providing a Through-the-Earth (TTE) communication link, the method comprising:
- determining a fundamental frequency of an alternating current (AC) power line noise;
- inputting a data stream representing a text message, digitally coded voice or other data;
- performing an inverse Fourier transform on a block of N data and overhead symbols to create a single Inter-Harmonic Modulation (IHM) waveform containing N separate modulated carriers, where a frequency Mth carrier Fm=(M+0.5)*Fac, where M is a positive integer with a range of 1 to N and Fac is a fundamental AC frequency;
- detecting an IHM magnetic field at a receiver using at least one loop antenna and amplifying and filtering a received signal to remove out of band interference;
- and
- transmitting the received signal.
A method of providing a Through-the-Earth (TTE) communication link, the method comprising:
- determining a fundamental frequency of an alternating current (AC) power line noise;
- inputting a data stream representing a text message, digitally coded voice or other data;
- performing an inverse Fourier transform on a block of N data and overhead symbols to create a single Inter-Harmonic Modulation (IHM) waveform containing N separate modulated carriers, where a frequency Mth carrier Fm=(M+0.5)*Fac, where M is a positive integer with a range of 1 to N and Fac is a fundamental AC frequency;
- combining signals from two or more loop antennas to maximize a signal to noise ratio at a receiver;
- and
- transmitting the combined signals.
Dependencies are inferred from the claim text.