Method and apparatus for the generation and transmission of signals for echo location and other signaling purposes, particularly in geophysical exploration
AssigneeHydroacoustics Inc.
InventorsDavid E. Nelson, David M. Berg
Life of this patent
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Abstract
A transmission which requires only a single source to transmit is generated in accordance with a code which is binary (a pulse train having two levels which produces a specific harmonic line spectrum). The pulses are generated by pulse time modulation of the position and duration of pulses in a sweep which extends to the upper end of the spectrum.
Claims22
The method, for echo location, seismic exploration and seismic signalling, in which transmissions from a single source of seismic energy are in the form of pulses which change in amplitude from a first to a second level and which sweep in frequency, which transmissions have a spectrum extending over a frequency range greater than that of said sweep, which method comprises the steps of generating a carrier train of pulses having spectral components which sweep in frequency over a range ending at a frequency at least as high as the highest frequency in said spectrum, and pulse time modulating said carrier pulses to shape said spectrum.
The method of generating a pulse code transmission which comprises generating a train of pulses which provide a harmonic line spectrum with N harmonics and applying simultaneous pulse width and pulse position modulation to said pulses to control the amplitude and phase of said harmonics.
Dependencies are inferred from the claim text.