Method and apparatus for delay analysis of energy transmitted through a medium
AssigneeCalifornia Institute of Technology
InventorRichard C. Heyser
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Abstract
A method and apparatus is disclosed for determining the manner by which an initial injection of wave energy is modified by a medium under test using a time delay spectrometer (TDS) and a fast Fourier transform (FFT). A switch allows either the time delay spectrum or an energy-time curve to be displayed. A differentiator at the input of the FFT corrects for inverse square loss of energy through the medium, i.e., compensates for spherical expansion of energy. Different arrangements of the TDS adapt the system to a medium having variable time delay, or adapt the system for measurement of harmonic distortion through the medium.
Claims24
A method for determining the manner by which wave energy is modified by a medium comprising the steps of
- transmitting through said medium wave energy which is swept in frequency over a predetermined range of interest,
- detecting said wave energy received through said medium at a remote point to obtain an output electrical signal which varies in frequency in a manner corresponding to the sweep of said wave energy, but delayed in time by an amount corresponding to the time delay of transmission through said medium, where said time delay may be zero,
- providing a generated signal swept in frequency in a manner corresponding to the sweep of said wave energy, but offset in time by an amount corresponding to the time delay of transmission of a particular path through said medium, where said particular path through said medium may be a direct, zero-time-delay path, and mixing said swept signal with said output electrical signal developed from energy waves detected, thereby to produce an IF signal for analysis in the frequency domain, and
- performing a further operation on the IF signal over the entire frequency spectrum of interest to produce a signal for display of amplitude or phase in the time domain.
Apparatus for determining the manner by which wave energy is modified by a medium comprising
- means for transmitting through said medium wave energy which is swept in frequency over a predetermined range of interest,
- means for detecting said wave energy received through said medium at a remote point to obtain an electrical signal which varies in frequency in a manner corresponding to the sweep of said wave energy, but delayed in time by an amount corresponding to the time delay of transmission through said medium, where said time delay may be zero,
- means for providing a generated signal swept in frequency in a manner corresponding to the sweep of said wave energy, but offset in time by an amount corresponding to the time delay of transmission of a particular path through said medium, where said particular path through said medium may be a direct zero time delay path, and mixing said swept signal with said electrical signal developed from energy waves detected, thereby to produce an IF signal useful for analysis in the frequency domain, and
- means for performing a further operation on the IF signal over the entire frequency spectrum of interest to produce a signal for display of amplitude or phase in the time domain.
Dependencies are inferred from the claim text.