Radio frequency spectroscopy apparatus and method using multiple frequency waveforms
First Claim
1. In an apparatus enabling a determination of the concentration of a chemical in a test sample including electromagnetic waveform generation means for generating a electromagnetic signal, probe means coupled to said generation means for transmission of said signal as an input signal into said test sample and formed for receipt of said signal after propagation through at least a portion of said test sample as an output signal, and detection means coupled for receipt of said input signal and said output signal and responsive thereto to quantify a change between said input signal and said output signal, the improvement in said apparatus comprising:
- said generation means generating a periodic electromagnetic signal having plurality of simultaneously present frequencies to produce a periodic waveform of known shape; and
said detection means being responsive to said input signal and said output signal to quantify a change in shape between said input signal and said output signal.
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Accused Products
Abstract
An apparatus and method for measuring the concentration of a chemical substance in a test sample based on a technique of waveform distortion analysis is disclosed. The apparatus includes a waveform generator that generates a periodic electromagnetic signal having a plurality of frequencies simultaneously present. Preferably the signal has a fundamental frequency and simultaneously present harmonic frequencies which shape the waveform. The shaped periodic signal is transmitted through the test sample by a probe assembly which also receives the transmitted signal from the test sample. Propagation of the shaped signal through the test sample results in a change in the waveform shape or distortion by the chemical, and a detector circuit is provided that quantifies the change in shape of the signal to determine the concentration of the chemical in the test sample. The harmonics producing the waveform shape and the fundamental frequency of the signal are both selected so that the change in shape of the signal is particularly responsive to the presence of a selected chemical substance. The magnitude of the distortion or change in shape of the signal can be directly correlated to the concentration of the selected chemical substance.
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Citations
17 Claims
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1. In an apparatus enabling a determination of the concentration of a chemical in a test sample including electromagnetic waveform generation means for generating a electromagnetic signal, probe means coupled to said generation means for transmission of said signal as an input signal into said test sample and formed for receipt of said signal after propagation through at least a portion of said test sample as an output signal, and detection means coupled for receipt of said input signal and said output signal and responsive thereto to quantify a change between said input signal and said output signal, the improvement in said apparatus comprising:
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said generation means generating a periodic electromagnetic signal having plurality of simultaneously present frequencies to produce a periodic waveform of known shape; and said detection means being responsive to said input signal and said output signal to quantify a change in shape between said input signal and said output signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. In a radio frequency spectroscopy apparatus including a radio frequency generator generating a periodic electromagnetic signal in the one megahertz to one gigahertz range, electromagnetic signal transmission means coupled to said generator for receipt of said signal therefrom and transmitting said signal into a test sample, electromagnetic signal receiving means receiving said signal after propagation through at least a portion of said test sample, and detection means coupled to receive said signal as transmitted into said sample and coupled to receive said signal as received from said sample, said detection means response to the transmitted signal and the received signal to produce an output quantifying a change therebetween, the improvement in said apparatus comprising:
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said generator generating a periodic waveform of non-sinusoidal shape; and said detection means being responsive to the transmitted signal and the received signal to quantify any distortion of said periodic waveform as a result of transmission through said test sample.
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10. In a method for detecting the presence of a chemical in a test sample including the steps of transmitting a periodic electromagnetic signal through a portion of said test sample, receiving said signal after propagation through said test sample, and quantifying any difference between the transmitted signal and the received signal, the improvement in said method comprising:
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during said transmitting step, transmitting a periodic signal having at least two frequencies simultaneously present to produce a shaped periodic waveform; and during said quantifying step, quantifying any distortion of said waveform as a result of propagation through said test sample. - View Dependent Claims (11, 12)
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13. A method of selecting an electromagnetic signal having a waveform useful in a transmission spectroscopy process to determine the concentration of a chemical in test sample comprising the steps of:
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transmitting a periodic electromagnetic signal having a waveform with a fundamental frequency and a broad based of harmonic frequencies simultaneously present to shape said waveform through a test sample containing said chemical; sequentially transmitting signals through said test sample having substantially the same waveform shape and different fundamental frequencies over a range of frequencies; detecting any distortion of said signals over said range of frequencies resulting from transmission of said signals through said sample; and selecting a signal having a frequency which is a multiple of a frequency for which significant waveform distortion was detected during said detecting step. - View Dependent Claims (14, 15, 16, 17)
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Specification