Determining gas absorption line from separate and alternating RF signals
AssigneeTexas Instruments Incorporated
InventorPhillip Michel Nadeau
Life of this patent
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Abstract
A method to detect a gas absorption line that includes alternately transmitting and sweeping two radio frequency (RF) signals through an absorption cell, wherein the two RF signals are transmitted at different frequencies separated by a range and are swept across a span of frequencies in a microwave and millimeter wave regions of a frequency spectrum. Receiving the RF signals by a receiver and analyzing the received signals by a closed loop system for relative absorption by a gas due to an absorption line of the gas in the span of the swept frequencies. Detecting the absorption line of the gas when the two RF signals straddle the gas absorption line and the relative absorption by the two RF signals is equal.
Claims12
A method to detect a gas absorption line, comprising:
- transmitting and sweeping two separate and alternating radio frequency (RF) signals from a signal generator through an absorption cell containing a gas, including transmitting the two alternating RF signals at different frequencies separated by a constant range, and including sweeping the two alternating RF signals across a span of frequencies in microwave and millimeter wave and THz regions of a frequency spectrum;
- receiving the RF signals from the absorption cell by a receiver;
- analyzing the received RF signals by a closed loop system for relative absorption by the gas due to an absorption line of the gas in the span of the swept frequencies;
- and
- detecting the absorption line of the gas when the two received RF signals straddle the gas absorption line and the relative absorption by the two received RF signals is equal.
A system for detecting an absorption line of a gas, comprising:
- a signal generator having a transmitter output and a control input, the signal generator, in response to the control input, generating two radio frequency (RF) signals, each at a different frequency, the two RF signals are separated by a constant frequency range, are alternately transmitted, and are swept across a span of frequencies in a microwave and millimeter wave region of a spectrum;
- an absorption cell filled with the gas at a pressure;
- a transmitter coupled to the output of the signal generator and transmitting the RF signals into the absorption cell;
- a receiver receiving absorption RF signals from the absorption cell;
- and
- a processor having an output coupled to the input of the signal generator and including a detector module having an input coupled to the receiver to compare the amplitudes of the two received absorption RF signals and to determine when an absorption line of a gas is detected based on a difference in the amplitudes between the two RF signals.
Dependencies are inferred from the claim text.