Calibration scheme for gas absorption spectra detection

A system for removing a background spectrum from a measured spectrum, comprising:

• an absorption cell containing a gas;
• a radio frequency (RF) transmitter to transmit a RF signal through the absorption cell;
• a detector to receive the RF signal;
• and
• a control module coupled to the transmitter and the detector to:
• estimate performance characteristics of the detector and performance characteristics of the gas cell;
• measure a transmission spectrum of the gas in the absorption cell;
• and
• combine the transmission spectrum with the performance characteristics of the gas cell and the detector to remove a background spectrum from the transmission spectrum.

A spectrometer, comprising:

• an absorption cell containing a gas;
• a radio frequency (RF) transmitter to transmit RF signals into the absorption cell;
• a RF receiver to receive the RF signals;
• and
• a RF signal generation and detection module coupled to the transmitter and the receiver to:
• generate the RF signals;
• detect the RF signals received by the receiver;
• measure a transmission spectrum based on the received RF signals, wherein the measured transmission spectrum includes an absorption line of the gas and a background spectrum;
• remove the background spectrum from the transmission spectrum leaving an absorption line spectrum, wherein the removal of the background spectrum calibrates the spectrometer;
• generate an error signal based on the absorption line spectrum;
• and
• adjust the transmitted RF signals to lock-in on the absorption line spectrum.