Carbon monoxide detection using passive and active millimetre wave radiometry

This paper investigates the use of the rotational molecular resonance lines of carbon monoxide for the detection of this gas. Active and passive techniques are investigated, concluding that a passive technique is feasible but that an active technique is not. The passive technique would use a three channel spectral radiometer tuned on and around the resonance line. Concentrations of 10 parts per million could be detected over a path length of 100 m. Such a system could be incorporated into a passive millimetre wave imager to detect and measure remotely concentrations of carbon monoxide. Using active techniques, it is shown that modulated radiation temperature changes are too small to be measured using radiometry.