Infrared emission and remote sensing

With initial support from the Colorado Office of Energy Conservation in 1987, the University of Denver (DU) developed an infra-red (IR) remote monitoring system. In less than a second the instrument measures the carbon monoxide to carbon dioxide ratio (CO/CO{sub 2}) in the exhaust of most vehicles passing through the IR light beam. It has been shown to give accurate readings for CO by double-blind studies of vehicles both on the road and on dynamometers. Recent improvements include the capability to monitor hydrocarbon exhaust levels, also using IR absorption. These readings have also been validated by the California Air Resources Board. Researchers from General Motors were the first to raise the question of IR emission interferences. Potential inaccuracies can occur if IR emission occurs in sufficient magnitude during absorption data collection. The GM researchers observed IR emission especially from trucks and vans. Uncertainty exists about its effect on the absorption data. The investigation shows that under normal operating conditions IR emission is not a problem for the DU remote sensing instruments.