Comparison of infrared radiometers used to gather background signature data

Over the past several years there has been a large quantity of infrared target and background signature data collected using imaging radiometers. As with any data, one of the primary questions that must be answered is, `How has the measurement system affected the data?' During the smart weapons operability enhancement (SWOE) signature measurement program this question was addressed using two `identical' AGEMA 880 dual band radiometer systems. These two systems were used to determine how much of the variation that is observed in the signature data can be accounted for by measurement system differences. Measurements were made at the Yuma Proving Ground over a 47 day period from 15 March to 30 April 1993. The radiometers were mounted side-by-side and the fields of view registered as closely as possible. Most of the background signature measurements were preceded by simultaneous blackbody measurements with all four radiometers. These blackbody measurements were used to compare the performance of the two systems under the various weather conditions experienced during the measurement period. The blackbody measurements have shown that over an ambient temperature range of almost 40 degree(s)C the variation between radiometer pairs was less than 1 degree(s)C for the long-wave (8 - 12 micrometers ) and less than 2.5 degree(s)C for the short-wave (3 - 5 micrometers ).