Road Navigation by a Passive Millimeter-Wave Imager Mounted on an Aircraft

Report No. ARL-TR-3017
Authors: Joseph D. Silverstein
Date/Pages: July 2003; 34 pages
Abstract: Simulations are carried out of the generation and integration of passive millimeter-wave (PMMW) digital video images of a simple scene consisting of a road bordered on either side by vegetation growth. The MMW road and growth brightness temperatures, their standard deviations, and the parameters of the simulated PMMW imaging system are based on realistic values. It is assumed that the simulated PMMW sensor is mounted on a low-flying aircraft. The processing consists only of straightforward integration of all or parts of consecutive video image frames. In the simulations the difference between the vegetation growth and road average brightness temperatures could have values from 1 K thru 15 K. The variation in the vegetation growth or road brightness temperature due only to terrain non-uniformities could have values from 0 K thru 2 K. Variations due only to system thermal noise could have values from 3 K thru 15 K. The number of consecutive frames integrated could be 2 thru 31. These simulations show that road navigation is possible for at least some combinations of the terrain and thermal noise brightness temperature variations studied, if the vegetation growth-to-road, average brightness temperature difference is 2 K or larger, and 31 consecutive frames or less are integrated. However, in order to accomplish road navigation when that brightness temperature difference is only 1 K, and for any of the combinations of terrain and thermal noise brightness temperature variations studied, more than 31 consecutive frames would have to be integrated. The simulations also show that, for fixed values of all the brightness temperature parameters, and for a given angular separation between consecutive brightness temperature measurements, if the antenna aperture size could be increased over that currently feasible for airborne PMMW imaging systems, the number of frames that would need to be integrated to achieve a given degree of vegetation growth-to-road brightness temperature contrast would be decreased.
Distribution: Approved for public release
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Last Update / Reviewed: July 1, 2003