Accession Number:

ADA036152

Title:

Reduction of Solar Glints From the Sea with a Linear Polarizer

Descriptive Note:

Informal technical rept.

Corporate Author:

ENVIRONMENTAL RESEARCH INST OF MICHIGANANN ARBOR

Personal Author(s):

Report Date:

1976-10-01

Pagination or Media Count:

31.0

Abstract:

Shipboard defense systems employing infrared warning receivers have experienced saturation of threat detection processing circuits due to the signal resulting from solar reflection from the rough sea surface. The saturation has made it necessary to blank the threat sector below the horizon for an azimuth extent of up to or - 23 deg either side of the azimuth of the sun. The analysis shows that the use of linear polarizer with a shipboard IR warning receiver can be expected to increase number of daylight hours that the sensor can be operated without any blanking, and to narrow the azimuth sector for which blanking is required for low sun angles. The linear polarizer will be most effective during the middle of the day during the spring, summer, and fall. The unpolarized receiver typically may have to be blanked over a or - 23 deg segment of its azimuth search below the horizon nine to eleven hours per day. With a linear polarizer the number of hours for which blanking will be necessary can typically be reduced to six to eight hours per day and the aximuthal extent of the blaking during the remaining hours reduced to or - 12 deg. Further consideration is needed of Navy operational practices and the types and frequencies of occurrence of various sea states encountered at various latitudes, a wave slope model valide for high slopes and wind speeds, and a simulation in which the ship defense system noise, threshold, and spatial resolution are parameters.

Subject Categories:

  • Military Intelligence
  • Infrared Detection and Detectors

Distribution Statement:

APPROVED FOR PUBLIC RELEASE