REDUNDANT AREA CODING SYSTEM (REARCS)

Abstract

Redundant area coding was proposed in an Air Force patent, James Maier inventor, to relieve the long integration time required to transmit a reconnaissance photograph through narrow-band communication circuits where upper limits of 4800 to 9600 bits/second prevail. Further development by Radiation Systems Division was funded by Rome Air Development Center’s Reconnaissance and Intelligence Division. Mr. Lawrence Gardenhire developed the analysis curves used. As redundant area coding was conceived, unimportant areas were reduced by applying different orders of resolution throughout one frame of imagery, by blanking redundant areas, or by applying encoding so one frame could consist of areas basically unchanged and areas coded to represent special land such as Forest or desert. What evolved were techniques of applying redundant reduction algorithms in both areas, producing a low/ high resolution picture. Where 3 to 1 reduction ratios were optimum for an average “busy” picture, reduction ratios exceeding 10 to I have been realized. A 9 x 9 inch, 2000 x 2000, 6-bit grey level picture that required 42 minutes to send at a 9600-bit/ second rate, or about 14 minutes for a 3 to 1 reduction, can now be sent in 5 to 6 minutes. A 10 to 1 reduction ratio makes transmitting imagery through existing ground circuits more of a reality and fulfills user requirements.