Digital image capture, processing and recording system upgrade for the APS-94F SLAR

The Argentine Army has been operating the APS-94F SLAR systems, on board the venerable OV-1D "MOHAWK" aircraft, since 1996. These systems were received from the U.S. Government through the FMS program. One major handicap of the system is due to the now obsolete imagery recording subsystem, which includes complex optical, thermal and electro-mechanical obsolete processes and components, that account for most of the degradations and distortions in the images obtained (not to mention the fact that images are recorded on a 9.5-inch silver halide film media, which has to be kept at -17 degreesC and has to be brought to thermal equilibrium with the environment eight hours before the mission). An integral digital capture, processing and recording subsystem was developed at CITEFA (Instituto de Investigaciones Cientificas y Tecnicas de las Fuerzas Armadas)to replace the old analog RO-495/U recorder, as an upgrade to this very robust and proven imaging radar system. The subsystem developed includes three custom designed ISA boards: (1) Radar video and aircraft attitude signal conditioning board, (2) Microprocessor controlled two-channel high speed digitizing board and (3) Integrated 12-channel GPS OEM board. The operator's software interface is a PC based GUI C++ application, including radar imagery forming and processing algorithms, slant range to ground range conversion, digitally controlled image gain, bias and contrast adjustments, image registration (GPS), image file disk recording and retrieval functions, real time mensuration and MTI/FTI (moving target indication-fixed target indication) image correlation. The system also provides for the added capability to send compressed still radar images in NRT (near real time) to a ground receiving station through a secure data link. Due to serious space limitations inside the OV-1D two-seat cockpit, a military grade ruggedized laptop computer and docking station hardware implementation was selected.