Saab Bofors Dynamics has developed an IRST-system (Infra Red Search and Track) named IR-OTIS (Optical Tracking and Identification System) and flight trials have been carried out with the system mounted on a Saab JA37 Viggen fighter aircraft. This paper consists of three major parts. First an overview of Saab's IRST-programs. The second part describes the system ( IR-OTIS(Viggen) ) that made flight trials during 1998 and 1999 and finally a report from the flight trials.
IR-OTIS has mainly three operating modes:
1) IRST-mode where the system covers several different FOS (Field Of Search).
2) FLIR-mode (Forward Looking IR) where the systems LOS (Line Of Sight) is directed from the aircraft.
3) Track-mode where the built-in-tracker controls the LOS.
It is also possible to switch from IRST-mode to track-mode automatically.
Physically the IR-OTIS(Viggen) consists of the SU (Sensor Unit) and the SPU (Signal Processing Unit).
The SU is operating in the longwave IR-band with a 288*4 detector. In all modes the Sensor Unit generates images in 25 Hz and it is also possible to choose one of three FOV.
The SPU consists of a Saab designed image processing hardware and several DSPs. Functions in the SPU includes a scene-based NUC (Non Uniformity Correction), anti-Narcissus, a point-target detector including estimation of SNR and a clutter classifier for CFAR, target association, a correlation target tracker and an AGC for image presentation.
We carried out over 50 flight trials during 1998 and 1999 in three different rounds. The functionality of the system has increased during the rounds and at the end of the trials all major goals were achieved.