Appendix D 



APN-241 Radar-Detection Experiment 



LT Scott A. Stoermer 



Synopsis 



During IRD 4, IIP conducted an experiment to determine the ability of the HC-130J's APN-241 

 radar system to detect and identify icebergs on or near the Grand Banks of Newfoundland. The 

 experiment occurred on 29 March 2005 onboard CG2006 between 1325 and 1750 UTC. 



General Features of the APN-241 



• The APN-241 is a low-power (1 1-150 watt) multi-mode surface-search and weather radar 

 located in the nose (radomc) of the HC-130J aircraft. The radar is controlled by a panel and 

 trigger-style control interface on the flight deck located between the pilots. 



• The APN-241 modes are weather (WX), surface search (MAP), and ground mapping (MGM). 

 The radar operates in 1 .5, 3, 5, 10, 20, 40, 80, 160 and 320 nm range scales, but each mode 

 does not permit the use of all range settings. Additionally, the radar has dynamic 

 range/antenna tilt functionality. 



• The radar sweeps 270° (±135°) from the nose in alternating sweep directions. The system is 

 sector adjustable (±15°, 30°, 60°), and the display is zoom capable (Figure 1). Essentially, the 

 radar will shift the sweep to a particular sector (as identified by the location of the display 

 cursor) and allow the user to select the sector width. The zoom feature then allows the user to 

 zoom in on the display cursor's position. 



• All four of the liquid-crystal 

 display panels on the flight- 

 deck main console can show 

 the radar display. Figure 2 

 shows radar return on display 

 2 and the digital map on 

 display 3. Additionally, the 

 system allows shared sweeps, 

 which means that one display 

 can show the entire (270°) 

 sweep, while another one 

 zooms on a sector. 



• The radar system is integrally 

 linked with the other systems 

 on the aircraft, including the 

 digital map, autopilot, 

 navigation system and Heads 

 Up Display (HUD). In fact, 

 the position of the cursor on 



Figure 1. Sector-zoom of target (iceberg). Target color (green to red) is 

 an indication of return strength. 



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