The AN/APS-116 was originally designed to provide the S-3A Viking aircraft with periscope detecting capability in high sea states. The AN/APS-134 incorporates all of the features of the AN/APS-116 while improving performance and adding new capabilities, including a unique maritime surveillance mode. As mentioned in the previous document, APS-507 is the Canadian designation for APS-134.

For periscope detection amid the clutter of rough weather or for high altitude surveillance, the APS-116 radar rejects clutter by using pulse compression and fast-scan processing. It operates in the X band and has four modes of operation:

a) Periscope and small target detection.
b) Navigation and weather avoidance.
c) Long-range maritime surveillance.
d) ISAR (Inverse Synthetic Aperture Radar) imaging. Synthetic-aperture radar (SAR) is a form of radar in which multiple radar images are processed to yield higher-resolution images than would be possible by conventional means. Inverse synthetic aperture radar (ISAR) is a technique to generate a two-dimensional high resolution image of a target.

APS-116 performance in test:

26 nm on a snorkel with the aircraft at 1,500 feet.
33 nm on a fast attack craft from 5,000 feet.
75 nm on a destroyer from 8,000 to 20,000 feet.

These are maximum ranges in sea state 3/4 and mean ranges are shorter. For example, the average range for a snorkel is 15.5 nm. Minimum resolution is 1.5 feet.

APS-134 is the international successor to APS-116, incorporating the latter's less security-sensitive improvements and a fast scan antenna.

Modes and Resolutions:

* Periscope detection in clutter with high resolution (1.5 ft.) 2,000 pps, 150 rpm, 32 nm display with adjustable false alarm rate.
* Long range search/navigation with medium ( 250 ft.) resolution, 500 pps, 6 rpm and 150 nm scale.
*Maritime surveillance with high resolution (short pulses), 500 pps, 40 rpm  150 nm scale.

The latest Orion P-3C's (circa 2010) are being updated with the APS-137. It has an improved ISAR (Inverse Synthetic Aperture Radar) capability to improve surface and overland detection. The APS-134 had a limited ISAR capability.

Reference:

1) The Naval Institute Guide To World Naval Weapon Systems By Norman Friedman. Extract from: Google books.
2) Ernest Cable <erncar(at)ns.sympatico.ca>
 
 

Aug 26/10