SAMPSON - Operation

Operation

Conventional radars, consisting of a rotating transmitter and sensor, have limited power, are vulnerable to enemy jamming and perform only one function - with separate units therefore required for surveillance, tracking and targeting.

As an active array, SAMPSON uses software to shape and direct its beam allowing several functions to be carried out at once and, through adaptive waveform control, is virtually immune to enemy jamming. Active arrays have both longer range and higher accuracy than conventional radars. The beam-directing software uses sophisticated algorithms to schedule looks so that the potentially hundreds of active tracks are maintained with maximum accuracy.

The SAMPSON uses two planar arrays to provide coverage over only part of the sky; complete coverage is provided by rotating the arrays, essentially similar to the way conventional radar systems operate. This is in contrast to the US AN/SPY-1 system (as used on the Ticonderoga class cruiser and Arleigh Burke class destroyer) or the Dutch/German/Canadian APAR system (as used on the Royal Dutch Navy's De Zeven Provinciën class frigates, the German Navy's Sachsen class frigates, and the Royal Danish Navy's Ivar Huitfeldt class frigates), which use multiple arrays fixed in place to provide continuous coverage of the entire sky. Whilst this may seem to be a disadvantage, the SAMPSON radar rotates at 30 revolutions per minute, meaning no part of the sky lacks coverage for more than one second on average - the precise time varies as the beams can also be swept back and forth electronically. In addition, the use of a smaller number of arrays allows the system to be much lighter, allowing placement of the arrays at the top of a prominent mast rather than on the side of the superstructure as in the US ships. Placing any radar emitter at higher altitude extends the horizon distance, improving performance against low level targets; SAMPSON is at approximately double the height above the waterline than the arrays of its US equivalents. Although precise details of the SAMPSON's performance in this regard are unlikely to enter the public domain, such factors may mitigate the disadvantages of fewer arrays.

BAE Systems have also claimed that Sampson eliminates the need for several separate systems. They suggest that on the Type 45 destroyer, the Alenia Marconi Systems/Signaal S 1850M long-range 3D radar that is designed to work in partnership with Sampson "really is superfluous and is not needed to perform the mission of the ship". BAE Systems believes that the reason the large volume search radar has been incorporated in to PAAMS is "more of a historic nature, associated with work sharing issues" that were a huge problem during the trilateral Project Horizon.

Some tasks are difficult to combine, for example (long range) volume search takes a lot of radar resources, leaving little room for other tasks such as targeting. Combining volume search with other tasks also results either in slow search rates or in low overall quality per task. Driving parameters in radar performance is time-on-target or observation time per beam. This is perhaps a the key reason why the Royal Navy selected the S1850M Long Range Radar to complement Sampson on the Type 45 destroyers. It is also a reason why NATO in its NATO Anti-Air Warfare System study (NAAWS) defined the preferred AAW system as consisting of a complementary Volume Search Radar and MFR. This - as NATO points out - gives the added advantage that the two systems can use two different radar frequencies; one being a good choice for long range search, the other a good choice for an MFR (which is especially nice as physics makes both tasks difficult to combine).

The performance of both the SAMPSON radar and the PAAMS' Aster missiles will give the Royal Navy an anti-air warfare capability to replace its long serving Type 42 destroyers. The first Type 45, HMS Daring was launched on February 1 2006. The ship was fitted with SAMPSON and S1850M radars in 2007. She underwent trials before being commissioned in July 2009.