The EuroDASS Praetorian DASS is an integral part of Eurofighter Typhoon defensive Aid Sub-System (DASS) providing threat assessment, aircraft protection and support measures in extremely hostile and severe environments. As the DASS is fully integrated, it does not require additional pods that take up weapon stations or would influence the aircraft's aerodynamic performance. In addition the modular nature of the DASS simplifies future upgrades and allows each partner nation or export customer the option to tailor the DASS to their individual needs.
History
The DASS for the Eurofighter Typhoon was intended to be a collaborative effort between the UK, Germany, Spain and Italy. However, integration of the system turned out to be very expensive, so much so that in November 1991, Germany left the programme and initiate its own defense system to equip its Typhoons. In February 1992, before signing the £1.5 billion contract for the DASS, Spain also had doubts about the financial viability and withdrew. This left only the UK and Italy in the consortium, now named EuroDASS (European Defensive Aids Sub-System), to be awarded an initial contract of £200 million ($340 million) with the work shares split 60% to GEC-Marconi (now Leonardo) and 40% Elettronica. By 1995, Spain had decided to rejoin the EuroDASS consortium and a contract was signed with Elettronica to allow INDRA to participate.
In May 1996, Germany had found their national system being developed by DASA was too expensive. In 1997, DASA looked to join the EuroDASS consortium proposing to use the towed radar decoy (TRD) it had developed. These discussions failed as GEC-Marconi had already developed their TRD, known as the Ariel, that had been tested up to mach 2 and was operational with the RAF while the DASA's TRD had only been tested up to mach 1.4 and was not integrated into the Defensive Aids Computer (DAC).
Technology
The Praetorian system is a modular system consisting of antennas for electronic countermeasures (ECM), electronic support measures (ESM), missile approach warning systems (MAW), laser warning receivers (LWR) and Towed radar decoy (TRD). The system is divided into 20 major line replaceable units (LRU) with all the components controlled by a Teldix GmbH Defensive Aids Computer (DAC) on MIL-STD-1553 databus. The DAC is connected via fiber optic cables to STANAG 3910 in the avionics, with the entire DAC system controlled by five Radstone PowerPC-4 processors, that have a tenfold increase in computing power compared to the original five Motorola 68020 CPUs. It is fully automatic, which greatly relieves the workload for the pilot in combat but the pilot can manually override.
ESM-RWR
The DASS includes electronic support measures (ESM) and is equipped with radar-warning-receivers (RWR). The RWR is designed to detect threat radars using super heterodyne, digital receiver antennas which are located into the wing tip pods giving full 360° coverage with an accuracy better than 1° in azimuth. These passive antennas can identify radio frequencies of 100 MHz up to 10 GHz, which is sufficient to detect nearly all types of radar systems and even to detect other RF sources such as radios or datalink systems. The data is compared with the database of radar signatures stored in the Electronic Support Measures suite (ESM). Using this information the ESM allows the identification of the radar and thus the platform it is deployed from and presents it on a moving map or multifunction display producing a 360° threat picture around the aircraft including identifying targets and even their zones of lethality. This allows the pilot to fly around these zones to avoid detection or being engaged. Thus the system not only warns a pilot but it helps him to look out for potential targets.
Laser Warning Receiver (LWR) To counter the threat of laser guided weapons a Laser Warning Receiver, LWR, are installed on UK and Saudi typhoons. These LWRs are optimized for low false alarm rates and can detect lasers pointing at the aircraft and find the direction of the laser source. There are four LWRs on the eurofighter fuselage capable of detecting any incoming laser radiation and determine its bearing, two are located in front of the canards on the front fuselage and the remaining two at the rear behind the wing.