Question on Radars: [Archive]

Gaf

01-05-2002, 07:19 AM

Here is something i have lying around which has some info on Grifo radars..

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FIAR developed a series of airborne, multimode fire control radars, one of which is known as P2800 or more commonly known as Griffo-M radar. The radar family ranges in size and capability from the P2801 Grifetto to the Grifo-M (P2800). Most share a common antenna and steering servomechanism, use a magnetron-based transmitter, and have a common data processor core. According to FIAR claims, all Grifo radars have good Electronic Counter Countermeasure (ECCM) qualities because of their wide-band frequency agility and low sidelobes.

The radars are built in three Line Replaceable Units (LRUs): antenna, transmitter, and receiver/processor.

The smallest radar is the P2801 Griffetto or Grifo ASV (Anti-Surface Vessel) that was proposed for the anti-ship version of the Italian-Brazilian AMX attack aircraft.
The Grifo ASV can use Track-While-Scan (TWS ) against seaborne targets and single-target tracking as well as air-to-ground ranging, ground mapping, terrain avoidance, freeze, beacon, air-to-air search and track, and air combat modes. The P2801 uses a magnetron operating at a low Pulse Repetition Frequency (PRF) to drive a flat-plate, monopulse antenna. A frigate-sized ship showing a radar cross-section of 10,764 sq ft (1,000 sq m) is claimed to be detectable at ranges greater than 55 nm (63 mi; 102 km). According to FIAR, in the air-to-air mode aircraft can be detected up to 22.4 mi (36 km).

Then there is the P2803 (Grifo-X), which is a larger system designed for light attack aircraft that shares the same system connectors with the Grifo ASV . The Grifo-X is a fully coherent, pulse-Doppler radar with the same multi-modal flexibility as the Grifo ASV , but possessing better look-up range and offering a limited look- down capability as well.

The P2800 Grifo-M is larger than the Grifo-X and uses a more elaborate multi- processor fire control system. It is designed to fit in the radar bay of a Mirage III or Mirage V interceptor-strike aircraft as an upgrade option. It is still more powerful than the Grifo-X with greater look-down range and discrimination through the use of Fast-Fourier-Transform (FFT ) Doppler- filtering techniques. Two versions are developed: the 2800 (Grifo-M) for Mirage-series aircraft, using a circular flat-plate array, and the P2804 (Grifo-F), a reconfigured system with an ellipitical scanner that fits in the antenna bay of a Northrop F-5E aircraft.

Pakistan has ordered the Grifo-M for its Mirage III fleet, with an option for 50 more systems. Singapore has also selected the P2804 for retrofit into its F-5 fleet.

A more recent version of Grifo, the Grifo 7 designed for installation into the Chinese built F-7 (MiG-21) is now being manufactured and installed by PAC on PAF F-7P aircrafts. The Kamra Avionics & Radar factory is also responsible to maintain-repair the Grifo-7 after there induction and has the facilities to do so.
The best option for S-7 radar is the P2800 (Grifo-M), since S-7 doesn’t have the small nosecone problem as the F-7P for which P2800 (Grifo-M) was scaled down and renamed Grifo-7.

The Grifo-M is said to be an excellent radar system, and which according to PAF “is equivalent or slightly better than the existing APG-66 of the F-16 radar”.
In adverse weather conditions the P2800 (Griffo-M) has a range of 60 nm (69 mi, 111 km) with a look-down shot-down range of 17-20 nm (20-23 mi, 32-37 km). So choosing a radar system for the S-7 is not that big a problem

Gaf

01-05-2002, 07:21 AM

The FIAR Grifo Radar

Over the past 20 years airborne fire control radar have become smarter as the advent of
micro processing has improved the speed and capacity of the system to search for, track, and
identify targets. At the same time, the physical size of the hardware has shrunk. Thus, it is possible
for in-service fighter aircraft to be given a state of the art radar system which, in turn, allows the use
of new generations of air to air missiles.
Although FIAR (Fabbrica Italiana Apparecchiatture Radoielettriche) was formed in milan
during 1941, as a manufacturer of electronic equipment for both the commercial and military
markets,
the company's involvement with radar only began in the early 1960s when it commenced production
of the NASARR F15AM II radar , under license from Autotecnics, for the FIAT build lockheed
F-104G. the F-15AM II is a multi mode radar , optimized for both air to air (target interception)
and air to ground ( navigation and bombing) roles. FIAR currently has a staff of 700 and forms
the airborne radar sector section of the systems and avionics equipment division within Alenia
Difesa. it is the only part of Gruppo finmeccanica to be quoted on the stock exchange.
The FIAR Grifo radar from Italy, The FIAR family of Grifo radar has achieved similar success.
four distinct versions of this radar have been adopted: the Grifo-M, and Grifo-7 for the Mirage
III/V and F-7, respectively, in service with the Pakistan air force, the Grifo-F for Singapore's F-5E
upgrade (redesigned as F-5S), and the Grifo-L for the Czech republic's aero vodochody L-159.
Although previously a smaller part of Italian industry, FIAR is now the lead element of GF-Sistemi
Avionici, a finmeccanica company.
Development of the Grifo pulse- doppler, multi-mode radar began in late 1980s, and following
a comprehensive series of flight testing on a company owned T-39 Saberliner test bed, is considered
complete. The four versions share a common architecture and much common hardware and
according to the company, offer feature normally associated highly expensive and complex aircraft.
FIAR entered the market in 1991 with the Grifo, a radar developed with private venture funding
to upgrade Singapore's F-5Es. it is testament to FIAR's expertise that it won the competition in
the face of stiff competition from British, Israeli, and American companies. Grifo is a pulse Doppler
multi mode, multi roll radar operating in the X band (I/J band), featuring a planer antenna. with a
performance claimed to be better than the APG-66 radar fitted to the F-16AB. it has five air to air
search modes, with the capability of tracking up to eight targets, four air combat modes and nine air
to surface modes. the last are refined by ground mapping and enhanced Doppler beam sharpening
mapping. its range 39 nm, the system weight between 80-85kg (176-187 pound) ( depending on the
antenna), and requires a 2KVA power supply. it is cooled by compressed air and the energy
dissipation is less than 1.5 KW, with 500W transmitter power. the Grifo offers low, medium and
high pulse repetition frequencies (PRFs), uses digital pulse compression and has low peak power.
Extensive use is made of built in test equipment (BITE) for maintenance simplicity and the mean time
before failure (MTBF) is between 200 and 250 hours: a major improvement on older system. For
air to air use, it has range-while- search (normal), range-while-search (adaptive), spot velocity
search, single target track, dual target track, situation awareness, track-while scan, air combat,
boresight acquisition, HUD acquisition, vertical acquisition and slew modes, In air to surface
operation, the Grifo can function in real beam map, Doppler beam sharpening , sea low, sea high,
ground moving target indicator, ground/sea moving target track, air to ground ranging, freeze,
expand and beacon modes, Further modes include raid assessment, terrain avoidance, precision
velocity update, beacon landing (similar to ILS) and IFF.
Grifo can be integrated with semi-active or active radar guided missiles such as
AMRAAM and MICA. and its can be use four type of AAM, During the system's development
program some 250 flying hours
were accrued in tracor's North American T-39D S aberliner airborne test bed. in addition, more
than 300 flight trails were conducted with a system mounted in an F-5E.
Deliveries to Singapore of its order for around 50 Grifo-F system, a version optimized
for the F-5E, began in the second half of the 1990s. In 1993 FIAR signed a second prestigious
deal, being selected for the modernization program for 95 Pakistani F-7P/MP fighters,The first Grifo
radar was due to be shipped to the air force's Chaklala site in july 1994 to fitted into MirageIII's.
This was a much more demanding requirement because of the smaller space available and lack of a
cooling system. To this end simplified version was developed, the Grifo-7, which weight only 55kg
(120 LB) and has 450W power with 850W energy dissipation. The modes available are search,
single target track and air combat (super search, bore sight and vertical) modes for air to air
operations, and air to ground ranging for ground attack.
Two years later, Pakistan again turned to FIAR, this time in support of a
modernization program for its ex-Australian MirageIII Os. The aircraft , being reworked by the
Pakistan Aeronautical Complex, needed to be fitted with new avionics, including radar, global
position system (GPS), inertial navigation system (INS), FLIR, upgraded electronic counter
measures (ECM), and ' hands on throttle and stick ' (HOTAS) controls, The radar selected was the
Grifo-M ( performance as the Grifo model), optimized for the MirageIII airframe, and Pakistan
purchased 35 systems. FIAR's latest contract was signed in 1997 with Aero Vodochody of the
Czech Republic. This was for 77 Grifo-L radar systems to equip the new L-159 multi role combat
aircraft. FIAR is constantly working on research and development programs that will improve and
develop the capabilities of the entire Grifo family. Continual upgrades of both software and hardware
components, enable the systems to remain state of the art.
The Grifo incorporate full range air to air and air to ground modes. the performance
demonstrated during the Saberliner tests against fighter targets included detection and lock-on
ranges, look-down capability, and air to ground ranging. The company told that these tests
"far exceeded the design objectives" of the radar but declined to be specific literature notes that
the radar is able to detect and track multiple targets ( up to eight) at all aspects and at all altitudes.
The system weight depending on the aircraft platform, "less then 80 kg".
Integration of a modern radar into new avionics architecture is never as simple as it
appears and it is understood that the Grifo-F for Singapore's F-5S experienced problems during
integration, though their exact nature has not been revealed. that said, FIAR issued a statement
during the 1996 Farnborough International air show noting that flight trail of the Grifo-7 in a
Pakistani F-7 in airplay 1996, were declared "completely satisfactory' by the Pakistan Air Force
and ministry of defense. Several sorties were flown ahead of the rainy seasons in order to test the full
operating of the radar in the country's challenging hot weather conditions. further trails are being
conducted to verify other parameters.
At present, the Grifo's claimed lower cost and the higher performance are its main selling
points. FIAR states it has "signed order for about 200 Grifo radars' with options on a further
100. other candidate aircraft for the Grifo are seen as being the A-4 Skyhawk, Mig-21, SUPER-7
and others.
The Super Skyranger is new low cost, multimode radar designed as a replacement for
Skyranger radar. Super Skyranger radar also proposed as retrofit for other "small nosed' fighters.
The company claims that super skyranger offers full look down/shoot down capability, using a
planner array antenna scanning + 30 digree, depending on the aircraft installation. it can provide
target range, range rate, and line of sight data (such as head- steer data for a slewable short-range
air to air missile) to the aircraft avionics systems. it does this using an ARINC-429 serial link (with
a 1553b option) and possesses what are described as " excellent ECCM features.

A modern fighter range can have a dozen or more radar modes, each optimized for a
specific task. No standard terminology exists for all modes. In preparing the data table we have
listed
only the most important nav\attack modes for each set. The most common are as follows:

AIR TO AIR
LOOK-DOWN ; The most common mode used in air combat, this provides clutter free
indication of low flying targets.
LOOK-UP ; If the target is flying at a similar or higher altitude to the fighter, look-up mode will
provide a longer detection range.
Single-target track ; In simpler radars, once a target of interest has been detected, the set can
then be locked onto it, allowing an attack to begin. The radar antenna will remain pointed at the
target, so other targets can only be observed by returning to search mode.
Track-While-Scan (TWS) ; Given enough data processing power, a radar can maintain a track
on several targets while continuing to scan the forward sector. This mode allows several targets to be
engaged simultaneously using fire and forget missiles, and gives enemy pilots no way of knowing that
their aircraft have been single out for attack. Since the radar is still scanning , it may take up to ten
seconds for the radar beam to re-scan each target, so the data processor will take some time to
establish a new track, or respond to a sudden change in target course. this delay can reduced by
using data -adaptive scanning. Also know as track priority. this replaces the conventional sector scan
used in search mode with a series of smaller scan each directed at one of the targets of interest.
Using this technique, tracks can be updated every few seconds.
Range-While-Search(RWS) ; By interleaving high and medium PRF( Pulse Repetition
Frequency) waveforms. a radar operating in this mode can sue the high PRF's for long range target
detection, and the medium to obtain range information.
Velocity Search ; This uses high PRF's to carry out a long range search. this gives the longest
possible range against head on targets, but provides velocity and azimuth data only.
Raid assessment ; (sometimes referred to as "situation awareness") In normal operating modes,
a formation of several closely grouped aircraft may appear as a single target when seen at long
range. Raid assessment mode uses signal processing to resolve the formation into its individual
aircraft.
Air Combat ; (often referred to as "Dogfight mode") This is a generic term for modes used at
short range when the aircraft and its target are maneuvering in air combat. The scan pattern can
either be fixed, or moved to anticipate target maneuvers. the most common are HUD, bore sight,
and vertical search.
HUD ; (sometimes referred to as "supersearch") This radar automatically scans the HUD field of
view, and will automatically lock on to the closest target.
Boresight ; The radar beam is pointed directly ahead of the aircraft, and the pilot maneuvers the
aircraft to place the beam onto the aircraft to be tracked. lock on is commanded manually.
Vertical search ; This is particularly useful when both aircraft are maneuvering in the vertical
plane, and involves setting the radar to scan vertically rather than horizontally.
Air to air ranging ; Measures the range to an air target.

AIR TO GROUND

Air to ground ranging ; Used to measure the slant range to a designated point on the ground
during gun or continuously computed point (CCIP) attack.
Real beam ground mapping ; (often referred to simply as 'ground mapping') By sweeping the
beam from side by side, the radar creates a radar image of the terrain ahead. this can be used to
locate and attack ground targets, or to update the aircraft's navigation system.
Sea search ; This mode is optimized for the task of detecting and tracking ship targets. Unlike
the land, the sea surface is itself moving, increasing the problems which the radar will have in
discriminating between the target and its surroundings.
Freeze ; The radar scans to build up an image, which is then electronically stored and presented
on the display, allowing the radar transmitter to be turned off . By computing the aircraft's
movements, the radar allows the pilot to use the Frozen image for some length of time, before the
transmitter is re-energised to take another radar 'snapshot'.
Expanded-beam ; This allows the pilot to select a small area of ground mapped terrain, then
magnify its image.
Doppler beam sharpening ; By processing the doppler shift in the returned echo, the radar
creates a high definition view of a small part of the ground mapped terrain. althoug this gives a higher
resolution than Expanded beam mode, it can only be used for targets which are 15* or more the
nose of the aircraft.
Terrain avoidance ; Detects high ground ahead of the aircraft, enabling the pilot to fly around it .
Terrain following ; Flies the aircraft at a pre selected height along the planned route .
MTI (Moving Target Indication) ; By processing the Doppler shift in the echoed from moving
targets on the ground . the radar can separate these from the ground clutter. Quality of MTI data
reduces at high aircraft speeds.