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Author Topic: JAS-39 Avionics  (Read 11818 times)

Offline PaulMM (Overscan)

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JAS-39 Avionics
« on: February 09, 2006, 11:46:55 am »
A thread to discuss the avionics of the very interesting JAS-39 Gripen.

I will post some information from the Aerofax book shortly.
"They can't see our arses for dust."
 
- Sir Sydney Camm

Offline PaulMM (Overscan)

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Ericsson PS-05/A radar
« Reply #1 on: February 10, 2006, 02:53:00 am »
LM Ericsson were given responsibility to develop the new PS-05/A radar for the Gripen. Ericsson have a long history of radar development, beginning in 1950 with cooperation and license production of a Thomson-CSF radar from 1950 for the Lansen, development of PS-01/A and PS-03/A indigenous pulse radar for the Draken, PS-37 solid-state pulse radar for the AJ-37 Viggen, then the first operational operational pulse-doppler radar in Europe, the PS-46/A for the JA-37 Viggen.

From 1981 Ericcson collaborated extensively with Ferranti (later GEC Marconi), who were working on the similar Blue Vixen radar. Ericsson's D80 computer was adopted on the Blue Vixen, while Blue Vixen's antenna platform and drive were used on the PS-05/A.

The first PS-05/A test radar was flown from 1987 in a Viggen. The first production standard radar flew in 1989, and testing was completed in 1993.

The PS-05/A radar  is software driven, allowing new modes to be incorporated relatively easily.

Basic modes
Air-to-air using high PRF and medium PRF waveforms.
  • Long-range search
  • multiple-target track-while-scan
  • multiple priority target tracking
  • short-range, wide-angle search and track for air combat
  • high-resolution single-target tracking
  • raid assessment

Air-to-ground
  • search
  • tracking
  • high resolution mapping
  • air-to-surface ranging

The main waveforms generated are
  • HPD - a high PRF, pulse-doppler mode for use against airborne approaching targets
  • MPD - a medium PRF pulse-doppler mode for use against approaching and receding targets- a special high resolution sub-mode is designed for target tracking
  • LPD - a mode using Doppler processing designed for use against surface targets
  • LPRF - a low-PRF mode with pulse-to-pulse frequency agility for use against surface targets and for real-beam mapping
  • AGR -  a mode exclusively designed for ground target ranging
  • DBS  - Doppler Beam Sharpening mode utilising Doppler processing for high resolution mapping, with high-angular coverage obtained by continuous antenna scanning
  • SLM (SpotLight Mode) - an SAR mode utilising Doppler processing for very high-resolution mapping.

The PS-05/A radar comprises six Line-Replaceable Units (LRUs):
  • Antenna Unit: lightweight 600 mm diameter low sidelobe monopulse planar array, with guard channel antenna, IFF dipoles and digital servo control, weighing 25 kg
  • Power Amplifier Unit and Transmitter Auxiliary Unit: 1kW average power, flexible waveform, liquid cooled, TWT
    system.  These two LRUs weigh 73 kg altogether
  • High-Frequency Unit: multiple channel receiver, monopulse design, pulse-to-pulse frequency-agile, microwave integrated circuit
    design, internally software controlled, 32 kg in weight
  • Signal and Data Processor: Ericcson D-80 processor, employing ASIC technology, hardware optimised for programming in Pascal, weighing 23 kg
  • Waveguide unit (2kg?)

Sources
  • Jane's Avionics 2002
  • Gerard Keijsper, Saab Gripen: Sweden's 21st Century Multi-role Aircraft Aerofax, 2003
  • Kinghorn et al, The Blue Vixen Radar for Sea Harrier FRS.2 GEC Review Vol 9 No 3 1994
  • Gripen Intl. website http://www.gripen.com
« Last Edit: February 10, 2006, 07:54:40 am by overscan »
"They can't see our arses for dust."
 
- Sir Sydney Camm

lewradar

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Re: JAS-39 Avionics
« Reply #2 on: February 10, 2006, 06:47:29 am »
In other words the PS-05/A is a good modern flat-plate puse doppler multimode radar like all the others in the world - they even all look the same now:  Israeli EL/M 3032; Eurofighter Captor; Mirage 2000 RDY; APGs 70, 65, 73 ....; Phazotron Zhuk; NIIP's N-011.

takes all the fun out of it. I preferred it when everyone's radars looked different and you could have lots of working out "... now why did they do it that way?"

Offline PaulMM (Overscan)

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Re: JAS-39 Avionics
« Reply #3 on: February 10, 2006, 07:01:20 am »
In one sense, you are completely correct. However, once you bring the JAS-39's datalink capabilities into play, things look a little different.

From Bill Sweetman's article for JEDOnline;

Quote
   
The TIDLS can connect up to four aircraft in a full-time two-way link. It has a range of 500 km and is highly resistant to jamming; almost the only way to jam the system is to position a jammer aircraft directly between the two communicating Gripens. Its basic modes include the ability to display the position, bearing, and speed of all four aircraft in a formation, including basic status information such as fuel and weapons state. The TIDLS is fundamentally different from broadcast-style links like Link 16. It serves fewer users but links them more closely together, exchanging much more data, and operating much closer to real time.

TIDLS information, along with radar, EW, and mapping data, appears on the central MFD. The display reflects complete sensor fusion: a target that is being tracked by multiple sources is one target on the screen. Detailed symbols distinguish between friendlies, hostiles, and unidentified targets and show who has targeted whom.

Today, Sweden is the only country that is flying with a link of this kind, and will retain that status until the F-22 enters service. The Flygvapnet has already proven some of the tactical advantages of the link, including the ability to spread the formation over a much wider area. Visual contact between the fighters is no longer necessary, because the datalink shows the position of each aircraft. Leader and wingman roles are different: the pilot in the best position makes the attack, and the fact that he has targeted the enemy is immediately communicated to the three other aircraft.

A basic use of the datalink is "silent attack." An adversary may be aware that he is being tracked by a fighter radar that is outside missile range. He may not be aware that another, closer fighter is receiving that tracking data and is preparing for a missile launch without using its own radar. After launch, the shooter can break and escape, while the other fighter continues to pass tracking data to the missile. In tests, Gripen pilots have learned that this makes it possible to delay using the AMRAAM's active seeker until it is too late for the target to respond.

But the use of the link goes beyond this, towards what the Swedish Air Force calls "samverkan," or close-cooperation. One example is the use of the Ericsson PS-05/A radar with TIDLS. An Ericsson paper compares its application, with identical sensors and precise knowledge of the location of both platforms, to human twins: "Communication is possible without explaining everything."

"Radar-samverkan," the Ericsson paper suggests, equips the formation with a super-radar of extraordinary capabilities. The PS-05/A can operate in passive mode, as a sensitive receiver with high directional accuracy (due to its large antenna). Two PS-05/As can exchange information by datalink and locate the target by triangulation. The target's signals will often identify it as well.

The datalink results in better tracking. Usually, three plots (echoes) are needed to track a target in track-while-scan mode. The datalink allows the radars to share plots, not just tracks, so even if none of the aircraft in a formation gets enough plots on its own to track the target, they may do so collectively.

Each radar plot includes Doppler velocity, which provides the individual aircraft with range-rate data. However, this data on its own does not yield the velocity of the target. Using the TIDLS, two fighters can take simultaneous range-rate readings and thereby determine the target's track instantly, reducing the need for radar transmission.

In ECM applications, one fighter can search, while the wingman simultaneously focuses jamming on the same target, using the radar. This makes it very difficult for the target to intercept or jam the radar that is tracking him. Another anti-jamming technique is for all four radars to illuminate the same target simultaneously at different frequencies.
"They can't see our arses for dust."
 
- Sir Sydney Camm

Offline PaulMM (Overscan)

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Re: JAS-39 Avionics
« Reply #4 on: February 10, 2006, 07:11:49 am »
Also, look at the work they are doing with sensor fusion. Here is a later version of the radar display above, which is now a multi sensor display, and the HSD which fuses all inputs into a single tactical display.
« Last Edit: February 10, 2006, 07:26:55 am by overscan »
"They can't see our arses for dust."
 
- Sir Sydney Camm