Radar thread - specs & discussions

pratik_das · Post by **pratik_das** » 02 Jan 2006 09:02

George J wrote:EHOG=Ever heard of Google?

If you had google for it you would have found out that in March 5th, 2004 it was stated that:
"The first delivery will take place after 44 months, the second after 53 mo-nths and the third after 59 months," said a defence ministry official.

Cheers

SaiK · Post by **SaiK** » 19 Jan 2006 00:57

url

The theoretical modelling required for the adaptation of AESAs as high speed long range datalinks and their adaptation to networking. It was a monster project involving around 1000 large scale simulation runs on a 60 CPU cluster (eq to a Cray)

SaiK · Post by **SaiK** » 23 Jan 2006 08:00

Radar-Absorbing Material: A Passive Role in An Active Scenario by Richard N. Johnson

Vick · Post by **Vick** » 21 Feb 2006 18:44

From Jane's

Israel upgrades Green Pine

David C Isby

Israel is upgrading the Elta EL/M-2080 Green Pine multifunction phased-array radar used with its Arrow 2 anti-missile system, writes David C Isby. According to press reports, Israel is concerned about the re-entry velocity associated with long-range missile threats such as the Iranian Shahab 3 and 4 and the possibility that they might employ terminal-phase penetration aids.

Israel wants to improve the resolution possible with the basic L-band Green Pine design, which was originally designed to deal with less capable ballistic missiles with 550 km to 650 km range.

The upgrade requires the replacement of components originally developed for the IAI Phalcon's airborne radar system and now used in the Green Pine, including improved transmit/receive units for the radar's 9x3 m antenna. The modifications will double the power output available for the radar and introduce improved software.

Modified radars would have improved target resolution and discrimination, using signal phase and polarisation changes to discriminate re-entry vehicles from decoys and other objects.

Pay particular attention to the bolded paragraph. The upgrade to the GP radar is based on the components of the radar on the Phalcon. Now, what does that say about the range and discretization capabilities of the Phalcon?

Vick · Post by **Vick** » 21 Feb 2006 20:39

From Jane's

Elta AESA is flying

Bill Sweetman, IDR Technology & Aerospace Editor
Singapore

Israel Aircraft Industries' Elta subsidiary is testing a prototype of a fighter radar with an active electronically scanned array (AESA). The first flight took place earlier this year in Elta's Boeing 737 testbed. The company says that it is ready to take orders for the new radar and that it could be delivered within 18 months of an order.

Designated EL/M-2052, the AESA radar is designed either for new-production applications or as a retrofit for the company's in-service EL/M-2032-series radars, some 400 of which are in service worldwide. As an upgrade, the radar would replace the old antenna and transmitter and use the existing power supply and radar processor.

One unusual feature is that the array comprises 'bricks' of 24 transmit-receiver modules, making it easy to assemble the AESA in different configurations to match the size and shape of an existing fighter nose. Smaller, lower-module-count versions can be air-cooled, reducing weight and making integration simpler.

Dileep · Post by **Dileep** » 22 Feb 2006 01:06

Designated EL/M-2052, the AESA radar is designed either for new-production applications or as a retrofit for the company's in-service EL/M-2032-series radars, some 400 of which are in service worldwide. As an upgrade, the radar would replace the old antenna and transmitter and use the existing power supply and radar processor.

That means this one is the first gen AESA where you just have a TX and LNA on the TX/RX module. Not too much advanced from PESA functionally.

JaiS · Post by **JaiS** » 24 Feb 2006 19:34

MOD Awards Contract to QinetiQ Primed Team to Demonstrate Advanced Radar Targeting System (ARTS) on a Tornado GR4A

The Ministry of Defence has awarded a contract to QinetiQ to demonstrate the advanced targeting capability offered by Electronically Scanned (E-Scan) radar technology. QinetiQ has teamed with SELEX Sensors and Airborne Systems and BAE Systems Customer Solutions & Support to integrate an Active Electronically-Scanned Array (AESA) on a Tornado GR4A for assessment by the RAF in 2007.

With growing interest in extending the in-service life of the GR4, the project will explore the use of Active E-Scan Array (AESA) and Synthetic Aperture Radar (SAR) in an air-to-surface role, including real-time target imaging, with a view to replacing the installed mechanically-scanned terrain following/ground mapping radar system originally designed in the 1970s.

"We anticipate that ARTS will offer considerable improvements in performance and significantly help reduce maintenance cost when compared with the current in-service solution," explained Andrew Sleigh, MD of QinetiQ's defence business. "By replacing the mechanically scanned antenna with an array made using discrete transmit/receive (T/R) modules we can achieve greater range and target resolution whilst at the same time benefiting from an inherently more robust design."

ARTS will run in parallel to the multi-national Advanced Multi-Mode Solid-State Airborne Radar (AMSAR) programmes and will focus on specific areas of capability development (SAR and Automatic Target Recognition (ATR)). ARTS will also focus on platform integration and aims to raise System Readiness Levels (SRLs). It is anticipated that AMSAR will continue to provide a programme through which to raise Technology Readiness Levels (TRLs) and explore the potential for AESA to contribute to other capability areas.

khukri · Post by **khukri** » 27 Feb 2006 02:48

Posted in Defense News:
Finmeccanica Plans E-scan Radar
Targets Retrofit Market for Combat Aircraft
By TOM KINGTON, ROME
February 20, 2006
Finmeccanica is planning to develop a low-cost, electronically scanned combat aircraft radar for the retrofit market, said a senior executive.
The program will be an early result of the nine-month-old Selex Sensors and Airborne Systems (S&AS), the coupling of Finmec-canica unit Galileo Avionica and BAE avionics units in the United Kingdom in an entity 75 percent controlled by Finmeccanica.
“An Italo-U.K. radar team has been set up, which has as one objective the development of a new e-scan combat radar with air to air, air to ground and SAR [synthetic aperature radar] capabilities,” said Giancarlo Grasso, chief executive of Selex S&AS. “The intention is to develop a competitively priced, compact product with sufficient flexibility to make it ideal for retrofits.”

Galileo Avionica is still selling the mechanically scanned Grifo combat aircraft radar, but Selex in the United Kingdom is marketing its new Vixen 500E electronically scanned radar. Capable of air-to-ground, air-to-air and SAR operations, the e-scan Vixen has been pitched to South Korea for its A-50 Light Attack/Fighter Lead In Trainer variant of the T-50 jet trainer, as well as to India for its Light Combat Aircraft.
Grasso said the newly planned radar, with its focus on price and retrofit usage, would cover a different market than the Vixen 500E. “It will co-exist in the portfolio with the Vixen e-scan radar,” he said.

Link to Vixen 500E:

http://www.selex-sas.com/datasheets/Vix ... 0e%20radar'

JaiS · Post by **JaiS** » 28 Feb 2006 15:36

Air force will soon have India’s first Aerostat in Kutch

Indian Air Force will soon have India’s first Aerostat operational in the border district of Kutch. This was disclosed by Air Marshal S.K.Jain here today.

Air Marshal who retired from the post of commander in Chief South Western Air Command today said that the Aerostat in Kutch is Helium filled balloon carrying ultra modern radar. He said that this would give IAF great operational advantage since the radar would be able to cross the barrier of direct land vision.

The Aerostat has been imported from Israel and has some US parts also fitted. The balloon goes to the height of about 15,000 to 20,000 ft and this gives aerial view to the radar across the border.

The Air Marshal said that two Aerostat have been imported. The other balloon machine is being installed along Punjab border.

To a question, he said that the war of future will be technology driven war and India was quite equipped for it. To sum it up he said “I can run the war without picking up phone”. We have such Internet and wide area network system, Air Marshal said.

Harry · Post by **Harry** » 03 Mar 2006 14:18

Janes Avionics shows the crappy Blue Fox to be a slotted array radar. Is this accurate or does it really use a cassegrain dish?

Paul Mead?

Sumeet · Post by **Sumeet** » 04 Mar 2006 05:01

Harry,

this is a pic of Blue Fox radar, hope it answers your question.

JCage · Post by **JCage** » 04 Mar 2006 05:09

Sumeet, is that Blue Fox or Blue Vixen?
Looks like it will require a rather large radome which fits in with the Vixen..

JCage · Post by **JCage** » 04 Mar 2006 05:13

Sumeet,

That is the APG -65 on the Harrier 2 Plus (AV-8B ), not the Blue Fox.

http://www.naval-technology.com/project ... rier5.html

Sumeet · Post by **Sumeet** » 04 Mar 2006 05:33

Oh yeah nitin

i realized just now that i made a mistake. I had stored pictures of radars on SHarr. but i got names mixed up and that is why i posted the wrong pic.

anyways i will locating pic for Blue Fox radar.

JaiS · Post by **JaiS** » 04 Mar 2006 14:08

Induction of AWACS

The Operational Requirements (ORs) are being finalized in consultation with Indian Air Force (IAF). Defence Research and Development Organisation has given its technical inputs to IAF regarding the short listed aircraft. Performance trade-offs and optimization of ORs for a complete aircraft have been provided to IAF commensurate with mission requirement.

Modified aircraft is expected to be ready for certification in 24 months. Certification, acceptance and integration of various indigenous Airborne Warning and Control Systems (AWACS) would take another 24 months. Therefore, a fully equipped indigenous AWACS aircraft is estimated to be ready in 48 months from the date of availability of aircraft.

This information was given by the Defence Minister Shri Pranab Mukherjee in a written reply to Shri Milind Deora in Lok Sabha today.

Source: Indian Press Information Bureau; issued March 3, 2006

JaiS · Post by **JaiS** » 04 Mar 2006 14:11

Northrop Grumman to Provide Hellenic Air Force F-16 Fleet with Advanced Capability Fire Control Radar System

BALTIMORE --- Northrop Grumman Corporation has been awarded a $63.9 million contract to provide AN/APG-68(V)9 airborne radars for F-16 Block 52+ aircraft for the Hellenic Air Force.

Northrop Grumman has a direct contract with the United States Air Force for this procurement, which is being managed by the Air Force Materiel Command, located at Wright-Patterson Air Force Base. Delivery of the first of 33 radar systems, which includes three spares, will commence in 2007. The contract also includes an option to provide radars for an additional 10 aircraft.

The AN/APG-68(V)9 radar is an advanced capability system that seven foreign countries have purchased as standard equipment on new F-16s or as upgrade kits for their existing F-16 fleets. To date, Northrop Grumman has delivered more than 250 AN/APG-68(V)9 radars.

The AN/APG-68(V)9 additionally offers a 33 percent increase in air-to-air detection range over earlier versions of the radar and introduces synthetic aperture radar, which provides high-resolution ground mapping. When combined with other weapon-system improvements, it enables F-16s with autonomous 24-hour, all-weather precision-strike capability. The AN/APG-68(V)9 is also available as an easily-installed upgrade kit for existing F-16 aircraft.

Boeing Installs MESA Antenna on First Peace Eagle Aircraft

ST. LOUIS --- Boeing has installed a Multi-role Electronically Scanned Array (MESA) antenna on the first of four 737-700s for Turkey's Peace Eagle airborne early warning and control (AEW&C) program.

The Northrop Grumman-built MESA antenna is the critical sensor aboard the aircraft. It is designed to provide optimal performance in range, tracking and accuracy. Additionally, the radar is able to track airborne and maritime targets simultaneously. The antenna is 35.5 ft. long, 11 ft. high and weighs more than three tons.

Delivery of the four Peace Eagle AEW&C aircraft is scheduled to be completed by the end of 2008.

Paul Mead · Post by **Paul Mead** » 04 Mar 2006 21:19

Blue Fox definitely uses a planar array antenna. I've got a picture from Janes on my disk somewhere.

Paul Mead · Post by **Paul Mead** » 05 Mar 2006 03:00

The Janes Avionics picture is direct from Ferranti, and is also found in Bill Gunston's "Modern Combat Aircraft 13: Harrier".

Its a very lightweight (84kg) frequency agile I band pulse (monopulse) radar derived from the Seaspray. Predicted MTBF of 120h, but nearer 300h (according to Gunston).

It has 4 air to air operating modes;

Search, with a Sector (B-Type) scan or PPI with multi-bar or single bar scan;
Attack, with lead-pursuit or chase in air combat and weapon aiming via HUD in surface attack
Boresight, for ranging on targets of opportunity
Transponder, for identification of friendly IFF returns

It retains ground/sea mapping etc from the Seaspray, I believe.

Harry · Post by **Harry** » 05 Mar 2006 10:24

That's sad because the Blue Fox is overwhelmingly outperformed by older, technologically inferior French and Russian sets. It can track only 1 target and suffers from sea clutter even after a block upgrade.

maitya · Post by **maitya** » 05 Mar 2006 12:26

Dileep wrote:That means this one is the first gen AESA where you just have a TX and LNA on the TX/RX module. Not too much advanced from PESA functionally.

You mean, no Phase Shifter on the Tx/Rx modules ... well, how the hell is it so advanced compared to PESA, then ...

maitya · Post by **maitya** » 05 Mar 2006 12:45

Harry wrote:That's sad because the Blue Fox is overwhelmingly outperformed by older, technologically inferior French and Russian sets. It can track only 1 target and suffers from sea clutter even after a block upgrade.

Being planar array, maybe the sidelobes have smaller values compared to the cassegrain ones. Regarding tracking 1 target only (plus the sea clutter issue), maybe the PSPs and RCs are primitive (compared to the French/Russian sets). But depressing figures, no doubt - then again, whack those MoD babus for taking so long to upgrade the IN Harries with EL/M-2032 ...

Singha · Post by **Singha** » 05 Mar 2006 13:24

EL2052>> existing power supply and radar computer.

the radar computer is just a computer and no doubt the performance will be limited by the existing RC's limit if anyone retrofits. AESA needs more RC power that is well known.

how does its ability to use existing power supply indicate its not a 'proper' AESA ?

if power be limited cant it operate in a lower power mode on EL2032 power supply ?

Israel very well knows unless its a full blown AESA it stands zero chances in export and upg market when nora, amsar, apg-xx and zhuk are all in the fray.

maitya · Post by **maitya** » 05 Mar 2006 16:28

Singha wrote:Israel very well knows unless its a full blown AESA it stands zero chances in export and upg market when nora, amsar, apg-xx and zhuk are all in the fray.

Ummm ... not too sure if IAF is not salivating at the prospect of "Western" (aka non-Russian) PESA in some of it's "western" birds

Betw, must hand-it to you this one - u got it right (1st one in BRF

) regarding the problems of a 650Kg clone (Bars-29) being shoehorned in place of a 360Kg unit for the 29's nose.
So we're back to slotted and planar arrays ...

chan · Post by **chan** » 05 Mar 2006 18:01

India’s quest for fighter could cost losers dearly
By Reuben F. Johnson / Asian Aerospace February 2006
[ex]

[...]
... the requirement that any fighter participating in the competition be equipped with an active electronically scanning array (AESA) radar. “We are ninety-five percent or better confident that having an AESA onboard is going to be a make-or-break condition of bidding on this program–it is the price of admission,” said one Western industry representative familiar with the program.

[...]Lockheed Martin’s venerable F-16 is the most popular aircraft in the region, but as of today only one model of the aircraft is equipped with an AESA, the Northrop Grumman (NG) AN/APG-80 that was developed for the F-16E/F Block 60. If Lockheed Martin were to sell the new variant of the Block 60 to the IAF (called block 70) they would have to pay the United Arab Emirates (UAE) an approximate 7 percent per aircraft royalty, as the desert kingdom funded the development of this configuration and has resale commission rights. Another solution would be for Northrup Grumman to retrofit the AN/APG-80 to the F-16C/D Block 50, making it a “Block 50 double plus” variant, but this involves costs and engineering problems that are not tackled lightly–most notably adding a liquid-cooling system.

[...]
Gripen International officials told Aviation International News that they were briefed here at Changi this week by the visiting chief of the IAF as to the requirements of the soon-to-be-issued tender. Ericsson, which supplies most of the electronics for the JAS-39, is bidding the Not Only a Radar (or NORA) AESA radar, which is supposed to contain some 1,000 transmit/receive (T/R) modules.

[...]The MiG-35 is to be an ambitious leap. It takes the MiG-29 and redesigns its structure, giving the aircraft an all-new digital internal infrastructure, and engines with a 3D thrust-vector control package similar to that of the Su-30MKI. Press releases and public statements on the MiG-35 have also stated that the Russians will not be outdone and will offer an AESA. The dark horse candidate in this case is the Israel Aircraft Industries (IAI) Elta EL/M-2052. IAI is showing this radar for the first time at Changi and although its spokesman will not confirm that the company is bidding with MiG on the Indian tender, it does state that the MiG-29/35 is one of the more near-term possibilities. The model seen here at the airshow is set up for a liquid-cooling system like most other AESAs, but IAI engineers claim that a version of this radar for the MiG-29 would be a smaller array, small enough that it could use an air-cooling system. Liquid-cooling systems can be a maintenance headache, so this is not a small accomplishment on the Israeli’s part.

Read the full article

The Gripen's NORA AESA which is offered also rocks ...
From KPF :

NORA – ACTIVE ELECTRONICALLY SCANNED ARRAY
Ericsson’s future airborne radar is Not Only a Radar, NORA , but also a complete electronic warfare system including jamming and data communication. The new radar will use an Active Electronically Scanned Array, AESA, built up with approximately 1000 individual transmit/receive modules. The antenna, mounted on a single-axis platform, will give well over 200 degree coverage in azimuth. NORA will offer superior performance by virtue of a number of core capabilities at Ericsson – beam agility, beam widening, multi-channel processing, target-specific waveforms and low radar cross-section.

In addtion it also offers :
-High resolution air-to-air and air-to-ground modes
-Outstanding tracking performance
-Comprehensive ECCM
-High Reliability
-Full support for AMRAAM missiles
-Modular construction

MIDIS – MODULAR, MULTI-FUNCTIONAL DEFENSIVE INFORMATION SYSTEM
A new dimension in electronic warfare: MIDIS is a highly modular and multi-functional defensive information system that meets the requirements for situation awareness, survivability and sensor fusion in tomorrow’s dense and complex signal environment. MIDIS introduces new principles for signal selection and adaptive processing allied with state-of-the-art technology of Ericsson’s in-house integrated Microwave MultiChip Modules (MMCM).

^^A new dimension in electronic warfare: MIDIS is a highly modular and multi-functional defensive information system.

MACS – MODULAR AIRBORNE COMPUTER SYSTEMS
Developed for the Gripen fourth-generation multi-role fighter, the Ericsson MACS is a standardized, highly modular multiprocessor real-time computer concept designed for severe airborne environments with their real-time applications. MACS meets all the requirements for demanding airborne situations and provides:

- High real-time performance
- Modular functionality and performance
- Low weight, volume and power consumption
- High reliability

^^Developed for the Gripen fourth-generation multi-role fighter, the Ericsson MACS is a standardized, highly modular multiprocessor real-time computer concept designed for severe airborne environments with their real-time applications.

quote]MOSCOW. Jan 30 (Interfax-AVN) - The MiG-35 multi-role fighter has the best chances to be selected as the winner in the Indian tender on acquisition of up to 200 light future-generation combat aircraft, a source in the international military-technical cooperation sphere told Interfax-Military News Agency Monday.

"Licensing of active phased array airborne radars production to India is the prerequisite for tenderers who wish to be selected. It is exactly because of this condition in the tender dossier that almost all tenderers, who submitted applications initially, refused to continue the participation," the source said.

According to him, the U.S. came with its F-16 & F-18 fighters with an active phased array radar, but is reluctant to issue a license to India for radar production.

The French Mirage 2000-5 does not meet the technical specifications of the tender in full, the source went on. "Only the French Rafale is equipped with an active phased-array radar, is suitable. Moreover, the French are not eager to hand over technologies either," he said.

Sweden's Gripen will most likely fail to satisfy the Indians either, as assembling the aircraft Sweden depends much on very close cooperation with suppliers from other countries.

He also said that the main advantage of the Russian side is the readiness to hand over all manufacturing technologies on the aircraft to the customer.

Its good that AESA is compulsory for the MRCA but are the Russians the only ones willing to transfer AESA technology to us ??

Rafale is going the AESA way as well (to comply with MRCA terms ?) >> link

Ditto for the Eurofighter >> link

Not to mention that UK's Selex has offered its Vixen 500E AESA radars to India for the Tejas and the Mig-35 and Seaspray 7000E 360-degree AESA radar to the Navy.

The 500E :

Check out the Official page of this new lightweight AESA radar >> http://www.selex-sas.com/datasheets/Vixen500E.pdf

The same company also makes the SEASPRAY series of AESA radars - namely the 6500E, 7000E and the 7500E in addition to the Eurofighters slotted array Captor radar. For more info > the official site > http://www.selex-sas.com/pukrad_sas.html

Force Mag reads : "Officials from UK-based SELEX Sensors and Airborne Systems disclosed that the company's X-band Vixen 500E airborne active phased-array fire-control radar, competing against IAI/ELTA's EL/M-2052 AESA radar, is being proposed for both the indigenous Tejas light combat aircraft and the MiG-35, while the Seaspray 7000E 360-degree AESA radar is being proposed for IN's to-be-upgraded 20 AgustaWestland Sea King Mk42Bs as well as for the IN's to-be-acquired maritime surveillance/ASW aircraft, for which Embraer's P-99A and Dassault's Falcon 900MPA are on offer."

Dileep · Post by **Dileep** » 05 Mar 2006 22:13

AFAIS, the Vixen is DDS based system, in contrast with the APG-80 and other(published) american thingies, which are multi channel baseband systems. DDS is as good as the software that drives it. It would be good only if we get the full capability SDK, so that we can put our magic into that. With Amrican system, you need the complete source code to tinker, which will NEVER happen. This one, it would be possible to give a full capability SDK without compromising the basic IP.

I like it already.

kantak · Post by **kantak** » 06 Mar 2006 12:32

Great news about the aerostats .
How can one protect the aerostat whose location will be well known .Like all fixed radar stations on the border they will be prime targets for the PAF in case of hostilities.

Any idea on the induction date for the phalcons?

Dileep · Post by **Dileep** » 11 Mar 2006 04:39

From MRCA thread

SaiK wrote:thanks for that dileep.. i also read AESA t/r modules can be divided into many roles.. a set of t/r modules for scanning, while a set does the jamming. a few of those t/r modules work as RWRs and some are used for X-band communication under a network centric system.

In what way a PESA could not perform these compared to AESA, if both has similar charecteristics? is it only because of electronic scanning that can "selectively" scan for tracking, communicating and jamming etc?

tia

Let me go a little bit deeper into technology here.

It is already explained how the beam is formed by making a number of emitters radiate waves with specific phase relationship. That is transmission. Let us now see reception.

The beam concept is bidirectional. Just like a dish antenna can both transmit and receive, the phased array can also trasmit and receive. All you need is to add the individual received signals with proper phase relationship.

Let us see how PESA works. You have a single high power signal source feeding a number of emitter modules. The emitter module just contain a variable phase shifter and an antenna element (simplified view!). There is no amplification of the outgoing signal. It just changes the phase of the signal. the received signal also pass through the same phase shifter and gats added up at the back.

You can see that you can not split or group the individual emitters in this technique.

In the first gen AESA, you just add active circuitry (amplifiers) into the individual modules. They are still fed with a master signal, because they should be synchronous to each other PRECISELY. This master signal is phase shifted and fed to a power amplifier. the received signal is fed through the phase shifter and combined at the back. The russian AESA projects have this scheme according to available info.

This scheme also can not do multiple roles for the modules, so it do not offer any functional advantage over PESA. However, it improves reliability and power efficiency.

Next improvement is using multi-channel TX/RX modules. Each module can be fed with multiple master signals. One channel can be selected at a time for operation. So, with a four channel system (eg. APG-79), you can form four different beams at the same time. Note that one module can do only one function at a time, so you got to divide up the modules. The received signals also travel back the same way.

Now, THAT PESA can not do. But this scheme makes the TX/RX modules to cost more and ulky.

The second gen AESA (eg Vixen) uses Direct Digital Synthesis (DDS). Here the outgoing signal is NOT from a master. It is generated using DSP techniques. You still nees a master clock, so all the modules are synchronized in frequency and phase. Each module will have DSP and processors and the master RC will talk to them setting up various waveforms and phases.

This scheme can generate any combination of waves, limited only by software. But this has a major problem. that is received signal.

In the previous techniques, the received signals just passed through the same phase shifter and automatically combined with proper phase relationships. The DDS system need to do it using DSP, the same way it generated the transmit signal. So, the received signal is DSP procesed at the module itelf.

In previous models, you do DSP processing at the combined signal, which has more amplitude. Here we have to process a lower amplitude signal, so the signal to noise ratio is much lower. So, the effective sensitivity of the receiver is much lower here. That in fact offset a lot of advantages.

But there are remarkable adantages. You are no longer limited to a single frequency. You can transmit and receive a spread spectrum signal. You can do frequency hopping. Also, you can do a lot better in weapon guiding, where receiver sensitivity is not THAT important.

And the blessing and curse of this system is the dependance on software. You can smarten or dumb down the performance without anyone knowing it. the manufacturer can provide a friendly user country with a software development kit with libraries, so the user country, like India can create kick-ass modes themselves. Or, the manufacturer can do it the Microsoft Way, by exporting a dumbed down library and SDK.

I have not seen any info about any American Radars, (incl APG-77) to have this architecture, but it may be in fact.

And finally, the photos of the AESA modules of DRDO indicate they belong to the last category.

SaiK · Post by **SaiK** » 11 Mar 2006 06:03

good.. and hopefully we will see light at the end of the tunnel (viz testing it on LCA etc). thanks.

Singha · Post by **Singha** » 11 Mar 2006 09:26

one more question, the range of a AESA radar is said to increase (like a telescope) with the diameter of the module array - APG77 > APG80. why is this so ?

also on APG79 type you explained, does a set of modules need to be assigned permanently to one of the four master signals or each module can timeslice the master signal - waiting until the reflection comes back before transmitting the next master signal ?

Dileep · Post by **Dileep** » 11 Mar 2006 10:55

Singha wrote:one more question, the range of a AESA radar is said to increase (like a telescope) with the diameter of the module array - APG77 > APG80. why is this so ?

also on APG79 type you explained, does a set of modules need to be assigned permanently to one of the four master signals or each module can timeslice the master signal - waiting until the reflection comes back before transmitting the next master signal ?

It will not be simply the diameter. More the number of modules, more sharply defined the beam, and more power output and receiver sensitivity. In other words, you can't spread out the existing modules into a larger diameter and expect it to yield better range.

Obviously, I have not seen the block diagram of the APG-79. But theoritically, you don't have to dedicate modules. You feed the four master signals to the modules all the time, and switch the individual channels at the module electronically.

Now, there are some more quirks with the phase shifter approach. The phase shifts are always discrete, normally 4bits = 16 levels. Also, the actual phase shifts depends upon the frequency. The distance between the modules is normally constant, and each module needs a different phase shift for a different frequency. All these makes the implementation VERY complicated. In a phase shifter based system, you can't form a beam at all frequencies at all directions.

DSs on the other hand don't have that limitation. But the design of the software is way more complicated.

No wonder not many people have them

SaiK · Post by **SaiK** » 11 Mar 2006 11:00

mmm.. good point dileep.. no wonder Brits are pissed off at unkill for JSF.. unkill denied the software transfer to brits, and they went eurofarting. brits wants those s/w for their share of $2 billion.

maitya · Post by **maitya** » 13 Mar 2006 10:47

Dileep wrote:From MRCA thread

In the first gen AESA, you just add active circuitry (amplifiers) into the individual modules. They are still fed with a master signal, because they should be synchronous to each other PRECISELY. This master signal is phase shifted and fed to a power amplifier.

This is where I always get lost ... amplifying a signal at the antenna (Tx/Rx module) element is all so fine - but how much is the question. I mean, until and unless it's a super-duper amplifier you'll still require a TWT to feed these amplifiers to get 5Kw (say, and 1 Kw avg) peak power - just a signal generator won't do. Now including a TWT increases the weight ...

Next improvement is using multi-channel TX/RX modules.

How is the multiple channel implemented - just plain ignorant

... using a 4 bit phase shifter (thus theoretically, 16 different phase possible) would have different amplitude but same frequency ... right?? (again am very ignorant

Each module will have DSP and processors and the master RC will talk to them setting up various waveforms and phases.

Each module a DSP

- I mean for a 1500 Tx/Rx module antenna you require 1500 DSPs ... no wonder they're bulky and heavy

and require an a/c to be designed around them and not the other way.

Or is it, you sort of hard-code the number of "bricks" you divide this modules and have dedicated DSPs and processors for each of these bricks.

And finally, the photos of the AESA modules of DRDO indicate they belong to the last category.

What photos saar? Pls share ...

Betw you don't mean the one that Harry posted in the ACIG, do you ...

Dileep · Post by **Dileep** » 13 Mar 2006 11:18

Maitya, each of the module output a few watts of power, and the power output of the modules get added up. So, if each module has say 6 watts typ, and there are 1000 modules, that is 6kW.

The multichannel TX/RX is conceived because of the same reason you mentioned. Each channel has a different frequency. The TX/RX unit can use any of them at a time. So, it makes it possible to form upto 4 beams simultaneously. Imagine four cables bringing in 4 master signals and a 4 position switch feeding the TX/RX circuitry. You can position the switch in any of the four positions.

In order to create the super-duple starterky radar people talk about as if they are available today actually needs a DSP in the TX/RX module. The biggest problem with a phase shifter is, it is frequency dependent. In order to use a complex waveform, you need time shift insensitive to frequency. It is possible only with DSP. Now, you might not need a full DSP processor in the module. You can load the waveform data into a local D/A system in the module and let it run the waveform. The big processing could happen at a main processor.

Now, there is another problem here. You need a very high clock rate D to A converter chip to synthesize the waveform, and they are not easy to come by. You can compromise and do the DSP in an intermediate frequency and upconvert for transmission. But then the capablities will reduce drastically. Probably the Vixen is doing that. But even DDS IF is fantastic technology.

The DRDO photos are from a 2001 article, posted here earlier

http://www.drdo.com/pub/techfocus/june2 ... letech.htm They doesn't confirm they use DDS, but that is my guess.

Paul Mead · Post by **Paul Mead** » 13 Mar 2006 12:08

You can also mix modes together with a mechanically scanned or passive phased array. You do this by interleaving the two modes. The radar does the two different modes one after the other in quick succession, and the radar computer interpolates the data for each mode separately. This is how Bars, RBE2 and Captor are able to work in air/air and air/ground mode "simultaneously".

Singha · Post by **Singha** » 13 Mar 2006 12:32

Methinks the first indian AESA will be the DRDO AEW platform as that permits a larger size and power budget for a starter effort. the second could be a maritime search radar meant for LRMP and helos in a mod below the nose. only the third proj around 2015 timeframe I expect will be a compact fighter aesa by then we should be able to organize help from foreign sources also to get over hurdles in compactness and so on.

the MMR must be completed and can find a permanent place in the HAL AJT after LCA shifts to aesa.

maitya · Post by **maitya** » 13 Mar 2006 14:02

Paul Mead wrote:You can also mix modes together with a mechanically scanned or passive phased array. You do this by interleaving the two modes. The radar does the two different modes one after the other in quick succession, and the radar computer interpolates the data for each mode separately. This is how Bars, RBE2 and Captor are able to work in air/air and air/ground mode "simultaneously".

Couple of years back, didn't the Phaza guys went to the town tom-tomming their "success" about being able to simultaneously (aka interleave) perform AA and AG modes in a slotted array ...
Lost the reference though

maitya · Post by **maitya** » 13 Mar 2006 14:13

Singha wrote:Methinks the first indian AESA will be the DRDO AEW platform as that permits a larger size and power budget for a starter effort. ... only the third proj around 2015 timeframe I expect will be a compact fighter aesa

For that we need to successfully progress from a L-band based to a X-band based Tx/Rx modules (while keeping the weight and cooling-issues down). Not sure, how difficult that is though ... N/Dileep, care to comment!!

the MMR must be completed and can find a permanent place in the HAL AJT after LCA shifts to aesa.

Yep ... agree - you still need to develop the algorithims. Nobody is going to hand them down to us. So, MMR or no-MMR (on LCA), we need to develop it for any future air-borne fire-control radar ...

JCage · Post by **JCage** » 13 Mar 2006 14:21

IMHO, the key issue will be making affordable compact AESA modules- that is where the challenge is.
On the hardware processing side, thanks to COTS and private sector SME's- we can churn out DSP's (using COTS chips), equal to the best available elsewhere.

>>Yep ... agree - you still need to develop the algorithims. Nobody is going to hand them down to us. So, MMR or no-MMR (on LCA), we need to develop it for any future air-borne fire-control radar ...

True! A very basic thing which most ppl forget.

JCage · Post by **JCage** » 13 Mar 2006 14:33

maitya wrote:
Paul Mead wrote:You can also mix modes together with a mechanically scanned or passive phased array. You do this by interleaving the two modes. The radar does the two different modes one after the other in quick succession, and the radar computer interpolates the data for each mode separately. This is how Bars, RBE2 and Captor are able to work in air/air and air/ground mode "simultaneously".
Couple of years back, didn't the Phaza guys went to the town tom-tomming their "success" about being able to simultaneously (aka interleave) perform AA and AG modes in a slotted array ...
Lost the reference though

The Captor claims the same. But actual working folks in the radar/shadar bijnez scoff at these claims. Per them, even the best slotted arrays cant track while scan and provide midcourse guidance to missiles, throughout their scan limits, but only within a subset. Mode interleaving is even harder. But what cn be done is to have very fast scans and then present a unified picture, every x seconds.

Dileep · Post by **Dileep** » 13 Mar 2006 20:10

With PESA, it is only possible to have one mode at a moment of time. But the modes can be changed quickly, so they can be interleaved. What should be noted is that it is the same case even for the first gen AESA. Nothing really wrong with it. It serves the purpose. AESA only offers a better management of the division of resources. It IS division nevertheless.

Regarding L band to X band migration in hardware, I don't think we have any showstoppers to reach 1st Gen AESA capability in hardware. It simply takes time, and a lot of it at that.

And for MRCA activities, I think we should select a good hardware platform, but the deciding factor should be how open that would be for our software? There is no point in getting the super-duper system with thousand modes if we can't write our own DSP and SAR software later.

Bharat Rakshak

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