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Acknowledgements

Prepa r ing a p ro j ec t o f t h i s na tu r e i s an a rduous t a sk and I was fortunate enough to get support from a large number of persons to whom I sha l l a lways r ema in g r a t e fu l . I wou ld l i ke t o r e co rd my gratitude to Central Electronics Ltd for allowing me to undertake this project.I would also like to thanks all the respondents for give me their precious time and relevant information and experience, I require which this project would have been different stories.Finally we extend our gratefulness to one and all who are directly or indirectly involved in the

success-Full completion of this project work.

Mahendra Kumar Verma

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CONTENTS

1. Company profile......................................................................41.1. The organisation CEL....................................................41.2. Divisions of CEL...........................................................4

2. Microwave electrionics division................................................52.1. Phase controlled module................................................52.2. Power deviders/combiners.............................................52.3. Hybrid couplers.............................................................62.4. Phase/frequency correlator.............................................72.5. C-band ferrite phase shifters..........................................72.6. X-band ferrite phase shifters..........................................8

3. Railway electronics...................................................................94. Solar photovoltic division.......................................................95. Cathodic protection.................................................................116. Ceramics..................................................................................12

7. Working of phased array radars............................................147.1 phased array antenna.......................................................147.2 possible arrangements.......................................................157.3 linear arrays......................................................................167.4 planner arrays...................................................................177.5 frequency scanning arrays.................................................187.6 phase increment calculating...............................................19

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1. COMPANY PROFILECentral Electronics Limited is a Public Sector Enterprise under the Department of Scientific and Industrial Research (DSIR), Ministry of Science & Technology, Government of India. It was established in 1974 with an objective to commercially exploit the indigenous technologies developed by National Laboratories and R&D Institutions in the country. CEL is one of the rare companies, which utilized the homegrown technologies during all these years of its existence. CEL has developed a number of products for the first time in the country through its own R&D efforts and in close association with the premier National & International Laboratories including Defense Laboratories. In recognition of all these efforts, CEL has been awarded a number of times with prestigious awards including “National Award for R&D by DSIR”.CEL is pioneer in the country in the field of Solar Photovoltaic (SPV) and it has developed state-of-the-art technology with its own R&D efforts. Its Solar products have been qualified to International Standards EC503/IEC1215 by the European Commission, Joint Research Centre, and ISPRA, ITALY. CEL, pioneer in the field of Railways Safety & Signaling, has been identified as a major indigenous agency for design and development of modern electronic Signaling and Safety equipment by Indian Railways. The equipment manufactured in CEL finds extreme usage in Railways in the form of Axle Counter, Axle Counter Block System and Train Approach Warning Devices. CEL’s Digital Axle Counter is approved as per European CENELEC safety level SIL-4 by RDSO (Research, Design and Standard Organization of Indian Railways) as an approved source in Part-I (i.e. approved for bulk production) for various Railway Safety and Signaling Equipments for more than 25 years. CEL has developed a number of critical components for strategic applications and is supplying these items to Defence

1.1 Divisions of CEL 1. Microwave electronics division2. Railway electronics 3. Cathodic protection4. Ceramics5. Photovoltic cells division

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2. MICROWAVE ELECTRONICS DIVISION

CEL has the capability and infrastructure for the design and manufacture of Microwave ferrite phase shifters or Phase Control Modules (PCM) for use in the phased array radars - a capability possessed by very few in the world.

In addition, CEL has also the Software & Hardware capability to design/manufacture DF systems. Phase/Frequency Correlators, Antennas, selected MW Components, such as Filters, Power Dividers/Combiners, Hybrid Couplers, specific MIC/MWIC components in Microstripline/Stripline/Finline geometry, design of ASIC, etc.

Technology linkages have been setup with the following prestigious R&D institutions/laboratories of the country.

Electronics Radar Development Establishment (LRDE), Bangalore. Defence Electronics Research Laboratory (DLRL), Hyderabad. Defence Research and Development Laboratory (DRDL), Hyderabad. Indian Institute of Technology (IIT), Delhi. Solid State Physics Laboratory (SSPL), Delhi. Defence Electronics Applications Laboratory (DEAL), Dehradun.

2.1. PHASE CONTROL MODULE : A Phase Control Module (PCM) forms the core element of the phased array radar that acquires the basic capability of inertialess switching of the RF beam and scanning in minimal time.

The design of C - and X- band phase shifters has been standardised at CEL. In this regard, significant progress has been made on the project in close collaborations with Indian Institute of Technology (IIT), Delhi and Solid State Physics Laboratory (SSPL), Delhi.

Presently, CEL is supplying PCMs to Electronics and Radar Development Establishment (LRDE), Bangalore, for use in the Rajendra Radar.Parameter C Band X BandBandwidth 500MHz 500 MHzRF Power 250 W Peak 150 W PeakSwitching Time 150 ms 150 msInsertion Loss 0.6-0.8 dB 0.7-0.9 dBOperating Temp. 0 to +60 C 0 to +60 CTemp. Stability 0.5 deg/ C 0.5 deg/ CWeight 80 gms 30 gms2.2. POWER DIVIDERS/COMBINERS : A power splitter is a passive device which accepts an input signal and delivers multiple output signals with specific amplitude and phase characteristics. We can design and develop N-port power dividers for any specified band and for given specifications. The dividers being reciprocal

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in nature may be used as power combiners as well.SPECIFICATIONS :Freq.Band Ins. Loss Return Loss Amplitude Balance Phase Balance0.5-2 GHz 0.2 dB 25 dB ±0.1dB ±1º2-8 GHz 0.4 dB 25 dB ±0.3 dB ±1.5º8-18 GHz 0.75 dB 20 dB ±0.5 dB ±2ºDLRL, Hyderabad has transferred the technology for these components to CEL.2.3. HBYBRID COUPLERS : Hybrid, a four port symmetrical device is a special class of directional couplers. Quadrature and 180 deg hybrids are the most commonly used microwave components. We can take up development of directional couplers in a specified configuration for a specified frequency band.SPECIFICATIONS :Freq.Band Ins. Loss Return Loss Amplitude Balance Phase Balance0.5-2 GHz 0.2 dB 25 dB ±0.1dB ±2.5º2-8 GHz 0.4 dB 24 dB ±0.3 dB ±3º8-18 GHz 0.75 dB 20 dB ±0.5 dB ±3.5ºThe basic design for the couplers has been acquired from DLRL, Hyderabad.4.4. PHASE/FREQUENCY CORRELATOR : Frequency correlators are used in systems for measuring frequency, and the phase correlators are used to correlate the phases of two signals of same frequency. Output of these devices are two video signals in quadrature, which correlate the phase/frequency of the incoming signals. CEL has complete production and development base for these devices. The basic design of these correlators has been transferred from Defence Electronics Research Laboratory, Hyderabad.PARAMETER SPECIFICATIONSFrequency Range 0.5 - 2GHz 2 - 8 GHzDeviation from Best Fit Straight Line

±15º ±15º

Input VSWR 2.5 Typ. 3.0 Max 2.5 Typ. 3.0 MaxOutput Video 50mv Min. 50 mv Min.Voltage Levels 300mv Max. 300mv MaxRF Input Power +8 to +12 dBm +8 to +12 dBmOperational Temp. -40ºC to +70ºC -40ºC to +70ºC

2.5. C-BAND FERRITE PHASE SHIFTER

Data Sheet: F0003

Electrical Specification

Frequency Range 5.0 to 6.5 GHz

Bandwidth 10%

Applications

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3-D Air, Ground and Naval Radars

Satellite Beam Forming Networks

Features

Frequency ranges available include S-Band to Ku-Band

High peak and average power designs

Integrated electronic driver Temperature compensation BITE Accurate differential and

insertion phase control Transmit/receive operati

Peak Power 4 kW

Average Power 75 W

Insertion Loss 0.9dB @ 20°C av.

Insertion Loss Modulation 0.25B @ 25°C av.

Return Loss 20 dB

PRF 10 kHz

Phase Accuracy(inclusive of insertion phase)

3° rms

Phase Bits 8

Frequency Bits 2

2.6. X-band dual channel ferrite phase shifter

Data Sheet: F0002

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Electrical Specification

Frequency Range 10.0 to 14.0 GHz

Bandwidth 15%

Peak Power 2 kW (approx)

Average Power 100 W

Insertion Loss 0.25dB max

Insertion Loss Modulation 0.02dB max

Return Loss 25 dB

Phase range 120°

Insertion Phase Shift repeatability between channels

2° max

Phase Dispertion over a 15% bw

1.5° max

Differential Phase Tracking between channels

±4° max

Differential Phase shift variation across operating Temperature range

30° max

Insertion Phase Variation 0.3°/°C max

Power Consumption +24V

Applications

3-D Air, Ground and Naval Radars

Beam Forming Networks Phase element for a Power

Divider or SPDT switch

Features

Frequency ranges available include S-Band to Ku-Band

High Peak and Average Power Designs

Optional Integrated Electronic Driver

Temperature Compensation BITE Accurate Differential and

Insertion Phase Control Transmit/Receive Operation

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600mA av current

Temperature Range

- Operating -15°C to +90°C

- Storage -40°C to +100°C

Connectors Waveguide WR75

3. RAILWAY ELECTRONICS

Electronic Systems GroupThis Unit of the company is a pioneer in the design and manufacture of Railway signaling and safety equipment and other electronic products.The Company is a pioneer in the design and manufacture of Railway signaling and safety equipment on turnkey basis. Various solutions provided include;

Single Section Digital Axle Counter DACF 700 A/ AP™

Salient Features: Track side electronic counting equipment Web type Axle Detector Compatible with 90R 52Kg and 60 Kg rail profiles Detection of all wheels with diameter > 400mm

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Normal operation during water logging on rails Easy to install, commission and maintain

Universal Axle Counter ACS - 55 / 56 / 57

Salient Features: Conventional & low cost Axle Counter Eliminates the need for wooden sleepers Centrally powered battery of 24 V/80 AH Green/Red LED indication for track clear/ occupied status Reset facility for maintenance.

Axle Counter Block System DBS-245B / SBS-247A

Salient Features: Electronic Signaling system for Block proving Last vehicle is checked automatically Line clear by pressing push button on SM Panel Train on Line and Line Closed conditions is achieved automatically Modular design of equipment Easy to install and maintain

Multi Section Digital Axle Counter MSDAC 730

Salient Features: Track side electronic field units Web type Axle Detectors Section wise vital relay output Can monitor upto 40 detection points ESM monitoring panel for maintenance Section wise reset facility

Train Actuated Warning Device - TAWD 62/63

Salient Features: Train detection at remote units for warning Automatic actuation and stopping of warning at gate Warning stops just after train departs LC gate 10 minutes stand by mode operation Data and power to remote units on 1/2 quad cable Solar powered system (24V DC) 100db audio warning to the road user

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Red and Yellow LED signals for road user

4. Solar Photovoltaic Division

The function of this business unit is to manufacture and market Solar Voltaic Cells, Modules and complete systems in India & Abroad. Central Electronics Limited (CEL) is the pioneer and the largest manufacturers of Solar-Photovoltaic (SPV) Cells, Modules and Systems in India. Through sustained in-house development and constant R&D efforts, spread over a decade of continuous efforts, the company has converted a laboratory into an industrial technology.

CEL, with its commitment to harness the solar energy, has opened up new vistas in the field of solar photovoltaic. Backed by an integrated production facility to manufacture Mono-Crystalline Silicon Solar Cells and Modules with the state-of-the-art screen-printing technology, the company has supplied more than 1.5 Lakhs SPV Systems in India and abroad, covering both rural and industrial applications

CEL products conform to stringent National & International Standards. The PV modules are tested to JPL Block V.1981 and European Solar Test Installation (ESTI) Standards. Our modules have been successfully tested by Solar Energy Centre (SEC) of the Ministry of Non-conventional Energy Sources (MNES), Govt. of India and JRC-EC, Ispra, Italy. CEL's Solar Photovoltaic modules are the only ones from India certified both for design and quality by the European Commissionn - Joint Research Centre at Ispra, Italy

o 5.CATHODIC PROTECTION

If your Organization is transporting petrochemicals through underground pipelines, you are probably spending a lot on maintenance costs. Because underground pipelines come into contact with water and water saturated soil which contain salt and oxygen.

Due to this combination, an electro-chemical reaction takes place between metal and surrounding soil, resulting in corrosion of a complex nature. This results in damage to underground pipelines and leakage of valuable petrochemicals that may go undetected for a long time.

Periodic change of pipelines, as a remedy, results in disruption of supply and involves extremely high investments.

CEL supplies Automatic Electronic Cathodic Protection (Anti-corrosion) Systems for the protection of Oil/Gas Pipelines to Organizations like Indian Oil Corporation (IOC), Oil &

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Natural Gas Corporation Ltd.(ONGC), Gas Authority of India Ltd. (GAIL), etc.

CEL supplies the CP Systems with Solar Photovoltaic or Thermo Electric power sources or for operation on Grid Supply.

CEL's cost effective Anti-Corrosion Technology for Underground Pipelines:

Now, CEL brings you the Solar Powered Cathodic Protection System, an impressed current type cathodic protection method that continuously guards underground pipelines against rust and corrosion, in all kinds of soils and weather.

This system forces a continual flow of electric current to pass from the embedded anode through the soil and into the pipeline, thus creating an electric field at the surface of the metal. The result is an invisible shield over the entire length of the pipeline to guard against all corrosive elements, at all times.

This extends the life of the pipeline and eliminates the need for replacement. In addition, the system is solar powered and runs on solar energy which is entirely free! This system also stores the energy provided by the solar photovoltaic cells in a battery bank.

This enables it to provide a continual source of energy, even in remote, unelectrified areas. This makes running costs almost negligible. However, it also compares favorably on investment even when it is worked on A.C. mains.

An added advantage is the fact that since the system is modular it is adaptable to small as well as long sections of pipelines and can be custom-built to fit individual needs.

o 6.CERAMICS

A variety of Piezo ceramics materials based on Lead Zirconate Titanate composition have been standardized for low power as well as high power applications. These materials can be tailor made to various shapes and sizes. To meet customer requirements, CEL's capability in the area of High Alumina up to 99% is planned to be exploited to meet potential large volume requirements of substrates, bearings, bulletproofing etc.

Piezoelectric Ceramics Transducer Elements:

Central Electronics Ltd. has standardized a variety of piezoelectric ceramic materials based on Lead Zirconate Titanate compositions, these materials can be tailor-made to various shapes and

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dimensions to suit individual requirements. The piezoelectric Ceramics Elements made by CEL are already in use in the industry, research institutions and defence establishments.

The major advantage of piezoelectric ceramic bodies is that they have a high electrical to mechanical or vice versa conversion efficiency, Which makes it a versatile material for a variety of transducer applications.

PZT-A is used for low power systems and in other applications where is required high di-electric constant, high voltage sensitivity, volume resistivity and stability over a wide temperature range. It is most suitable for making the low power transducers, acoustic sensing elements, flaw detection probes etc.

PZT-B is used for high power applications where high electro-m3echanical coupling co-efficient and low di-electric losses under high driving field and a high coercive field are essential. This accepts more AC driving field without depoling and is ideally suited for high power electro-acoustic devices, ultrasonic cleaners, high voltage generators, high power sonar, etc.

PZT-C is again used for high power applications. It is an excellent choice when the highest electrical drive is required. Due to its excellent dielectric stability and low mechanical loss at high drive conditions it is used for ultrasonic welding, ultrasonic mixing/dispersion, ultrasonic surgery and some chemistry etc.

PZT-5J is used for low power applications where high permittivity and a high piezo electric voltage constant required. This material is used in fuses, hydrophones and other applications that require a combination of high energy and high voltage output.

PZT 5H is again used for low power applications where extremely high permittivity, coupling co-efficient and piezoelectric charge constant required. It is an excellent material for field flow sensors, level sensors, ultrasonic NDT applications and material imaging applications

MATERIAL CHARACTERISTICS

APHYSICAL PROPERTIES *

SYMBOL PZT -A PZT-B PZT-C PZT-5H PZT-5J PZT-5C

1 Density gm/cc r 7.6 7.5 7.6 7.4 7.5 7.62 Curie Temperature Tc. 320 C 300 C 300 C 210 C 225 C 1803 Mech. Q Qm 85 400 1000 70 70 60B DIELECTRIC PROPERTIES:1 Dielectric Constant at 1

KHzK3t 1600 1250 1000 3250 2600 4200

2 Dissipation factor at 1 KHz

D.F. 0.02 0.005 0.004 .02 .02 .02

3 Resistivity W.cm 10 12 10 12

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C ELECTRO-MECHNICAL DATA:1 Coupling co-efficient kp 0.55 0.52 0.51 0.56 0.62 0.65

K31 0.31 0.28 0.30 0.34 0.37 0.40K33 0.68 0.65 0.60 0.68 0.72 0.70

2 Piezoelectric Charge constant (10 12 Coulombs/Newton)

d33 3.50 2.40 225 580 480 700

3 Piezoelectric voltage constant  (10 -3 volts -meter/Newton)

g33 25 22 25.4 20 20 17.4

D FREQUENCY CONSTANTS:1 Radial Mode (Hz -meter) Np 2000 2200 2340 2000 - 19802 Thickness Mode (Hz-

meter)N3T 1800 1900 2070 1950 1980 1890

* These typical values are provided for design information only. Standard tolerances are +/- 20% of these values measured after 24 hours of Polarization at 25oC.

Piezoelectric Elements

Circular Discs of different diameters to a maximum of 100 cm and thickness upto 15 mm can be supplied.

Frequency Discs available upto 10 MHz Square plates. Cylinders and Rings. Piezoelectric elements for gas ignition. Transducer plates for Electronic Buzzers, Alarms, etc./

o Working of phased array radar

7.1 Phased Array Antenna

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Figure 1: left: two antenna elements, fed with the same phase, right: two antenna elements, fed with different phase shift

A phased array antenna is composed of lots of radiating elements each with a phase shifter. Beams are formed by shifting the phase of the signal emitted from each radiating element, to provide constructive/destructive interference so as to steer the beams in the desired direction. In the figure 1 (left) both radiating elements are fed with the same phase. The signal is amplified by constructive interference in the main direction. The beam sharpness is improved by the destructive interference.

In the figure 1 (right), the signal is emitted by the lower radiating element with a phase shift of 22 degrees earlier than of the upper radiating element. Because of this the main direction of the emitted sum-signal is moved upwards.

(Note: Radiating elements have been used without reflector in the figure. Therefore the back lobe of the shown antenna diagrams is just as large as the main lobe.)

The main beam always points in the direction of the increasing phase shift. Well, if the signal to be radiated is delivered through an electronic phase shifter giving a continuous phase shift now, the beam direction will be electronically adjustable. However, this cannot be extended unlimitedly. The highest value, which can be achieved for the Field of View (FOV) of a phased array antenna is 120° (60° left and 60° right). With the sine theorem the necessary phase moving can be calculated.

The following figure graphically shows the matrix of radiating elements. Arbitrary antenna constructions can be used as a spotlight in an antenna field. For a phased array antenna is decisive that the single radiating elements are steered for with a regular phase moving and the main direction of the beam therefore is changed. E.g. the antenna of the RRP   117 consists of 1584 radiating elements arranged in an analogue beamforming architecture. More sophsticated radar sets use the benefits of a Digital Beamforming architecture.

Advantages Disadvantages

high gain width los side lobes Ability to permit the beam to jump from one

target to the next in a few microseconds Ability to provide an agile beam under computer

control arbitrarily modes of surveillance and tracking free eligible Dwell Time multifunction operation by emitting several

beams simultaneously

the coverage is limited to a 120 degree sector in azimuth and elevation

deformation of the beam while the deflection

low frequency agility very complex structure (processor,

phase shifters) still high costs

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Fault of single components reduces the capability and beam sharpness, but the system remains operational

7.2 Possible arrangements

Linear arrays

Figure 3: linear array of a phased-array antenna

These antennae consist of lines whose elements are fed about a common phase shifter. A number of vertically about each other mounted linear arrays form a flat antenna.

Advantage: simple arrangement Disadvantage: Ray deflection only in a single plane possible Examples given:

o PAR-80 (horizontal beam-deflection) ando RRP-117 (vertical beam-deflection)o Large Vertical Aperture (LVA), an antenna with fixed beam pattern.

This kind of the phased-array antenna is commonly used, if the beam-deflection is required in a single plane only because a turn of the complete antenna is anyway carried out ( RRP-117).

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Figure 4: planar array of a phased-array antenna

Planar Arrays

These antenna arrays completely consist of singles radiating elements and each of it gets an own phase shifter. The elements are ordered in a matrix array. The planar arrangement of all elements forms the complete phased-array antenna.

Advantages: Beam steering in two planes or even the digital beamforming is possible. Disadvantage: complicated arrangement and more electronically controlled phase shifter needed   Examples given: AN-FPS-85 and Thomson Master-A

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Figure 5: frequency scanning array

7.3 Frequency Scanning Array

Frequency scanning is a special case of the phased array antenna where the main beam steering occurs by the frequency scanning of the exciter. The beam stearing is a function of the transmitted frequency. This type of antenna is called a frequency scanning array. The normal arrangement is to feed the different radiating elements from one folded waveguide. The frequency scanning array is a special case of serial feeding type of a phased array antenna and is based on a particular property of wave propagation in waveguides. The phase difference between two radiating elements is n·360° at the normal frequency.

By changing the frequency, the angle Θs between the axis of the main beam and the normal on the array antenna changes. Height information is generated using the following philosophy:

If the transmitted frequency rises then the beam travels up the face of the antenna; If the transmitted frequency falls then the beam travels down the face of the antenna.

As frequency is varied, the beam axis will change, and scanning can be accomplished in elevation. The radar set is designed so that it keeps track of the frequencies as they are transmitted and then detects and converts the returned frequencies into 3D display data.

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7.4 Phase increment calculating

Note that frequency scanning reduces the value of using frequency change as a means of achieving other valuable effects (benefits of pulse compression).

The phase shift Δφ between two successive elements is constant and is called phase-increment. How large is this phase shift to reach a certain value of the beam steering?

A linear arrangement by isotropic radiating elements is looked at.

Figure 6: grafic derivation of the formula

Example given:

A radar set works with a wavelength of λ=10 cm. The distance between the radiating elements is 15 cm. We can neglect the propagation time differences by the feeder.

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The beam steering shall be Θs= 40°.

Task: Which value shall have to have the phase shifter no. 8 (on the left side) to get this beam steering?

We start with the calculation of the phase-increment. Because of the trigonometrical function we need a calculator anyway: Δφ =(360°·15 cm/10 cm)·sin(40°) = 347.1°.

This means the radiating element no. 8 needs the phase shift value φ8  = 7 · 347.1 = 2429.7°.   On reason of the periodicity of the sine function a phase shifting of n·360° is the same as 0°. Therefore we can as long as deduct 360° till there is a angle between 0° and 360° of the result. We get therefore for the phase shifter number 8 (left corner) a phase shift value of φ8 = 269.7°.

A part of this phase shift is realized by the delay in the feeding line yet.

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