Cellphone Radar System - Seminar Paper

INTRODUCTION TO RADAR

Surveillance radar is the primary sensor of any modern air defense system. Radar is an electronic system used for the radiolocation or detection of objects by radio wa-ves. The location is achieved by measuring the distance or range of an object from the radar as well as its angular positions, the azimuth and elevation. Radar transmits electromagnetic signals and receives echoes from target objects. Em waves travel at the velocity of light (300.000 km/s).

Distance = speed X time

It works on the principle of DOPPLER EFFECT

i) RADAR EQUATION

The radar equation, also called the range equation, relates the range from which radar can detecfa target to the characteristics of the radar system. It is Useful not only for determining range but it serve as a means for understanding the factors alfecting the radar performance.

b) RADAR CROSS SECTION

I he RCS is the property b\ which an object returns a magnitude of the incident radar signal back to the radar. RCS may be defined as the area of an imaginary perfect reflector, which returns the same magnitude of the incident radar signal as the target or object. Its unit is meter square.

CHALLENGES TO THE SYSTEM

1) ARM (Anti Radiation Missile)

Anti radiation missile fitted with passive seeker, designed to detect radar signals forces the radar to shut down or run at the risk of being destroyed. Although the seeker is of relatively small diameter it has got very high sensitivity. Eventhough the j main beam may not be directed towards the incoming missile, the seeker of modern j ARM is sensitive enough to home on the smaller levels of energy contained in the ; side lobes of the transmitter.

2) JAMMING

Another challenge to the system is the use of Electronic Counter Measure (ECM) by enemy aircraft. This is nothing but a noise signal generated by the target, such that the radar cannot sense the returned echo signal. Thus an anti aircraft system will not be able to look on to the enemy aircraft in order to engage it. Therefore radar can be rendered useless in a tactical circumstance.

PROTECTION OF THE SYSTEM

1) REDUCING THE SIZE

A  bulky transmitter unit will always accompany conventional _ Radar systems.

This makes the system more vulnerable to attack. Inorder to reduce the system size a !

technique known as ACTIVE ARRAY TECHNOLOGY is used. By this method the

antenna is made up of a large number of transmit/receive (T/R) modules. Within each I

module, the T&R modules are mounted physically close to the radiating elements, an i

arrangement that virtually eliminates microwave losses, a typical antenna system will be

made up of several thousands of T/R units, each providing about 10W of power. This

technique also enables the radar operator to electronically steer the beam to the required I

direction. \

2) EMISSION CONTROL

Avoiding detection by ARM: The simplest and oldest technique of countering an j ARM is by strict emission control. This can involve operating the radar only for restricted periods, radiating only in specific sectors and shitting down if an ARM is launched against it.

Adaptive beam formation: This technique allows the radiation pattern of the antenna to be varied as required, matching it to the target and tactical circumstances. Thereby  dramatically  reducing   its  vulnerability  to jamming.   It  overcomes  the ! disadvantages of traditional side lobe cancellation schemes and allows for many jammers to be counted at once.

3) NETWORKINGS

If an air defense system is to practice good emission control yet remain compact effective, individual radar and control centers need to be networked, wherever possible the radar should be supplemented by other network sensors such as passive trackers.

4) MOBILITY

This allows radar to be moved where it is needed in the light of current tactical circumstances, either to cover a new sector of to replace a destroyed system. In the latest generation of surveillance radars emphasis is being laid on increasing the mobility of the entire system. In connection with mobility the most manufacturers define a term known as setup and tear don time i.e. the time it take to deploy.

5) DECOY

Another method of an ARM is to lure the missile with a decoy, able to produce signals that resemble those of the radar being protected. The false signals have to match the frequency, pulse repetition frequency and other features of the radar. The better the j technology in there ARM, the more the realistic the decoy must be. It is not necessary to reproduce the power level of the radars main beam: a lower level will be enough to look like a side lobe.

STEALTH TECHNOLOGY

Stealth or low observable technology is a magic word in the cutting edge military weapons. Able to strike with greater accuracy, stealth aircraft's & worships are virtually invisible to most type of military sensors.

It aims to reduce radar, infrared acoustic.

visual & avionics signatures of aircraft without significantly compromising performance [ range and play load. Low observable aircraft would degrade the adversaries' anti-air

capabilities consisting of variety of advanced sensors, seeker & guided weapons to detect | engage & destroy it both from ground based installations as well as from airborne ! weapon platforms.

Many different components are juggled to make stealth aircraft work. Special radar absorbent materials, unique architecture, color, flawlessly smooth surfaces, concealed engines & ordinance & electronic counter measures all combined to enable stealth aircraft to outfit most current defense systems.

METHODS OF IMPLEMENTATION

The five important areas of aircraft signatures, exploited by sensors and seekers during a compact engagement are radar reflection. IR radiation, and acqoustic, visual &avionic signatures. Among these signatures, except for radar reflection others are self-emissions emanating from the aircraft during its operation. Among these \ve shall be discussion means of countering 2 of the common means of detecting aircraft.

REDUCTION OF RCS

SCATTERING RADAR WAVES: The most widely used method of'detecting an

aircraft is with the help of radar. As most aircraft have a round shape, due to aerodynamic requirements they reflect a part of the incident radar wave. This results in a definite RCS lor a given type of aircraft. This is evident from the figure below.

Stealth aircraft is made up of sharp triangular sheets fitted on to the airframe. This is not favorable to aerodynamic flight. Hence the waves impinging on the surface of the flight is reflected away from the transmitter. This helps to reduce the effective RCS of the craft.

I SING RADAR CROSS-SECTION MATERIALS (RAM):

The reflected signal depends on the impedance match between the surface and the layer. Special materials can be designed to absorb and or attenuate radar reflection from the surface of a target by tuning its complex dielectric permitivity and magnetic permeability. The ideal absorber should therefore comprise of a thin layer of materiel having equal values of permitivity and permeability over wide range of frequencies. By controlling materiel type, thickness, impedances and internal optical design, a variety of RAMs can be designed whose performance can be optimized for a single narrow band frequency, multiple frequencies, or over a wide frequency spectrum. Dielectric absorbers are based on carbon and fcrrite based compound, which are inevitably heavy and bulky.

REDUCTION OF IR SIGNATURE

I Here arc two significant sources of IR radiation from air breathing propulsion system n.tmcK hot parts and jet intakes. By using modern heat image sensors i.e. infrared sensors the difference can be seen between a flying object itself and the surrounding air .In the aircraft exhaust gases are mixed with the cool bypass air by means of a opening at the rear end. I he opening is made of zigzag edges so that incident radar waves are scattered aw a-..

INTRODUCTION

This is a very cost effective means by which a wide-ranging radar system can be implemented. This technique has numerous advantages and has got the unique potential indestructibility. Celldar is even capable of identifying stealth aircraft. This can be easily implemented as cell phone masts, which are already installed by cell phone companies.

CONCEPT OF OPERATION

The basic concept behind how the revolutionary Cell Phone Radar. CELLDAR system operates is described below.

Using Cell Phone Transmissions

The Cell Phone Radar system is a passive system working by using existing transmissions made by digital cell phone base stations. When a target object enters the detection region, these cell phone transmissions are reflected by it and detected at one ore more Cell Phone Radar systems.

Acoustic sensor augment detection

In addition to the reflected cell phone base station transmissions, the Cell Phone Radar also has acoustic sensors to detect noise emissions from the target object This provides additional information to assist in positioning of the target.

Processing Cell Phone Radar Data

The data collected by the Cell phone Radar System is then sent back in real time to a central control system via a communication network. Here the data is processed to determine the position and speed of target.

APPLICATIONS

• Airborne early Warning system
• Traffic monitoring
• Coastal surveillance
• Ground based air defense
• Battlefield reconnaissance
• COASTAL SURVEILLANCE

ADVANTAGES

CELLDAR does not transmit any energy and so its use cannot be detected. CELLDAR provides a low cost solution when compared to its equivalent active radar competitors.

CELLDAR is a multistatic system which means there are many transmitters to enhance radar cross section of targets when compared to monostatic radar. Virtual indestructibility due to large number of cell base stations.

CONCLUSION

The celldar system has enormous potential of becoming the most sought after surveillance technique in the years to come, ll is said that if the X-rays are combined with the system when one can see through walls and buildings thus tracing people's movements down to their homes.