Intelligent Jamming Solution to Defeat the Growing Menance of Remotely Controlled Improvised Devices (Rcieds) Using Electronic Counter Measures

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Intelligent Jamming Solution to Defeat the Growing

Menance of Remotely Controlled Improvised Devices

(Rcieds) Using Electronic Counter Measures

Prof. G. Kumaraswamy Rao

Former Director DLRL DRDO Hyderabad

Director R&D, BIET, IB Patnam

Prof. Kaluri V Ranga Rao

Professor Emeritus JNTUH Hyderabad

Abstract–Radio Controlled Improvised Explosive Device (RCIED) has become a powerful weapon in the hands of Insurgents fighting an Asymmetric war. In the Afghanistan and Iraq war increasing number of IEDs are causing 60% to

65% of war casualties in terms of soldiers’ lives and military

equipment. The use of IEDs and RCIEDs have percolated to civilian sector. It is estimated that 80,000 innocent civilians lost their lives and 1.5 lakh persons were fatally injured due to IED/RCIEDs in last 5 years. USA alone has spent 12.5 billion dollars (INR 75,000 crores) in last 3 years on research to mute RCIED explosions.

In this article the genesis of IED/RCIED, its proliferation to civilian areas will be presented. The methods and technologies to prevent/mute RCIEDs their inadequacies will be discussed. A new approach for an intelligent jammer is presented along with detailed hardware block diagram. It uses an elegant, simple scheme for time synchronization of multiple jammers.

In this paper, calculation of jammer power vis-à-vis the maximum jamming ranges achievable are modeled and computed when the insurgent is using a Thuraya (GEO) Satellite Phone.

Keywords – ECM, Jammer, RCIED, Thuraya Satellite Phone.

I. I

NTRODUCTION

In today’s world IED (Improvised Explosive Device) is a dreaded weapon in the hands of insurgents, terrorists and anti law elements, naxalities etc. It is feared by organized governments, law enforcing agencies, armed forces, and innocent civilians. IEDs have become one of the main cause of deaths among military troops and taking a heavy toll of lives of innocent civilians in urban areas. Statistics shows in Iraq 63% of coalition forces death occurred due to IEDs/RCIEDs (Remote/Radio Controlled IEDs). In Afghanistan 66% of troops died due to IEDs/RCIEDs. IEDs not only killed thousands of military personnel but maimed or injured tens of thousands of troopers. IEDs blasted trucks, armoured vehicles and tanks into pieces. IEDs placed in urban areas by insurgents at busy populated junctions, killed large number of innocent civilians across the world, and many fold in number of civilians were maimed due to permanent loss of limbs . The number of IED explosions across the world daily soared from single digit to double digit. Governments across the world have been spending huge amount of money to devise methods to prevent explosions. USA alone has spent more than 12.5 Billion dollars in past 3 years on research of countering IEDs. And so far there doesn’t appear tobe an effective reliable way of stopping

IEDs. It is an irony that IEDs are built from primitive technology, but demands high complex technology methods for preventing them from explosion.

A. Why IEDs are preferred by insurgents

In an Asymmetric war between the insurgents / terrorists and organized nations, the insurgents know that they cannot defeat a technological far superior advanced military force, they are numerically outnumbered, they have a poor financial support and a ill equipped organization.

Insurgents resort to use of IED[3]. They want the moral confidence and political will of the governments to be sapped. They need the propaganda glare of visual and print media to sustain their existence.

B. Advantages of IEDs

IED has tremendous advantages. It is easy to make, easy to obtain explosives, ready availability of components used in IED construction, relative ease of technology with which one can make IED, and nature of free society. It is light weight and very cheap to assemble. IEDs when exploded in busy urban areas cause maximum number of deaths and casualties creating psychological scare among civilian population. Implanter of IED in most cases is undetected, unpunished, as such more and more terrorists are emboldened to lay IEDs at public places.

C. Definition of IEDs

“An IED is a home made bomb constructed and deployed in improvised manner (provide from whatever materials at hand), incorporating destructive, lethal, pyrotechnic or incendiary chemicals and designed to destroy or incapacitate personals or vehicles”.

“An explosive weapon not originated from an industrial production line may be classified as an IED”.

D. IEDs Vs LAND Mine

:

Many a times IEDs and Land Mines are grouped together. However they are different. Land mines are laid to prevent soldiers, vehicles and tanks to cross a particular area or region. They may remain there for long time sometimes for years. An intruder, a foot soldier or a vehicle/tank may step on to a landmine causing it to explode and thereby killing the soldier or damage the vehicle/tank. Landmines are used only by military. They are manufactured in factories meant for them.

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II. H

ISTORICAL

D

EADLY

IED A

TTACKS

A. 21 May 1991:

At Sriperumbudur in Tamil Nadu Ex. Prime Minister of India Sri Rajiv Gandhi was killed along with 14 others, in a suicide IED attack.

B. 19 April 1995:

At Oklahoma in USA, the IED bomb killed 169 civilians. Ammonium Nitrate fertilizer and nitro methane were used in the blast.

C. 11 March 2004:

Madrid (Spain) Train Attack: 10 IED explosions rocked through 4 commuter trains. 191 persons died and more than 1800 injured.

D. 7 July 2005:

London bombings: 52 people perished in the IED blasts in a series of controlled attacks in London Transportation Systems. 4 suicide bombers took part in this ghastly carnage.

Recent IED attacks:

21 Feb 2013:Hyderabad Dilsukhnagar 17 civilians died.

15 April 2013: At Boston USA, 3 persons were killed, many were injured. Explosive was put in a household pressure cooker.

III. P

RINCIPLES OF

IEDS

A.

An IED is triggered by the firing system. Ex: a pressure plate, mobile phone, radio, command wire, timer etc. A signal is sent to the initiator which activates the main charge (eg. artillery, grenades, mines, home made explosives, combinations of several explosives). The whole system is powered by a power source. (ex. car battery)

Fig.1. Components and Principles of IED Switching

Fig.2. IED Simplified Definition

B. Components used in IED are given below:

1. Detonator, 2. Main charge (explosive), 3.Initiation mechanism (switch), 4. Power source, 5. Container.

Nails, glass, ball bearings, metal fragments, rocks etc. added to increase the effect of explosion at long distance and cause maximum damage and destruction.

C. Damage caused by an IED

IEDs cause damage due to the following phenomenon. a) IED explosion causes a powerful shock wave. Since the combustion (deflagration) energy is very high the shockwave is created.

b) Explosion causes the components like nails, ball bearings, rocks to travel far away with large kinetic energy. This is called defragmentation.

c) The oxygen required to oxidize the combustible substance is present in the chemical compound.

D. Detonator

Main Charge (explosives) like TNT, Ammonium Nitrate (agriculture fertilizer), PEA etc. is chemically stable, less sensitive with very high density and low atomic number. They are safe to handle and do not explode if accidentally dropped . Main charge requires additional primary explosive charge to explode. This additional explosive charge is called the detonator. Detonation system is the mechanism that initiates the primary explosion to set off the main blast viz. Blasting Cap.

A blasting cap contains an easy-to-ignite explosive that provides the initial activation energy to start explosion in the main charge which is more stable. Blasting cap is set off by a short burst of current. Blasting Cap is stored separately and not inserted into the main explosive charge until just before use, keeping the main charge safe. Explosives commonly used in blasting caps are mercury fulminate, Lead dioxide, lead styphnate and terly.

E. Main charger (Explosive):

The main explosive used are:

a) Salts containing chemical groups with oxygen, mixed with combustible substances like carbon, hydrogen compounds. Ex. Nitrates, chlorates, perchlorates etc. b) Commercial available or home made organic

substances with nitro, nitroxy, nitramine groups. c) Peroxides

d) Above mixtures with commercial or military explosive.

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F. Initiation Mechanism:

The initiation mechanism is the switch which triggers the primary explosion. The switches are categorized into 3 (three) types namely (i) Electrical, (ii) Mechanical and (iii) Miscellaneous. Large varieties of initiation mechanism are used as triggers. They are a) Anti handling b) Delay c) Ambient and d) Command.

Anti handling initiation mechanism use the phenomenon like (i) Pressure, (ii) Pressure release, (iii) Pull, (iv) Pull / Release, (v) Tilt, (vi) Anti penetration, (vii) Lift, (viii) Pendulum, (ix) Tension etc.

Delay switches are based on the devices (i) Mechanical Timer, (ii) Clock/Watch, (iii) Quartz Watch, (iv) Electronic Timer, (v) Pyrotechnics, (vi) Thermal, (vii) Electrochemical, (viii) Chemical etc.

Ambient switches are based on (i) Temperature, (ii) Smoke / Gas, (iii) Sound, (iv) IR Rays, (v) Proximity, (vi) Humidity, (vii) X rays, (viii) Light etc.

Command switches are (i) Car Remote, (ii) Cordless Bell, (iii) FM Radio, (iv) Command Wire, (v) Aero modelling etc.

Based on the method used Initiators can be categorized as a) Command Wire b) Victim Operated c) Vehicle Borne d) Radio controlled (RCIEDs).

Types of devices used for RCIED are shown in fig. 4..

Fig.4. Remote Controlled Initiators

G. Power Sources:

The power source is required to provide the electrical power to the IED. Various power sources used are

(i) Car Batteries (ii) Storage Batteries

H. Containers:

Types of containers, shape of containers in which the IED is placed. Plays an important part on the effectiveness and lethality of the blast. IED bombs uses as containers (i) Steel or plastic pipe sections with caps. (ii) Belt with bags filled with explosive (iii) Vehicle Bomb (iv) Service mail

packages (v) Containers like fire extinguishers, propane bottles, trash cans, gasoline cans etc.

Container used for IEDs is shown in fig. 5.

Fig.5. Pressure Cooker Container recently used in IED explosion at Boston USA.

IV. C

ATEGORIZATION OF

IEDS

A. IEDs categorized by its usage:

(i) Military: Insurgents, guerillas, rebels etc use IEDs to kill or injure soldiers, destroy armoured vehicles, damage tanks etc.

(ii) Civilian: Disgruntled groups, religious fundamentalists use IEDs to kill innocent civilians to create insecurity in the minds of population.

(iii) Carrying by person: IED components are transferred from one place to another for assembling through airports, bus & train stations.

(iv) Suicide Bombers:

1. Personal Suicide Bombers use IEDs to kill a VVIP 2.Vehicle mounted explosives driven into strategic

important installations. These are called vehicle borne IEDs (VBIEDs). These carry large amount of explosives and causes larger explosions.

B. IEDs categorized by its trigger methods:

(i) Timer uses pocket watch or Electronic Timer.

(ii) Remote Controlled IED (RCIED) users door bell, garage door opener, car key, long distance remote phone, cell phone etc. (iii) Infrared (counter measure for Electronic Jamming). (iv) Pressure sensitive bars, (v) Trip wire, (vi) Activation by suicide bomber either by pulling or releasing tension.

(vii) Changing physical conditions like temperature, pressure, light, sound, magnetic field etc.

C. IEDs are categorized based on explosives:

(i) Artillery shells used by military.

(ii) Conventional high explosive charges. (iii) Home Made explosives etc..

D. IEDs categorized based on composition of

explosives:

(i) Chemical (ii) Biological (iii) Radio active (dirty bomb). (iv) Chlorine (v) liquid explosives.

E. IEDs categorized based on containers:

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F. IEDs categorized based on purpose:

(i) Military: Designed for armor penetration by using shaped charge, or an explosively formed penetration. (ii) Anti personnel: Contain fragmentation generating

objects such as mails, ball bearings, rocks to cause death and injury at greater distances other than blast pressure alone.

V. T

ACTICS USED BY

I

NSURGENTS

IEDs are placed in mud, road corners, soft drink cans, animal carcases etc. IEDs explode underneath or to the side of the vehicle for maximum amount of damage. However as vehicle armour is improved IEDs are placed at elevated places, such as road sides, utility poles, trees etc.

VI. D

ESTRUCTION OF

IEDS

IEDs discovered before it is exploded need to be handled by trained personnel only. In most cases because of varieties of explosives, unexploded destruction is very dangerous. Before an IED is transported, firing mechanism should be separated from main charger. RCIEDs need to be handled by remote controlled robot. To collect the sample of explosive for finding the composition of Explosive, Robot is used. IED is destroyed by forced detonation if it is not possible to separate the firing circuit or IED should be burnt at a suitable place. To reduce the environmental stresses caused by detonation, underwater detonation is recommended. Explosives composing of water soluble ammonium nitrate etc. may be treated by water. Other organic IEDs are treated by suitable solvents.

VII. N

EUTRALIZATION OF

IEDS

Design and construction of IED is unknown. Standard disposal methods used in demining may be inapplicable (if IED is equipped with timer. The process is highly dangerous). Detonators and triggering mechanisms of IEDs may be unreliable and can be initiated at an unpredictable time. IE used may be unstable, i.e. sensitive to external influences like shock, temperature etc.

VIII. P

OST

E

XPLOSION

A

CTIVITIES

Residues of the IE, its traces should be analyzed using mass-spectrometry and Trace Analysis. This information is preserved for future to identify the insurgent group and build the data base.

IX. F

IRING

P

LACE

R

EGULATIONS

The firing place regulations are given in the below table. Table 1: Firing Place Regulations

Amount of Explosive (kg) Distance (m)

< 2.0 45

2.0 - 4.5 55

4.5 - 9.0 70

9.0 - 13.5 80

13.5 - 18.0 85

18.0 - 25.0 95

The mentioned distances do not include a protection against fragments of explosion.

X. T

ECHNOLOGIES USED

I

N

D

ETECTION OF

IEDS

A. Detection of IEDs

(i) With so many varieties of IEDs, it is an open question if suitable detection methods would ever be available (ii) Advantage of these explosives is that they are either commercially available or can be produced at home in a simple way.

(iii) Knowledge about how to produce explosives are available from different sources like (a) Anarchist Arsenal, (b) Black Book, (c) Home made detonators etc.

(iv)Unlike military explosives like TNT, RDX, PETN the range of possible combinations for IEDs are very large (exceed 200). Each has its own chemical characteristics, so detection becomes extremely difficult.

B. Difficulties in Detection of IEDs

Detection of Explosive is very complex due to the following:

(i) It is impossible to foresee in advance where the IED will be found.

(ii) Triggering mechanism is unknown

(iii) Since IED cannot be touched or moved, detection and disposal equipment has to be moved to the site.

(iv)Since IED and Triggering mechanism is highly unpredictable, analysis can be carried out only from a distance that too by robots.

(v) If IED is placed very near to the wall in the corner or in between obstacles, detection should work with one-side access..

C. Methods used in IED Detection

IED Detection can be grouped into 2 categories. (i) Bulk Detection Methods

(ii) Vapour Detection methods

(1) Bulk Detection of Explosives:

This is done by viewing images made by X-Ray scanners. There are 2 varieties in this group:

(a) Detection of non-explosive components (detonators, triggering mechanisms, metallic shells, electronic circuits). (b) Detection of explosives: X rays have high penetrating ability (2-3 cm steel. X rays have high special resolution (10-20 micro mt). X rays allow detailed images. However X–rays require access from 2 sides.

(2) Other Methods of Bulk Detection

Other methods for Bulk Detection are:

(i) Neutron methods (ii) Electromagnetic imaging. (iii)γ – rays etc.

Bulk detection is not used for scanning of person, as it is a health hazard.

(3) Vapour Detection Methods:

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from the explosives.

(4) a) Single energy X-Ray systems:

These are used at airports. This may not detect the explosives but can identify the control wires, batteries, detonators and other components of bomb.

b) Dual Energy X-ray systems

Principle lies in determining 2 different attenuation coefficients. Atoms of higher and lower atomic number are detected like metals (Dense elements) food & clothes (less dense elements)

c) Crompton Scattering:

Explosive have low atomic number (high density energy of a scattered proton is determined by wavelength of incident photon and scattered angle).

Volatility is characterized by concentration of saturated vapours near surface of explosive. Different explosives have different volatile characteristics. Appropriate sensors are used to trace out the characteristics. Output of sensors is compared with stored characteristics of explosive and name of explosive declared.

XI. S

ENSORS USED FOR

V

APOUR

D

ETECTION

(i) Electronic nose:

This consists of a chemical sensing system. Each vapour has a signature (finger print). Pattern recognition electronic techniques are used to identify the signature presented to a database and the particular explosive is recognized.

(ii) Optical Sensors:

When light falls on the matter, a particular chemical composition is found on the air. This has a particular spectrum which is recorded and analysed. Promising technologies are (a) Ultraviolet visible – near infrared spectroscopy, (b) Laser induced fluorescene, (c) Photo Acoustic spectroscopy.

(iii) Biological Sensors:

Biological Sensors that are capable of detecting explosives are a) Dogs b) Rats c) Bees d) Antibodies. Trained dogs are capable of finding many industrially produced explosives. Dogs are trained to detect, a limited number of explosives commonly used, and they are useful in large cities. Rats and Bees are used in country side. [2]

(iv) High Power Laser Vehicle:

Fig.6. Soldier worn buried bomb detectors

M/s Cassidian has developed a Laser Vehicle to detect the explosive from a distance High power Laser induces acoustics. The characteristics of the acoustic is different for different explosives. This characteristics is used to identify the explosive. The vehicles provide stand-off capability to neutralize IED threats. [6]

Recently soldier worn buried bomb detectors also are developed.

XII. E

MERGING

IED D

ETECTION

T

ECHNOLOGIES

Detection of IED is a very difficult task since there are innumerable number of varieties of explosives and triggering mechanisms. Bulk detection techniques are convenient and preferable for IED detection in airports etc. For inspection of people electromagnetic methods are preferable since they are safe for humans and electrical appliances. Vapour Detection is effective for conducting general monitoring over large area for extended period of times and for detecting roadside bombs.

XIII. J

AMMING OF

RCIED (R

EMOTE

/ R

ADIO

C

ONTROLLED

IED)

(i) What is a RCIED ?

IED is exploded by a trigger. If the trigger is generated using a Radio Transmitter and Receiver link, it is called RCIED. The link between the insurgent and the IED is wireless.

Main advantages of RCIED are (a) More effective, accurate and precise bombing is possible so this causes more destruction (b) Absence of wire gives insurgent autonomy while maintaining control. (c) Since the insurgent is far away from the scene of explosion, safety to the insurgent is ensured (d) No possibility of being apprehended by Law Enforcing authorities during the operation.

XIV

. C

ATEGORIZATION OF

I

EDS

B

ASED ON

T

RIGGER

Trigger to the IED can be (a) Event Based (b) Remotely controlled

A. Event Based:

The events that triggers the explosion can be by 1. Setting alarm time in a watch, 2. Pressure actuated, 3. Trip wire by the victim etc.

B. Remotely controlled (RCIED).

Command to generate trigger from a distance comes from commercially available electronic devices. In earlier times, the initial threat came from Low frequency devices namely (i) Garage Door Openers, (ii) Car fob keys, (iii) Radio controlled toys, (iv) Car alarms, (v) Wireless Door bells etc. However the recent threat points to the use of devices like 1. Long Range Cordless Telephone (LRCT), 2. Cell Phones, 3. Satellite phones etc.

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Fig.7. Electronic devices built into an RCIED threat

XV. P

REVENTION OF

RCIED E

XPLOSION

There are 2 ways to prevent destruction caused by RCIEDs. 1. Predetonation by scooping 2. Jamming/ Mitigation of RCIED. [1]

A. Predetonation by scooping

All the trigger devices used by insurgents are available in commercial market. As such the protocols of digital codes etc. are known. If due to any reason a RCIED remain unexploded, it needs to be deactivated by separating the trigger circuit. In view of high risk involved robots are used for this purpose. If removing trigger device is not possible, IED has to be predetonated by sending the required code and frequency from a distance. This is called scopping. Since the code and frequency is known for the device used which is obtained from commercial data sheets. Before predetonating the area surrounding the RCIED is sanitized and cordoned off and Bomb Disposal Squad wear protective clothing.

B. Jamming / Mitigation of RCIED.

This method is more effective and efficient. This is mostly used for protection of vehicles or convoy of vehicles. For protecting the convoy of vehicles more jamming power is required compared to protection of a single vehicle. Every jammer will have a particular circular radius around which jamming is effective. Jamming power determines the maximum distance of influence of jamming. As long as the jammer is on, the protection is ensured.

C. Difference between ES (Electronic) Jamming and

RCIED Jamming

: [4]

(i) Response time permitted in EW jamming can be longer, whereas the response time of RCIED jamming is very short, because the trigger needs to be blocked before the transmitted information activates the trigger to cause explosion. This can be only 1–10 milli secs.

(ii) EW detection is more sophisticated and equipment bulky and costly. This is because the transmission and its modulations are quite unknown. In a RCIED jamming, since the devices used are from commercial market, their frequencies, modulations etc. are known. Tuning requirement is much simpler.

(iii) If the RCIED jammer response time is not fast, it can not mute the IED.

(iv) Duration of jamming transmission is dependent on speed of vehicle, which leaves the danger zone in a few seconds.

XVI. C

RITICAL

D

ESIGN

C

ONSIDERATIONS FOR

A RCIED J

AMMER

(i) Since RCIED uses commercial transmissions, knowledge about their frequency, modulation etc. are known. Tuning requirement of jammer is relatively simpler.

(ii) Two timing parameters are very critical to RCIED jamming.

a) Maximum delay time between initiation of enemy's transmission to start of jamming. This should be less than 1 to 10 milli secs in many cases.

b) Duration of jamming should be such that efficient jamming is possible in a synchronized manner. Jammer should jam atleast 30% of enemy’s transmission.

(iii) Jamming power in the required band should be such that a reasonable distance between jammer and IED is ensured. Jammer power should considerably degrade the S/N ratio and increases the BER (Bit Error Rate). Present day digital systems are more tolerant to jamming since they use anti jamming techniques like spread spectrum, error correction codes etc.

(iv) RCIEDs uses commercial available electronic devices. Unfortunately these devices are operated at different frequencies and it occupies a large part of EM spectrum. The jammer is required to jam all these frequencies since the device used by insurgents is unknown.

XVII. T

YPES OF

J

AMMING USED FOR

RCIED

RCIEDS are extremely diverse in design and may choose to employ a trigger technique from the umpteen number of devices available. This encompasses the widest range of spectrum namely 20MHz to 3000 MHz. This makes the job of jammer extremely complex and difficult. The various techniques that are available for jamming are (i) Tone Jamming, (ii) Barrage Jamming (iii) Swept Jamming (iv) Pulse Jamming (v) Smart Jamming or Reactive Jamming (vi) Follow on Jamming

The most popular and effective way used in case of RCIED jamming is Barrage Jamming. However because of number of disadvantages in Barrage Jamming the modern trend is to use smart / reactive jammers.

The jamming effectiveness is related to the jamming (J) to Signal (S) ratio also called JSR, (db).

JSR = ERPJ–ERPS–LJ+ LS+ GRJ- GR

Where ERPJ = Effective radiated power of jamming station in dbw

ERPS= Effective radiated power of insurgent’s Txsignal in dbw.

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dBi

GR= Bomb Rxantenna gain in the direction of Insurgent’s Transmitter.

Fig.8. A typical configuration for location of insurgent’s Tx, Bomb Rxand Jammer

XVIII. B

ARRAGE

J

AMMING

A.

Since the insurgents use a wide variety of trigger devices at different times and different places, the integrated jammer need to take into consideration all varieties of devices used. Some of the trigger devices used by insurgents are:

(i) Keyless Automobile Door Openers, (ii) Remote Controlled Toys, (iii) Wireless Doorbell Buzzer, (iv) Ciizen Band Radio, (v) HF / VHF /UHF Trans receivers (Walkie-talkies), (vi) Cellular / Mobile Phones, (vii) Satellite Phones.

The range of spectrum of frequencies used is given in the table below: [5]

Table 2 Range of spectrum of frequencies used

The carrier frequency of jammer is modulated by a noise wave form whose spectrum bandwidth is very large. Since the triggering device used by the insurgents in unknown, the frequency spectrum is spread. The trigger to the bomb receiver is thus countered. The bandwidth of modulating noise is made large enough to encompass the whole of band of frequencies used by the trigger devices. The frequency spectrum of a barrage jammer need to be from 20 MHZ to 5 GHZ. Since no amplifier is available with such a wide bandwidth, the frequency is divided into three sub bands. It is further subdivided into macrobands

i.e. (i) 20–100 MHZ, (ii) 100–176 MHZ, (iii) 176–400 MHZ, (iv) 890–960 MHZ(GS), (v) 1710–1880 MHZ (DCS), (vi) 1920–2170 MHZ (CDMA), (vii) 2400–2500 MHZ (Wi-Fi). This will increase the jammer effectiveness by increasing power per HZ.

B. Disadvantage of Barrage Jammer:

(i) Since the frequency used by the insurgent is not known, all frequencies need to be jammed. This requires huge amount of power and jammer size becomes unwieldy.

(ii) In order to increase the area of operation of effective jamming, requirement goes up to increase the power and thus the size and weight of equipment goes up. (iii) Barrage Jammers interfere with so many frequencies.

Hardly any wireless device function, until the vehicle protection jammer passes out of the zone. This may severely impede with emergency health calls and communication with or from the jammer vehicle is not possible i.e. friendly communication is cut off. The above limitations made to search for new techniques. Smart/Reactive Jammer is one of the technologies

XIX. J

AMMER

R

EQUIREMENT FOR

RCIED

U

SING

T

HURAYA

S

ATELLITE

P

HONE

In the simulation example given, the jamming power Vs Maximum Effective Slant Range of Jamming area for J/S ratios of 0, 3, 10dB is modeled and computed. The table and graph shows the Jammer power Vs the Maximum Slant Range.

A. Calculation of power required for the downlink

link jamming of a PCS (Personal Communication

Satellite) Thuraya

Thuraya is one of the Personal Communication Satellite available to civilian use. At present it is a regional Satellite catering to Middle East and South Eastern Countries including India. In the 26/11 carnage at Mumbai, terrorists used the Thuraya satellite phones to talk to their masters. Its head office is located in Dubai. These satellite has GEO orbit and as of now three satellites were launched. Communication to Sat-phone is through L band and Satellite to Gateway works in ‘C’ band.

Satellite Parameters

# Maximum power of SSPA = 17 watts

#Antenna is a huge Mesh of dimensions 12.25 mts x 6 mts # Has 250 to 300 spot beams

# On board signal processing = 48 dB # FDMA Carrier Channel BW 27.7 KHZ # Channel bit rate 46.8 KBS (QPSK used) # Each spot beam covers 450 Kms in diameter

Satellite Phone Parameters

# Frequency:1616–1626.5 MHZ (L Band) # Time Division Duplexing

# TDMA/FDMA, GSM # Power 0.57 watts average # EIR P 1.9 dBW

# Sensitivity -117.9 dB

Type of Device Frequency Range Max. Power

Output Citizen Band

Radio

26 to 28 MHZ 12 W

Radio controlled Children toys

27,35,40,49,72, 75MHZ 2,4,5.0 GHZ

100 mw RC Car FOB

Keys

300 to 315 MHZ 430 to 450 MHZ 860 to 870 MHZ

50 mw

Cordless Telephone

1880 to 1900 MHZ 1920 to 1930 MHZ

250 mw

GSM 824 to 894 MHZ

880 to 960 MHZ 1710 to 1880 MHZ

500 mw

Satcom Phones 1626.5 to 1660.5 MHZ

1525 to 1559 MHZ

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Downlink Budget

# Pt = 17 watts = 12.30 dBW

#λ = C/f = (3x108)/1.6x109) = .1875 mt #Gt = 4ΠAe/ λ2= 4Πx12.25x16/ λ2= 48 dBi #Path loss = (4ΠR/ λ)2

= 20 (Log 4x3.14x35.786x103/ .1875)

# Processing gain (FEC+Emphasic+weighting) = 8dB # Gr Satellite Phone Antenna = 5 dBi

# Pr = Pt+Gt+Gr–Path loss + Processing Gain = 12.3+48+5-187.6+8 = -114.3 dBW

Jammer Power & Maximum Distance from the

Satellite Phone (IED bomb)

Pj = Jammer Power = 10 watts (10 dBW) Gj = Jammer Antenna gain = 0 dBi

Gr = Satellite Phone off Axis antenna gain = -5dBi Path loss = 20 log 4ΠR/ λ = 20 Log 67 R

Power Received at satellite phone = 10-5-20 log 67 R But J/S = 1 (0dB)

-114.3 = 5-20 Log 67 R So Rmax = 13.7 KMS

Jammer power required for thuraya down link jamming is given in the below table

Table 3: Thuraya down link jamming Jammer

Power

Max. slant Range for J/S=1 (0dB)

Max. slant Range for J/S=10dB

Max. slant Range for J/S=3dB

5 watts 9.74 kms 3.1 kms 6.89 kms

10 watts 13.7 kms 4.35 kms 9.75 kms 15 watts 16.86 kms 5.33 kms 11.94 kms 20 watts 19.47 kms 6.16 kms 13.79 kms 25watts 21.77 kms 6.88 kms 15.41 kms

Graph 1: RCIED using Thuraya Satellite Phone

XX. R

EACTIVE

/S

MART

J

AMMERS

Reactive Jammers are the present emerging technology Reactive Jammers perform wideband scan of the radio spectrum and react to observed signals. The advantage is that the jammer energy is focused on the observed spectral activity. This leads to large improvement in jamming efficiency. Jammer power per HZ increases. Reactive Jammers are meant for, protection of a single vehicle or a convoy of vehicles against RCIED explosion.

Reactive Jammers have two (2) timing phases, namely (i) Look through phase, (ii) Jamming Phase. During look through phase they carry out regular scan and analyze the radio spectrum. In the jamming phase they react to potential threat and start transmission of jamming signal. Wide frequency band can be covered and selective jamming applied on threat signals. This reduces enormously the size and weight of the equipment. Thus consumption of power from the battery of the vehicle also comes down.

Reactive jammers consists of three (3) major blocks of equipment. (i) ESM Receiver, (ii) FPGA Digital Signal Processing Computation Unit, (iii) Jammer Amplifier Unit. An ESM (Electronic Support Measure) Receiver consists of an antenna, Scanning Microwave fitters, Mixer, A/D etc. It detects the threat trigger signal. The FPGA DSP Computation Unit analyses, evaluates and distinguishes the potential threat signal. It also provides the fast tuning signals to the microwave fitters. Since extremely fast reaction times are required a proprietary computing block using fast FPGAs is built in place of a computer or lap top. The FPGA DSP Unit consists of all the necessary proprietary algorithms to tune, scan and analyze the threat trigger signal. It also provides the required tuning signals to the fast synthesizer in the jammer block. The jammer consists of a fast synthesizer, noise wave form Generator Mixer and Power amplifiers.

A. A New Configuration for an intelligent RCIED

Jammer.

The block diagram of the ESM Receiver and the Jammer Amplifier Unit are shown. The key challenges involved are (i) Fast and reliable Spectrum Sensing. The reaction time in detection and tuning the amplifier is extremely short.

Fig.9. ESM Receiver

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and amplifiers which are complex to make and so the cost is exorbitantly high. The sensitivity of the ESM receiver should be high so that even low power threat signals are detected in presence of large receiver noise.

B. FPGA Digital Signal Processor

Depending on necessity the RCIED Jammer can be classified into 3 varieties (i) Single Channel Responsive Protection Jammer, (ii) Parallel Channel Responsive Protection Jammer, (iii) Multiple Responsive Protection Jammer. Sl. No. (i) & (ii) above uses a single Jammer Hardware mounted on the vehicle. . Sl. No. (iii) uses two or more Jammer Hardware mounted on different vehicles in the vehicle convoy. The threat from single RCIED trigger signal is met by the jammer mentioned at Sl. No. (i). In case the insurgents resort to explode two or more RCIEDs in a daisy chain simultaneously, protection jammers at Sl.No. (ii) & (iii) are used. The technologies becomes more complex and expensive.

The high speed FPGA DSP Processing unit performs the following tasks (i) Spectrum analysis: Calculates FFT in every frequency step. (ii) Data Analysis: Uses appropriate detection algorithms to locate the signal activity. (iii) Identification of threat. Eliminates the Radio/TV and known friendly transmission, (iv) Decision. Among the unknown potential signals, the threat signals are identified and appropriate tuning commands generated and sent to Jammer Amplifier Unit. Some of the Jamming schemes used are (i) Narrow band noise sweep, (ii) Wide band (barrage) noise, (iii) Prepared signals from memory for known apprior signals obtained from intelligence sources.

i) Criticality of timing durations

Apart from the requirement that the reaction time of the system must be extremely small, the other crucial timing parameters for the system are the (i) Duration of time for look through (ii) Duration of time for jamming, (iii) Time synchronization between multiple protection jammers

ii) Single Channel Protection Jammer

The time available is shared between look through period and jamming period.

Fig.11. Timing Diagram

The Jam period should occupy atleast 60% of the trigger transmission period. If the jam duration is large it is likely a new threat may enter the jam period which will be lethal to the equipment. It is important to note that it is permitted to waste a portion of jamming power on a false alarm, but real threat should not be missed. Time duration for LT is determined by the frequency resolution required. TLT  -1/∆f. where ∆f is the frequency resolution of the threat. Requirement for TLT and TJam are contradicting to each other. Optimum values can be worked out and implemented. In this configuration only one RCIED can be countered.

iii) Parallel Channel Protection Jammer

The insurgents keep on adopting new techniques to overcome jamming. One of the tactics is to use two or

more RCIEDs located at a distant apart and all are triggered simultaneously. In this configuration the jammer power is shared in parallel. The timing diagram is given below:

Fig.12. Timing Diagram

Because of number of threats, the jam duration allotted to each one of the threats reduces and jam efficiency reduces.

iii) Multiple Responsive Protection Jammer

Two or more jammer units are mounted on different vehicles in the convoy. Each RCIED is jammed by a different jammer thereby retaining the original jamming efficiency. But this configuration suffers from an effect called ‘ring around’ or ‘ping pong’. This is illustrated in figure below for a case of two jammers.

Fig.13.Ring Around’ or ‘Ping Pong’

During LT2 Jammer2 may see JAM1 frequency along with trigger threat frequency. This may be misinterpreted as trigger threat, and accordingly acted upon. The same scenario holds good to jammer1. ‘Ring around’ effect can be overcome by synchronizing the timing of both jammer units. For this purpose a GPS may be used for time synchronization of clocks.

iv) A New Method for Time Synchronization

However a less complex novel method has been worked out, and tested to overcome the ‘Ring around’ effect.The timing diagrams are shown below for a case of two jammers, one of them is called Master and another Slave. At regular intervals synchronizing pulses are exchanged between the two jammers and the clocks of the two jammers are synchronized. A small portion of the timing is used for exchange mainly to find out the distance between jammers.

Fig.14. Synchronization of Jammer

• F1 = Transmitted pulse of frequency F1 from Master. • F2 = Transmitted pulse of frequency F2 from Slave. • F2 is Transmitted from Slave as soon as F1 has ended. LT

JAM RCIED

1 L T

JAM RCIED

2

LT

JAM RCIED

3

LT

JAM RCIED

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• Similarly F1 is transmitted from Master for the second time after the end of F2 pulse.

• To is the time at Master, between two F1 pulses. • To is the time at Slave, between two F12 pulses. • To = 2T1 + 2t.

To is measured at Master and Slave.Since ‘t’ is the duration of F1 and F2 and is known, T1 is computed. But T1 = Distance between Jammers⁄Velocity of EM Signal.

LT1 is started after (T1–t) time after end of F1 pulse at Master and after end of F2 pulse at Slave. LT1 and LT2 are now synchronized.

LT1 JAM1 LT1 JAM1

LT2 JAM2 LT2 JAM2

Fig.15. Synchronization of Jammer

LT1 and LT2 start at the same time. However LT2 is longer by T1 (Time equivalent of Distance between Jammers) plus ‘t’, i.e. LT2 = LT1 + T1 + ‘t’. Slave observes the JAM1 frequency and avoids this frequency being set during its jam duration. It sets the next frequency F2. A similar type of time synchronization can be adapted to synchronize the multiple jammers. This ensures that each jammer transmits a different trigger frequency.

XXI. C

ONCLUSION

In this paper we have reviewed the IEDs and RCIED technologies presently prevalent. In particular, extensive coverage is made on the RCIED jamming. An example of Barrage Jammer for an RCIED using a Thuraya Satellite Phone is illustrated and Jamming distances for various powers has been worked and results shown in the form of graph. Reactive Jammers are explained in detail and the importance of timing, synchronization has been brought out. A novel simple solution for synchronization of two jammers has been brought out along with timing diagram. We have shown the hardware details of a new smart jammer which can be used for multiple triggers. Future RCIED jammers will be faster, intelligent, and will have reduced weight and size with increasing jamming efficiencies.

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EFERENCES

[1] Poisel R.A., Modern Communications Jamming Principles and Techniques, Artech House Inc., 2004.

[2] R.Miles,A.Dogaria &J.Michel. “Bringing bombs to light” IEEE Spectrum Vol.49 No.2 pp34-39, Feb 12

[3] D.Eshel. “Defeating IEDs” AOCJ. Electronic Defense (JED) Vol.30 No.12 pp 38-42, December 2007.

[4] O.Holt. “Technology Survey: Sampling of Communication Jammers” AOC J. Electronic Defense (JED) Vol.31 No.2pp 43-46, February 2008.

[5] K.Wilgucki,R. Urban, G.Baranowski, P.Skarzynski “Automated Protection System Against RCIED” Military Communication Institute, ul. Warszawska 22A,05-130, Zegrze, Poland. [6] John Keller “High-Power Laser on Avenger Combat Vehicle

Destroys IEDs in Tests”

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UTHOR

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ROFILE

Prof. G.Kumaraswamy Rao

obtained M.E. from Osmania University with first rank. He joined DRDO in 1968 and has served the organization for 36 years in various capacities as Scientist and retired as Director & scientist ‘H’ of DLRL Hyderabad. During his tenure he has designed and developed a ground control Electronic Guidance system for a short range Surface to Air Missile Trishul. As Program Director he has guided mega programs of Army, Navy, Air force amounting to 5000 crore Rs.. During his tenure as Director, DLRL was awarded the best Electronics Lab award by hon. Prime Minister of India. Presently he is working as Professor at Bharat Institute of Engg., & Tech., Mangalpally.