Seminar Report

CHAPTER 1

INTRODUCTION

Driving is a compulsory activity for most people. People use cars to move from one place

to another. The number of vehicles is increasing day by day. It is produced tacked tightly

and risk to accident. In the current scenario the world is plagued by accidents which are

primarily due to human errors in judgment and hence thousands of lives are lost. These

accidents can be avoided if only there was a mechanism to alert the driver of approaching

danger. This can be done by monitoring the distance between nearby cars and alerting the

driver whenever the distance becomes too short. In this we propose the use of Bluetooth

Technology by which we can check the speed of the car whenever it comes dangerously

close to any other vehicle up front, thereby saving very many lives. This technique will

make the use of the fact that at a time eight Bluetooth devices can communicate with each

other.

Bluetooth is a new short-range wireless technology designed to enable wireless

communication between diverse devices. It is gaining increasing popularity and acceptance

in the world today. There is a growing body of research on the subject, but very few, if any

of the

analyses, provide a balanced view of the technology, which describe

its pros and cons and implications for businesses.

The key features of Bluetooth technology are robustness, low power,

and low cost. Now-a-days, the car users expect more and more

accessories available in their cars, but these accessories available are

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able to control by user manually using different and stand alone

controllers.

Since Bluetooth devices are capable of communicating with

eight other devices simultaneously we can monitor and check the

speeds of up to eight cars simultaneously, thus preventing

accidents. Thus if we have two Bluetooth enabled devices in two

cars the devices automatically communicate with each other when

they come in the range of up to 100 meters of each other. The

range is dependant on the power class of the product. Power

transmission rates vary in many Bluetooth devices depending upon

the power saving features available in a particular unit, bandwidth

requirements, transmission distance.

In this we use automatic braking system to stop the car when

any other car comes near. For this we use mini computers this will

send the signal to automatic breaking system

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CHAPTER 2

Literature Review

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The statistics of road accidents is tremendous and highlights the

need for such a system. The following is a statistic on the number of

road accidents occurring each year.

ROAD ACCIDENT STATISTICS OF INDIA 1970-2003

Sl.No. Year Total No. of Road Accidents

(in numbers)

Total No. of Persons Killed (in numbers)

Total number of Registered Motor Vehicles (in thousands)

No. of Accidents sper ten thousand Vehicles

No. of Persons Killed per ten thousand Vehicles

1 2 3 4 5 6 7

1 1970 114100 14500 1401 814.42 103.50

2 1980 153200 24000 4521 338.86 53.09

3 1990 282600 54100 19152 147.56 28.25

4 1991 295131 56278 21374 138.08 26.33

5 1992 275541 60113 23507 117.22 25.57

6 1993 284646 60380 25505 111.60 23.67

7 1994 325864 64463 27660 117.81 23.31

8 1995 351999 70781 30295 116.19 23.36

9 1996 371204 74665 33786 109.87 22.10

10 1997 373671 76977 37332 100.09 20.62

11 1998 385018 79919 41368 93.07 19.32

12 1999 386456 81966 44875 86.12 18.27

13 2000 391449 78911 48857 80.12 16.15

14 2001 405637 80888 54991 73.76 14.71

15 2002 407497 84674 58924 69.16 14.37

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16 2003 406726 85998 67033 60.68 12.83

CHAPTER-3

OLD TECHNOLOGY

Everyday the media brings us the horrible news on road accidents. Once a

report said that the damaged property and other costs may equal 3 % of the

world’s gross domestic product. The concept of assisting driver in longitudinal

vehicle control to avoid collisions has been a major focal point of research at many

automobile companies and research organizations. The idea of driver assistance

was started with the ‘cruise control devices’ first appeared in 1970’s in USA. When

switched on, this device takes up the task of the task of accelerating or braking to

maintain a constant speed. But it could not consider the other vehicles on the

road.

An ‘Adaptive Cruise Control’ (ACC) system developed as the next generation

assisted the driver to keep a safe distance from the vehicle in front. This system is

now available only in some luxury cars like Mercedes S-class, Jaguar and Volvo

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050000

100000150000200000250000300000350000400000450000

PERSON'S KILLED

1 3 5 7 9 11 13 15

YEARS

Series2

Series1

trucks the U.S. Department of transportation and Japan’s ACAHSR have started

developing ‘Intelligent Vehicles’ that can communicate with each other with the

help of a system called ‘Co operative Adaptive Cruise Control’ .this paper

addresses the concept of Adaptive Cruise Control and its improved versions

3.1 ADAPTIVE CRUISE CONTROL (ACC)

3.1.1 PRINCIPLE OF ACC

ACC works by detecting the distance and speed of the vehicles ahead by using

either a Lidar system or a Radar system [1, 2].The time taken by the transmission

and reception is the key of the distance measurement while the shift in frequency

of the reflected beam by Doppler Effect is measured to know the speed. According

to this, the brake and throttle controls are done to keep the vehicle the vehicle in a

safe position with respect to the other. These systems are characterized by a

moderately low level of brake and throttle authority. These are predominantly

designed for highway applications with rather homogenous traffic behavior. The

second generation of ACC is the Stop and Go Cruise Control (SACC) [2] whose

objective is to offer the customer longitudinal support on cruise control at lower

speeds down to zero velocity [3]. The SACC can help a driver in situations where all

lanes are occupied by vehicles or where it is not possible to set a constant speed or

in a frequently stopped and congested traffic [2]. There is a clear distinction

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between ACC and SACC with respect to stationary targets. The ACC philosophy is

that it will be operated in well structured roads with an orderly traffic flow with

speed of vehicles around 40km/hour [3]. While SACC system should be able to deal

with stationary targets because within its area of operation the system will

encounter such objects very frequently.

3.1.2 CONSTITUENTS OF AN ACC SYSTEM:

1. A sensor (LIDAR or RADAR) usually kept behind the grill of the vehicle to obtain

the information regarding the vehicle ahead. The relevant target data may be

velocity, distance, angular position and lateral acceleration.

2. Longitudinal controller which receives the sensor data and process it to

generate the commands to the actuators of brakes throttle or gear box using

Control Area Network (CAN) of the vehicle.

3.2 SENSOR OPTIONS:

Currently four means of object detection are technically feasible and applicable in

a vehicle environment .They are

1. RADAR

2. LIDAR

3. VISION SENSORS

4. ULTRASONIC SENSOR

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The first ACC system used LIDAR sensor.

3.2.1 LIDAR (Light Detection and Ranging)

The first acc system introduced by Toyota used this method. By measuring the beat

frequency difference between a Frequency Modulated Continuous light Wave

(FMCW) and its reflection [3].

Fig 3.1.Range estimation using FMCW-LIDAR

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A company named Vorad Technologies has developed a system which measured

up to one hundred meters. A low powered, high frequency modulated laser diode

was used to generate the light signal. Most of the current acc systems are based

on 77GHz RADAR sensors. The RADAR systems have the great advantage that the

relative velocity can be measured directly, and the performance is not affected by

heavy rain and fog.

LIDAR system is of low cost and provides good angular resolution although these

weather conditions restrict its use within a 30 to 40 meters range.

3.2.2 RADAR (Radio Detection and Ranging):

RADAR is an electromagnetic system for the detection and location of reflecting

objects like air crafts, ships, space crafts or vehicles. It is operated by radiating

energy into space and detecting the echo signal reflected from an object (target)

the reflected energy is not only indicative of the presence but on comparison with

the transmitted signal, other information of the target can be obtained. The

currently used ‘Pulse Doppler RADAR’ uses the principle of ‘Doppler effect’ in

determining the velocity of the target [5].

3.2.2.1 PULSE DOPPLER RADAR:

The block diagram of pulse Doppler radar is as shown in figure.2.

The continuous wave oscillator produces the signal to be transmitted and it is pulse

modulated and power amplified. The ‘duplexer’ is a switching device which is fast-

acting to switch the single antenna from transmitter to receiver and back. The

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duplexer is a gas-discharge device called TR-switch. The high power pulse from

transmitter causes the device to breakdown and to protect the receiver. On

reception, duplexer directs the echo signal to the receiver. The detector

demodulates the received signal and the Doppler filter removes the noise and

outputs the frequency shift ‘fd’.

Fig3.2. Block diagram of pulse Doppler radar

3.2.2.3 RADAR ANTENNA SCHEMES:

Radar systems employ a variety of sensing and processing methods to determine

the position and speed of vehicles ahead. Two such important schemes are:

1. mechanically steered antenna

2. electronically steered antenna

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1. Mechanically steered antenna:

A parabolic reflector is used as mechanically steered antenna. The parabolic

surface is illuminated by the source of energy placed at the focus of the parabola.

Rotating about its axis, a circular parabola is formed. A symmetrical beam can

be thus obtained. The rays originating from focus are reflected parallel to the axis

of parabola. [fig (3).]

Fig 3.3 Parabolic reflector antenna

2.Electronically steered phased array radar antenna

A phased array is a directive antenna made up of a number of individual

antennas, or radiating elements. The radiation pattern is determined by the

amplitude and phase of current at each of its elements. It has the advantage of

being able to have its beam electronically steered in angles by changing phase of

current at each element. The beam of a large fixed phased array antenna is

therefore can be rapidly steered from one direction to another without

mechanical positioning [1, 5].

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Consider the following figure with ‘N elements placed (equally separated)

with a distance‘d’ apart. Suppose they have uniform response to signals from all

directions. Element ‘1’ is taken as reference with zero phase.

Fig 3.4 Phased array elements (example: reception of the beams)

From simple geometry, we can get difference between path lengths of

beam1 and that of beam2 is x = d sinθ, where ‘θ’ is the angle of incidence of the

beams. This gives phase difference between adjacent elements as Φ= 2π (d sinθ)/

λ, where ‘λ’ is the wave length of the signal. But if the current through a ferro

electric element is changed, the dielectric constant ‘ε’ is changed since electron

density is changed, and for an electromagnetic radiation,

Φ= 2πx / λ

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=2πxf/v,

here the velocity v = f λ

= 1/ (√μ ε)

Hence Φ=2πxf (√μ ε).

So if ‘ε’ is changed ‘Φ’ also changes and inserting ‘N’ phase shifting elements to

steer the beam, we can obtain an electronically steered beam.

Regardless of the scanning mechanism the radars typically operate in the

millimeter wave region at 76-77 GHz.

The system should be mounted inside the front grille of the car as shown in figure

(5). So its size is to be small. A typical radar produced by Delphi-Delco Electronic

systems is having the size of two stacked paper back books(14x7x10 cm)[1].

CHAPTER 4

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NEW TECHNOLOGY

4.1 Bluetooth: Bluetooth was originally developed by mobile phone company Ericsson

in 1994. Looking for a unique name for the technology, they settled on

"Bluetooth" after a tenth century Viking king called Harald "Bluetooth"

Blatand. During his reign, he united Denmark and Norway and was well

known for his ability to help people communicate. Presumably,Ericsson's hope

was that Bluetooth technology could do the same. Bluetooth wireless

technology is a short range radio communication system designed for

communication of devices like mobile phones, PDAs, notebooks, PCs, printers

and headsets. It should be cheap and low power consumption for easy

implantation into mobile devices. First it should mainly replace cables, now

this is forming complex system for communication which is able to create

pico-networks not only based on packet data transfer (ACL) but also for voice

services (SCO).

Bluetooth technology operates in the unlicensed Industrial, Scientific

and Medical (ISM) band at 2.420- 2.485 GHz, using a spread spectrum,

frequency hopping, full-duplex signal at a nominal rate of 1600 hops sec-1.

Bluetooth technology’s Adaptive Frequency Hopping (AFH) capability was

designed to reduce interference between wireless technologies sharing the 2.4

GHz spectrum.

AFH works within the spectrum to take advantage of the available

frequency. This is done by detecting other devices in the spectrum and

avoiding the frequencies they are using. This adaptive hopping allows for more

efficient transmission within the spectrum, providing users with greater

performance even if using other technologies along with Bluetooth technology.

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The signal hops among 79 frequencies at 1 MHz intervals to give a high

degree of interference immunity.

The Open Systems Interconnection (OSI) Reference Model was developed

by the International Standard Organization (ISO). It presents a generic proto

Communications. The ‘open systems’ component refers to its suitability for

wired or wireless network architecture. This standard is excessive in many

respects, but it provides a good comparison to the Bluetooth Protocol stack.

The heart of the Bluetooth specification is the Bluetooth protocol stack. By

providing well layers of functionality, the Bluetooth specification ensures

interoperability of Bluetooth devices and encourages adoption of Bluetooth

technology. The radio layer defines the requirement for a Bluetooth transceiver

operating in the 2.4 GHz band.

4.2BLUE TOOTH – NETWORKS

In bluetooth, a Piconet is a collection of up to 8 devices that frequency hop

together. Each Piconet has one master usually a device that initiated

establishment of the Piconet, and up to 7 slave devices. Master’s Blue tooth

address is used for definition of the frequency hopping sequence. Slave

devices use the master’s clock to synchronize their clocks to be able to hop

simultaneously

4.2.1 A Piconet

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Fig4.1 A piconet system

When a device wants to establish a Piconet it has to perform inquiry

to discover other Blue tooth devices in the range. Inquiry procedure

is defined in such a way to ensure that two devices will after some

time, visit the same frequency same time when that happens,

required information is exchanged and devices can use paging

procedure to establish connection. When more than 7 devices needs

to communicate, there are two options.

The first one is to put one or more devices into the park state.

Blue tooth defines three low power modes sniff, hold and park.

When a device is in the park mode then it disassociates from and

Piconet, but still maintains timing synchronization with it.

The master of the Piconet periodically broadcasts beacons (Warning)

to invite the slave to rejoin the Piconet or to allow the slave to

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request to rejoin. The slave can rejoin the Piconet only if there are

less than seven slaves already in the Piconet. If not so, the master has

to ‘park’ one of the active slaves first. All these actions cause delay

and for some applications it can be unacceptable for eg: process

control applications that requires immediate response from the

command centre (central control room).

Radio communication is subjected to noise and interference, as the 2.4

GHz frequency is shared between the all devices in piconet. The Bluetooth

specification has solved this problem by employing what is called as

spectrum spreading, in which the Bluetooth radio hops among different

frequencies very quickly. There are 79 hops starting at 2.402 GHz and

stopping at 2.480 GHz, each of which is displaced by 1 MHz. The Bluetooth

avoids interference by hoping around these 79 frequencies 1600 times per

second. So in order to avoid it we use bluetooth equipped car, in which each

car have bluetooth transmitter and receiver. And every car should have mini

computer to monitor the relative position of the car with the other car.

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Figure 4.2- shows the how does the pc card receives the signal

DATA

CARRIER

FREQUENCY SHIFTED SIGNAL

4.3 OPERATION:

The Bluetooth radio is a short distance, low power radio operating in the

unlicensed spectrum of 2.4 GHz and using a nominal antenna power of 20 dB.

The modulation used in bluetooth is Gaussian frequency shift keying, in which

zeros are represented by low frequency and ones are represented by high

frequency as shown in the figure 2.

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Figure 4.3-shows the Gaussian frequency shift keying

At the 10 dB level, the range is 100 meters, meaning the equipment must

be within 100 meters to each other (about 328 feet) to communicate using the

Bluetooth standard. With the help of this technology, we can send data to seven

devices(cars). The group of eight devices is known as Piconet. Figure 4 shows

the screen of the computer inside our car. Our car will monitor seven other cars

which are closest to us. Based on the distance the tabulation is plotted.

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CAR 6

CAR 1CAR 4

CAR 3

CAR 7

CAR 8CAR 5

CAR 2

BLUETOOTH DISTANCEDEVICE NAME CAR1 6mCAR 2 20mCAR 3 60mCAR 4 10mCAR 5 40mCAR6 30mCAR 7 50m

CAR 5 60m

CAR 7 70m

CAR 3 90m

Figure 4.4 –shows the screen of the mini computer inside the car

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CAR TO BE OVERTAKEN

CAR NEEDS SERVICE

If a car comes within 10m, it is indicated by a red colour (warning signal) in

the computer and then it will send braking signal to the corresponding car. If

there are more than 8 cars means, piconet extends to scaternet.

There is a problem during overtaking. This can be solved as follows. In the

figure 5 the red car wants to overtake the blue car. The red car driver just

touches the car in the computer that he wants to overtake.After receiving the

signal, the blue car driver allows the red car to go, after the acknowledgement

signal is given by the blue car to the red car.

When any car comes close together, Bluetooth device sends warning signal to

the car. Based on the type of warning signal received, the computer sends

signal to the brake control system to slow down the speed of the car. There are

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Figure 4.5 - shows problem during overtaking and the solution

various types of control signals. One type of signal controls the speed of the

car and the other type of control signal is to overtake the car which is moving

forward.

4.4AUTOMATIC BRAKE SYSTEM:

The automatic brake system is the next generation braking system for

controlling the speed of the car. On receiving the control signal from the

traveling car, the computer inside the car manipulates the signal and gives

control signal to the braking system.

There are four main components to an automatic braking system:

speed sensors

pump

valves

controller

(I) Speed Sensor

The speed sensor is used to determine the acceleration or deceleration of the

wheel. A picture of this sensor is shown .

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Figure 4.6 Speed Sensor in an ABS

These sensors use a magnet and a coil of wire to generate a signal. The

rotation of the wheel or differential induces a magnetic field around the

sensor. The fluctuations of this magnetic field generate a voltage into the

sensor.The ABS controller interprets this signal.

Since the voltage inducted on the sensor is a result of the rotating wheel,

this sensor can become inaccurate at slow speeds. The slower rotation of

the wheel can cause inaccurate fluctuations in the magnetic field and thus

cause inaccurate readings to the controller.

(II) Valves

The valves within an ABS serve three distinct functions. The first

function of the valves is to open and allow the hydraulic fluid from the brake

pedal or the pump to reach the braking system. The second function of the

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valves is to maintain the current pressure provided to the braking system.

This is accomplished by closing the valve to resist further pressure from

the brake pedal. The third function of these valves is to reduce the amount

of hydraulic pressure at the braking system. This is accomplished by

opening the valves to allow the hydraulic fluid to be released from the

braking system.

The majority of problems with the valve system occur due to clogged

valves. When a valve is clogged it is unable to open, close, or change

position. An inoperable valve will prevent the system from modulating the

valves and controlling pressure supplied to the brakes.

(III) Pump

The pump in the ABS is used to restore the pressure to the hydraulic

brakes after the valves have released it. A signal from the controller will

release the valve at the detection of wheel slip. After a valve release the

pressure supplied from the user, the pump is used to restore a desired

amount of pressure to the braking system. The controller will modulate the

pumps status in order to provide the desire amount of pressure and reduce

slipping. A picture of the pumping system is shown in Figure 5.

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Figure 4.7. ABS Valves and Pumping System

Similar to the valves, the major limitation or mode of failure is due to

blockage within the pump. A blockage within the pump will prevent the pump

from supplying the correct pressure to the pumping system.

(IV) Controller

The entire system is observed and manipulated by the ABS controller.

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The computer constantly monitors the distance between each of these cars

and when it senses that the car is getting too close it moves the hydraulic

valves to increase the pressure on the braking circuit, effectively increasing the

braking force on the wheels. If the distance between two vehicle is within the

100m the Bluetooth devices get enabled and if the distance come closer within

10m the automatic braking system takes the control. After the speed of the car

is reduced and distance increased the hydraulic valves decreases the pressure

on the braking circuit, thus effectively decrease the braking force on the

wheels. The following steps show the various functions of the hydraulic

valves:

in position one, the valve is open; pressure from the master cylinder

is passed right through to the brake.

in position two, the valve blocks the line, isolating that brake from the

master cylinder. This prevents the pressure from rising further should

the driver push the brake pedal harder.

in position three, the valve releases some of the pressure from the

brake.

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FORCE APPLIED BY THE DRIVER

ANTI-LOCK BRAKING SYSTEM

ELECTRICAL SIGNAL FROM THE COMPUTER

ELECTROMAGNET

STEEL PLATE

LEVER MECHANISM TO BRAKING SHOES

SPRING

Figure 4.8 -Block diagram of automatic braking system

The processed signal from the computer is given to the electromagnet and it

gets magnetised and moves the spring downwards,the other end of the spring

is attached to the steel plate. The movement of steel plate is nothing but a force

and it will add with the force applied by the driver. The signal is then given to

the anti-lock braking system and it takes the control is shown in the figure 9.

In the figure 7 when car A and car B come within the range of 100m

both the Bluetooth devices get enabled and if any one of the car comes too fast

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Within 10m

Sends warning signal Receives signal and control the speed of car

then the bluetooth device sends a warning signal to the other car and it

processes the signal and gives it to the automatic braking system.

CONCLUSION

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The Bluetooth technology is being widely adopted by the Industry leaders.

The possibility for new applications is very exciting with this Versatile

technology. It provides a simple, logical answer to all the Problems-which is

built a single common radio into every mobile computer, then neither do

companies have to worry about WAN, nor do communication companies need

to worry about building external cables.

The Bluetooth communication device will thus be a small, low powered radio

in a chip that will talk to other Bluetooth enabled products. Bluetooth has been

designed to solve a number of connectivity problems experienced by the

mobile workers & consumers. Thus, this technology helps make the electronic

devices more user friendly and helps address various other problems like

accidents. This study involves design a new system to decrease the hot

temperature inside a car that affecting the health of the car driver and the car

driver is able to control some of the car accessories by using mobile phone.

Once the car is equipped with the Bluetooth module and control system, the

car accessories is able to connect with microcontroller and control by the

mobile application. By using this system, car driver is able to use their existing

mobile device to control car accessories such as power window instead buy a

new controller to control the system.

The Java MIDlet program can install in most of the mobile phone or Personal

Digital Assistant even laptop. Hence, the mobile device can used to control the

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car accessories rather than buying different standalone controller to control

different accessories. The controller is a flexible controller, where the

controllable accessories are easy to manage. The controllable accessories are

set depending on users demand because the mobile application is not hard

wired and able to change.

BIBLIOGRAPHY

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http://technology.newscientist.com

www.webopedia.com

www.Globus.org

Howstuffworks .com/Bluetooth

http://en.wikipedia.org/wiki/Anti-lock_braking_system.

Theodore S. Rappaport, wireless communication Principles.

Jean-Paul J\1.G.Linnartz, wireless communication,1993, 1995

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