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CHAPTER 1 INTRODUCTION TO BIOMETRIC SYSTEM

Biometric system refers to the identification of humans by their 

characteristics or traits. Computer science, biometrics to be specific, is usedas a form of identification and access control. It is also used to identify

individuals in groups that are under surveillance.

Biometric identifiers are the distinctive, measurable characteristics used to

label and describe individuals. The two categories of biometric identifiers

include physiological and behavioral characteristics.

A biometeric would identify by ones voice DNA, hand print or behavior.

Behavioral characteristics are related to the behavior of a person, including

 but not limited to typing, gait, and voice. Some researchers have coined theterm behaviometrics to describe the latter class of biometrics.

More traditional means of access control include token-based identification

systems, such as a driver's license or  passport, and knowledge-based

identification systems, such as a  password or  personal identification number .

Since biometric identifiers are unique to individuals, they are more reliable

in verifying identity than token and knowledge-based methods, however, the

collection of biometric identifiers raises privacy concerns about the ultimate

use of this

Biometric recognition, or biometrics, refers to the automatic identification of 

a person based on his/her anatomical (e.g., fingerprint, iris) or behavioral

(e.g., signature) characteristics or traits. This method of identification offers

several advantages over traditional methods involving ID cards (tokens) or 

PIN numbers (passwords) for various reasons:

(i) the person to be identified is required to be physically present at the

 point-of-identification;

(ii) identification based on biometric techniques obviates the need to

remember a password or carry a token.

With the increased integration of computers and Internet into our everyday

lives, it is necessary to protect sensitive and personal data. By replacing

PINs (or using biometrics in addition to PINs), biometric techniques can

 potentially prevent unauthorized access to ATMs, cellular phones, laptops,

and computer networks. Unlike biometric traits, PINs or passwords may be

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specifically, a trait with 'good' permanence will be reasonably invariant over 

time with respect to the specific matching algorithm.

Measurability (collectability) relates to the ease of acquisition or 

measurement of the trait. In addition, acquired data should be in a form that

 permits subsequent processing and extraction of the relevant feature sets.

Performance relates to the accuracy, speed, and robustness of technology

used .

Acceptability relates to how well individuals in the relevant population

accept the technology such that they are willing to have their biometric trait

captured and assessed.

Circumvention relates to the ease with which a trait might be imitated using

an artifact or substitute.

 No single biometric will meet all the requirements of every possible

application.

2.1 The basic block diagram of a biometric system

2.1 Modes of biometric system

A biometric system can operate in the following two modes.

2.1.1 Verification mode:

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Fingerprint biometrics are used in a variety of applications including

electronic door locks, smart cards, vehicle ignition control systems, USB

sticks with fingerprint controlled access, and many others. Digital signal

 processing elements in fingerprint scanners perform complex DSP functions

such as filters, transforms, feature extraction, matching operations and other 

algorithms.

Fingerprint sensors can use capacitive, optical, pressure, or thermal

technologies to obtain an image of a finger’s features. The most common

fingerprint sensor solution first illuminates the print with a laser or LED

light and then captures the image using a CCD or less expensive CMOS

sensor. Fingerprint sensors are typically self contained modules that include

an analog to digital converter to translate the analog information into a

digital data stream. Resolution, dynamic range and pixel density are factors

that contribute to the image quality and influence the accuracy of the sensor.Once the image is captured the digital information is transferred to a digital

signal processor to generate a match. The first step in the matching process

is conditioning the scanned fingerprint. Finger print readers rarely use the

full fingerprint for identification. Rather, DSPs use algorithms to extract the

unique features and patterns of each print to generate a unique digital code.

The second step in the software flow is to take the code generated from the

scanned image and compare it to a database of potential matches. The

compare step requires the system to have access to print information in a

networked database or a non-volatile memory unit.

The need for real-time signal processing in biometric fingerprint scanning

makes the C55x DSP a compelling solution for this application. The low

 power capabilities of the C55x in both active and passive modes make it a

match for fingerprint scanning applications because, for a greater percentage

of the time, the processor is in a low-power mode. The peripheral integration

of the C55x DSP includes on-chip LDOs, on-chip memory and a USB Phy

for connectivity. Placing peripherals on-chip lowers the overall system cost

 by simplifying board layout and reducing the total chip count. When

communications peripherals are placed on the same die as the processor it isalso important to protect your device from sources of ESD. Any IOs or 

communication peripherals that could come in contact with human touch or 

other source of ESD should be protected. Devices like the TPD3E001

 provide multichannel ESD protection up 15kV for USB 2.0 interfaces.

The LCD Bridge found on the C55x can be used to display messages or 

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options menus. Integrating a TSC2003 touch screen controller to the

application provides a way for the user to select options from a displayed

menu. Audio functionality can also be included in this application to provide

user feedback in the form of alerts and pre-recorded voice commands. This

is accomplished using the I2S capability of the C55x to provide a digital

audio stream to an audio DAC. Devices like the DAC3120 Bconvert the

digital audio stream into an analog signal and increase system integration by

including a built in class AB amplifier capable of driving a 2.5 watt mono

speaker.