Electronic Infosystems

8/2/2019 Electronic Infosystems

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Electronic Infosystems

by:

Witkorio

Penkorio Armani

Wieluneiro

Wyspiacze

Sowissimo

Sopellini


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1. List and shortly discuss functional blocks of a mechatronic system (5).

1. Physical System ModellingMechanics of solids, translational and rotational system, fluid systems, electrical, thermal,

micro- and nano-systems, psychical system analogies, rotational electromagnetic mem(?).

2. Signals and SystemsMechatronics modeling, signals and systems in mechatronics, response of dynamic systems,

root locus methods, frequency response methods, state variable methods, stability,

controllability and observability, observers and Kalman filters, optimal control design,

adaptative and nonlinear control design, neural networks and fuzzy systems, intelligent

control for mechatronics, identification and design optimization.

3. Computers and Logic SystemsDigital logic, communication systems, fault detection, logic system design, asynchronous and

synchronous sequential (?), computer architectures and microprocessors, system interfaces,

programmable logic controllers, embedded control computers.

4. Software and Data AcquisitionData acquisition systems, transducers and measurements systems, A/D and D/A conversion,amplifiers and signal conditioning, computer-based instrumentation systems, software

engineering, data recording.

5. Sensors and ActuatorsFundamentals of time and frequency sensor and actuator characteristics.

Sensors: linear and rotational, acceleration, force, torque, pressure, flow sensors,

temperature measurements, ranging and proximity sensing, light detection, image and vision

systems, fiber optic devices, micro- and nano-sensors.

Actuators: electro-mechanical actuators, motors DC, AC, stepper, piezoelectric actuators,

pneumatic and hydraulic actuators, micro- and nano-actuators.


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2. Explain directions of integration in mechatronic systems (2).

The Integration of Components (hardware integration) results from designing the mechatronic

system as an overall system and embedding the sensors, actuators, and microcomputers into the

mechanical process. This spatial integration may be limited to the process and sensor, or to the

process and actuator. Microcomputers can be integrated with the actuator, the process or sensor, or

can be arranged at several places.

Integrated sensors and microcomputers lead to smart sensors, and integrated actuators and

microcomputers lead to smart actuators.

The Integration of Information Processing (software integration) is mostly based on advanced

control functions. Besides a basic feedforward and feedback control, an additional influence may

take place through the process knowledge and corresponding online information processing. This

means a processing of available signals at higher levels, including the solution of tasks likesupervision with fault diagnosis, optimization, and general process management.

3. Describe principle of operation of Linear Voltage Differential

Transformer (LVDT). Draw block diagram of a typical measurement circuit.

The LVDT (Linear/Rotational Voltage Differential Transformer) is a tube with a plunger, the

displacement of the plunger being the variable to be measured. The tube is wrapped with at least

two coils, an excitation coil and a pickup coil. An AC current (typically 1 kHz) is passed through the

excitation coil, and an AC signal is detected from the pickup coil and compared in magnitude and in

phase (0 or 180) to the excitation current.

Support electronics are needed for the demodulation, which is called

synchronous detection. The plunger carries a ferromagnetic slug,

which enhances the magnetic coupling from the excitation coil to the

pickup coil. Depending on the position of the slug within the pickup

coil, the detected signal may be zero (when the ferrite slug is centered

in the pickup coil), or increasing in amplitude in one or the other

phase, depending on displacement of the slug.


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And this is what I consider to be the measurement method circuit:

4. Describe principle of operation of piezoelectric, piezoresistive and optic

fiber sensors.

Piezoelectric sensors utilize a mass in direct contact with the piezoelectric component or crystal.

When a varying motion is applied to the sensor, the crystal experiences a varying force excitation

(F = ma), causing a proportional electric charge q to be developed across it.

Piezoresistive sensors are based on resistance properties of electrical conductors. If a conductor is

stretched or compressed, its resistance alters due to dimensional changes, and the changes in the

fundamental property of material called piezoresistance.

Optic fibers can be used to sense strain, liquid level, force, and temperature with very high

resolution. The relative change in the transmitted intensity or spectrum is proportional to the change

in the sensed parameter. Typical applications damage sensors, vibration sensors, cure-monitoring

sensors.


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5. Draw functional block diagram of one measurement path in ADXL202

micromechanical accelerometer. Describe usage of each block.

The ADXL202 is a complete acceleration measurement system on a single monolithic IC. It contains a

polysilicon surface micromachined sensor and signal conditioning circuitry which implements a force-

balance control loop. The ADXL202 is capable of measuring both positive and negative acceleration

to a maximum level of 2 g.

Dont know if its this, but anyway, I have no better iea.

Direct Conversion Modulator

Cy, Cx changing capacity is the method of setting bandwidth of measurement.

Synchronous demodulator


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6. Describe principle of operation of convective accelerometer.

Convectionrefers to the movement of molecules within liquids or gases.

Natural convection, or free convection, occurs due to temperature differences which affect thedensity, and thus relative buoyancy, of the fluid. Heavier (more dense) components will fall while

lighter (less dense) components rise, leading to bulk fluid movement. Natural convection can only

occur, therefore, in a gravitational field.

The MEMSIC accelerometers are a complete dual axis motion measurement system on a monolithic

CMOS IC. The principle of operation of the MEMSIC devices is based on heat transfer by natural

convection. The devices measure internal changes in heat transfer caused by acceleration. The

devices are functionally equivalent to traditional proof-mass accelerometers.

The MEMSIC devices are capable of measuring accelerations with a full-scale range from below 1.0g

to above 100g. The evices can measure both ynamic acceleration (e.g. vibration) an sta tic

acceleration (e.g. Gravity).

When there is an

acceleration,

there is different

bowl of heated

air, which is

measured by

temperature

sensor.


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7. What are the applications and topologies of micromechanical

gyroscopes?

Applications of gyroscopes:

gyrocompasses which complement or replace magnetic compasses (in ships, aircraft andspacecraft, vehicles in general)

assistance in stability (bicycle, Hubble Space Telescope, ships, vehicles in general) Gyroscopes can be used as part of an inertial guidance system GPS navigation systems (extrapolation of trajectory) Cooperation with accelerometer in automotive airbag systems Gyroscopic effects are used in toys like tops, yo-yos, and Powerballs measurement of parameters of rotation

a) Single spring mass with

translational drive shares the

same flexure for both the drive

and sense modes

b) Dual mass spring with

translational drive can be

arrangedto form tuning fork

resonators to reject

translational vibration

c) Single-gimbaled mass with

translational drive

d) Single-gimbaled mass with

torsional drive

Single-gimbaled structures have

an advantage of decoupling the

drive and sense modes, but may

have poor linear acceleration

rejection and temperature

performance.

e) Dual-gimbaled mass with

translational drive is employed

to improve the linear

acceleration rejection and

stability at the price of

increased structural complexity.


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8. Draw block diagrams of an interrogator and a biodevice in the

intracranial pressure monitoring system. How binary data are transmitted

in both directions? Draw state diagram in data link layer and descibe

meanings of each state.

The intracranial pressure monitoring (ICPM) system consists of an interrogator and subcutaneously

implanted biodevice that are connected via wireless electromagnetic link. The interrogator is an

external device that provides an external power source, creates a communication link, and controls

the biodevice. The biodevice can have intracranial pressure as well as a temperature sensor.

The innovative approach in ICPM system is that the electromagnetic induction is used to both power

the biodevice and provide for a communication link. The advantage of the approach is that the

biodevice is hermetically sealed before implanting it in a patient, thus making the whole procedure

potentially less hazardous to the patient. The elimination of the battery to power the biodevice,

avoids the problems related to safety hazards, battery size, power, and duration.


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The electromagnetic field created by the interrogator serves as a wireless link for powering and

communicating to the biodevice. The communication link is established by powering electromagnetic

waveform for half-duplex communication. Modulation of the electromagnetic waveform in the

interrogator and demodulation in the biodevice establish the communication link from theinterrogator to the biodevice.

Modulation of the inductive load that powers the biodevice is used to create a communication link

from the biodevice to the interrogator.

interrogator biodevice

The communication protocol is based on a dialogue mode of operation, in which the biodevice

carries out the interrogator initiated commands.

Initially, there is no data link between the interrogator and the biodevice. If the interrogator is within

the power transmission range, the biodevice is powered, incepts the carrier, and enters verification

dialogue.


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Upon the successful verification, the interrogator and biodevice enter the application state. Typical

operations in the application state include transmission of intracranial pressure data from the

biodevice to the interrogator and recalibration of the sensor.

The application state is followed by the termination state in which the carrier is terminated. If, at any

state, the communication fails, the interrogator terminates the carrier.

9. Show graphically block diagram of an electronic compass and explain

usage of each block.

1. 2 dimensional field sensor usually magnetoresistive technology (cheaper than flux-gate) and higher sensitivity than Hall

elements

uses property of changing resisitivity in the presence of an external magnetic field magnetic field sensor elements are grouped in a Wheatstone bridge, consisting of four

magnetoresistive strips

2. signal conditioning unit The basic task of the SCU is to significantly amplifiy signals from MR sensors. Furthermore,

depending on the desired system accuracy, the SCU has to fulfil up to three further

requirements. These are the elimination of the following error sources:

Offset voltages Vox, Voy at the SCU output Sensitivity difference S between x- and y- channel of the SCU Non-orthogonality of sensors


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3. direction determination unit Evaluation of the azimuth in a high resoulution compass is performed by the microcontroller.

Votage values Vx and Vy must be corrected with respect to offset, sensitivity difference and,

if required, non-orthogonality. If these requirements are fulfilled, the azimuth can be

computed with arctan function.

4. display or interface to other system10. What is a flipping effect in magnetoresistive sensor and how it can be

used for offset compensation in an electronic compass?

MR sensors are bi-stable. It means that when MR sensor is subjected to a reversible magnetic field in

its flipping direction, its internal magnetization Mx and thus its characteristic Vo vs. Hy is reversed or

flippe. If the flipping is one repetitively, the esire output voltage will change polarity, thus

appearing as amplitude of an ac signal. However the offset voltage does not change polarity, thus

appearing as a dc offset of that signal.


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11. Describe error sources (4) in azimuth calculation in an electronic

compass, and how they can be compensated?

Error sources:

Offset voltages Vox, Voy at the SCU output

Sensitivity difference S between x- and y- channel of the SCU

Non-orthogonality of sensors

Tilt error

Offset compensation

MR sensors are bi-stable. It means that when MR sensor is subjected to a reversible magnetic field in

its flipping direction, its internal magnetization Mx and thus its characteristic Vo vs. Hy is reversed or

flippe.

If the flipping is done repetitively, the desired output voltage will change polarity, thus appearing as

amplitude of an ac signal. However the offset voltage does not change polarity, thus appearing as a

dc offset of that signal.

Sensitivity difference compensation

At a given temperature, S can be compensated by adjusting the SCU for equal output voltage

swings Vy,pp and Vx,pp during compass rotation. The output voltage swings can be equalized by

adjusting the amplification of one SCU channel. An alternative software solution would be to correct

one output voltage mathematically. As the ratio Vy,pp/Vx,pp equals the ratio of sensitivities


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Sy/Sx=(S+S)/S, Vy can be corrected as follows:

Tilt error can be compensated by converting the measured earth field components mathematically

into the horizontal components. This technique is often referred to as electronical gimbalingand

requires additional sensor elements:

A third magnetic field sensor Sensors for pitch and roll


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12. Describe two methods of electronic compass calibration. What

informations are remembered at the end of the calibration process?

Assume usage of a tilt sensor.

Calibration of the electronic compass can be performed in two ways:

1. Rotation of the compass on xy plane parallel to the earth surface.

2. Rotation of the compass on xy plane perpendicular to the earth surface

and directed to the magnetic north.

At the end of the calibration process ax_min; ax_max; ay_min; ay_max ; cx_min; cx_max; cy_min;

cy_max are remembered.

13. What is an ATM, what additional functions can have and how it can be

connected to a Bank Computer?

An ATM is simply a data terminal with two input and four output devices. Like any other data

terminal, the ATM has to connect to, and communicate through, a host processor. The host

processor is analogous to an Internet Service Provider (ISP) in that it is the gateway through which all

the various ATM networks become available to the cardholder (the person wanting the cash).


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Most host processors can support either leased-line or dial-up machines. Leased-line machines

connect directly to the host processor through a four-wire, point-to-point, dedicated telephone line.

Dial-up ATMs connect to the host processor through a normal phone line using a modem and a toll-

free number, or through an Internet service provider using a local access number dialed by modem.

The cash-dispensing mechanism has an electric eye that counts each bill as it exits the dispenser. The

bill count and all of the information pertaining to a particular transaction is recorded in a journal. The

journal information is printed out periodically and a hard copy is maintained by the machine owner

for two years. Besides the electric eye that counts each bill, the cash dispensing mechanism also has

a sensor that evaluates the thickness of each bill. If two bills are stuck together, then instead of being

dispensed to the cardholder they are diverted to a reject bin. The same thing happens with a bill that

is excessively worn, torn, or folded. The number of reject bills is also recorded so that the machine

owner can be aware of the quality of bills that are being loaded into the machine. A high reject rate

would indicate a problem with the bills or with the dispenser mechanism.

14. List and briefly describe top chassis and save devices used in ATMs (at

least 8). Why retained card bin is used in ATM?

Top chassis devices

1. External VGA monitor

2. External pointing device3. External keyboard

4. I/O adapter panel

5. Power (on/off) switch

6. Maintenance mode switch

7. Status indicator

8. Journal printer

Save devices

Cash dispenser draws notes (or other dispensable media) from the dispense cassettes, stacks, and

transports them to the consumer, through the slot in the fascia.


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If a note is unacceptable (too mutilated or crumpled to dispense), or if a multiple pick occurs, the

dispenser diverts the note(s) to the divert cassette.

Dispense cassettes

When the consumer inserts an envelope into the deposit slot, the Depositor transports it to the

Deposit Cassette. As the envelope is transported, it is imprinted by the Deposit Printer with a

message of up to 55 characters.

An optional Intelligent Depository Module (IDM) is available that will accept a variety of deposit

items (various sizes of checks, envelopes, and documents) in addition to the standard deposit

envelope.

After the consumer's deposit envelope is imprinted by the Deposit Printer, the envelope is delivered

to the Deposit Cassette. Deposit Cassettes can hold approximately 500 filled deposit envelopes andare available in either standard (nonlocking) or Secure Deposit Cassettes that close and lock

automatically when removed from the Depositor.

The retained card bin holds all activator cards that are not returned to consumers.

15. Describe 3 levels of administrator management in Diebold ATMs.]

ani w slajdach ani na googlu tego nie znalazlem take nie wiem...:(


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16. What cryptographic algorithms are used in ATMs, what are their

features and how they are combined in PIN encryption and decryption

processes?

DES (Data Encryption Standard) - DES uses a single secret key to encrypt the PIN at the ATM and the

same key to decrypt the PIN after it is receive by the processor, to verify the carholers ientity. A

key consists of 64binary bits of which 56 bits are usual

Triple DES (3DES) it uses two 64-bit keys (effectively 128 bits) and apply them three times. The

procedure for encryption is exactly the same as single DES, but it is repeated three times. Higher

level of security.

Encryption and decryption of PIN-code with 3DES

Encryption: O = EK1(DK2(EK1(I)))

Decryption: O = DK1(EK2(DK1(I)))

E/D DES Encryption/Decryption

K1,K2 secret keys

I/O data blocks: input/output

17. How aperture and shutter speed influence to sharpness and depth of

field of an acquired photo? How to maximize depth of field in camera with

variable focal Length (3)?

Aperture is referred to the lens diaphragm opening inside a photographic lens. The size of the

diaphragm opening in a camera lens REGULATES amount of light passes through onto the film inside

the camera the moment when the shutter curtain in camera opens during an exposure process. The

size of an aperture in a lens can either be a fixed or the most popular form in an adjustable type (likean SLR camera). Aperture size is usually calibrated in f-numbers or f-stops. i.e. those little numbers


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engraved on the lens barrel like f22 (f/22),16 (f/16), f/11, f/8.0, f/5.6, f/4.0, f/2.8, f/2.0, f/1.8 etc.

Moving from one f-stop to the next doubles or halves the size of the amount of opening in your lens

(and the amount of light getting through).

When a lens focuses on a subject at a distance, all subjects at that distance are sharply focused.Subjects that are not at the same distance are out-of-focus and theoretically are not sharp. However,

since human eyes cannot distinguish very small degree of unsharpness, some subjects that are in

front of and behind the in-focus subjects can still appear sharp. The zone of acceptable sharpness is

referred to as the depth of field. Thus, increasing the depth of field increases the sharpness of an

image.

Shutter speed - The time elapsed between the opening and closing of the shutter is referred to as

shutter speed. It is usually denoted by an integer whose reciprocal gives the shutter speed in second.

For example, shutter speeds 3, 100, 250, and 1000 really mean 1/3 sec, 1/100 sec, 1/250 sec, and

1/1000 sec. It is also possible that the shutter may open for more than a second. A shutter speed of

greater than or equal to a second is frequently denoted by an integer followed by a double quote.

For example, 1", 2", and 4" are 1 sec, 2 sec, and 4 sec. Slow shutter speeds are often used in low light

conditions, extending the time until the shutter closes, and increasing the amount of light gathered.

Very fast shutter speeds are used to freeze fastmoving subjects, for example at sporting events. Very

slow shutter speeds are used to intentionally blur a moving subject for artistic effect.


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18. How image is captured in CCD and CMOS sensors? Compare properties

of both sensors.

Image Capture with CCD

Image capture with CMOS


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Properties of CCD and CMOS image sensors

Current digital camera designs use one of two main techniques: in the first, a single CCD or CMOS

sensor records only one color at each cell, and then interpolates (read: makes an educated guess) the

remaining color values to produce the final color for each pixel in the digital image. The other

technique, much less commonly used since it adds significantly to the cost of the camera, is to use a

beam-splitting prism to direct light of each color to three separate image sensors, each of which

records only one color.

19. What is the difference between Mosaic and Foveon X3 image capturingtechniques?

Until now, all other image sensors have featured a just single layer of pixels and each pixel captures

only one colour of light, which has been filtered through a single colour filter. Since mosaic-based

conventional image sensors capture only one-third of the colour, complicated algorithms are

required to interpolate the colour they miss. Interpolation leads to colour errors, colour artifacts and

a loss of image detail. Low pass filters must then be used to reduce colour artifacts. The use of low

pass filters adversely affects sharpness and resolution of the final image captured.

The Foveon X3 direct image sensor can capture all primary RGB colours at each and every pixel,

insuring the capture of full and complete colour. Using three silicon-embedded layers of pixel

sensors, stacked to take advantage of silicon's ability to absorb red, green, and blue light at different


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respective depths, it efficiently reproduces colour more accurately, and offers sharper resolution,

pixel for pixel, than any conventional image sensor.

20. List and describe usage of microprocessors in Canon EOS cameras. What

are the purpose of Electromagnetic Diaphragm, Arc Form Drive and

UltraSonic motor?

EMD (Electromagnetic Diaphragm) is a diaphragm drive control actuator, which is a component

integrating both a stepper motor and a diaphragm blade mechanism in a single unit. EMD controls

diaphragm blade by a stepper motor and aperture diameter by electronic pulse signal from the

camera body.

Arc Form Drive (AFD) is the original Canon EOS motor. It is relatively noisy and slow and it does notallow simultaneous auto and manual focus.


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UltraSonic Motor (USM) consist of two metal rings which vibrate at a very high frequency. This

technology makes focusing precise, virtually noiseless and very quick. The USM requires minimal

battery power. Ring ultrasonic lenses also support full-time manual (FTM) focus. This means one you

can touch up the focus manually without first having to switch the lens from autofocus to manual

focus mode.


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21. Describe 5 basic operation modes of a digital camera. What is the task of

an exposure compensation method?

Operation modes:

P - Program Mode P* - Flexible Program Mode (???)

Automatic-assist, just point and shoot. Unlike full

auto mode, you can usually control flash and a

few other camera settings.

Flexible program mode is used to change

between various combinations of equivalent

exposures to allow the user to change the

shutter speed or to control depth of field but

allow the camera to continue control of the rest

of the exposure.

Tv - Shutter-Priority Mode Av - Aperture-Priority Mode

Photographer sets the shutter, and the camera

will attempt to deliver a good exposure.

Photographer sets the aperture (f-stop) and the

camera will attempt to deliver a good exposure.

M - Manual Exposure Mode A-DEP - Depth of Field

Full manual mode, the photographer must setboth the shutter and the aperture.

Auto Depth-of-Field is a seldom used feature thatis great for ensuring that your subjects will be in

focus; especially when they are some distance

from each other.

When the camera is set on A-DEP, the

photographer doesn't need to set an aperture F

number as the camera does this for them.


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Exposure compensation is a technique for adjusting the exposure value indicated by a photographic

exposure meter. This can be done by the "EV Compensation. Typically the EV compensation ranges

from -2.0 EV to +2.0 EV with adjustments in steps of 0.5 or 0.3 EV.

Exposure is adjusted by changing either the lens f-number or the exposure time; which one is

changed usually depends on the camera's exposure mode.

If the mode is aperture priority, exposure compensation changes the exposure time.

if the mode is shutter priority, thef-number is changed.

22. Describe general structure of UPC-A barcode. What is the difference

between UPC-A and EAN13?

UPC-A code structure

Number

system

Manufacturer

code

Item

code

Check

Digit

X XXXXX XXXXX K

The number system is a single digit which identifies the

"type" of product

EAN13 code structure

Country

code

Manufacturer

number

Product

number

Check

digit

XXX XXXX XXXXX K

XXX XXXXX XXXX K

XXX XXXXXX XXX K

XXX XXXXXXX XX K

Poland 590, USA and Canada 00-09

Exceptions:

1. Codes with prefix 2 (internal codes and codes of goods with different quantity),

2. Codes with prefixes 977-979 (books and publications).

Jak ju zostaniemy kasjerkami w Bieronce to chocia bziemy wieziedco znacz te cyferki na koach kreskowych


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23. Describe physical structure of OCIA interface. How communication

between host and peripheral device is performed?

OCIA interface (Optically Coupled Interface Adapter)

The OCIA is a bi-directional optically isolated interface which consists of four signals, all of which are

with respect to the host, and uses the negative logic convention. Each of the interface signals is

actually consists of the signal and a signal return (current loop). Therefore, each signal can be

referred to as a "signal pair".

Host unit controls the speed of transmission in both directions. When the peripheral is ready to transmit a byte of data, RDATA will be set to a logical "1".

This will alert the host to serially clock 1 "ready" bit and 8 receive data bits out of the

peripheral over the RDATA signal pair. On the last clock pulse received from the host the

peripheral will set RDATA to a logical "0", indicating to the host that no data is ready for

transmission.

24. What is the purpose of a barcode scanner? Describe principle of

operation of pen, CCD and laser scanners. What are their advantages and

disadvantages?

A barcode reader (or barcode scanner) is an electronic device for reading printed barcodes. It

consists of a light source, a lens and a light sensor translating optical impulses into electrical ones.

Additionally, nearly all barcode readers contain decodercircuitry analyzing the barcode's image data

provided by the sensor and sending the barcode's content to the scanner's output port.

Programming of barcode scanners are performed with use of special code books or from PC with usespecial software.


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In a pen scanner light from a light source is focused at the tip of the wand. A photodetector senses

changes in the reflected light as the wand is drawn across the bar code symbol. Widths and spaces

between bars are measured. Dark bars in the bar code absorb light and white spaces reflect light so

that the voltage waveform generated by the photo diode is a representation of the bar and spacepattern in the bar code. This waveform is decoded by the scanner, which sends the actual code via

interface in the ASCII form.

CDD scanner use CCD type photo detector and allow a complete image across the barcode to be

scanned continuously. This removes the need to physically swipe the scanner across the code. The

whole barcode is illuminated by a row of LEDs and the CCD sensor will "take a picture" of the code

typically 100 times per second. In general, CCD scanners must be positioned within 1 or 2 cm of the

code, but unlike pen scanners, code wear is avoided. Long Range CCD scanners are available with agreater depth of field typically 10cm. With no moving parts, these types of scanner are extremely

reliable and offer rapid read rates.

Laser scanners work the same way as pen type readers except that they use a laser beam as the light

source and typically employ either a reciprocating mirror or a rotating prism to scan the laser beam

back and forth across the bar code. As with the pen type reader, a photodiode is used to measure the

intensity of the light reflected back from the bar code. In both pen readers and laser scanners, the

light emitted by the reader is rapidly varied in brightness with a data pattern and the photodiode

receive circuitry is designed to detect only signals with the same modulated pattern.

25. Explain two modes of operation of a fiscal device. What information are

stored In fiscal memory?

Fiscal functions

A fiscal device (cash dispenser, printer) has built-it, EEPROM fiscal memory, which stores information

about retail sales and taxes for at least 5 years.

At the end of each working day, a sale report is printed and recorded in the fiscal memory.

Fiscal device can operate in two modes:

non-fiscal (training), fiscal.

In non-fiscal mode an operator of the cash registers has the possibility to learn its functionality and

to simulate sales transactions with issue of customer receipts. This operating mode, very useful for

staff training. All receipts printed in this mode are non-fiscal.

If training is completed,fiscalisation of the cash registertakes place. This is the moment of making a

one-time, unrepeatable action initiating the work of the module of the cash register with fiscal

memory finished by the printing of a fiscal day report.


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26. Draw functional block diagram explaining transmission of code from

remote control via RF or IR medium. Describe briefly usage of each block.

Buttons - a few buttons :)

Transmitter - sends to the receiver, via transmission medium the sequence of bits. The medium can

be: infrared rays (IR) or radio frequency (RF) signal. The IR medium is usually a modulated

transmission, similar to those used in TV remote controllers. The RF medium is usually 433.92MHz

transmission (315, 392 and 900 are also common), OOK (100% AM) modulated. In case of high-end

systems, the FSK modulation is sometimes used. The RF transmitters are usually 1-transistor based

generators, stabilised by LC circuit, crystal oscillator or SAW filter. The integrated RF transmitter ICs

(or hybrid circuits) are also available on the market.

Encoder:

Prepares the transmitted code the sequence of bits, each with a given length, usually PWMcoded.

The sequence, in simplest form depends only on RF transmitter serial number and buttonpreseed.

Additionaly, the sequence can include information about battery state (voltage), whichbuttons are pressed, how they are pressed (single press, continous pressing) etc.

Sophisticated encoders are protected against battery drainout due to accidential long pressof button e.g in the pocket. The interval between transmissions lowers the medium RF

power.

Encoder serial number can be In-System Programmed (final production phase) or given byjumpers on PCB

There are two types of encoders: with variable code and with constant code The encoder IC works with direct battery power supply (3,3V, 6V, 12V) There are integrated encoder and RF transmitter solutions (rfHCS family of Microchip)


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RF RECEIVERS

Hybrid superreactional receivers (Attention! They make EEM noise; if more than oneis installed, they interfere with each other).

Hybrid superheterodyne receivers (better sensitivity, selectivity and range) Single IC RF receiver solutions e.g. from Micrel.

IR RECEIVERS

e.g. Monolithic TV remote receivers with digital output

27. Explain expressions: code scanning and code grabbing. How to

protect against these methods?

The transmitted code sequence is the same for every press of the remote button. Oldest solution.

Possible threats to a constant code system:

The coe can be recore without knowlege of the systems owner. Then, the coecan be used again to authorise the system. The method is called code grabbing

and can be realised (in case of IR systems) with a simple universal TV remote or a

eicate coe-copier e.g.

Generation and transmission of all codes possible to make with a given encoder type the method is code scanning.

Before the variable code introduction, the antiscanning method has been applied ifthe linear approach to a correct code was detected, the decoder would be blocked

for some time.

Variable Code Systems:

Code word changes with every press of remote button The code which have been received becomes invalid it does not authorise the

system any more (protection against code-grabbing)

Instead of simple code comparison (constant code systems) the code analysis andtracking algorithms have to be used a numerical effort and hardware is required

Sophisticated algorithms require memory to hold transmission history; coe woris dependent on serial number and the codes already transmitted.

The security level of these systems is high


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28. What informations are included in the transmitted code word in Keeloq

system? Describe operations which take place in encoder and decoder

during transission of code.

The transmitted code word depends on:

Encoder key input status,

Encoder serial number, programmed ISP

encryption key a value characteristic for a given encoder

The value of synchronization counter

So-called discrimination value - a constant, which is ciphered in a variable code portion of

transmitted data.

Encryption key and serial number are constants written into encoers EEPROM uring prouction

(ISP).


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Encryption keys for all encoers known by the ecoer are not stored in the memory when

neee, they are calculate from serial number an manufacturers coe (saves non-volatile memory

requirements for decoder).

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Electronic Infosystems