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Transcript of Laser Synopses
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A
SYNOPSES
ON
Data Communication & Security SystemUsing LASER
Submitted To
Electronics &Communication Engineering Department
of
MAHARANA PRATAP ENGINEERING COLLEGE ,
KOTHI, MANDHANA, KANPUR
SESSION :- (2009-10)
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ACKNOWLEDMENT
We wish to express our deep sense of gratitude to those whose encouragement and co-
operation has been a source of inspiration. Specially, it is an honor to thank Mr. Sunil
Kushwaha for acknowledge our Project topic Data Communication & Security
SystemUsing LASER.
We would also like to express our thanks to all those respected faculty
members of Department of Electronics & Communication Engineering who have
helped us and gave their permission for initiate our project.
Group Members
NEERAJ SAHU
MAHENDRA SHUKLA
AMIT KUMAR
ADISH JAIN
Staff Counselor Submitted By
Electronics & Communication
Engineering Department
NEERAJ SAHU
(0604631060)MAHENDRA SHUKLA(0604631047)AMIT KUMAR(0504631006)
ADISH JAIN (0604631005)E.C. - IV Year
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E.C. 4th year
ABSTRACT
In this project we will transmits the data using a LASER beam by inputting the data from
our PC then receive the corresponding data wirelessly and transmitted data will visible on
DIGITAL DISPLAY SYSTEM.
The laser module (TIM202) module is a small (38x14x14 mm) semicunductor;similar to those types used in laser pointers which takes 3V 45mA and outputs 3-5mW
670nm laser beam. We implement a simple LASER data link using this semiconductor
laser module and some kind of receiver. We will use a fiber optic receiver module as a
receiver. module is designed for 665nm wavelength and it can operate up to 5 mbit/s.Now we connected the circuit to the serial-port of a PC. Using a PC circuit can be operate
with different communication speeds. At the receiver side well use a display system onwhich we can see the transmitted data
( text or number ).
Undertaking the laser for security system therefor If any person try to hack the
transmitted data from communication medium (LASER path through air) the securityalarm will get ON. Well also show in our project how to protect a object by using
LASER beam.
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CONTENT
Introduction of Datacommunication
Security system
LASER
LASER Cunstruction
LASER Physics
Spectral Outputs of Several LASER
Sensors
PC Interfacing
RS-232
RS232 Data Interface
Signals
RTS/CTS handshaking
IC Used
Circuit Diagram for Data Communication
Transmitter Block Diagram
Reciever block Diagram
Security System Circuit Diagram
An introduction of Visual Basic
References
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Introduction of Data Communication:-
To send digital information through the laser communication device, the inputaudio
signal must be converted into a series of digital bits. Before this can beaccomplished,some formatting has to be performed on the analog audio signal comingfrom the CD
player. The analog input is a 100-200mVp-p signal. It is first sent through a filtering
circuit to block any DC offset and center the input signal at 0V. The signal is then
amplified with a gain of 20 using an opamp. Finally, a filter and clamping circuitare usedto attenuate frequencies below 10Hz and flip the negative values positive forA/D
conversion. The conversion is completed using an AD7819 chip. This chip samples the
analog signal at 125kHz (controlled by a clock signal from 555 timer) and outputs to an8-bit parallel interface. Sampling is accomplished by reading the voltage level of the
analog signal at a certain time interval (for this system, the sample period is 8 s). This
voltage is then assigned one of 256 distinct voltage levels and given an 8-bit sequence todescribe the voltage level in digital terms.
The 8-bit sequence is then sent in parallel (8 lines sending the bits all at the same time) to
an array of transistors. The transistors switch 8 lasers off and on to transmit the digitalsequences. A 1 turns a given laser on while a 0 turns it off. The laser light pulses are
sensed by eight phototransistors that are give off a 1 when excited by laser light and a0 when not excited.To reverse the process for output to the audio speaker, digital to analog conversion needs
to take place. To do this, the digital bits from the laser are fed into a latch (74HC161) that
sustains the digital values coming from the lasers until another value overwrites it. Aftergoing through an inverter array, the 8-bit signal arrives at the D/A converter chip. This
chip takes each 8-bit digital sample and converts it to one of the 256 voltage levels used
by the A/D chip. The output analog signal is then amplified by a variable gain opamp
circuit and taken to the speaker.
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Security System:-
Torch powered by 3V or above power-supply is used for generating a laser beam. A
combination of plain mirrors M1 through M6 is used to direct the laser beam around theobject that you want to protect . The laser beam is directed to finally fall on an LDR that
forms part of the receiver unit .Any interruption of the beam by a thief/ trespasser
(Hacker for data communication) will result into energisation of the alarm. The 3Vpower-supply circuit is a conventional full wave rectifier-filter circuit.
Any alarm unit that operates on 230V AC can be connected at the output. The
receiver unit comprises two identical step-down transformers (X1 and X2), two 6V relays(RL1 and RL2), an LDR, a transistor, and a few other passive components. When
switches S1 and S2 are activated, transformer X1, followed by a full-wave rectifier and
smoothing capacitor C1, drives relay RL1 through the laser switch. The laser beamshould be aimed continuously on LDR. As long as the laser beam falls on LDR, transistor
T1 remains forward biased and relay RL1 is thus in energized condition. When a person
crosses the line of laser beam, relay RL1 turns off and transformer X2 gets energized to
provide a parallel path across N/C contact and the pole of relay RL1. In this condition,the laser beam will have no effect on LDR and the alarm will continue to operate as long
as switch S2 is ON. When the torch is switched on, the pointed laser beam is reflected
from a definite point/place on the periphery of the any object. Making use of a set of
properly oriented mirrors one can form an visible net of laser rays as shown in the blockdiagram. The final ray should fall on LDR of the circuit.
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Note. LDR should be kept in a long pipe to protect it from other sources of light, and its
total distance from the source may be kept limited to 500 meters.
Laser:-
A laser is a device that emits light (electromagnetic radiation) through a process calledstimulated emission. The term laser is an acronym forlight amplification by stimulated
emission of radiation. Laser light is usually spatially coherent, which means that the
light either is emitted in a narrow, low-divergence beam, or can be converted into one
with the help of optical components such as lenses. Typically, lasers are thought of asemitting light with a narrow wavelengthspectrum ("monochromatic" light). This is not
http://en.wikipedia.org/wiki/Lighthttp://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Stimulated_emissionhttp://en.wikipedia.org/wiki/Acronymhttp://en.wikipedia.org/wiki/Coherence_(physics)http://en.wikipedia.org/wiki/Coherence_(physics)http://en.wikipedia.org/wiki/Beam_divergencehttp://en.wikipedia.org/wiki/Lenshttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Electromagnetic_spectrumhttp://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Stimulated_emissionhttp://en.wikipedia.org/wiki/Acronymhttp://en.wikipedia.org/wiki/Coherence_(physics)http://en.wikipedia.org/wiki/Beam_divergencehttp://en.wikipedia.org/wiki/Lenshttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Electromagnetic_spectrumhttp://en.wikipedia.org/wiki/Light -
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true of all lasers, however: some emit light with a broad spectrum, while others emit light
at multiple distinct wavelengths simultaneously. The coherence of typical laser emissionis distinctive. Most other light sources emit incoherent light, which has aphase that varies
randomly with time and position.
Laser construction:-
A laser consists of a gain medium inside a highly reflectiveoptical cavity, as well as a
means to supply energy to the gain medium. The gain medium is a material withproperties that allow it to amplify light by stimulated emission. In its simplest form, a
cavity consists of two mirrors arranged such that light bounces back and forth, each time
passing through the gain medium. Typically one of the two mirrors, the output coupler, is
partially transparent. The output laser beam is emitted through this mirror.Light of a specific wavelength that passes through the gain medium is amplified
(increases in power); the surrounding mirrors ensure that most of the light makes manypasses through the gain medium, being amplified repeatedly. Part of the light that is
between the mirrors (that is, within the cavity) passes through the partially transparentmirror and escapes as abeam of light. .
The process of supplying the energyrequired for the amplification is calledpumping. Theenergy is typically supplied as an electrical current or as light at a different wavelength.
Such light may be provided by a flash lamp or perhaps another laser. Most practical
lasers contain additional elements that affect properties such as the wavelength of theemitted light and the shape of the beam.
Laser physics:-
A helium-neon laser demonstration . The glowing ray in the middle is an electric
discharge producing light in much the same way as a neon light. It is the gain mediumthrough which the laser passes, notthe laser beam itself, which is visible there. The laser
beam crosses the air and marks a red point on the screen to the right.
http://en.wikipedia.org/wiki/Phase_(waves)http://en.wikipedia.org/wiki/Laser_constructionhttp://en.wikipedia.org/wiki/Active_laser_mediumhttp://en.wikipedia.org/wiki/Optical_cavityhttp://en.wikipedia.org/wiki/Optical_cavityhttp://en.wikipedia.org/wiki/Output_couplerhttp://en.wikipedia.org/wiki/Optical_amplifierhttp://en.wikipedia.org/wiki/Optical_amplifierhttp://en.wikipedia.org/wiki/Light_beamhttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Laser_pumpinghttp://en.wikipedia.org/wiki/Laser_pumpinghttp://en.wikipedia.org/wiki/Laser_pumpinghttp://en.wikipedia.org/wiki/Xenon_flash_lamphttp://en.wikipedia.org/wiki/Helium-neon_laserhttp://en.wikipedia.org/wiki/Active_laser_mediumhttp://en.wikipedia.org/wiki/Phase_(waves)http://en.wikipedia.org/wiki/Laser_constructionhttp://en.wikipedia.org/wiki/Active_laser_mediumhttp://en.wikipedia.org/wiki/Optical_cavityhttp://en.wikipedia.org/wiki/Output_couplerhttp://en.wikipedia.org/wiki/Optical_amplifierhttp://en.wikipedia.org/wiki/Light_beamhttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Laser_pumpinghttp://en.wikipedia.org/wiki/Xenon_flash_lamphttp://en.wikipedia.org/wiki/Helium-neon_laserhttp://en.wikipedia.org/wiki/Active_laser_medium -
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Spectrum of a helium neon laser showing the very high spectral purity intrinsic to nearly
all lasers. Compare with the relatively broad spectral emittance of a light emitting diode.See also: Laser science
The gain medium of a laser is a material of controlled purity, size, concentration, and
shape, which amplifies the beam by the process of stimulated emission. It can be of any
state: gas, liquid,solid orplasma. The gain medium absorbs pump energy, which raisessome electrons into higher-energy ("excited") quantum states. Particles can interact with
light both by absorbing photons or by emitting photons. Emission can be spontaneous or
stimulated. In the latter case, the photon is emitted in the same direction as the light thatis passing by. When the number of particles in one excited state exceeds the number of
particles in some lower-energy state,population inversion is achieved and the amount of
stimulated emission due to light that passes through is larger than the amount ofabsorption. Hence, the light is amplified. By itself, this makes an optical amplifier. When
an optical amplifier is placed inside a resonant optical cavity, one obtains a laser.
The light generated by stimulated emission is very similar to the input signal in terms of
wavelength, phase, and polarization. This gives laser light its characteristic coherence,and allows it to maintain the uniform polarization and often monochromaticity
established by the optical cavity design.
The optical cavity, a type ofcavity resonator, contains a coherent beam of light between
reflective surfaces so that the light passes through the gain medium more than oncebefore it is emitted from the output aperture or lost to diffraction or absorption. As light
circulates through the cavity, passing through the gain medium, if the gain (amplification)
in the medium is stronger than the resonator losses, the power of the circulating light canrise exponentially. But each stimulated emission event returns a particle from its excited
state to the ground state, reducing the capacity of the gain medium for further
amplification. When this effect becomes strong, the gain is said to be saturated. Thebalance of pump power against gain saturation and cavity losses produces an equilibriumvalue of the laser power inside the cavity; this equilibrium determines the operating point
of the laser. If the chosen pump power is too small, the gain is not sufficient to overcome
the resonator losses, and the laser will emit only very small light powers. The minimumpump power needed to begin laser action is called the lasing threshold. The gain medium
will amplify any photons passing through it, regardless of direction; but only the photons
aligned with the cavity manage to pass more than once through the medium and so havesignificant amplification.
The beam in the cavity and the output beam of the laser, if they occur in free space rather
than waveguides (as in an optical fiber laser), are, at best, low order Gaussian beams.However this is rarely the case with powerful lasers. If the beam is not a low-orderGaussian shape, the transverse modes of the beam can be described as a superposition of
Hermite-GaussianorLaguerre-Gaussian beams (for stable-cavity lasers). Unstable laser
resonators on the other hand, have been shown to produce fractal shaped beams. [5] Thebeam may be highly collimated, that is being parallel without diverging. However, a
perfectly collimated beam cannot be created, due to diffraction. The beam remains
collimated over a distance which varies with the square of the beam diameter, and
eventually diverges at an angle which varies inversely with the beam diameter. Thus, abeam generated by a small laboratory laser such as a helium-neon laserspreads to about
1.6 kilometers (1 mile) diameter if shone from the Earthto theMoon. By comparison, the
http://en.wikipedia.org/wiki/File:Red-YellowGreen-Blue_LED_spectra.pnghttp://en.wikipedia.org/wiki/Laser_sciencehttp://en.wikipedia.org/wiki/State_of_matterhttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Liquidhttp://en.wikipedia.org/wiki/Liquidhttp://en.wikipedia.org/wiki/Solidhttp://en.wikipedia.org/wiki/Plasma_(physics)http://en.wikipedia.org/wiki/Plasma_(physics)http://en.wikipedia.org/wiki/Excited_statehttp://en.wikipedia.org/wiki/Quantum_statehttp://en.wikipedia.org/wiki/Population_inversionhttp://en.wikipedia.org/wiki/Optical_amplifierhttp://en.wikipedia.org/wiki/Phase_(waves)http://en.wikipedia.org/wiki/Cavity_resonatorhttp://en.wikipedia.org/wiki/Exponential_growthhttp://en.wikipedia.org/wiki/Lasing_thresholdhttp://en.wikipedia.org/wiki/Optical_fiberhttp://en.wikipedia.org/wiki/Optical_fiberhttp://en.wikipedia.org/wiki/Gaussian_beamhttp://en.wikipedia.org/wiki/Transverse_modehttp://en.wikipedia.org/wiki/Hermite_polynomialshttp://en.wikipedia.org/wiki/Gaussian_functionhttp://en.wikipedia.org/wiki/Gaussian_functionhttp://en.wikipedia.org/wiki/Laguerre_polynomialshttp://c/Documents%20and%20Settings/aaaaa/Desktop/015/New%20Folder/Laser.htm#cite_note-4#cite_note-4http://en.wikipedia.org/wiki/Collimated_lighthttp://en.wikipedia.org/wiki/Beam_divergencehttp://en.wikipedia.org/wiki/Beam_divergencehttp://en.wikipedia.org/wiki/Diffractionhttp://en.wikipedia.org/wiki/Helium-neon_laserhttp://en.wikipedia.org/wiki/Earthhttp://en.wikipedia.org/wiki/Earthhttp://en.wikipedia.org/wiki/Moonhttp://en.wikipedia.org/wiki/Moonhttp://en.wikipedia.org/wiki/File:Red-YellowGreen-Blue_LED_spectra.pnghttp://en.wikipedia.org/wiki/Laser_sciencehttp://en.wikipedia.org/wiki/State_of_matterhttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Liquidhttp://en.wikipedia.org/wiki/Solidhttp://en.wikipedia.org/wiki/Plasma_(physics)http://en.wikipedia.org/wiki/Excited_statehttp://en.wikipedia.org/wiki/Quantum_statehttp://en.wikipedia.org/wiki/Population_inversionhttp://en.wikipedia.org/wiki/Optical_amplifierhttp://en.wikipedia.org/wiki/Phase_(waves)http://en.wikipedia.org/wiki/Cavity_resonatorhttp://en.wikipedia.org/wiki/Exponential_growthhttp://en.wikipedia.org/wiki/Lasing_thresholdhttp://en.wikipedia.org/wiki/Optical_fiberhttp://en.wikipedia.org/wiki/Gaussian_beamhttp://en.wikipedia.org/wiki/Transverse_modehttp://en.wikipedia.org/wiki/Hermite_polynomialshttp://en.wikipedia.org/wiki/Gaussian_functionhttp://en.wikipedia.org/wiki/Laguerre_polynomialshttp://c/Documents%20and%20Settings/aaaaa/Desktop/015/New%20Folder/Laser.htm#cite_note-4#cite_note-4http://en.wikipedia.org/wiki/Collimated_lighthttp://en.wikipedia.org/wiki/Beam_divergencehttp://en.wikipedia.org/wiki/Diffractionhttp://en.wikipedia.org/wiki/Helium-neon_laserhttp://en.wikipedia.org/wiki/Earthhttp://en.wikipedia.org/wiki/Moon -
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output of a typical semiconductor laser, due to its small diameter, diverges almost as soon
as it leaves the aperture, at an angle of anything up to 50. However, such a divergentbeam can be transformed into a collimated beam by means of a lens. In contrast, the light
from non-laser light sources cannot be collimated by optics as well.
Although the laser phenomenon was discovered with the help ofquantum physics, it is
not essentially more quantum mechanical than other light sources. The operation of a freeelectron lasercan be explained without reference toquantum mechanics.
Spectral output of several types of lasers:-
http://en.wikipedia.org/wiki/Lens_(optics)http://en.wikipedia.org/wiki/Quantum_physicshttp://en.wikipedia.org/wiki/Free_electron_laserhttp://en.wikipedia.org/wiki/Free_electron_laserhttp://en.wikipedia.org/wiki/Free_electron_laserhttp://en.wikipedia.org/wiki/Quantum_mechanicshttp://en.wikipedia.org/wiki/Quantum_mechanicshttp://en.wikipedia.org/wiki/Quantum_mechanicshttp://en.wikipedia.org/wiki/Lens_(optics)http://en.wikipedia.org/wiki/Quantum_physicshttp://en.wikipedia.org/wiki/Free_electron_laserhttp://en.wikipedia.org/wiki/Free_electron_laserhttp://en.wikipedia.org/wiki/Quantum_mechanics -
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Sensor:- A Photo detector is used for detection of the intensity modulated data.
http://en.wikipedia.org/wiki/File:Laser_spectral_lines.svg -
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A sensor is a device which measures a physical quantity and converts it into a signalwhich can be read by an observer or by an instrument.
For example, a mercury thermometer converts the measured temperature into expansionand contraction of a liquid which can be read on a calibrated glass tube. A thermocouple
converts temperature to an output voltage which can be read by a voltmeter. For
accuracy, all sensors need to be calibrated against known standards.Sensors are used in everyday objects such as touch-sensitive elevator buttons and lamps
which dim or brighten by touching the base. There are also innumerable applications for
sensors of which most people are never aware. Applications include automobiles,machines, aerospace, medicine, industry, and robotics.
A sensor's sensitivity indicates how much the sensor's output changes when the measured
quantity changes. For instance, if the mercury in a thermometer moves 1cm when the
temperature changes by 1, the sensitivity is 1cm/1. Sensors that measure very smallchanges must have very high sensitivities.
Technological progress allows more and more sensors to be manufactured on a
microscopic scale as micro sensors using MEMS technology. In most cases, a microsensor reaches a significantly higher speed and sensitivity compared with macroscopic
approaches.
LDR:- It refers to light dependent resister. The resistence of LDR is increased in dark.It is used as a sensor of light.
PC Interfacing:-
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RS-232
In telecommunication RS-232 (Recommended Standard 232) is a standard for serialbinary data signals connecting between a DTE (Data terminal equipment) and a DCE(Data Circuit-terminating equipment). It is commonly used in computer serial ports. A
similarITU-T standard is V.24.
Standard details:
In RS-232, data is sent as a time-series of bits. Both synchronous and asynchronous
transmissions are supported by the standard. In addition to the data circuits, the standard
defines a number of control circuits used to manage the connection between the DTE and
DCE. Each data or control circuit only operates in one direction that is, signaling from aDTE to the attached DCE or the reverse. Since transmit data and receive data are separate
circuits, the interface can operate in a full duplex manner, supporting concurrent data
flow in both directions. The standard does not define character framing within the data
stream, or character encoding.
RS232 Data Interface
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RS-232 is simple, universal, well understood and supported but it has some serious
shortcomings as a data interface. The standards to 256kbps or less and line lengths of
15M (50 ft) or less but today we see high speed ports on our home PC running very highspeeds and with high quality cable maxim distance has increased greatly. The rule of
thumb for the length a data cable depends on speed of the data, quality of the cable.
Signals:-
Commonly-used signals are:
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I. Transmitted Data (TxD)Data sent from DTE to DCE.
II. Received Data (RxD)
Data sent from DCE to DTE.
III. Request To Send (RTS)Asserted (set to 0) by DTE to prepare DCE to receive data. This may require action onthe part of the DCE, e.g. transmitting a carrier or reversing the direction
IV. Clear To Send (CTS)Asserted by DCE to acknowledge RTS and allow DTE to transmit.
Data Terminal Ready (DTR) Asserted by DTE to indicate that it is ready to be connected.If the DCE is a modem, this may "wake up" the modem, bringing it out of a power saving
mode. This behaviour is seen quite often in modern PSTN and GSM modems. When this
signal is de-asserted, the modem may return to its standby mode, immediately hanging upany calls in progress.
V. Data Set Ready (DSR)Asserted by DCE to indicate an active connection. If DCE is not a modem (e.g. a null
modem cable or other equipment), this signal should be permanently asserted (set to 0),
possibly by a jumper to another signal.
VI. Data Carrier Detect (DCD)Asserted by DCE when a connection has been established with remote equipment.
VII. Ring Indicator (RI)Asserted by DCE when it detects a ring signal from the telephone line. The standard
defines RTS/CTS as the signaling protocol for flow control for data transmitted from
DTE to DCE. The standard has no provision for flow control in the other direction.
Various implementations of compatible ports may reassign other pins for flow control.
RTS/CTS handshaking
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The standard RS-232 use of the RTS and CTS lines is asymmetrical. The DTE asserts
RTS to indicate desire to transmit to the DCE. The DCE asserts CTS in response to grantpermission. This allows for half-duplex modems that disable their transmitters when not
required, and must transmit synchronization preamble to the receiver when they are re-
enabled. There is no way for the DTE to indicate that it is unable to accept data from theDCE.
A non-standard symmetrical alternative is widely used: CTS indicates permission fromthe DCE for theDTE to transmit, and RTS indicates permission from the DTE for theDCE to transmit. The "request to transmit" is implicit and continuous. Thus, with this
alternative usage, one can think of RTS asserted (logic 0) meaning "ready to receive
characters" from the DTE, rather than a "request to transmit" to the
DCE.
Signal rate selection
The DTE or DCE can specify use of a "high" or "low" signaling rate. The rates as well aswhich device will select the rate must be configured in both the DTE and DCE. The
prearranged device selects the high rate by setting pin 23 to ON.
Loopback testing
Many DCE devices have a loop back capability used for testing. When enabled, signals
are echoed back to the sender rather than being sent on to the receiver. If supported, the
DTE can signal the local DCE (the one it is connected to) to enter loop back mode by
setting pin 18 to ON, or the remote DCE (the one the local DCE is connected to) to enterloop back mode by setting pin 21 to ON. The latter tests the communications link as well
as both DCE's. When the DCE is in test mode it signals the DTE by setting Pin 25 toON.A commonly used version of loop back testing doesn't involve any special capability
of either end. A hardware loop back is simply a wire connecting complementary pins
together in the same connector. SeeLoopback.
Loopback testing is often performed with a specialized DTE called a Bit Error Rate
Tester (BERT).
Timing signals
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Some synchronous devices provide a clock signal to synchronize data transmission,
especially at higher data rates. Two timing signals are provided by the DCE on pins 15and 17. Pin 15 is the transmitter
Clock, or send timing (ST); the DTE puts the next bit on the data line (pin 2) when this
clock transitions OFF to ON (so it is stable during the ON to OFF transition when theDCE registers the bit). Pin 17
is the receiver clock, or receive timing (RT); the DTE reads the next bit from the data line(pin 3) when this clock transitions from ON to OFF.
Alternatively, the DTE can provide a clock signal, called transmitter timing (TT), on pin
24 for transmitted data. Again, data is changed when the clock transitions from OFF to
ON and read during theON to OFF transition. TT can be used to overcome the issue where ST must traverse a
cable of unknown length and delay, clock a bit out of the DTE after another unknown
delay, and return it to theDCE over the same unknown cable delay. Since the relationbetween the transmitted bit and TT can be fixed in the DTE design, and since both
signals traverse the same cable length, using TT eliminates the issue. TT may be
generated by looping ST back with an appropriate phase change to align it with thetransmitted data. ST loop back to TT lets the DTE use the DCE as the frequency
reference, and correct the clock to data timing.
RS232 physical properties
The RS232 standard describes a communication method capable of communicating in
different environments. This has had its impact on the maximum allowable voltages etc.
on the pins. In the original definition, the technical possibilities of that time were taken
into account. The maximum baud rate defined for example is 20 kbps. With currentdevices like the 16550A UART, maximum speeds of
1.5 Mbps are allowed.
IC Used :-For the security system comparator IC is required. we can use one of the given below
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Advantages :-
Two internally compensated op amps in a single package
Eliminates need for dual supplies
Allows directly sensing near GND and VOUT also goes to GND
Compatible with all forms of logic
Power drain suitable for battery operation
Pin-out same as LM1558/LM1458 dual operational amplifier
Circuit Diagram for Data Communication :-
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For Audio Transmission:-
Simple Transmitter:-
Simple Reciever:-
For Digital Data:-
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Transmitter Block Diagram:-
possible circuits for receiving:-
PCPOWERSUPPL
Y
AMPLIFIRESWITCHING
DEVICE
LASER
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Before trying the HBFR-2521 fiberoptical receiverr module I tried to use Simple infra-red detectoras the detector /that circuit was also sensitive to visible light). That circuit
did not give any useful results because it was too slow. I thought that using simple thistype prototransistor circuit were not usable in this application.
Good results up to 9600 bps using the following receiving circuit:
+5v
|| collector
| /---> |/ phototransistor
light |---> |\
| V emitter|_________________________ 0 and +5 out|/\ 1.5k/\
|gnd
The circuit it gives out 0 and 5 volts which is not compatible with RS232. The circuit
must be followed with MC1488 (or some other) rs232 driver to convert this to RS232. Ihave not tried this circuit, but the idea seems to be worth to try.
Security System Circuit Diagram:-
http://www.epanorama.net/counter.php?url=http://www.hut.fi/~then/circuits/irdetector.htmlhttp://www.epanorama.net/counter.php?url=http://www.hut.fi/~then/circuits/irdetector.htmlhttp://www.epanorama.net/counter.php?url=http://www.hut.fi/~then/circuits/irdetector.htmlhttp://www.epanorama.net/counter.php?url=http://www.hut.fi/~then/circuits/irdetector.html -
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Here we will use a dark detector circuit.if the laser beam falls continuously on the LDR
so the buzzer will in OFF position. When the LASER beam is interrupted the buzzerreached in ON position.
we can use IC555 (timer IC) as a comparator.
Programming Language Used:-
Visual Basic
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HistoryMicrosoft released Visual Basic in 1987. It was the first visual development tool from
Microsoft, and it was to compete with C, C++, Pascal and other well-knownprogramming languages. From the start, Visual Basic wasn't a hit. It wasn't until release
2.0 in 1991 that people really discovered the potential of the language, and with release3.0 it had become the fastest-growing programming language on the market.
What Is Visual Basic?Programmers have undergone a major change in many years of programming variousmachines. For example what could be created in minutes with Visual Basic could take
days in other languages such: as "C" or "Pascal". Visual Basic provides many interesting
sets of tools to aid you in building exciting applications. Visual Basic provides these tools
to make your life far easier because all the real hard code is already written for you.With controls like these you can create many applications which use certain parts of
windows.
Visual Basic
Paradigm :- Event-driven
Developer :- Microsoft
Latest release :- VB6/ 1998
Typing discipline :- Static, strong
Influenced by :- Quick BASIC
Influenced :- Visual Basic.NET
OS :- Microsoft Windows
Visual Basic (VB) is a third-generation event driven programming language andassociated development environment from Microsoft for its COM programming model.
Visual Basic was derived from BASIC and enables the rapid application development(RAD) of graphical user interface (GUI) applications, access to databases using
DAO,RDO or ADO and creation ofActive X controls and objects. Scripting languagessuch as VBA and VB Script are syntactically similar to Visual Basic, but performdifferently.
A programmer can put together an application using the components provided with
Visual Basic itself.Programs written in Visual Basic can also use the Windows API, but doing so requires
external function declarations.In business programming, Visual Basic has one of the largest user bases. In a survey
conducted in 2005, 62 percent of developers reported using some form of Visual Basic. Itcurrently competes with C++, C# and Java for dominance in the business world. Java
Script is another competitor to Visual Basic.
The final release was version 6 in 1998. Microsoft extended support will end in 2008 andthe designated successor is Visual Basic .NET.
Areas of Application:
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The term "Personal Programming" refers to the idea that, wherever you work,whatever you do, you can expand your computer's usefulness by writing applications to
use in your own job. Personal Programming is what Visual Basic is all about. Using
Visual Basic's tools, you quickly translate an abstract idea into a program design you canactually see on the screen. VB encourages you to experiment, revise, correct, and
network your design until the new project meets your requirements. However , most ofall, it inspires your imagination and creativity.Visual Basic is ideal for developing applications that run in the new Windows 95
operating system. VB presents a 3-step approach for creating programs:
1. Design the appearance of your application.
2. Assign property settings to the objects of your program.
3. Write the code to direct specific tasks at runtime.
Visual Basic can used in a number of different areas, for example:
Education
Research
Medicine
Business
Commerce
Marketing and Sales
Accounting
Consulting
Law
References
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www.wikipedia.org
www.google.com
www.infomit.com www.engineeringproject.4u.com
http://www.wikipedia.org/http://www.google.com/http://www.infomit.com/http://www.engineeringproject.4u.com/http://www.wikipedia.org/http://www.google.com/http://www.infomit.com/http://www.engineeringproject.4u.com/