24-01-2010, 05:31 PM
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SYNOPSIS
The intelligent wireless video camera described in this paper is
designed using wireless video monitoring system, for detecting the
presence of a person who is inside the restricted zone. This type of
automatic wireless video monitors is quite suitable for the isolated
restricted zones, where the tight security is required.
The principle of remote sensing is utilized in this, to detect the
presence of any person who is very near to reference point with in the
zone.
A video camera collects the images from the reference points and then
converts into electronic signals. The collected images are converted
from visible light into invisible
electronic signals inside a solid-state imager. These signals are
transmitted to the monitor,
In this paper for the demonstration purpose three reference points are
taken. Each reference point is arranged with two infrared LEDâ„¢s and
one lamp. This arrangement is made to detect the presence of a person
who is near the reference point. The reference point is nothing but
restricted area, when any person comes near to any reference point,
then immediately that particular reference point output will become
high and this high signal is fed to the computer. Now the computer
energizes that particular reference point lamp and rotates the video
camera towards that reference point for collecting the images at that
particular reference point. To rotate the video camera towards
interrupted reference point, stepper motor is used.
The present wireless video camera described in this
is designed using wireless video monitoring system, for detecting the
presence of a person who is inside the restricted zone. This type of
automatic wireless video monitors is quite suitable for the isolated
restricted zones, where the tight security is required.
Once upon a time much importance is not given for the security system.
But as we see today lot of terrorism has grown up across the country
and need has aroused to develop different types of security systems for
various applications to safe guard the zones of various types like,
military zones, railway yards, scrap yards, borders etc., this kind of
automatic video monitoring systems can be installed at indo-pak
borders, where the terrorists are crossing borders. In fact our
country is spending lot of its revenue to safe guard the borders. By
installing this type of security systems everywhere at critical points,
lot of revenue can be saved by minimizing the manpower.
Basic operational principle:
The video surveillance unit is designed for the widest
possible viewing range and portability. The unit consists of a Stepper
Motor, which drives the camera towards reference points automatically
by the computer and a transmitter
transmits the images collected by the camera to a distant end. Thus a
automatic controlled wireless camera is very useful for surveillance of
places where the particular location makes it inconvenient or
impractical for a wired operation of the unit. The robotic action made
by the stepper motor is attached to the camera allows surveillance of
maximum area with one single camera. Such setup can be very flexible to
the user and can save valuable company resources. There are several
types of security systems existed in the Market; one of the most common
security systems is CCTV (Closed Circuit Television). The CCTV
consists Video Surveillance Camera used as security-monitoring device
plays a major roll in security systems. One reason for this is the
fact that a picture is worth then a thousand words. This is
especially true in a court of law where an eyewitness is required who
can place the criminal at the scene of a crime.
CCTV systems are also helpful in the residential security
Market. They allow homeowners to see their callers, thus establishing
their identity before they open an outside entrance door. This is an
important feature too, because other wise, they might open their door
to a criminal.
The Infrared sensing circuit consists of two infrared LEDâ„¢s for
transmitting the signal as well as receiving the signal. The signal
transmitted by the transmitting LED omits the signal in a line like
laser beam, the radiated signal from the transmitting LED is invisible
and harmless. Whenever the human body interrupts the transmitting
signal, there the signal is reflected and this reflected signal is
received by the infrared receiving LED.
INFRARED TRANSMITTER / RECEIVER SECTION:
This section is designed for detecting the presence of a person who is
inside the restricted zone within the range. It is basically an
infrared proximity detection system. Here high efficiency IR-LED is
driven by PNP Transistor SK100 with a modulating frequency of about
10KHz. This frequency is available from Pin 5 of LM 567 IC (versatile
PLL tone decoder IC). The 47W resistor connected in series with the IR
LED limits the IR-LED current.
The basic function of the detector circuit is by radiating energy into
space through IR LED and detecting the echo signal reflected from an
object. The reflected energy that is returned to the receiving LED
indicates the presence of a person who is within the range. A portion
of the transmitted energy is intercepted by the target and re-radiated
in many directions. The radiation directed back towards the system is
collected by the receiving LED causes to produce a high signal at Pin
No.8 of LM567 IC. The output of the receiver is fed to the computer.
Whenever the computer receives a high signal from the reference point,
the computer drives the stepper motor through the driving transistors
and rotates the motor towards that particular reference point. Three
similar circuits are designed for the three different reference points.
Diagram of the sensing circuit:
COMPUTER:
The computer is playing a major role in this .The main
function of the computer is to identify the interruption made by the
person, where exactly the signal is interrupted, at which reference
point identifying the point and displays the information on the screen.
The other major function of the computer is to drive the stepper
motor. This block is also responsible for identifying the reference
point. Here any normal configuration computer can be employed. The
software program defining the operations for the computer is written in
ËœCâ„¢ language.
The output of the obstacle sensor is fed to the computer through
the parallel port. The original purpose of Parallel port was to enable
communication between a PC and a peripheral. Another use that has
become very popular is transferring information or receiving the
information. In this project work the received information from the
detector circuit is used to drive the motor. Which is useful for the
system for identifying the interrupted reference point. With the help
of associated software written in ËœCâ„¢ language the received information
can be displayed on computer screen.
A computer is an electronic device, which processes information under
the control of a set of instructions called program. It has the ability
to accept the data, execute the program, and perform mathematical and
logical operations on data. The result of the operations can be
reported through output. Infact, a computer is a complete system in
itself. The computer as a system is a combination of Hardware and
Software components that jointly offer the necessary services to the
user.
The computer reads the data received through parallel
port and can store the data; the same data will be displayed on
computer screen. The program contains instruction about what has to be
done with the data. The CPU executes the programs stored in the main
memory by performing fetch instruction from memory and right data
either to a memory location or on an output device. The main components
of the CPU are, ALU (Arithmetic and Logic Unit), CU (Control Unit), and
a set of registers. The control unit is responsible for the moment of
data and instructions in and out of the memory and CPU. It is also
responsible for the decoding of an instruction and determining as to
what is desired by the same. The complete electronic Hardware is
interfaced with parallel port.
HOW THE COMPUTER DRIVES THE STEPPER MOTOR
To drive the stepper motor in both the directions (clockwise or
anticlockwise) the system is programmed to produce the pulses in a
sequence at four different outputs, these sequential programmed outputs
energizes the motor windings one after another in a sequence. To drive
the motor in clockwise, the sequence starts from top to bottom,
similarly to drive the motor in anti-clockwise the sequence starts from
the bottom to top. Like wise the motor rotates in both the directions.
The output of the computer through parallel port is used to drive the
switching transistors; finally these switching transistors drive the
stepper motor. These transistors provide the required current to
energize the motor. The stepper motor used in this project work is
capable to drive up to 3Kg loads, i.e., the holding torque is 3Kg.
The output of the computer is also used to drive the three
relays and one buzzer. Whenever any human body interrupts any reference
point, the computer energizes the alarm at the same time the computer
energize the corresponding relay also. These relay contacts are used to
energize the three different lamps corresponds to the three reference
points independently. The circuit diagram of relays and buzzer driven
by the computer is shown below.
Stepper Motor Drive Circuit:
The stepper motor used in this is having four windings and these
windings are energized one after another in a sequence according to the
code produced by the computer through motor drive circuit. This motor
rotates in step wise and the step angle is 1.80. Varying the pulse
rate can vary the speed of the motor. The pulses are produced by the
computer can be controlled through the program by which motor speed can
be varied. The stepper motor used in this project work is capable to
drive up to 3kg load.
Each reference point is arranged with two infrared sensors and both the
sensors are arranged side by side within the distance of one inch
approximately and both are directed towards the space with the zone.
The energization sequence for the forward and backward movements of the
stepper motor is fed from computer with the help of software written in
ËœCâ„¢ language. The ratings of the motor employed are 12V dc 4-coil.
The driving circuit of the motor is designed using BC 547 (low power
Transistor) and 2N5296 (Medium power Transistor). These two
transistors are configured in emitter following mode for amplifying the
current rating. The motor winding when it is energized, it consumes
350 mA approximately.
The following is the diagram of the stepper motor drive circuit
TRANSMITTER:
The output of the video camera is fed to this
transmitter, for transmitting the video signals in amplitude
modulation. The video signal coming out of video camera is nothing but
pure composite video signal and this signal is fed to this AM
transmitter. The transmitter circuit generates a continuous frequency
of 100MHz approximately, which is used to form a permanent page link between
the transmitter and receiver, and this is known as carrier frequency.
The output of video camera is fed to this carrier input as a modulating
wave. This is a frequency modulated radio transmitter. The radiating
power of the transmitter is less than 20mw, so that the range between
transmitter and receiver can be less than 25 feet.
The AM transmitter consists three sections namely
(1) VHF Oscillator
(2) Driver Stage or Modulator
(3) Final Amplifier Stage.
The output of the VHF oscillator is treated as carrier and the same is
fed to the modulator section. The output of the VHF oscillator is fed
to collector and the final output taken from the emitter of the PNP
transistor of the modulator section. Since it is a PNP transistor there
wonâ„¢t be any phase reversal (1800 phase shift), because this transistor
is configured in common base mode. Therefore finally at the output of
this stage, a perfect AM wave can be obtained. In the amplifier section
2 N 3866-NPN Transistor is used to amplify the input signal.
The Complete Circuit Diagram of transmitter including three stages is
as follows
The carrier is designed for transmitting the picture details. At the
receiving end, a small television set of 4 screen is used to display
the picture caught. In this way using this wireless video camera we can
detect the entry of unauthorized persons especially in case of military
to detect our enemies crossing the border.
COMPLETE CIRCUIT DIAGRAM
REFERENCES:
(1) Basic Radio and Television. BY: S.P. SHARMA
(2) Digital and Analog Communication Systems By: K. Sam Shanmugam
With the help of above two books we came to know how the signals are
transmitted using Radio transmitter and these two books helped us while
designing the transmitter and receiver.
(3) Practical transistor circuit design and analysis By: GERALD E.
WILLIAMS
(4) Basic electronics By: GROB
(5) Electronic circuit guidebook “ sensors By: JOSEPH J.CARR
(6) Modern Television Practice By: R.R. Gulati
(7) The Complete Guide to video By: Martin Clifford
(8) Computer Controlled System - By: Karl J.ASTROM
(9) C++ An Introduction to Programming “
By: JESSE LIBERTY. JIM KEOGH
(10) C ALL Clear - By: RAVINDRA
(11) Practical Electronics monthly magazines
(12) Elector India monthly magazines
