CHAPTER – 1

Synopsis

The search vehicle designed with stepper motors is quite suitable for the defense application. Generally these kinds of vehicles are used in jungles for searching the anti-social elements. The system can be called as autonomous, because the vehicle itself detecting objects and according to the position of the object the vehicle takes diversion either right turn or left turn automatically. Some times the vehicle travels in reverse direction also, this happens when the vehicle finds a huge objects like trees, rocks etc., infrared sensors are used and they are arranged at front side of the vehicle. For this purpose four sets of sensors are used and each set contains two IR sensors. Two sets of sensors are arranged at left and right sides of the vehicle and the third set is arranged at middle of the vehicle. Fourth set of sensors also used for detecting pits or valleys, which is arranged at the front side of the vehicle. From each set, IR signal is delivered through one sensor like a laser beam, whenever the object interrupts the beam, the signal is reflected and this reflected signal is detected by another sensor. The outputs of all the three sensors are fed to Micro-controller, and according to the interrupted signals received by the sensors, the controller circuit drives the stepper Motors. These Motors drives the vehicle in different directions. For example, whenever the right sensors are interrupted, the vehicle takes left turn and moves in forward direction. Similarly if the left sensor is interrupted, vehicle takes right turn. Whenever the middle sensor is interrupted, vehicle moves in reverse direction up to certain distance and takes right or left turn.

The vehicle is called as search vehicle, because this vehicle is equipped with wireless video camera for collecting and transmitting the video images to the nearest monitoring station. At the monitoring station a small television set is used, so that presence of a person in the forest can be identified at monitoring station

In addition to the above an LDR is also used as a light-sensing device, and it is interfaced with the trigger circuit. The idea of using this circuit is to energize the vehicle headlamps automatically whenever the natural light disappears, with the help of this auto lighting system, during the nighttime also images can be transmitted. The output of the trigger circuit is used to drive the relay and this relay contact is used to energize the headlamps. Provision is made such that during the day time these lights remains in off condition.

CHAPTER – 2

EXECUTIVE SUMMARY

This project report describes about the project work “Autonomous Search Vehicle with Wireless Video Camera” used for the Navigation in the Forest. The project is part of a long-term vision, of developing an unmanned vehicle that moves in the forest or desert for identifying the anti social elements. The same vehicle also can be used to study the life of animals.

The main goal of the project is to present a working solution for autonomous search navigation, to be implemented in a vehicle for operation in forest terrains. The Autonomous Ground Vehicle (AGV) designed with stepper motors, driven by the microcontroller detects the objects like trees, bushes, stones etc., detecting the objects is main task for the perception is obstacle detection, which is essential for a safe autonomous vehicle. Detecting obstacles implies an active perception of the environment. Typical sensors for this kind of task include optical sensors and cameras, in this project work both are used. Four pairs of IR LED’s are used as optical sensors and all the four pairs are arranged at front side of the vehicle. These sensors act as Laser rangefinders have the great advantage of providing the information about the objects, which are infront of the vehicle. Since it is a prototype module we have arranged only four sets of sensors, but for the real operation many more number of sensors are to be used, and they are supposed to be arranged all four sides of the vehicle. The main advantage of using these optical sensors is, it not only detects the object also these can detect the pits as well as valleys. In this project work one set of sensors is used for detecting the pits and valleys, the other three sets of sensors are used to detect the obstacles.

In addition to the optical sensors, video camera is also used in this project work and the output of this camera is transmitted through the transmitter, hence this camera can be called as wireless video camera. At the receiving station, color or black and white television set can be used. The camera used for the purpose is miniature, arranged at front side of the vehicle.

The complete vehicle, which carries the total electronic circuitry including camera is designed to operate at 12V DC. For this purpose 7.5 AH maintenance free battery is used. To drive the vehicle, heavy-duty stepper motors are used at rear side, and the vehicle wheels are directly coupled to the motor shafts. Two motors are used, and each motor is capable to drive up to 5kg loads, because the holding torque of the motor is 5kg. To charge the battery, a separate charger is deigned with 12 V step down transformer.

Construction of Autonomous Ground Vehicles has been an intense research area for the last decade. A number of successful applications in agriculture and the mining industry, many engineers, have been demonstrated. It is reasonable to believe that similar solutions are relevant for a forest-based AGV. However, the forest environments have enough peculiarities to make the proposed development project highly advanced, and full of challenging tasks for research.

CHAPTER - 3

INTRODUCTION

The research work will deal with obstacle detection problems, where cameras, infra-red detectors, and other sensors are utilized to detect objects close to the vehicle. Another area of research is route navigation and control algorithm that take into account the specific problems involved in controlling a forest machine in a forest environment. The suggested hardware solution will involve micro controller and the sensors are interfaced with controller, which drives both the motors according to the received information from the sensors. This arrangement is believed to simplify and speed up the development work significantly.

This document is a pre-study for the project Autonomous Navigation for Forest Machines. The general requirements and conditions for the development of such a product are not addressed in this document. Instead, this paper focuses on one of the necessary components: autonomous navigation, which involves sensing and moving safely according to a fixed or changing plan in the environment of the vehicle. The proposed project aims at developing a system design, including algorithms and hardware specifications for such a vehicle.

The software and hardware will be installed in a standard forest machine, selected and prepared in collaboration with the manufacturer. A first version, which can be called as prototype module of the system will be installed and demonstrated on a smaller-sized vehicle. This vehicle can be called, as robot and this robot will also be important for speeding up and simplifying the development.

The research work will deal with obstacle detection problems, where cameras, infrared detectors, and other sensors are utilized to detect objects close to the vehicle. The suggested software solution involves a behavior-based architecture, commonly used in modern robotics. The vehicle’s tasks are defined as behaviors, such as finding obstacles and Avoid obstacles. Each of these behaviors is specified separately and works essentially reflexively, i.e. the action is a direct function of the sensor input. Control logic is often used to express complex behaviors in a compact and efficient way. Safety issues involve avoidance of accidents and damage to vehicles and environment. These problems will be given the highest priority in the project. Besides pure research, the project also involves a lot of engineering work, where existing technology is combined with innovative research results into a working product.

The preliminary project plan runs over four months. A major part of the work is assumed to be done by engineering students. Robot driving has concentrated on forward-looking sensing, by sensing the obstacles. This is an appropriate first step, but real deployment of mobile robots will require additional sensing and reasoning to surround the robot with safeguard sensors and systems. Our group is currently building short-range sensing to surround objects to improve the safety of the system. These kind of obstacle sensors can be arranged in other vehicles like city buses, which helps the driver to avoid collision with objects. Busses drive at relatively slow speeds, in crowded urban environments. One of the most frequent types of accidents in transit busses is side collision, where the driver does not have adequate awareness of objects near the bus, then turns too sharply and sideswipes a fixed object or (less often) hits a pedestrian. Preventing these accidents requires short-range sensing along the side and front of the bus, detecting fixed objects, detecting and tracking moving objects, predicting the motion of the bus itself, and a suitable driver interface for alerting the driver. In the military context, our focus is short-range sensing for full automation of scout b vehicles. An autonomous vehicle moving through a cluttered environment, such as a forest, may need to move between objects (e.g. trees) with very little clearance on either side of the vehicle. The conventional approach is to sense trees with forward-looking sensors, enter those trees into a map, and estimate the clearance as the vehicle moves forward and the trees move out of the field of view of the forward-looking sensor. If sensor data is noisy, or if the vehicle slips and slides in mud, the estimated clearance may be incorrect. It is better to directly and continuously sense nearby objects all along the side of the vehicle as it moves through the forest.

Civilian and military vehicles, and both driver assistance and full automation, need to pay special attention to moving objects, and particularly to humans. People move in unpredictable ways. Seeing a person with a forward-looking sensor, or having the driver note the position of a person in front of a bus, is no guarantee that the person will remain safely out of the vehicle’s way.

Description about different types of Autonomous Vehicles is provided in the next chapter.

CHAPTER – 4

BRIEF DESCRIPTION ABOUT VARIOUS TYPES OF AUTONOMOUS VEHICLES

Autonomous land vehicles have been an intense area of research and development for the last decades. An excellent introduction and summary of the state-of-the-art is given in this chapter. In this section we report on successful projects in application areas that relate to the proposed forest based system we are aiming at.

Forest Vehicles

In our search for research related to our proposed development project, we found many research articles related to Ground Navigation Vehicles from the different people from all over the world, these valuable research articles are found in web sites. Only one project with similar goals has been found: The ROFOR project run by Anibal Ollero, University of Seville, Spain. Not much information are to be found on the project, which has been going on since 1997. The objective of the project is the design, development and implementation of a control system for a forest processor machine (felling, cutting and to heap up). The project also includes the design of the robot arm and vehicle control system. The latest information (http://www.esi.us.es/AICIA/2000/inge_e.html) to be found reports:

“In this project a forest processing machine has been partially automated. thus, autonomous and tele-operated functions have been combined in the control system. A distributed control system has been developed and implemented in the machine. The system can be implemented by using both cable and wireless communications between the operator cabin and a PLC in the processing unit. The tele-operation system integrates the joystick and other devices for machine operation, and a graphical interface for the visualization of the processing functions during operation. The system also includes functions for machine diagnosis, operator and machine production control, and communications with a control centre using GSM. The tasks during 2000 have been mainly devoted to debugging, integration of the system, and testing.”

Path tracking Vehicles

Path tracking methods aim at keeping the vehicle approximately on a pre defined path, and bring it back to the path when unacceptable deviations occur. Various approaches for this task have been presented for AGV usage.

The main goal of the path tracking vehicle is to present a working solution for autonomous path tracking navigation, to be implemented in a vehicle for operation in forest terrains. The Autonomous Ground Vehicle (AGV) should operate in two modes: Path Recording, and Path Tracking. In the Path Recording mode, a human driver drives along the chosen path, recorded in the computer memory. In the Path Tracking mode, the computer assumes control over propulsion and steering. The vehicle then automatically travels along a memorized path. The operation has to account for unplanned deviations from the path, caused by imperfect sensing of position, and also by the vehicle sliding and jumping along the path. Another important part involves detection of new obstacles appearing on the path. In some cases the system should stop the vehicle and alert the human operator, who should be given the option of manually correcting the vehicle position, or giving the system the green light to go ahead along the original path.

Agricultural vehicles

A lot of research and development with autonomous vehicles for use in agriculture has been conducted the last decades. The primary agricultural activities addressed have been harvesting, mowing and applications of pesticides. O’Connor et al. at Stanford University developed a system for agricultural equipment that follows a preplanned path. A four-antenna system with Differential GPS (DGPS) provided a heading accuracy of 0.1 degrees and offset accuracy of 2.5 cm. A row-following system for harvesting in cauliflower fields was developed by Marchant et al. At Carnegie-Mellon Robotics Institute an autonomous vehicle for cutting forage using vision-based perception on the cut and uncut regions of crop was developed . The developed system used DGPS combined with wheel encoders and gyro data to compute estimates of both position and attitude. The vision sensing included functions for vehicle guidance (row-following), “end-of-row” detection, correction of illumination due to shadows and obstacle detection. An adaptive Fisher discriminant classifier was used to segment the images in cut/uncut regions by pixel wise classification based on RGB values. The obstacle detection was implemented with similar techniques where each pixel was classified as “normal” or “abnormal” relative to a training image. The probabilities for a pixel belonging to the probability distributions constructed from the training image were used to decide if the pixel belongs to an obstacle or not. Regions with a large number of such pixels were identified as obstacles. Three onboard computers were used, one for image analysis, one for control and one for task management. A pure pursuit algorithm is used for the path tracking task.

Mass excavation

Automatic digging is an active field of research. One approach is to let a human operator select the digging point and to let the autonomous system take over to complete the dig. Another, more difficult, approach is to use active sensing and automatically select the dig point. Stentz et al. [Sten01] developed a fully autonomous 25-ton hydraulic excavator for loading a truck with soft material such as dirt. The machine uses laser rangefinders to recognize the truck, detect obstacles and controlling the digging and loading process. The scanners scan vertically and are mounted on a pan table swept left and right, thereby covering all space of interest. According to the authors, the excavator is a fully operational prototype but is “unlikely to appear commercially as such, at least not initially”. It does not work under all weather conditions. The system is able to detect most obstacles, but “could not be left alone to work a complete shift without incident”. One suggested way to use it commercially is to demand a human operator to remain on the machine to monitor for safety, but to let the computer take over the actual digging/loading. Alternatively, a remote operator could monitor the work, check plans for repositioning and manually make corrections when necessary.

Mining machines

Mining is an important application domain for autonomous off-road vehicles. Stentz et al. [StOl99] report on a development of two mining aids: a system to measure and control forward motion of a continuous miner, and a system to measure and control the machine’s heading. Both measures are important to ensure high cutting quality of the coal. The heading task is solved by Kalman fusion of a fiber-optic gyro with a laser/camera system. The motion is computed by correlating stereo images of the roof of the mine, taken with a short delay. A recent project, reported in [ACFR01], use a scanning laser to detect guideposts located on the side of the haul road. The system aims at determining safe manual driving control of large haulage vehicles.

Target machines

The final target machine will be a standard forest machine, configured for the automatic computer control and for the need of sensors of various kinds. This is the most common approach to AGV design: simply automate an existing manual vehicle. To simplify things, many manufacturers provide an “automation option” on manual vehicles. E.g. Kalmar Industries (of Finland) who manufactures container straddle carriers and forestry logging equipment. Komatsu-Haulpack (large mining trucks and excavators) and Vost-alpine (underground mining equipment) also offer automation options for their products. However, in our case it will be necessary to install an automation interface since the plan is to use a standard forest machine from Partek Forest AB.

Some parts of the project can be run without access to a real forest machine. For this purpose a development robot should be purchased and installed in a “miniature forest” inside or outside the research premises. Some parts, such as cameras or laser detectors, have to be mounted on the real target machine that can provide a realistic environment for development and testing. Of course, the final complete system will be also installed on a real forest machine and tested under real conditions.

Development robot

The project will benefit from an additional platform in development and testing, for the following reasons:

It will increase the productivity of the development work since a full sized forest machine will need considerably more effort to access and use.

The modifications of the forest machine are not trivial and can be performed in parallel with the development work.

A lot of hardware and software will have to be purchased, learned and tested as part of the project. This work is most efficiently done in-doors, but need a reasonably realistic substitute for the eventual target machine In addition to serving the goals of this project, a development robot will be useful since the research team will learn both hardware and software relevant for many future projects. The equipment can also be used for teaching robotics, aim at developing education in autonomous systems for off-road use. The approach with a small-scaled robot is encouraged in [HaCa01], and also considered as a better alternative than computer simulation. After developing and testing on a small-scale robot, the systems can be transferred to the target vehicle, requiring much less modification than a simulated counterpart.

Two main alternatives for a development robot exist: buying standard equipment or having a custom designed robot constructed and manufactured. The latter alternative has the advantage of providing a platform that can mimic certain characteristics of the real forest machine that can be of value for the development work. This would for example be the construction of the steering device. The controller for a vehicle with articulated joint steering will differ significantly from the controller in a vehicle with a differential drive or with Ackerman (“carlike”) steering. Other important characteristic that is lost in a standard robot is the size aspects. The placement of sensors such as cameras or laser range scanners affects the behavior of the autonomous vehicle to a large extent. However, even a custom designed robot will differ significantly from the final target machine. Extensive work will therefore have to be performed on the target machine, regardless of the choice of development robot. The advantage with buying a standard robot is first of all that it is available and works immediately (in a reasonably ideal world).

Block Diagram

CHAPTER – 5

BLOCKDIAGRAM AND ITS BRIEF DESCRIPTION

The main block in the Block diagram is Obstacle Sensing circuit Designed with IR Sensors. The obstacle sensing block is designed with LM567 IC, this is a tone decoder IC, also it generates tone frequency. For identifying the obstacles 3 sets of sensors are used with three different 567 IC’s, similarly for detecting the pit or valleys another set of sensors are used. All these four sets of sensors are arranged at front side of the vehicle. Each sensing block is designed with two IR LEDs , Namely transmitting LED and receiving LED. Both the sensors are arranged side by side with in half-inch distance. The tone generator part of the IC is configured as astable mode of operation, which produces a perfect square wave of 10 KHz approximately and it is amplified using a transistor. The amplified signal is radiated through the transmitting IR LED. The signal delivered by the IR LED transmits in a line like LASER beam, when ever this signal is interrupted by an object, the radiating signal will be spread in the air because of the object, this signal is tracked by the another IR LED which is called as optical signal sensor. On receipt of optical signal, the tone decoder part of the IC detects the signal through the optical sensor and generates a high signal for the micro controller. Like wise the controller is getting signals from the four sensing blocks, according to the received information from the sensors, the controller controls the stepper motors in all directions.

Especially the new era of Robotic field mainly deals with fuzzy logics and artificial intelligence. That means, these gadgets should be in a position to identify the obstacle before it and do some appropriate calculation to overturn. This project also uses this theory. The actual theory is “Collision avoidance theory”. This theory was developed by using range finding sensors. We installed a new kind of IR sensors having the range. When object obstacles in that range the IR beam will be reflected back and the Receiver will absolve it. Here the receiver is connected to micorcontroller. Infrared reflex sensors are most typically used for distance measurements by transmitting a modulated infrared light pulse and measuring the intensity of the reflection from obstacles nearby. In practice, infrared sensors can only be used for detection of objects, not for range measurements.

MICRO-CONTROLLER

The received information from the optical sensors fed to micro-controller, for storing as well as controlling stepper motors. Micro-controller unit is constructed with ATMEL 89C51 Micro-controller chip. The ATMEL AT89C51 is a low power, higher performance CMOS 8-bit microcomputer with 4K bytes of flash programmable and erasable read only memory (PEROM). Its high-density non-volatile memory compatible with standard MCS-51 instruction set makes it a powerful controller that provides highly flexible and cost effective solution to control applications.

Micro-controller works according to the program written in it. Most microcontrollers today are based on the Harvard architecture, which clearly defined the four basic components required for an embedded system. These include a CPU core, memory for the program (ROM or Flash memory), memory for data (RAM), one or more timers (customisable ones and watchdog timers), as well as I/O lines to communicate with external peripherals and complementary resources — all this in a single integrated circuit. A microcontroller differs from a general-purpose CPU chip in that the former generally is quite easy to make into a working computer, with a minimum of external support chips. The idea is that the microcontroller will be placed in the device to control, hooked up to power and any information it needs, and that's that.

A traditional microprocessor won't allow you to do this. It requires all of these tasks to be handled by other chips. For example, some number of RAM memory chips must be added. The amount of memory provided is more flexible in the traditional approach, but at least a few external memory chips must be provided, and additionally requires that many connections must be made to pass the data back and forth to them.

For instance, a typical microcontroller will have a built in clock generator and a small amount of RAM and ROM (or EPROM or EEPROM), meaning that to make it work, all that is needed is some control software and a timing crystal (though some even have internal RC clocks). Microcontrollers will also usually have a variety of input/output devices, such as analog-to-digital converters, timers, UARTs or specialized serial communications interfaces like I²C, Serial Peripheral Interface and Controller Area Network. Often these integrated devices can be controlled by specialized processor instructions.

Originally, microcontrollers were only programmed in assembly language, or later in C code. Recent microcontrollers integrated with on-chip debug ciruit accessed by In-circuit emulator via JTAG (Joint Text Action Group) enables a programmer to debug the software of an embedded system with a debugger.

More recently, however, some microcontrollers have begun to include a built-in high-level programming language interpreter for greater ease of use. BASIC is a common choice, and is used in the popular BASIC Stamp MCUs (Master Control Unit). Microcontrollers trade away speed and flexibility to gain ease of equipment design and low cost. There's only so much room on the chip to include functionality, so for every I/O device or memory increase the microcontroller includes, some other circuitry has to be removed. Finally, it must be mentioned that some microcontroller architectures are available from many different vendors in so many varieties that they could rightly belong to a category of their own. Chief among these are the 8051 family.

Stepper Motor Drive Circuit

The output of the microcontroller is used to drive the stepper motor through drive circuit, and the motor used in this project work is having four windings, therefore the controller drives the motor through four outputs.  The stepper motor windings are energized one after another in a sequence according to the code produced by the controller through motor drive circuit.   This motor rotates in step wise and the step angle is 1.8⁰.   The speed of the motor can be varied by varying the pulse rate.   The pulses are produced by the controller 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 5kg load.

ABOUT STEPPER MOTOR

The stepper Motor used in this project work is indigenous one,which is an easy and reliable device to convert electrical energy into mechanical motion. It does not have the accuracy or the response speed of a dc motor. It is, however, utilized in many applications such as disk drives, printers, recorders, plotters, copiers, scanners, fax machines, robots, machine tools, automobiles, and medical equipment for its ease of use. Since each input change causes exactly one step rotation, a stepper motor may be operated in an open loop system. Typical step angles are 0.9^o, 1.8^o, 3.6^o, 7.5^o, 15^o, and 30^o.

Stepper motors are frequently applied to problems that require precision positioning without rotor position feedback. The most common stepper motors have multiple field windings and a permanent magnet rotor. The rotor is made to rotate by means of electronically commutating (switching) the current in the field windings. These motors are design to operate indefinitely with DC voltage applied to one or more fields in order to hold the rotor in a fixed position.

The rotor will rotate in discrete steps when the fields are energized in a specific sequence. Depending upon the sequence, the rotor may rotate clockwise (CW) or counter clockwise (CCW). Stepper motors are designed to rotate a fixed number of degrees with each step. A 1.8-degree stepper motor requires 200 steps for the rotor to make a full revolution.

Stepper motors have multiple stepping modes, full stepping, half-stepping and micro stepping. During full stepping, the rotor rotates the designed angular distance (1.8 degrees for example) each step. To rotate the motor, only four distinct input combinations or states are required to rotate the rotor. Repeating the sequence of states in the proper order results in what appears to be a continuously rotating rotor.

Half stepping is achieved on the same stepper motor by using an 8-state sequence. The rotor now rotates only half the designed angular rotation per half step. For a 1.8-degree stepper motor, the rotor will rotate 0.9 degrees for each half-step thus requiring 400 half steps for the rotor to make a full revolution. The chief advantage of half stepping is higher position control precision. Micro stepping requires extremely complex field current switching and allows an infinitely small rotation. Micro stepping is beyond the scope of this experiment. (For more information on stepper motor operations, read chapter – 11).

There are inherent problems with stepper motors that designers must be aware of to properly apply them. Due to rotor mass and finite energy in the field, stepper motors can only step so fast before the rotor will begin to skip steps and eventually stop completely. The primary cause of this high-speed stall is reduced field current at high speeds. This reduced field current is caused by back EMF generated by the turning rotor. One way to increase the top speed is to increase the field current at higher speeds. Elaborate field current control schemes have been devised to increase the current at high speeds without melting down the motor at slow speeds.

TRIGGER CIRCUIT BLOCK

This block is designed with 555 timer IC and an LDR is used as a light sensing device, the same is wired with timer IC. The idea of building this block is to energize the vehicle head-lamps automatically, whenever the natural light disappears. Two lamps are provided at the front side of the vehicle and these lamps energized through the relay contact.

The timer IC configured as Schmitt trigger mode of operation, triggers at 1/3Vcc. When the LDR is exposed to the light intensity, the resistance of the LDR will become less than 1KW and makes the voltage at comparator input less than 1/3Vcc which in turn triggers the timer IC and generates a high signal at its output (Pin No.3). When the IC is triggered relay will be energized automatically, this relay contact is used to provide supply to the lamps. For this purpose normally closed contact is used, when the relay energized closed contact becomes open and breaks the supply to the lamps. When the natural light disappears, the resistance of the LDR will become more than 500K, which in turn comparator input voltage increases more 2/3Vcc, there by the relay remains in de-energized condition. When the relay remains in de-energized condition, normally closed contact remains in closed condition and provides supply to the lamps. Hence these lamps energized automatically when the natural light disappears.

TRANSMITTER

The output of the video camera is fed to transmitter as modulating waves and these waves are super imposed over the carrier and transmitted as modulated waves. The carrier is designed for transmitting the picture details. At the receiving end, a small television set of 4” screen is used. The video camera and the television set, both are purchased from the market. They are readily available in Hyderabad electronic market.

The transmitter circuit generates a continuous frequency of 100MHz approximately, which is used to form a permanent 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 detailed description is provided in the next chapter. For the demonstration purpose black & white television set is used, the block diagram of this simple TV along with its brief description is provided in this chapter. The details are as followed.

The block diagram of simplified block & white TV receiver shown below

In above block diagram, the receiving antenna intercepts radiated RF signals and the turner selects desired channels frequency band and converts it to common IF band of frequencies. The receiver employs two or three stages of IF amplifiers. The output from the last IF stage is de-modulated to recover the video signal. This signal that carries picture information is amplified and coupled to the picture tube, which converts the electrical signal back into picture elements of the same degree of black and white. The picture tube is very similar to the cathode-ray tube used in an oscilloscope. The glass envelope contains and electron-gun structure that produces a beam of electrons aimed at the fluorescent screen. When the electron beam strikes the screen. Light is emitted. A pair of deflecting coils mounted on the neck of picture tube in the same way as the beam of camera tube scans the target plate deflects the beam. The amplitudes of currents in the horizontal and vertical deflecting coils are so adjusted that the entire screen called raster, gets illuminated because of the fast rate of scanning.

The video signal is fed to the grid or cathode of picture tube. When the varying signal voltage makes the control grid less negative, the beam current is increased, making the spot of light on the screen brighter. More negative grid voltage reduces brightness. If the grid voltage is negative enough to cut-off the electron beam current at the picture tube, there will be no light. This state corresponds to black. Thus the video signal illuminates the fluorescent screen from white to black through various shades of grey depending on its amplitude at any instant. This corresponds to brightness changes encountered by the electron beam of the camera tube while scanning picture details element by element. The rate at which the spot of light moves is so fast that the eye is unable to follow it and so a complete picture is seen because of storage capability of the human eye.

The path of sound signals is common with the picture signal from antenna to video detector section of the receiver. Here the two signals are separated and fed to their respective channels. The frequency modulated audio signal is demodulated after at least one stage of amplification. The audio output from the FM detector is given due amplification before feeding it to the loudspeaker.

CHAPTER-6

CIRCUIT ANALYSIS

The detailed circuit description of the project work “Autonomous Search Vehicle with Wireless Video Camera” is explained along with circuit diagram. For better understanding total circuit diagram is divided into various sections and each section circuit description with its circuit diagram is provided in this chapter. The details are as follows.

INFRARED TRANSMITTER / RECEIVER SECTION:

This section is designed for detecting the obstacles which are in front of the vehicle 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 10 KHz. This frequency is available from Pin 5 of LM 567 IC (versatile PLL tone decoder IC). The 47. 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 Microcontroller. Whenever the controller receives a high signal from the reference point, the microcontroller drives the stepper motor through the driving transistors and rotates the motor automatically. Four similar circuits are designed for the four sets of optical sensors. The following is the diagram of sensing circuit.

The output of the sensing circuit is inverted using a switching transistor, i.e., whenever the signal is interrupted by sensing the presence of an object which is at very near to the reference point, the final output of the inverter will become high automatically and this high signal is fed to the controller.

MICROCONTROLLER

Circumstances that we find ourselves in today in the field of microcontrollers had their beginnings in the development of technology of integrated circuits. This development has made it possible to store hundreds of thousands of transistors into one chip. That was a prerequisite for production of microprocessors, and the first computers were made by adding external peripherals such as memory, input-output lines, timers and other. Further increasing of the volume of the package resulted in creation of integrated circuits. These integrated circuits contained both processor and peripherals. That is how the first chip containing a microcomputer, or what would later be known as a microcontroller came about.

Memory unit

Memory is part of the microcontroller whose function is to store data. The easiest way to explain it is to describe it as one big closet with lots of drawers. If we suppose that we marked the drawers in such a way that they can not be confused, any of their contents will then be easily accessible. It is enough to know the designation of the drawer and so its contents will be known to us for sure.

Memory components are exactly like that. For a certain input we get the contents of a certain addressed memory location and that’s all. Two new concepts are brought to us: addressing and memory location. Memory consists of all memory locations, and addressing is nothing but selecting one of them. This means that we need to select the desired memory location on one hand, and on the other hand we need to wait for the contents of that location. Besides reading from a memory location, memory must also provide for writing onto it. This is done by supplying an additional line called control line. We will designate this line as R/W (read/write). Control line is used in the following way: if r/w=1, reading is done, and if opposite is true then writing is done on the memory location. Memory is the first element, and we need a few operation of our microcontroller.

Central Processing Unit

Let add 3 more memory locations to a specific block that will have a built in capability to multiply, divide, subtract, and move its contents from one memory location onto another. The part we just added in is called “central processing unit” (CPU). Its memory locations are called registers.

Registers are therefore memory locations whose role is to help with performing various mathematical operations or any other operations with data wherever data can be found. Look at the current situation. We have two independent entities (memory and CPU) which are interconnected, and thus any exchange of data is hindered, as well as its functionality. If, for example, we wish to add the contents of two memory locations and return the result again back to memory, we would need a connection between memory and CPU. Simply stated, we must have some “way” through data goes from one block to another.

Bus

That “way” is called “bus”. Physically, it represents a group of 8, 16, or more wires. There are two types of buses: address and data bus. The first one consists of as many lines as the amount of memory we wish to address, and the other one is as wide as data, in our case 8 bits or the connection line. First one serves to transmit address from CPU memory, and the second to connect all blocks inside the microcontroller.

Input - output unit

Those locations we’ve just added are called “ports”. There are several types of ports: input, output or bi-directional ports. When working with ports, first of all it is necessary to choose which port we need to work with, and then to send data to, or take it from the port.

When working with it the port acts like a memory location. Something is simply being written into or read from it, and it could be noticed on the pins of the micro-controller.

The following is the Circuit diagram of Micro-controller

HOW THE CONTROLLER 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 controller 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 5Kg loads, i.e., the holding torque is 5Kg. When the winding is energized, each winding consumes 1 Amp approximately.

The following is the diagram of 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 AM transmitter consists three sections namely

(1) VHF Oscillator

(2) Driver Stage or Modulator

(3) Final Amplifier Stage

VHF Oscillator :

This section is designed with BC 547 general purpose NPN switching transistor. This is a low power transistor and it is biased with R1 & R2. With the help of tank circuit designed with inductance & capacitance, and by varying the values of these two components the frequency can be varied very linearly from 30 to 300MHz. The frequency can be varied either by adjusting the gap between the turns of inductance (L1) or by varying the value of capacitance (T1). T1 is nothing but a trimmer means variable capacitor. Since we are not applying any signal to the transistor base, the above circuit can be used as VHF oscillator. The output of this oscillator is treated as carrier and the same is fed to the modulator section.

MODULATOR:

In this section C2570 transistor is used, this is a PNP transistor, popularly known as high frequency switching transistor. The output of the video camera in the form of composite video signal is applied to the base of this transistor. This circuit is configured in common base mode, the advantage of this mode is, it has low input impedence and provides high output impedence. The output of the VHF oscillator is fed to collector and the final output taken from the emitter of this PNP transistor. Since it is a PNP transistor there won’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. The another advantage of this circuit is, it has constant voltage gain through out the frequency range.

The following is the circuit diagram of Modulator

AMPLIFIER STAGE:

In this section 2 N 3866-NPN Transistor is used to amplify the inputed signal. This is a medium power transister. This transistor is configured as common emitter mode. A parallel tuned circuit is designed using L3,L2 AND T2, in this T2 is the trimmer i.e., variable capacitor and withthe help of this T2, the circuit can be tuned to Match the carrier frequency, then resonance will occur at maximum impedence. Hence, with constant voltage gain and current gain, the signal will be transmitted through the antenna.

The circuit diagram of AMplifier is given below:

The Complete Circuit Diagram of transmitter including three stages is as follows

POWER SUPPLY:

The power Suppply is a Primary requirement for the project work. Therequired DC power supply for the total circuitry is derived from the mains line. For this purpose center tapped secondary of 12V-0-12V transformer is used. From the power supply unit three different DC voltages of +12V , +5V and +9V are derived using rectifiers and filters. With the help of positive voltage regulators, a constant voltage source of +5V and +9V are derieved, for this purpose 7805 and 7809 3Pin Voltage regulators are used so that, though the mains supply varies from 170V to 250V, the output DC levels remains constant.

Rectification is a process of rendering an alternating current or voltage into an unidirectional one. The component used for rectification is called ‘Rectifier’. A rectifier permits current to flow only during the positive half cycles of the applied AC voltage by eliminating the negative half cycles or alternations of the applied AC voltage. Thus pulsating DC is obtained. to obtain smooth DC power, additional filter circuits are required.

A diode can be used as rectifier. There are various types of diodes. But, semiconductor diodes are very popularly used as rectifiers. A semiconductor diode is a solid state device consisting of two elements are being an electron emitter or cathode, the other an electron collector or anode. since electrons in a semiconductor diode can flow in one direction only-form emitter to collector- the diode provides the unilateral conduction necessary for rectification.

The rectified Output is filtered for smoothning the DC, for this purpose 1000 Micro-farade capacitor is used in the filter circuit. The filter capacitors are usually connected in parallel with the rectifier output and the load. The AC can pass through a capacitor but DC cannot, the ripples are thus limited and the output becomes smoothed. When the voltage across the capacitor plates tends to rise, it stores up energy back into voltage and current. Thus the fluctuation in the output voltage are reduced considerable.

The following is the circuit diagram of Power supply.

CHAPTER - 7

DETAILS ABOUT I R SENSOR

INTRODUCTION

This Handbook is intended to be used as a sensor selection reference during the design and planning of perimeter   security systems.  The Handbook   contains   acompendium of sensor technologies that can be used to enhance perimeter security and intrusion detection in both permanent and temporary installations and facilities.

OPERATIONAL REQUIREMENTS

The application of security measures is tailored to the needs and requirements of the facility to be secured.   The security approach will be influenced by the type of facility or material to be protected, the nature of the environment, and the client’s previous security experience and any perceived threat.  These perceptions form the basis for the user’s initial judgment; however, these perceptions are rarely sufficient to develop an effective security posture. The nature and tempo of activity in and around the site or facility, the physical configuration of the facility/complex to   be   secured, the surrounding natural   and   human environment, along with the fluctuations and variations in the weather, as well as new or proven technologies are all factors which should be considered when planning a security system In addition to the large variety of permanent Federal and State facilities located within the confines of the United States that require perimeter security, there  is  a family  of  American military, humanitarian, diplomatic  and peacekeeping  complexes overseas, many  of  which,  although transitory in nature require a dynamic and creative approach to  the  challenge  of  perimeter  security.   Many of the technologies discussed in this handbook can, with some adaptation, be applied to these situations.    Typical examples of these complexes include:  logistic depots,  ship and  aircraft  unloading and servicing  facilities,  vehicle staging areas, personnel billeting compounds, communications sites  and   headquarters compounds.  Although the personnel and vehicle screening challenges at each site will vary with the nature of the environment and the potential threat, the role of perimeter security will be similar in all cases. Basically stated, the role of a perimeter security system is fourfold: deter, detect, document and deny/delay any intrusion of the protected area or facility.   In the case of American facilities and complexes located in foreign countries, this challenge is further complicated when U.S. forces cannot patrol or influence the environment beyond the immediate  "fenceline".   In situations such as these, the area within the fenceline (the Area of Responsibility  - AOR), should be complemented by an area of security surveillance   beyond the fence,  (preferably   a   cordon sanitaire) where in the perimeter, from an early warning perspective is extended outward.   This is particularly essential in situations where the host government security forces cannot provide a reliable outer security screen, or the   area to be secured abuts a built-up industrial, business, public or residential area.

SYSTEM INTEGRATION

      The integration of sensors and systems is a major design consideration and is best accomplished as part of an overall    system/installation/facility   security screen. Although sensors are designed primarily for either interior or exterior applications, many sensors can be used in both environments.  Exterior detection sensors are used to detect unauthorized entry into clear areas or isolation zones that constitute the perimeter of a protected area, a building or a fixed site facility.  Interior detection sensors are used to detect penetration into a structure, movement within a structure or to provide knowledge of intruder contact with a critical or sensitive item.

  DETECTION FACTORS

      Six factors typically affect the Probability of Detection   (Pd) of most area surveillance  (volumetric) sensors, although to varying degrees.  These are the:1) amount  and  pattern of emitted energy;    2)  size  of  the object;  3) distance to the object;  4) speed of the object; 5)  direction  of  movement and 6)  reflection/absorption characteristics of the energy waves by the intruder and  the environment (e.g. open area, shrubbery, or wooded).  Theoretically, the more definitive the energy pattern, the better.  Likewise, the larger the intruder/moving object the higher the probability of detection.  Similarly, the shorter the distance from the sensor to the intruder/object, and the faster the movement of the intruder/object, the higher the probability of detection.  A lateral movement that is fast typically has a higher probability of detection than a slow straight-on movement.  Lastly, the greater the contrast between the intruder/moving object and the overall reflection/absorption characteristics of the environment (area under surveillance), the greater the probability of detection.

 SENSOR CATEGORIES

Exterior intrusion detection sensors detect intruders crossing a particular boundary or entering a protected zone.  The sensors can be placed in clear zones, e.g. open fields, around buildings or along fence lines.   Exterior sensors must be resilient enough not only to withstand outdoor weather conditions, such as extreme heat, cold, dust, rain, sleet and snow, but also reliable enough to detect intrusion during such harsh environmental conditions.

Exterior intrusion sensors have a lower probability of detecting intruders and a higher false alarm rate than their interior counterparts.   This is due largely   to   many uncontrollable factors such as: wind, rain, ice, standing water, blowing debris, random animals and human activity, as well as other sources to include electronic interference. These factors often require the use of two or more sensors to ensure an effective intrusion detection screen.

Interior intrusion detection sensors are used to detect intrusion into a building or facility or a specified area

inside  a  building or facility.  Many of these sensors are designed for indoor use only, and should not be exposed to weather elements. Interior sensors perform one of three functions:  (1) detection of an intruder approaching or penetrating a secured boundary, such as a door, wall, roof, floor, vent or window,  (2) detection of an intruder moving within a secured area, such as a room or hallway and, (3) detection of an intruder moving, lifting, or touching a particular object.  Interior sensors are also susceptible to false and nuisance alarms, however not to the extent of their exterior counterparts.  This is due to the more controlled nature of the environment in which the sensors are employed.

TECHNOLOGY SOLUTIONS

With the advent of modern day electronics, the flexibility   to integrate a variety of equipment   and capabilities greatly enhances the potential to design an Intrusion Detection System to meet specific needs. The main elements of an Intrusion Detection System include:  a) the Intrusion Detection Sensor(s), b) the Alarm Processor, c) the Intrusion/Alarm Monitoring Station, and   d) the communications structure that connects these elements and connects the system to the reaction elements.  However, all systems also include people and procedures, both of which are of equal and possibly greater importance than the individual technology aspects of the system.  In order to effectively utilize an installed security system, personnel are required to operate, monitor and maintain the system, while an equally professional team is needed to assess and respond to possible intrusions. Intrusion detection sensors discussed in this Handbook have been designed to provide perimeter security and include sensors for use in the ground, open areas, inside rooms and buildings, doors and windows.  They can be used as standalone devices or in conjunction with other sensors to enhance the probability of detection.  In the majority of applications, intrusion detection sensors are used   in conjunction   with   a   set of   physical   barriers   and personnel/vehicles access control systems. Determining which   sensor(s) are to be employed   begins   with   a determination of what has to be protected, its current vulnerabilities, and the potential threat.  All of these factors are elements of a Risk Assessment, which is the first set in the design process.

PERFORMANCE CHARACTERISTICS:

      In the process of evaluating individual intrusion detection sensors, there are at least three performance characteristics which should be considered:  Probability of Detection (PD), False Alarm Rate (FAR), and Vulnerability to Defeat  (i.e. typical measures used to defeat or circumvent the sensor). A major goal of the security planner is to field an integrated Intrusion Detection System (IDS), which exhibits a low FAR and a high PD and is not susceptible to defeat. Probability of Detection provides an indication of sensor performance in detecting movement within a zone covered by the sensor.  Probability of detection involves not only the characteristics of the sensor, but also the environment, the method of installation and adjustment, and the assumed behavior of an intruder. False Alarm Rate indicates the expected rate of occurrence of alarms high is not attributable to intrusion activity.  For purposes of this Handbook, "false alarms" and "nuisance alarms" are included under the overall term "False Alarm Rate", although technically, there is a distinction between the two terms.  A nuisance alarm is an alarm event which the reason is known or suspected  (e.g. animal movement/electric disturbance) was probably not caused by an intruder.    A false alarm is an alarm when  the  cause  is unknown  and  an  intrusion  is therefore  possible,  but  a determination  after  the fact indicates  no  intrusion  was attempted.   However, since the cause of most alarms  (both nuisance/false) usually cannot be assessed immediately, all must be responded to as if there is a valid intrusion attempt.

          Vulnerability to Defeat is another measure of the effectiveness of sensors.  Since there is presently no single sensor which can reliably detect all intruders, and still have an acceptably low FAR, the potential for "defeat" can be reduced by designing sensor coverage using multiple units of  the same sensor, and/or including more  than  one type of sensor, to  provide overlapping of the coverage area and mutual protection for each sensor.

ENVIRONMENTAL CONSIDERATIONS

      Most security zones have a unique set of environmental factors which are taken into consideration when designing the system, selecting the sensors, and performing the installation.   Failure to consider all the factors can result in excessive "false alarms" and/or "holes" in the system.

      Each potential intrusion zone, whether it be  a perimeter fence, an exterior entrance, a window, an interior door, a glass partition or a secured room, will have special "environmental"  factors to be considered.   External zones are likely to be affected by the prevailing climate, daily/hourly fluctuations in weather conditions, or random animal activity as well as man-made "environmental" factors such as activity patterns, electrical fields and/or radio transmissions, and vehicle, truck, rail or air movement.

      There are a wide variety of other considerations, which must be assessed when placing sensors to monitor the perimeter   of   an   area or building.    A   fundamental consideration   is   the need to   have   a   well-defined clear/surveillance or isolation zone.  Such a zone results in a reduction of FARs caused by innocent  people,  large animals,  blowing  debris,  etc.   If  fences  are  used  to delineate  the clear zone or isolation zone, they should  be carefully  placed,  well constructed and  solidly  anchored, since  fences  can  move  in  the  wind  and  cause  alarms. Consideration should also be given to dividing the perimeter into independently alarmed segments in order to localize the area  of  the possible intrusion and improve response  force operations.  Internal  zone  sensors can  also  be  impacted  by  a combination  of  external stimuli, such as machinery  noise and/or  vibrations,  air movement  caused  by  fans  or  air conditioning/heating units, and changes  in  temperature  to mention  a  few.  Many of these and others will be discussed in  the  individual Technology Reviews presented in  Section Two.

ALARM MONITORING SYSTEMS

      In addition to the Off-the-Shelf Intrusion Technology that is discussed in this Handbook, there is a variety of alarm monitoring systems available.  Although each system is unique in the number and variety of options available, all systems perform the basic function of annunciating  alarms and  displaying  the alarm locations in  some  format.   The front-end  (control function) of most of these systems is configured  with standard 486 or Pentium computer  utilizing Windows, DOS, UNIX or OS/2 as the operating system.  Many of these systems operate with proprietary software, written  by the manufacturer of the security system.

ALARM ASSESSMENT

      State-of-the-art alarm assessment systems  provide  a visual  and  an audible indication of an alarm.   The  alarm data is displayed in one of two forms - either as text on  a computer/monitor   screen   or   as   symbols   on   a   map representation  of  the area.  Most systems  offer  multiple levels  (scales)  of  maps which can be helpful  in  guiding security  personnel  to  the location  of  the  alarm.   The urgency of the audible/visual alarm cue can vary as  to  the nature  of  the  alarm  or  the  location  of  the  possible intrusion  (e.g.  high priority versus low priority  areas). In  most security systems, several of these capabilities are combined to provide the Security Operations Center personnel with   a  relatively  comprehensive  picture  of  the  alarm situation.    One   option  offers  a  visual   surveillance capability  which automatically provides the Security  Alarm Monitor with a real-time view of the alarm/intrusion zone.

SENSOR INTEGRATION

      From  a  technology  perspective, the  integration  of sensors   into  a  coherent  security  system   has   become relatively  easy.  Typically, most sensor  systems  have  an alarm  relay,  from  points a, b  or  c,  and  may  have  an additional relay to indicate a tamper condition.  This relay is  connected to field panels via four wires,  two  for  the alarm relay and two for the tamper relay, or two wires, with a  resistive network installed to differentiate  between  an alarm  and  tamper condition.  Most monitoring systems will also provide a means of monitoring the status of the wiring to each device.   This is called line supervision.   This monitoring of the wiring provides the user with additional security by indicating if circuits have been cut   or bypassed.

      Additionally, different sensors can be integrated to reduce false alarm rates, and/or increase the probability of intrusion detection.  Sensor alarm and tamper circuits can be joined together by installing a logic  "and" circuit. This "and" system then requires multiple sensors to indicate an alarm condition prior to the field unit sending an alarm indication.   Usage of the logic "and" circuit can reduce false alarm rates but it may decrease the probability of detection because two or more sensors are required to detect an alarm condition prior to initiating an alarm.

COMMUNICATIONS

      Communications between the front-end computer and the field elements  (sensors, processors) usually employ   a variety of standard communications protocols.  RS-485, RS-232, Frequency Shift Keying (FSK), and Dual Tone Multi Frequency   (DTMF) dial are the most common, although occasionally manufacturers will use their own proprietary communications protocol which can limit the option for future upgrades and additions.  In order to reduce the tasks required to be handled by the computer, some systems require a preprocessing unit located between the computer and the field processing elements.  This preprocessor acts as the communications coordinator to "talk" to the field elements thus relieving the computer of these responsibilities.

POWER SUPPLY

      Regardless of how well designed and installed, all intrusion detection systems are vulnerable to power losses, and many do not have an automatic restart capability without human intervention.  Potential intruders are aware of this vulnerability and may seek to "cut" power if they cannot circumvent the system via other means.  It is critical that all elements of the system have power backups incorporated into the design and operation to guarantee uninterrupted integrity of the sensor field, alarm reporting, situation assessment, and response force reaction.

COST CONSIDERATIONS

      The costs of an Intrusion Detection System are easy to underestimate.  Sensor manufacturers often quote a cost per meter, cost per protected volume, for the sensor system. Often this figure is representative of the hardware cost only, and does not include the costs of installation, any associated construction or maintenance.  Normally, the costs associated with procuring the sensor components are outweighed by the costs associated with acquiring and installing the assessment and alarm reporting systems.

SENSOR APPLICATIONS

Most sensors have been designed with a specific application in mind. The environment categorizes these applications where they are most commonly employed. The two basic environments or categories are Exterior and Interior. Each of the two basic categories has a number of sub-sets, such as fence, door, window, hallway, and room. The first two of the following set of graphics show a "family tree" illustration of the sensors most applicable to the these two environments (exterior/interior). As mentioned previously, some of the technologies can be used in both environments and consequently are shown on both graphics.

CHAPTER-8

Detailed Description About Video Cameras

The video camera is a kind of transducer, which produces electrical energy from light energy. I.e., the input to the video camera is light energy and this light energy is converted into electrical signals. Video converting the complete spectrum of visible light into electrical frequencies.

There are two basic types of video cameras: monochrome (Black and White) and color. Monochrome cameras are lower in price, but color is more realistic. Both have advantages and both are desirable. By using both types we can intersperse black and while pictures with color to produce special effects. But, as far as camera features are concerned, black and while cameras can have features found in the most expensive color cameras monochrome cameras require less light than color cameras and operate with battery power. They do not have as many adjustments as color cameras, hence they are easier to use.

The video camera not only converts the light reflected from a scene into an analogous video voltage, but it also supplies the necessary sync and blanking pulses to go along with it. In short, the video camera produces the equivalent of an NTSC (National Television Standards Committee) signal, the same sort of signal that is generated by a television broadcasting station.

There is one exception, though. At the TV broadcasting station the composite video signal is loaded on to a carrier wave so as to be able to cover the distance between the station and all the receivers tuned to it. The composite video signal, recorded on videotape by the VCR accompanying the camera, can be inserted into the in-home VCR for reproduction on the television screen. But that missing factor, the carrier wave, must be introduced. This is handled by the converter section of the VCR, supplying a carrier wave whose frequency is that of either channel 3 or channel 4. Thus the composite video signal, now complete with a carrier, can be sent into the TV receiver via its antenna terminals. All that is required of the TV set is that it’s tuner be adjusted to the frequency of the carrier that is, either the frequency of channel 3 or channel 4, whichever frequency is used by the converter

A video camera can be used indoors or out. For in-home use power for operating the camera can be obtained from the AC power line by using an adaptor or the battery pack, as an additional piece of equipment. The amount of power used by a camera is least when various camera functions are manually operated. It takes battery power to make use of cameras automatic features. Thus a camera could need 7.6 watts approximately with its auto focus in the manual position. The camera used in this project work is designed to operate 12V DC.

The trend in video camera design is to produce cameras that are as lightweight and as compact as possible. The camera used in this project work is known as Board camera and the weight of this camera is less than 200 grams. The details of the Board camera collected from Internet, the details along with the picture is as follows

"Board" Camera

The "Board" camera is an entire camera on a single TINY circuit board. Anytime you have ever seen someone with a camera hidden in a teddy bear, wall clock or smoke detector, it has been a board camera. Though it is very small, and perfect for hidden-camera applications, the wires are very sensitive to damage. This camera should not be used for outside use.

The photograph of the actual camera used in this project work is provided at the end of this chapter.

We may find references to cameras as being all solid state, often neglecting to add that the camera does contain a camera tube, known as pickup tube. These tubes are identified by various names selected by camera manufactures, including Saticon, Newvicon, Plumbicon, Trinicon, Univicon, Viconf, and Vidicon. Unless the camera manufacturer has its own picture tube manufacturing division, it is quite likely that the various camera tube types are supplied by the same source.

CAMERA OPTICS

As in motion picture film cameras, the optics represent the most important part of the camera and this includes the lens or the lens system and the viewfinder.

FOCAL LENGTH

In a film camera focal length is the distance from the optical center of the lens to the film. In a video camera it is the distance between the optical center of the lens and the target area of the picture tube. A short focal length means light inside the camera, whether film or video, has a shorter distance to travel, and so less light is lost, hence the attractiveness of keeping the focal length as short as possible. Focal length is measured in millimeters (mm) and is supplied as a range.

OPERATING POWER

The operating power requirements of a video camera are approximately 6 to 8.5 watts DC. This doesn’t sound like much and it is not if the camera is being used indoors and is connected to an outlet supplying 230 volts AC, changed to 12 volts DC by a converter. But it is another matter if the camera is being operated outdoors and must rely on batteries for power. Under such conditions a camera having the smallest power requirement would be the most desirable one if this were the only feature being considered.

The video camera used in our project work is arranged over a revolving disk, naturally 12V battery pack must be provided over the disk to drive the camera.

LENSES

There are two types of lenses: fixed and adjustable. A fixed lens is so-named since its focal length cannot be changed. This is the type of lens used on inexpensive film cameras. Its angle of view is constant and if you want to get closer to a scene or farther away, you can only do so by moving the camera, probably by walking with it.

ZOOM LENS

The zoom lens is an adjustable type. Since its focal length is variable you can use this lens to make the angle of view wider or narrower, with in the limits of the lens. This means you can make a scene seem to come closer or farther away without moving the camera physically but just by making a lens adjustment.

However, the fact that a lens is a zoom type does not automatically make it a better quality lens. Nor is the focal length determined by whether the camera is color or monochrome. Thus you might get a black-and-white camera having a zoom lens with a greater focal length range than a color camera.

FOCUSING.

The purpose of focusing is to get as clear and sharp an image as possible. In focusing the lens is adjusted for the best image clarity. The region behind and in front of the subject that is also in focus is called depth of focus or field of focus.

Focusing can be done manually, semi automatically, and completely automatically. There is also a type of focusing, known as macro focus, in which the subject is brought very close to the camera lens.

MANUAL FOCUS

Manual focusing, also called mechanical focusing, is an arrangement in which a focusing control, mounted on the camera can be rotated clockwise or counter clockwise. It is supplied with distances marked on the control, which is a ring positioned near the lens. With manual focusing it is necessary to adjust the focusing ring to correspond to the distance from the subject to the lens.

AUTO FOCUS

In the auto focus mode simply point the camera at the subject and start shooting. The focus will be continuously adjusted as the subject-to-camera distance changes, as long as the subject remains in the center of the frame.

There are certain conditions under which auto focus does not work well. You may find it difficult to get proper focus with objects that reflect strong light, such as glass or metal or objects made of black wool or black velvet, or objects that coexist far and near. For such shooting conditions set the focus auto/manual control to its manual focusing position.

Auto focusing is easy and so there is a natural tendency to rely on it and to let the camera do all the work.

SEMI AUTOMATIC FOCUSING

With this system the camera focuses on the subject. But as the subject moves it is necessary to depress a focusing button to refocus. This becomes a series of focusing steps.

LIGHTING

As a general rule as you increase the amount to light on the subject being video graphed, the quality of the picture recorded on the tape becomes better. This is not usually a problem outdoors, except when shooting around nightfall. In the home you may need floodlights, even with window shades pulled up. It may sound like disadvantages to need to use artificial lighting, but since you have control of the light, something you do not have outdoors, you can get some dramatic and unusual effects.

You will need to experiment with lighting and you may find it helpful to buy floodlights and reflectors similar to those used in photography consider also that lighting is often best when done from front and rear. And a caution: never point your camera directly at the light since this could damage the picture tube in the camera.

LUX

The lux is the international system unit of illumination and equals one lumen per square meter. The plural of this word is luxes or luces, but is commonly ignored. Thus, the singular form, lux, is now used with all numbers, such as 1 lux, 50 lux, etc., this is industry procedure and is followed in this report. The abbreviated symbol for lux is lx.

CAMERA SENSITIVITY

The sensitivity of a camera is expressed in lux units and may be indicated in the cameras spec sheet. For a camera using an f1.5 lens the sensitivity could 75 lux with the cameras sensitivity switch set in its high position.

Sensitivity figures are sometimes specified as a range. Thus a camera could have sensitivity from 75 lux to 100,000-lux illumination. The camera could also have a high gain switch to permit using the camera under low light conditions. The high gain switch can be activated to prevent underexposure. Some cameras also feature a back light control to be used when the overall brightness of the scene would otherwise cause the subject to be underexposed.

CHAPTER - 9

DETAILS ABOUT STEPPER MOTOR

The motor consists of a rare earth permanent magnet located between the tops and bottoms half of the rotor stack. A series of laminations of high quality electrical steel, each with 50 teeth on the circumference, encompass the permanent magnet and create 50 natural different positions on the rotor.

The stator consists of a series of laminations of high quality electrical steel, each with 48 teeth on the inner circumference, held with in an aluminum ring to provide mechanical rigidity and to prevent corrosion. The stator to allow for optimum heat dissipation of heat locates the windings of the motor. Three are two phases or windings in a stepper motor.

STEPPER MOTOR OPERATION:

Stepper motor operates on phase switched dc power. Basically two types of drives are used to operate stepper motors. In a bipolar drive, the direction of current flow through the winding will be controlled. In a uni-polar drive the center tap of each winding is used and connected to the power source. Switching either end of winding to ground then controls current flow. When operated in this configuration, it is referred to as four phase motor. The motor shaft advances to in step of 1.8 degree (200 steps per revolution) when a four step (full step mode) input sequence is used and in steps of .9 degree (400 steps per revolution) when an eight step (half step mode)input sequence is used. The four step and eight step switching sequences are given in the motor data sheets.

Holding torque:

It is the maximum torque required to change the motor shaft angle, when the stator windings are excited at the rated voltage.

Detent torque:

It is the torque required to change the motor shaft position without exciting the stator windings. This helps to hold the motor shaft in position when the motor is not energized.

If greater holding torque is required, one or both motor windings can be energized with dc voltage when the motor is not stepping.

RESONANCE:

Basically stepper motors have a tendency to oscillate with each step. The condition is most visible at speeds below one revolution per second. A resonant condition can be observed when the motor is operated at its natural frequency or at sub harmonics of the frequency. System mechanics, inertia and friction determine the exact resonant characteristics. Suddenly audio and vibration level of the motor may increase or torque may drop. Some times the motor may loose synchronism or it may reverse its direction. This simplest method to avoid resonance is to start the motor at an instantaneous speed above the resonant frequency and low enough to pull the load in to synchronization. This technique is not effective at low speeds.

MICRO STEPPING:

Full step and half step systems suffer like, rough operations at low speeds operating speeds that Cause the motor to oscillate widely (usually between 0.5 and 1 rpm), and limited resolution. All these problems can be over come by employing micro stepping drive systems. Micro stepping systems utilize the same hybrid stepper motor (usually 200 full stepper revolution) and precise current control to position the motor rotor at locations in between the normal full step positions. While full step or half step drives produce coils current that are either “on” or “off”, micro stepping drives proportion the current smoothly between the motor coils. Instead of tuning one phase “off” and another “on” to produce motion micro stepping drives slowly increase the current in one phase while slowly decreasing the current in the other phase. If the phase currents are held at intermediate values, the rotor maintains an intermediate position. This position is very accurate and repeatable. The frequency of these currents determines the rotor speed.

Micro stepping drives can smoothly accelerate or decelerate through speeds that would cause resonance or position loss in a conventional full step system.

The application of precise sinusoidal currents causes the rotor to move smoothly from one pole of the motor to the next without stopping or oscillating, micro stepping drives with resolutions of 125 micro steps per revolution (125*200=25000 steps per revolution) are available. There are many applications where the increased positional resolution of micro stepping is not needed, but the acceleration and resonance control provides smooth operation of the motor. Typical speed ranges of micro stepping drives are greater than 500000:1.

SPEED CAPABILITY

Stepper motor can be operated from vary speeds (.01 rpm) to high speeds (50 rpm). The performance of a stepper motor depends to a great extent on the control circuit used to drive the motor. Only with an appropriately designed control circuit, a stepper motor can be operated at rates up to 10000 steps per second (300 rpm). The torque falls of at high speeds, so the user has to carefully study the torque per speed characteristics of a motor before using in an application. The user must take in to account some factors before deciding on a stepper motor. There is a relation ship between speed per torque, motor inductance, supply voltage, and motor heat that makes each parameter dependent on the other.

EFFECTS OF MOTOR SUPPLY VOLTAGE:

Motor performance at mid range and high range speeds (top speed and torque at high speed) can be improved by increasing the voltage to the motor. The motor will operate at a higher temperature when the voltage to the motor is increased, so some means of cooling the motor may be necessary. More over, if a particular application requires the motor to be operated at low speeds only then it is convenient to operate at the lowest possible voltage to avoid excessive heating.

EFFECTS OF MOTOR INDUCTANCE

For a given supply voltage, a low inductance motor will give better performance at higher speed (top speed and high-speed torque), but will operate at high temperatures.

This is because a low inductance motor required more current then do a high inductance motor. High inductance motors produce higher maximum torque and operate cooler, but their top speeds is limited and torque falls of more rapidly as speed rises then with a low inductance motor. More over low inductance motor produce a fairly flat speed per torque curve. For a given supply voltage, the high inductance motor runs cooler than a low inductance motor. For any given supply voltage, the high inductance motor will run cooler than the low inductance motor.

ADVANTAGES Of STEPPER MOTOR:

1) Inherently a digital device, number of pulses determine distance, frequency sets the speed

2) Drift free.

3) The step angle error is very small and non-cumulative.

4) Rapid response to starting, stopping and reversing.

5) Brush-less design for reliability simplicity.

6) High torque per package size.

7) Stable at zero speed.

8) Holding torque at stand still.

9) Can be shelled repeatedly and in-definitely without damage.

10) No extra feed back components required.

11) Bi-directional operation.

TYPICAL APPLICATION Of STEPPER MOTORS:

The broad capabilities of stepper motors have made them the electrical actuator of choice in many fields of automation applications range from machines and equipment requiring very delicate motion control to a broad spectrum of automation categories including pick and place machines, cut to length machines, valve control, machine-tool applications for metal curing and transfer of lines for automobile factories.

TYPICAL APPLICATIONS:

1) Silicon crystal growing.

2) Packing systems.

3) Cut to length of wire, cables, metals plastic.

4) Sheet metal fabrication.

5) Laser positioning.

6) Office peripheral equipment

7) Grinding.

8) Metal punching.

9) Rotary tables.

10) X-Y tables.

11) Welding.

CHAPTER – 10

DETAILS ABOUT WIRELESS COMMUNICATION

Model of a communication system:

The overall purpose of the communication system is to transfer information from one point to in space and time, called the source to another point, the user destination. As a rule, the message produced by a source is not electrical. Hence an input transducer is required for converting the message to a time varying electrical quantity called a message signal. At the destination point another transducer converts the electrical waveform to the appropriate message.

The information source and the destination point are usually separated in space. The channel provides the electrical connection between the information source and the user. The channel can have many deferent forms such as a microwave radio link over free space a pair of wires, or an optical fiber. Regardless of its type the channel degrades the transmitted single in a number of ways. The degradation is a result of signal distortion due to imperfect response of the channel and due to undesirable electrical signals (noise) and interference. Noise and signal distortion are two basic problems of electrical communication. The transmitter and the receiver in a communication system are carefully designed to avoid signal distortion and minimize the effects of noise at the receiver so that a faithful reproduction of the message emitted by the source is possible.

The transmitter couples the input message signal to the channel. While it may sometimes be possible to couple the input transducer directly to the channel, it is often necessary to process and modify the input signal for efficient transmission over the channel. Signal processing operations performed by the transmitter include amplification, filtering, and modulation. The most important of these operations is modulation a process designed to match the properties of the transmitted signal to the channel through the use of a carrier wave.

Modulation is the systematic variation of some attribute of a carrier waveform such as the amplitude, phase, or frequency in accordance with a function of the message signal. Despite the multitude of modulation techniques, it is possible to identify two basic types of modulation: the continuous carrier wave (CW) modulation and the pulse nodulation. In continuous wave (CW) carrier modulation the carrier waveform is continuous (usually a sinusoidal waveform), and a parameter of the waveform is changed in proportion to the message signal. In pulse modulation the carrier waveform is a pulse waveform (often a rectangular pulse waveform), and a parameter of the pulse waveform is changed in proportion to the message signal. In both cases the carrier attribute can be changed in continuous or discrete fashion. Discrete pulse (digital) modulation is a discrete process and is best suited for messages that are discrete in nature such as the output of a teletypewriter. However, with the aid of sampling and quantization, continuously varying (analog) message signal can be transmitted using digital modulation techniques.

Modulation is used in communication systems for matching signal characteristics to channel characteristics, for reducing noise and interference, for simultaneously transmitting several signals over a single channel, and for overcoming some equipment limitations. A considerable portion of this article is devoted to the study of how modulation schemes are designed to achieve the above tasks. The success of a communication system depends to a large extent on the modulation.

The main function of the receiver is extract the input message signal from the degraded version of the transmitted signal coming from the channel. The receiver performs this function through the process of demodulation, the reverse of the transmitter’s modulation process. Because of the presence of noise and other signal degradations, the receiver cannot recover the message signal perfectly. Ways of approaching ideal recovery will be discussed later. In addition to demodulation, the receiver usually provides amplification and filtering.

Based on the type of modulation scheme used and the nature of the output of the information source, we can divide communication systems into three categories:

1.analog communication systems designed to transmit analog information using analog modulation methods

2. digital communication systems designed for transmitting digital information using digital modulation schemes and

3. hybrid systems that use digital modulation schemes for transmitting sampled and quantized values of an analog message signal.

Other ways of categorizing communication systems include the classification based on the frequency of the carrier and the nature or the communication channel

With this brief description of a general model of a communication system, we will now take a detailed look at various components that make up a typical communication system using the digital communication system as an example. We will enumerate the important parameter of each functional block in a digital communication system and point out some of the limitations of the capabilities of various blocks.

ELEMENTS OF A DIGITAL COMMUNICATION SYSTEM

The overall purpose of the system is to transmit the messages (or sequences of symbols) coming out of a source to a destination point at as high a rate and accuracy as possible. The source and the destination point are physically separated in space and a communication channel of some sort connects the source to the destination point. The channel accepts electrical/electromagnetic signals, and the output of the channel is usually a smeared or distorted version of the input due to the non-ideal nature of the communication channel. In addition to the smearing, the information-bearing signal is also corrupted by unpredictable electrical signals (noise) from both man-made and natural causes. The smearing and noise introduce errors in the information being transmitted and limits the rate at which information can be communicated from the source to the destination. The probability of incorrectly decoding a message symbol at the receiver is often used as a measure of performance of digital communication system. The main function of the coder, the modulator, the demodulator, and the decoder is to combat the degrading effects of the channel on the signal and maximized the information rate and accuracy.

Information source

Information sources can be classified into two categories based on the nature of their outputs: Analog information sources, and discrete information sources. Analog information sources, such as a microphone actuated by speech, or a TV camera scanning a scene, emit one or more continuous amplitude signals (or functions of time). The output of discrete information sources such as a teletype or the numerical output of a computer consists of a sequence of discrete symbols or letters. An analog information source can be transformed onto a discrete information source through the process of sampling and quantizing. Discrete information sources ate characterized by the following parameters:

1. Source alphabet (symbols or letters)

2. Symbol rate

3. Source alphabet probabilities

4. Probabilistic dependence of symbols in a sequence

From these parameters, we can construct a probabilistic model of the information source and define the source entropy (H) and source information rate (R) in bits per symbol and bits per second, respectively.(the term bid is used to denote a binary digit.)

To develop a feel for what these quantities represent, let us consider a discrete information source-a teletype having 26 letters of the English alphabet plus six special characters. The source alphabet for this example consists of 32 symbols. The symbol rate refers to the rate at which the teletype produces characters: for purposes of discussion, let us assume that the teletype operates at a speed of 10 characters or 10 symbols/sec. If the teletype is producing messages consisting of symbol sequences in the English language, then we know that some letters will appear more often than others. We also know that the occurrence of a particular letter in a sequence is somewhat dependent on the letters preceding it. For example, the letter E will occur more often than letter Q and the occurrence of Q implies that the next letter in the sequence will most probably be the letter U, and so forth. These structural properties of symbol sequences can be characterized by probabilities of occurrence of individual symbols by the conditional probabilities of occurrence of symbols.

An important parameter of a discrete source is its entropy. The entropy of a source, denoted by H, refers to the average information content per symbol in a long message and is given units of bits for symbol where bit is used as an abbreviation for a binary digit. In our example, if we assume that all symbols occur with equal probabilities in a statistically independent sequence, then the source entropy is five bits per symbols. However, the probabilistic dependence of symbols in a sequence, and the unequal probabilities of occurrence of symbols considerably reduce the average information content of the symbols. naturally we can justify the previous statement by convincing ourselves that in a symbol sequence QUE, the letter U carries little or no information because the occurrence of Q implies that the next letter in the sequence has to be a U.

The source information rate is defined as the product of the source entropy and the symbol rate and has the units of bits per second. The information rate, denoted by R, represents the minimum number of bits per second that will be needed, on the average, to represent the information coming out of the discrete source. Alternately, R represents the Minimum average data rate needed to convey the information from the source to the destination.

Source Encoder/Decoder

The input to the source encoder (also referred to as the source coder) is a string of symbols occurring at a rate of r_s symbols/sec. The source coder converts the symbol sequence into a binary sequence of 0’s and 1’s by assigning code words to the symbols in input sequence. The simplest way in which a source coder can perform this operation is to assign a fixed-length binary code word to each symbol in the input sequence. For the teletype example we have been discussing, this can be done by assigning 5-bit code world 00000 through 11111 for the 32 symbols in the source alphabet and replacing each symbol in the input sequence by its pre-assigned code word. With a symbol rate of 10 symbols/sec, the source coder output data rate will be 50 bits/sec.

Fixed-length coding of individual symbols in a source output is efficient only if the symbols occur with equal probabilities in a statistically independent sequence. In most practical situation symbols in a sequence are statistically dependent, and they occur with unequal probabilities. In these situations the source coder takes a string of two or more symbols as a block and assigns variable-length code words to these block. The optimum source coder is designed to produce an output data rate approaching R, the source information rate. Due to practical constraints, the actual output rate of source encoders will be greater than the source information rate R. the important parameters of a source coder are black size, code word lengths, average data rate, and the efficiency of the coder (i.e., actual output data rate compared to the minimum achievable rate R).

At the receiver the source decoder converts the binary output of the channel decoder into a symbol sequence. The decoder for a system using fixed-length code words is quite simple, but the decoder for a system using variable-length code words will be very complex. Decoders for such systems must be able to cope with a number of problems such as growing memory requirement and loss of synchronization due to bit errors.

Communication Channel

The Communication channel provides the electrical connection between the source and the destination. The channel may be a pair of wires or a telephone link or free space over which the information bearing signal is radiated. Due to physical limitations, communication channels have only finite bandwidth (B HZ), and the information bearing signal often suffers amplitude and phase distortion as it travels over the channel. In addition to the distortion, the signal power also decreases due to the attenuation of the channel. Furthermore, the signal is corrupted by unwanted, unpredictable electrical signals referred to as noise. While some of the degrading effects of the of the channel can be removed or compensated for, the effects of noise cannot be completely removed. From this point of view, the primary objective of a communication system design should be to suppress the bad effects of the noise as much as possible.

One of the ways in which the effects of noise can be minimized is to increase the signal power. However, signal power cannot be increased beyond certain levels because of nonlinear effects that become dominant as the signal amplitude is increased. For this reason the signal-to-noise power ratio (S/N ), which can be maintained at the output of a communication channel, is an important parameter of the system. Other important parameters of the channel are the usable bandwidth (B), amplitude an phase response, and the statistical properties of the noise.

If the parameters of a communication channel are known, then we can compute the channel capacity C, which represents the maximum rate at which nearly errorless data transmission is theoretically possible. For certain types of communication channels it has been shown that c is equal to B log₂ (1+S/N) bits/sec. The channel capacity C has to be greater than the average information rate R of the source for errorless transmission. The capacity c represents a theoretical limit, and the practical usable data rate will be much smaller than C. as an example, for a typical telephone link with a usable bandwidth of 3KHz and S/N = 10³, the channel capacity is approximately 30,000 bits/sec. At the present time, the actual data rate on such channels ranges from 150 to 9600 bits/sec.

Modulator

The modulator accepts a bit stream as its input and converts it to an electrical waveform suitable for transmission over the communication channel. Modulation is one of the most powerful tools in the hands of a communication systems designer. It can be effectively used to minimize the effects of channel noise, to match the frequency spectrum of the transmitted signal with channel characteristics, to provide the capability to multiplex many signals, and to overcome some equipment limitations.

The important parameters of the modulator are the types of waveforms used, the duration of the waveforms, the power level, and the bandwidth used. The modulator accomplishes the task of minimizing the effects of channel noise by the use of large signal power and bandwidth, and by the use of waveforms that last for longer durations. While the use of increasingly large amounts of signal power and bandwidth to combat the effects of noise is an obvious method, these parameters cannot be increased indefinitely because of equipment and channel limitations. The use of waveforms of longer time duration to minimize the effects of channel noise is based on the well-known statistical law of large numbers. The law of large numbers states that while the outcome of a single random experiment may fluctuate wildly, the overall result of many repetitions of a random experiment can be predicted accurately. In data communications, this principle can be used to advantage by making the duration of signaling waveforms long. By averaging over longer durations of time, the effects of noise can be minimized.

To illustrate the above principle, assume that the input to the modulator consists of 0’s and 1’s occurring at a rate of 1 bit/sec. The modulator can assign waveforms once every second. Notice that the information contained in the input bit is now contained in the frequency of the output waveform. To employ waveforms of longer duration, the modulator can assign waveforms once every four seconds. The number of distinct waveforms the modulator has to generate (hence the number of waveforms the demodulator has to detect) increases exponentially as the duration of the waveforms increases. This leads to an increase in equipment complexity and hence the duration cannot be increased indefinitely. The number of waveforms used in commercial digital modulators available at the present time ranges from 2 to 16.

Demodulator

Modulation is a reversible process, and the demodulator accomplishes the extraction of the message from the information bearing waveform produced by the modulator. For a given type of modulation, the most important parameter of the demodulator is the method of demodulation. There are a variety of techniques available for demodulating a given modulated waveform: the actual procedure used determines the equipment complexity needed and the accuracy of demodulation. Given the type and duration of waveforms used by the modulator, the power level at the modulator, he physical and noise characteristics of the channel, and the type of demodulation, we can derive unique relationship between data rate, power bandwidth requirements, and the probability of incorrectly decoding a message bit. A considerable portion of this text is devoted to the derivation of these important relationships and their use in system design.

Channel Encoder/Decoder

Digital channel coding is a practical method of realizing high transmission reliability and efficiency that otherwise may be achieved only by the use of signals of longer duration in the modulation/demodulation process. With digital coding, a relatively a small set of analog signals, often two, is selected for transmission over the channel and the demodulator has the conceptually simple task of distinguishing between two different waveforms of known shapes. The channel coding operation that consists of systematically adding extra bits to the output of the source coder accomplishes error control. While these extra bits themselves convey no information, they make it possible for the receiver to detect and/or correct some of the errors in the information bearing bits.

There are two methods of performing the channel coding operation. In the first method, called the block coding method, the encoder takes a block of k information bits from the source encoder and adds r error control bits. The number of error control bits added will depend on the value of k and the error control capabilities desired. In the second method, called the convolutional coding method, the information bearing message stream is encoded in a continuous fashion by continuously interleaving information bits and error control bits. Both methods require storage and processing of binary data at the encoder and decoder. While this requirement was a limiting factor in the early days of data communication, it is no longer such a problem because of the availability of solid-state memory and microprocessor devices at reasonable prices.

The important parameters of a channel encoder are the method of coding. Rate or efficiency of the coder (as measured by the ratio of data rate at input to the data rate at the output), error controls capabilities, and complexity of the encoder.

The channel decoder recovers the information bearing bits from the coded binary stream. The channel decoder also performs error detection and possible correction. The decoder operates either in a block mode or in a continuous sequential mode depending on the type of coding used in the system. The complexity of the decoder and the time delay involved in the decoder are important design parameter.

Wireless communication, as the term implies, allows information to be exchanged between two devices without the use of wire or cable. A wireless keyboard sends information to the computer without the use of a keyboard cable; a cellular telephone sends information to another telephone without the use of a telephone cable. Changing television channels, opening and closing a garage door, and transferring a file from one computer to another can all be accomplished using wireless technology. In all such cases, information is being transmitted and received using electromagnetic energy, also referred to as electromagnetic radiation. One of the most familiar sources of electromagnetic radiation is the sun; other common sources include TV and radio signals, light bulbs and microwaves. To provide background information in understanding wireless technology, the electromagnetic spectrum is first presented and some basic terminology defined.

CHAPTER – 11

SOFTWARE DETAILS

pk1 bit 01h

pk2 bit 02h

ONOFF BIT 03H

MOVFOR BIT 04H

STEP_CNTL DATA 30H

STEP_CNTR DATA 31H

LAST_POS DATA 32H

INT_DLY1 DATA 33H

INT_DLY2 DATA 34H

STEP_CNTL1 DATA 35H

STEP_CNTR1 DATA 36H

COUNT DATA 37H

COUNT1 DATA 38H

ORG 0000H

ljmp RESET

ORG 000BH

push ACC

push PSW

lcall WHEEL_LEFT

pop PSW

pop ACC

reti

ORG 001BH

push ACC

push PSW

lcall WHEEL_RIGHT

pop PSW

pop ACC

reti

RESET:

mov P1, #0FFH

mov p2,#00h

mov P3, #0ffH

mov SP, #60H

mov STEP_CNTL, #00h

mov STEP_CNTR, #00h

mov STEP_CNTL1, #00h

mov STEP_CNTR1, #00h

MOV COUNT,#00H

MOV COUNT1,#00H

mov TMOD, #11H

mov IE, #8AH

mov TH0, #7FH

mov TL0, #7FH

mov TH1, #7FH

mov TL1, #7FH

CLR ONOFF

CLR PK1

CLR PK2

clr MOVFOR

setb TR0

setb TR1

MAIN: mov a,p1

anl a,#0fh

cjne a,#05h,run

go: CLR MOVFOR

CLR PK1

CLR PK2

SETB ONOFF

LCALL DDELAY

CLR ONOFF

SETB PK1

CLR PK2

LCALL DDELAY

ljmp main

RUN: cjne a,#06h,run1

CLR ONOFF

CLR MOVFOR

CLR PK2

SETB PK1

ljmp main

RUN1: cjne a,#03h,run2

CLR ONOFF

CLR MOVFOR

SETB PK2

CLR PK1

LJMP MAIN

RUN2: cjne a,#0fh,run3

CLR MOVFOR

CLR PK1

CLR PK2

SETB ONOFF

LCALL DDELAY

CLR ONOFF

SETB PK2

CLR PK1

LCALL DDELAY

ljmp main

run3: cjne a,#07h,run4

SETB MOVFOR

CLR PK1

CLR PK2

CLR ONOFF

ljmp main

run4: cjne a,#00h,run5

ljmp go

run5: cjne a,#01h,run6

ljmp go

run6: cjne a,#04h,run7

ljmp go

run7: LJMP MAIN

WHEEL_LEFT:JB ONOFF,TOP

JB MOVFOR,TOP3

ret

TOP: JNB ONOFF,NOTCH21

inc COUNT

mov A, COUNT

cjne A, #3FH, NOTCH21

mov COUNT, #00H

MOV DPTR,#0800H

mov A, STEP_CNTL1

movc A, @A+dptr

mov P2,A

inc STEP_CNTL1

mov A, STEP_CNTL1

cjne A, #08h, NOTCH21

mov STEP_CNTL1, #00h

NOTCH21:

RET

TOP3: JNB MOVFOR,NOTCH311

inc COUNT1

mov A, COUNT1

cjne A, #3FH, NOTCH311

mov COUNT1, #00H

MOV DPTR,#0800H

mov A, STEP_CNTR1

add A, #08H

movc A, @A+dptr

mov P2,A

inc STEP_CNTR1

mov A, STEP_CNTR1

add A, #08H

cjne A, #10h, NOTCH311

mov STEP_CNTR1, #00h

NOTCH311:

RET

WHEEL_RIGHT:jb pk1,run21

jb pk2,run11

ret

run21: jnb pk1, STOP_FORW

inc INT_DLY2

mov A, INT_DLY2

cjne A, #3FH, SKIP_INT0

mov INT_DLY2, #00H

MOV DPTR,#0400H

mov A, STEP_CNTL

movc A, @A+dptr

mov P2,A

inc STEP_CNTL

mov A, STEP_CNTL

cjne A, #08h, NOTCH2

mov STEP_CNTL, #00h

NOTCH2:

ljmp SKIP_INT0

STOP_FORW:

SKIP_INT0:

ret

run11: jnb pk2, STOP_REVW

inc INT_DLY1

mov A, INT_DLY1

cjne A, #3FH, SKIP_INT1

mov INT_DLY1, #00H

MOV DPTR,#0400H

mov A, STEP_CNTR

add A, #08H

movc A, @A+dptr

mov P2,A

inc STEP_CNTR

mov A, STEP_CNTR

add A, #08H

cjne A, #10h, NOTCH3

mov STEP_CNTR, #00h

NOTCH3:

ljmp SKIP_INT1

STOP_REVW:

SKIP_INT1:

ret

ddelay: MOV R4,#70

Zz2: MOV R5,#70

Zz1: MOV R6,#70

DJNZ R6,$

DJNZ R5,Zz1

DJNZ R4,Zz2

RET

DELAY:

MOV R4,#6FH

DJNZ R4,$

RET

ORG 0400H

STEP_M2:

db 9fh

db 5fh

db 6fh

db 0afh

db 9fh

db 5fh

db 6fh

db 0afh

STEP_M3:

db 0f9h

db 0f5h

db 0f6h

db 0fah

db 0f9h

db 0f5h

db 0f6h

db 0fah

ORG 0800H

STEP_M21:

db 0aah

db 66h

db 55h

db 99h

db 0aah

db 66h

db 55h

db 99h

STEP_M31:

db 99h

db 55h

db 66h

db 0aah

db 99h

db 55h

db 66h

db 0aah

END

CHAPTER – 12

FABRICATION DETAILS

The fabrication of one demonstration unit is carried out in the following sequence:

1. Finalizing the total circuit diagram, listing out the components and their sources of procurement.

2. Procuring the components, testing the components and screening the components.

3. Making layout, preparing the inter connection diagram as per the circuit diagram, preparing the drilling details, cutting the laminate to the required size.

4. Drilling the holes on the board as per the component layout, painting the tracks on the board as per inter connection diagram.

5. Etching the board to remove the un-wanted copper other than track portion. Then cleaning the board with water, and solder coating the copper tracks to protect the tracks from rusting or oxidation due to moisture.

6. Assembling the components as per the component layout and circuit diagram and soldering components.

7. Integrating the total unit inter wiring the unit and final testing the unit.

8. Keeping the unit ready for demonstration.

PCB FABRICATION DETAILS:

The Basic raw material in the manufacture of PCB is copper cladded laminate. The laminate consists of two or more layers insulating reinforced materials bonded together under heat and pressure by thermo setting resins used are phenolic or epoxy. The reinforced materials used are electrical grade paper or woven glass cloth. The laminates are manufactured by impregnating thin sheets of reinforced materials (woven glass cloth or electrical grade paper) with the required resin (Phenolic or epoxy). The laminates are divided into various grades by National Electrical Manufacturers association (NEMA). The nominal overall thickness of laminate normally used in PCB industry is 1.6mm with copper cladding on one or two sides. The copper foil thickness is 35 Microns (0.035mm) OR 70 Microns (0.070 mm).

The next stage in PCB fabrication is artwork preparation. The artwork (Mater drawing) is essentially a manufacturing tool used in the fabrication of PCB’s. It defines the pattern to be generated on the board. Since the artwork is the first of many process steps in the Fabrication of PCBs. It must be very accurately drawn. The accuracy of the finished board depends on the accuracy of artwork. Normally, in industrial applications the artwork is drawn on an enlarged scale and photographically reduced to required size. It is not only easy to draw the enlarged dimensions but also the errors in the artwork correspondingly get reduced during photo reduction. For ordinary application of simple single sided boards artwork is made on ivory art paper using drafting aids. After taping on a art paper and phototraphy (Making the –ve) the image of the photo given is transformed on silk screen for screen printing. After drying the paint, the etching process is carried out. This is done after drilling of the holes on the laminate as per the components layout. The etching is the process of chemically removing un-wanted copper from the board.

The next stage after PCB fabrication is solder masking the board to prevent the tracks from corrosion and rust formation. Then the components will be assembled on the board as per the component layout.

The next stage after assembling is the soldering the components. The soldering may be defined as process where in joining between metal parts is produced by heating to suitable temperatures using non-ferrous filler metals has melting temperatures below the melting temperatures of the metals to be joined. This non-ferrous intermediate metal is called solder. The solders are the alloys of lead and tin.

CONCLUSIONS

This project effectively deals with the detection of anti-social elements, study of animal life and probing of mineral wealth. Since it is a prototype module we have come with enough accomplishments, which will accrue in the long run. With enough funding there is much scope for R&D work and we can overcome the shortcomings. For example using a satellite enabled GPS system we can exactly know the location of the vehicle. We can even incorporate automatic triggering of bombs and bullets on the antisocial elements before they destroy the vehicle. Since it is battery operated we can utilize the solar charging.

However we hope that this module will definitely paves way to the new explorations in the scientific world.

REFERENCES:

The following are the references made during design, development and fabrication of the project work “Autonomous Search Vehicle using Wireless Video Camera”

(1). Basic electronics By: GROB

(2). Mechatronics – Electronic Control Systems in Mechanical and electrical Engineering – By: W. Bolton

(3) Electronic Circuit guide book – Sensors – By JOSEPH J.CARR

(4) The 8051 Micro-controller Architecture, programming & Applications

By: Kenneth J. Ayala

(5) Mechanism and Machine Theory By: J.S. Rao, R.V. Dukkipati

(6) Practical transistor circuit design and analysis

By: GERALD E. WILLIAMS

(7). Robotic Engineering An Integrated Approach

By: Richard D. Klafter, Thomas A. Chmiclewski, Michael Negin

(8) Programming and Customizing the 8051 Micro-controller By: Myke Predko

(9) The concepts and Features of Micro-controllers - By: Raj Kamal

(10) Digital and Analog Communication System By: K. sam Shanmugam

(11) Digital Electronics. By JOSEPH J.CARR

(12). Electronics for you Monthly Magazine

(13). Practical Electronics “ “

(14). Elector India “ “

In addition to the above books, most of the information collected from the Internet. The following are the references.

[Arki99] “Behavior-Based Robotics,” Arkin, R., ISBN 0-262-01165-4 ,

MIT Press, 1999.

BySi98] Byrne, J.,Singh, S., ”Precise Image Segmentation for Forest Inventory,” CMU-RI-TR-98-14, Carnegie Mellon University,1998.

[Clar99], Clark, S.,”Autonomous Land Vehicle Navigation Using Millimetre Wave Radar,” Ph.D. thesis, The University of Sydney January, 1999.

[ChAl93] Chatila, R., Alami, R., Lacroix, S., Perret, J., Proust, C., “Planet Exploration by Robots: From Mission Planning to Autonomous Navigation,” In Proc. Intl. Conf. Advanced Robotics, pp. 91-96, Tokyo, Japan, November 1993.

[ChIb99] Cherif, M., Ibanez-Guzman, J., Laugier, C. , Goh, T., "Motion Planning for an All-Terrain Autonomous Vehicle," Int. Conf. on Field and Service Robotics, Pittsburgh, PA, USA, August, 1999.

[ChLa95] Cherif, M., Laugier, C., ”Motion Planning of Autonomous Off- Road Vehicles Under Physical Interaction Constraints,'' IEEE Int. Conf. on Robotics and Automation (ICRA), pp. 1687-1693, Nagoya, Japan, 1995.

[DrSa01] Driankov, D., Saffiotti, A. (Eds), “Fuzzy Logic Techniques for “Autonomous Vehicle Navigation,” Springer-Verlag [DuJe00] Dudek, G., Jenkin, M., “Computational Principles of Mobile Robotics,” Cambridge University Press, 2000, p69.

[Durr91] Durrant-Whyte, H., “An autonomous Guided Vehicle for Cargo handling,” International Journal of Robotics Research, 15(5) pages 407-440, 1991.

[HeKr93] Hebert, M. Krotkov, E. “3-D Measurements from Imaging

Laser Radars. Intl. J. Image and Vision Computing,” 10(3):170-178,

April 1992. Antibes, France, September 1993.·

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LM World

Autonomous Search Vehicle

Synopsis

Stepper Motor Drive Circuit

ABOUT STEPPER MOTOR

CHAPTER - 9

DETAILS ABOUT STEPPER MOTOR

SPEED CAPABILITY

EFFECTS OF MOTOR INDUCTANCE

DETAILS ABOUT WIRELESS COMMUNICATION

Model of a communication system:

ELEMENTS OF A DIGITAL COMMUNICATION SYSTEM

Information source

Communication Channel

Modulator

Demodulator

Channel Encoder/Decoder

CONCLUSIONS

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