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Wireless IR Headset_Report

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Full report of Wireless IR Headset. It is working and we got a rage of 6-7m clearly on both pcb & bread bord.

Full report of Wireless IR Headset. It is working and we got a rage of 6-7m clearly on both pcb & bread bord.

If anyone want more details or any help mail me
athul100001@gmail.com

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    Wireless IR Headset_Report Wireless IR Headset_Report Document Transcript

    • College of Eng: Munnar Dept. of ECE WIRELESS IR HEADSET Minor project Report Submitted in partial fulfillment of the requirements For the award of B.Tech Degree in Electronics & Communication Engineering Of the Cochin University of Science and Technology By AKHIL M 13102602 NIDHEESH V.V 13102626 SOORAJ.S 13102639 Under the guidance of Mr. Jayakrishnan K.R & Mr. Albert Jose APRIL 2012 DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING COLLEGE OF ENGINEERING MUNNAR-685612Wireless IR Headset Page 1
    • College of Eng: Munnar Dept. of ECE ACKNOWLEDGEMENT We express our thanks to Dr K.G.Balakrishnan, Principal, College Of Engineering, Munnar, for allnecessary help extended to us in the fulfilment of this minor project. We express our thanks to Mr Biju V.G, Head of the Department of Electronics and CommunicationEngineering, College of Engineering, Munnar, for all necessary help extended to us in the fulfilment of thisminor project. We have great pleasure to express our gratitude and obligations to Mr K.R. Jayakrishnan, AssistantProfessor Department of Electronics and Communication Engineering, College of Engineering, Munnar, forhis valuable guidance, constant encouragement and creative suggestions to make this minor project a great success. We have great pleasure to express our gratitude and obligations to Mr Albert Jose, LecturerDepartment of Electronics and Communication Engineering, College of Engineering, Munnar, for hisvaluable guidance, constant encouragement and creative suggestions to make this minor project a greatsuccess. We also express our sincere gratitude to all the Staff Members of Department of Electronics andCommunication Engineering, College of Engineering, Munnar, for their valuable help and encouragement,which lead to the successful accomplishment of this minor project. We are also thankful to my friends for their valuable suggestions and encouragements. Above all I thank the ALMIGHTY, without whose blessing we would ever be able to completeour work. AKHIL M NIDHEESH V.V SOORAJ SWireless IR Headset Page 2
    • College of Eng: Munnar Dept. of ECE ABSTRACT Infrared Rays form a part of the electromagnetic spectrum which has a wavelength rangingfrom 0.7 to 400 um. It is known widely for its heating effects and the role it plays in atmosphere.Infrared rays find large applications in electronic and wireless applications due to certainadvantages provided by its inherent properties. In the past few decades, an unprecedented demand for wireless technologies has been takingplace. Mobiles, Laptops, assistants (PDAs), and mobile phones, to name just a few examples, arebecoming part of the everyday life of a growing number of devices that communicate wirelessly.Radio and infrared (IR) are currently the main parts of the electromagnetic spectrum used totransmit information wirelessly. IR is becoming more popular every day and it is being preferreddue to its inherent advantages like low power requirements, security, effective short distancecommunication as compared to its Radio counterpart. In this project we aim to design and build a hardware model of IR transmitter and receiver thatis capable of communicating data over a short range. The device we plan to build could beintegrated with the digital devices to transmit signals in the audio frequency range of 20Hz to20000Hz over a range of 4 to 5 metres. Also we aim to study the properties of the IRcommunication in terms of the range acquired and the power requirements of the system.Wireless IR Headset Page 3
    • College of Eng: Munnar Dept. of ECE CONTENTSNo Content Page No1. Overview 3-7 1 .1 Introduction 3 1.2 Technology Overview 4 1.3 Evolution of Infrared Communication System 5 1.4 System configuration of Wireless IR Communication Systems 72. Objectives 83. Infrared Systems 9-13 3.1 Properties 9 3.2 Advantages 10 3.3 Disadvantages 11 3.4 Applications 114. Hardware description 14-19 4.1 Design Considerations 14 4.2 Block Diagram 15 4.3 Circuit Diagram 17 4.4 Working 18 4.5 Power Consideration 19Wireless IR Headset Page 4
    • College of Eng: Munnar Dept. of ECE5. Simulation, Analysis and Amendments 20-21 5.1 Simulation 20 5.3 Observations 21 5.4 Amendments 216. PCB Fabrication 227. PCB Layout 268. List of components 279. Results and Inference 2810. References 2811. Datasheets 29Wireless IR Headset Page 5
    • College of Eng: Munnar Dept. of ECE 1. OVERVIEW1.1 Introduction In the past few decades, a demand for wireless technologies has tremendously increased.Both industrial and private customers are demanding products -for a wide range of applications-that incorporate wireless features, which allow them to exchange, receive, or transmit informationwithout the inconvenience of having to be fixed to any particular location. The benefits of wireless technologies are not limited to user convenience- in terms of mobility-and flexibility in the placement of terminals. Significant reductions in cost and time also can beachieved, in a number of applications, using wireless solutions. Reconfiguring computer terminalsor microcontroller systems (in places such as laboratories, conference rooms, offices, hospitals,production floors, or educational institutions), for instance, can be done relatively cheaply andquickly with wireless networks. Maintaining and reconfiguring wired networks, on the other hand,is usually carried out in more expensive, time-consuming, and complicated ways (especially insituations where cables are grounded or installed in inaccessible places). Furthermore, cables aresusceptible to damage, which means potential disruption to the network operation. Radio andinfrared (IR) are currently the main parts of the electromagnetic spectrum used to transmitinformation wirelessly. By the term “radio”‖ we refer to the radiofrequency and microwave partsof the spectrum, and “IR”‖ to the Near-infrared part of it. In homes, some member prefers to watch television while others don’t. It becomes difficult foryounger member to go against the will of elder, especially in Indian scenario, so younger have tosuffer in most of cases. Wired headphones do not give flexibility for mobility and more users toaccommodate (usually due to predefined design), so wireless headphones are required to meetthe requirement. We in this project intend to make wireless system using Infrared technology, soas to counter this problem. Thus, Infrared cordless headphones would be used for watching TVand movies with full enjoyment but without disturbing the peace at homeWireless IR Headset Page 6
    • College of Eng: Munnar Dept. of ECE 1.2 Technology Overview Radio and infrared (IR) are currently the main parts of the electromagnetic spectrum used totransmit information wirelessly. By the term “radio”‖ we refer to the radiofrequency andmicrowave parts of the spectrum, and “IR”‖ to the near infrared part of it. Infrared rays have awavelength ranging from 0.7 to 400 µm which corresponds to a frequency ranging from 1THz to400 THz. Most of today’s wireless communication is based on radio frequency but IR frequency is alsobeing used and is becoming popular these days (due to its inherent advantages) over its radiocounterpart for a number of applications. From a spectrum management point of view, for example, IR offers potentially hugebandwidths that are currently unregulated worldwide. The radio part of the spectrum, on theother hand, gets more congested every year, and the allocation of radio frequencies is increasinglydifficult and expensive. Moreover, due the fact that the authorities that regulate the allocation ofradio frequencies vary from one country to another so device are to be modelled accordingly indifferent country. Another advantage of IR over radio is its immunity to electromagnetic interference (EMI).Thismakes IR the preferred option in environments where interference must be minimized oreliminated. In addition, IR does not interfere with and is not affected by radio frequencies, whichis particularly relevant in hospitals, as explained in a number of published articles in the area. IR also presents advantages over radio in terms of security. Because IR radiation behaves likevisible light, it does not penetrate walls, which means that the room where the energy isgenerated encloses the emitted signal completely (assuming there are no windows or transparentbarriers between rooms). This prevents the transmitted information from being detected outsideand implies intrinsic security against eavesdropping. Further advantages of IR over radio includethe low cost, the small size, and the limited power consumption of IR components. Despite the advantages presented by the infrared medium, IR is not without its drawbacks.Infrared wireless links are susceptible to blocking from persons and objects, which can result in theattenuation of the received signal. In addition, wireless IR systems generally operate inenvironments where other sources of illumination are present. If this background illumination haspart of its energy in the spectral region used by wireless IR transmitters and receivers, itintroduces noise in the photo detector, which limits the range of the system. Moreover, optical wireless systems are also affected by the high attenuation suffered by the IRsignal when transmitted through air, and by atmospheric phenomena such as fog and snow thatfurther reduce the range of the system and deteriorate the quality of the transmission whenoperating outdoors.Wireless IR Headset Page 7
    • College of Eng: Munnar Dept. of ECE1.3 Evolution of Infrared Communication Systems Optical wireless communication systems have experienced a huge development since thelate1970s when IR was first proposed as an alternative way (to radio) to connect computernetworks without cables. IBM was one of the first organizations to work on wireless IR networks. The first reports onIBM’s experimental work were published between 1978 and 1981. They have described a duplexIR link that achieved a bit rate of 64 kbps using PSK and a carrier frequency of 256 kHz In 1983, Minami et al. from Fujitsu described a full-duplex LOS system that operated underthe same principles as the network described by Gfeller. That system consisted of an opticalsatellite attached to the ceiling and connected to a network node via a cable, and of a number ofcomputer terminals that communicated to the server via the optical satellite. It operated at 19.2kbps (over 10 m) with an error rate of 10−6 when working under fluorescent illumination. By 1985,the Fujitsu team had managed to improve the data rate of its system to48 kbps, as reported byTakahashi and Touge. In the same year (1985), researchers from two other companies (Hitachi and HP Labs)presented their own work in the area of wireless IR communications. In the case of Hitachi, Nakataet al. reported a directed-LOS network system that replaced the optical satellite on the ceiling withan optical reflector. This system achieved a data rate of up to 1 Mbps with a BER of less than 10−7for a distance of 5 m. In 1987, AT&T Bell presented their work on optical wireless communications. They reported adirected-LOS system that operated at 45 Mbps over a wavelength of 800 nm. More recently, Showa Electric reported a 100-Mbps short-range IR wireless transceiver thatoperated over a maximum range of 20 m and used LEDs for the transmitter and avalanche photo-detector (APDs) for the receiver. Another system, proposed by Singh et al. in 2004 [24], was basedon the idea of a base station attached to the ceiling and connected to the network via a backbone. The proposed network operated at 100 Mbps and was based on DPPM with carrier sensemultiple access with collision detection (CSMA/CD) for the Media Access Control (MAC) protocolWireless IR Headset Page 8
    • College of Eng: Munnar Dept. of ECEFig 1.3.1 Chronology of indoor optical wireless communication researchWireless IR Headset Page 9
    • College of Eng: Munnar Dept. of ECE 1.4 System Configurations of Wireless IR Communication Systems Optical wireless systems for indoor and outdoor use can be arranged in a number of configurationsdepending on the specific requirements of a system. In general, the topologies used for indoor opticalwireless communication systems are classified according to two parameters: (1) the existence of a nunobstructed path between the transmitter and the receiver (LOS– non-LOS), and (2) the degree ofdirectionality of the transmitter, the receiver, or both (directed, non-directed, or hybrid).Wireless IR Headset Page 10
    • College of Eng: Munnar Dept. of ECE 2. OBJECTIVE The objective of the project is to design an efficient infrared transmitter-receiver systemthat would be capable of transmitting Infrared electromagnetic signals in the audio frequencyrange of 20Hz to 20 KHz over a range of 4 to 6 metres. The device would be used in conjunctionwith the multimedia devices, Computers and Laptops to transmit music from one place to a pair ofcordless headphones by employing the principles of wireless infrared communication without anydegradation in the quality of the music. Also we intend to study the properties of the system interms of the range and the power requirements. Special emphasis is being laid into the communication of the music signals over a large rangeand to study the degradation of the signal over a range. Also measures are being taken and a studyis being done to increase the angular range and the linear range of the system. The objective atend is to obtain a low cost effective IR system ready for marketing purpose.Wireless IR Headset Page 11
    • College of Eng: Munnar Dept. of ECE 3. Infrared Systems3.1 Properties of Infrared System:Infrared radiation (IR) is electromagnetic radiation with a wavelength between 0.7 and 300micrometres,which equates to a frequency range between approximately 1 and 430 THz. Its wavelength is longer (andthe frequency lower) than that of visible light, but the wavelength is shorter (and the frequency higher)than that of terahertz radiation microwaves. Fig. 3.1.1 Infrared SpectrumInfrared Radiation behaves similar to the visible light, so it exhibits all the properties that light does such as a) Reflection b) Refraction c) Diffraction d) DiffusionAttenuationAtmospheric attenuation is defined as the process whereby some or all of the energy of anelectromagnetic wave is lost (absorbed and/or scattered) when traversing the atmosphere.AbsorptionAbsorption, in the context of electromagnetic waves and light, is defined as the process of conversion ofthe energy of a photon to internal energy, when electromagnetic radiation is captured by matter. Whenparticles in the atmosphere absorb light, this absorption provokes a transition (or excitation) in theparticle’s molecules from a lower energy level to a higher one.Wireless IR Headset Page 12
    • College of Eng: Munnar Dept. of ECEScatteringScattering is defined as the dispersal of a beam of particles or of radiation into a range of directions as aresult of physical interactions. When a particle intercepts an electromagnetic wave, part of the wave’senergy is removed by the particle and re-radiated into a solid angle centred at it. The scattered light ispolarized, and of the same wavelength as the incident wavelength, which means that there is no loss ofenergy to the particle3.2 Advantages over RF a) Wider and Unregulated SpectrumFrom a spectrum management point of view, for example, IR offers potentially huge bandwidthsthat are currently unregulated worldwide. The radio part of the spectrum, on the other hand, getsmore congested every year, and the allocation of radio frequencies is increasingly difficult andexpensive. Moreover, due to the fact that the authorities that regulate the allocation of radiofrequencies vary from one country to another. Device needs to be modelled accordingly fordifferent country so as to avoid a potential risk of system or production compatibility in differentgeographical locations. b) High noise immunity:Another advantage of IR over radio is its immunity to electromagnetic interference (EMI).Thismakes IR the preferred option in environments where interference must be minimized oreliminated. In addition, IR does not interfere with and is not affected by radio frequencies, which isparticularly relevant in hospitals, as explained in a number of published articles in the area. c) Higher security:IR also presents advantages over radio in terms of security. Because IR radiation behaves likevisible light, it does not penetrate walls, which means that the room where the energy is generatedencloses the emitted signal completely (assuming there are no windows or transparent barriersbetween rooms). This prevents the transmitted information from being detected outside andimplies intrinsic security against eavesdropping. In addition, IR offers the possibility of rapidwireless deployment and the flexibility of establishing temporary communication links. Furtheradvantages of IR over radio include the d) low cost e) The small size (Portable) and f) The limited power consumption.This is explained by the fact that wireless IR communication systems make use of the same Opto-electronic devices that have been developed and improved over the past decades for optical fibrecommunications and other applications. One such component is the light-emitting diode (LED),which, due to its now faster response times, high radiant output power, and improved efficiency,is becoming the preferred option for short-distance optical wireless applications.Wireless IR Headset Page 13
    • College of Eng: Munnar Dept. of ECE3.3 Disadvantages: a) Direct line of sight communication Optical wireless links are susceptible to blocking from persons and objects, which can result inthe attenuation of the received signal or in the disruption of the link (depending on theconfiguration of the system).That is the Wireless IR systems operate only in direct line of sightcommunication. b) Shorter Range Wireless IR systems generally operate in environments where other sources of illuminationare present. This background illumination has part of its energy in the spectral region used bywireless IR transmitters and receivers, and introduces noise in the photo detector, which limits therange of the system .Moreover, optical wireless systems are also affected by the high attenuationsuffered by the IR signal when transmitted through air, and by atmospheric phenomena such asfog and snow that further reduce the range of the system and deteriorate the quality of thetransmission when operating outdoors.3.4 Applications a) Infrared filter Infrared (transmitting/passing) filters can be made from many different materials. One type ismade of polysulfone plastic that blocks over 99% of the visible light spectrum from “white” lightsources such as incandescent filament bulbs. Infrared filters allow a maximum of infrared outputwhile maintaining extreme covertness. Currently in use around the world, infrared filters are usedin Military, Law Enforcement, Industrial and Commercial applications. Active-infrared night vision:the camera illuminates the scene at infrared wavelengths invisible to the human eye. Despite adark back-lit scene, active-infrared night vision delivers identifying details, as seen on the displaymonitor. b) Thermography Infrared radiation can be used to remotely determine the temperature of objects (if theemissivity is known). This is termed thermography, or in the case of very hot objects in the NIR orvisible it is termed pyrometry. Thermography (thermal imaging) is mainly used in military andindustrial applications but the technology is reaching the public market in the form of infraredcameras on cars due to the massively reduced production costs.Wireless IR Headset Page 14
    • College of Eng: Munnar Dept. of ECE Thermo graphic cameras detect radiation in the infrared range of the electromagneticspectrum (roughly 900–14,000 Nano meters or 0.9–14 µm) and produce images of that radiation.Since infrared radiation is emitted by all objects based on their temperatures, according to theblack body radiation law, thermography makes it possible to "see" ones environment with orwithout visible illumination. The amount of radiation emitted by an object increases withtemperature; therefore thermography allows one to see variations in temperature. c) Tracking: Infrared homingInfrared tracking, also known as infrared homing, refers to a passive missile guidance systemwhich uses the emission from a target of electromagnetic radiation in the infrared part of thespectrum to track it. Missiles which use infrared seeking are often referred to as "heat-seekers",since infrared (IR) is just below the visible spectrum of light in frequency and is radiated stronglyby hot bodies. d) Infrared heatingInfrared radiation can be used as a deliberate heating source. For example it is used in infraredsaunas to heat the occupants, and also to remove ice from the wings of aircraft (de-icing). FIR isalso gaining popularity as a safe method of natural health care & physiotherapy. Far infraredthermometric therapy garments use thermal technology to provide compressive support andhealing warmth to assist symptom control for arthritis, injury & pain. Infrared can be used incooking and heating food as it predominantly heats the opaque, absorbent objects, rather thanthe air around them. e) CommunicationsIR data transmission is also employed in short-range communication among computer peripheralsand personal digital assistants. These devices usually conform to standards published by IrDA, theInfrared Data Association. Remote controls and IrDA devices use infrared light-emitting diodes(LEDs) to emit infrared radiation which is focused by a plastic lens into a narrow beam. The beamis modulated, i.e. switched on and off, to encode the data. The receiver uses a silicon photodiodeto convert the infrared radiation to an electric current. It responds only to the rapidly pulsingsignal created by the transmitter, and filters out slowly changing infrared radiation from ambientlight. Infrared communications are useful for indoor use in areas of high population density. IRdoes not penetrate walls and so does not interfere with other devices in adjoining rooms. Infraredis the most common way for remote controls to command appliances.Wireless IR Headset Page 15
    • College of Eng: Munnar Dept. of ECE f) SpectroscopyInfrared vibrational spectroscopy (see also near infrared spectroscopy) is a technique which can beused to identify molecules by analysis of their constituent bonds. Each chemical bonding amolecule vibrates at a frequency which is characteristic of that bond. A group of atoms in amolecule (e.g. CH2) may have multiple modes of oscillation caused by the stretching and bendingmotions of the group as a whole. If an oscillation leads to a change in dipole in the molecule, thenit will absorb a photon which has the same frequency. The vibration all frequencies of mostmolecules correspond to the frequencies of infrared light. Typically, the technique is used to studyorganic compounds using light radiation from 4000–400 cm−1, the mid-infrared. A spectrum of allthe frequencies of absorption in a sample is recorded. This can be used to gain information aboutthe sample composition in terms of chemical groups present and also its purity (for example a wetsample will show a broad O-H absorption around 3200 cm−1).Wireless IR Headset Page 16
    • College of Eng: Munnar Dept. of ECE 4. Hardware description4.1 Design Consideration: Optical fibre technology has undergone major developments in the past decades; and aswireless IR communication systems use some of the same components employed in optical fibresystems, wireless IR systems benefit from mature and efficient devices that are available at arelatively low cost The selection of the opto-electronic components for the transmitter and thereceiver is generally done according to the configuration desired for a system. Directed topologiesrequire directed sources and detectors, while non-directed links require wide emission beams andwide FOVs. One of the things that can be observed from the information of different systemsdeveloped so far is that wireless IR communications employs (1) light emitting diodes and (2) laserdiodes for wireless IR transmitters. LEDs present wider emission beams than LDs, which makesthem the preferred option of the indoor non-directed and the hybrid configurations. In addition,they are generally considered as eye safe, which means that they can be used at higher emissionpowers than LCD4.1.1 Channel model from transmitted signal power to generated photocurrent :( intensitymodulation and direct detection)Wireless IR Headset Page 17
    • College of Eng: Munnar Dept. of ECE Block DiagramBLOCK DIAGRAM EXPLANATIONTransmitterInfrared headphone has a transmitter connected to audio output from anv audio source like TV,radio etc. The transmitter has 5 parts 1) Audio Device 2) Audio Interface 3) Audio Amplifier 4) IR Driver 5) IR LEDWireless IR Headset Page 18
    • College of Eng: Munnar Dept. of ECE Audio device is as explained before. The audio output is given to an audio interface circuitwhich is a transformer connected in step up mode. The output is given to an audio amplifiermainly RC coupled amplifier where it is amplified to drive the IR driver. The IR driver has a Highcurrent transistor which is used to drive IR LED connected to emitter. The IR LED generates theinfrared radiation corresponding to audio Input.ReceiverThe receiver section is what the user carries with him. The receiver section has 4 points. 1) IR Interface 2) Audio Amplifier 3) Audio Interface 4) Headphone The IR interface is photo transistor. Then receives the IR radiations and producescorresponding electrical signals. This is given to audio amplifier where it is amplified and given toaudio interface circuit. It gives the input to the headphone where the transmitted audio signal isreceivedWireless IR Headset Page 19
    • College of Eng: Munnar Dept. of ECE Circuit diagramTransmitterReceiverWireless IR Headset Page 20
    • College of Eng: Munnar Dept. of ECE4.4 Working of the circuit:The circuit essentially can be divided into two major sub circuits:1. The transmitter circuit 2. The Receiver CircuitThe transmitter Circuit:The transmitter circuit consists of a transformer and the two transistor amplifier stage which isused to amplify the audio signals supplied to the circuit. The audio signal ranges within frequencyfrom 20Hz to 20,000Hz. The transformer is connected in inverse so as to amplify signals and offersimpedance matching. The signal is then given to an audio amplifier. The three resistors R1, R5 andR2 are used for the dc biasing of the transistorQ1 which is BC547A a NPN transistor having a Baseto Emitter Voltage rating of 6.0 V. The Red LED is used for the biasing of the transistor Q2 which isa BD140 transistor which is a PNP transistor capable of handling high currents. The resistance R4 isused to control the emitter current. When base voltage increases the transistor is ON and thecollector voltage decreases simultaneously. The red LED connected to its collector glows whencollector voltage decreases. The voltage is given to the base of transistor BD 140. The low voltagemakes the BD 140 transistor off and its collector voltage increases and the LED emits radiations. A9v battery or adapter provides voltage supply.The Receiver Circuit:The transmitted IR rays are received by a photo transistor and converted to correspondingelectrical signals. This is amplified by audio amplifier comprising of T4 and T5. When base voltageof T4 increases making it ON and thus collector voltage decreases. This is given to base of IS and itbecomes OFF and its collector voltage increases. This amplified signal is given to audio interfacewhere it is given to head set and the audio signal is received.Wireless IR Headset Page 21
    • College of Eng: Munnar Dept. of ECE4.5 Power Budget Considerations The power budget is one of the most important considerations when designing a Wirelesscommunication system because it defines the battery size and the operation time of portableunits. Power consumption is determined by a number of factors, such as the electronic and theoptical components used, the modulation scheme, the topology, and the emitted power of awireless system. The type of technology used also affects power consumption. IR transceivers present a lower power requirement than their RF counterparts. An opticalwireless transceiver operating at 1 Mbps consumes 150 mW, while a radio LAN transceiverconsumes 1.5 W, which corresponds to a 25 Percept extra drain on the power supply of a laptop. The power consumption of a system is strongly affected by the power emitted by thetransmitter. This power should be high enough to cover the desired range of a particular system,as well as to supply the receiver with sufficient energy. The power at the receiver is determined by the range of the link, the topology used thegeometry of the room where the system is operating, and the reflective properties of its walls andceiling. In addition, the use of an optical collimating element can minimize the power consumptionat the transmitter by transforming an extended source into a concentrated source with narrowemission angles. When this is the case, care must be taken to comply with eye safety regulations.The use of collimated sources also allows the use of narrower receivers, which, due to theirdirective nature, can present high optical gain increasing the sensitivity of the receiver andreducing the need for a high transmitted power for a given distance. The use of angle-diversityreceivers and multi-spot transmitters also help to reduce power consumption while maintainingwide coverage.Optical Concentrators and Power Requirements Another way of improving power consumption is through the use of an optical concentrator atthe receiver. This is possible due to the fact that an optical concentrator improves the sensitivity ofthe receiver, which means that a lower emitted power may be required at the transmitter (for agiven range) compared to the same system without a concentrator. To optimize the powerconsumption, it is also important to transmit only the relevant information, to use an effectivesignal coding, and to perform the required signal processing at low power if possibleWireless IR Headset Page 22
    • College of Eng: Munnar Dept. of ECE 5 Simulation, Analysis and Amendments 5.1Simulation:The circuit was simulated by the LT Spice Software to obtain the following plots atthe transmitter.Figure: - Spice Output wave form.Wireless IR Headset Page 23
    • College of Eng: Munnar Dept. of ECE 5.2 Observation: In order to study the range of the IR Transmitter-Receiver system, we supplied the transmitterwith a sinusoidal signal and observed the output wave form at the DSO. The output received at thereceiver and the DSO was also observed to be sinusoidal for a range of 3 metres. The quality of themusic received was exceptionally good for a range of 1.5 metre after which it started deteriorating.An Optical Concentrator was then employed at the transmitting LED side. It was observed that thevolume and the quality of the music received were highly improved. 5.3 Amendments 1. Wider Line of Sight Infrared Communication is line of sight communication. Due to this if there is an obstructionplaced between the transmitter and the receiver then the transfer of the data stops.Improvements to this headphone technology will be provided by the project team, where we willuse a lens in front of the LEDs to diffuse the light to provide a wider line of sight for the infraredheadphones to catch–there by reducing chances of losing the signal .This method of diffusing theinfrared beam also means the listener needs no longer to sit directly in front the infraredtransmitter which plugs into your TV or other audio source. When it comes to TV/movie watchingand untainted enjoyment of the sound infrared cordless headphones have a number of advantageswhich make them ideal for a comfy relaxing viewing experience. 2. Better Range Use of power amplifiers and an array of high power LEDs arranged at different angles will beused to increase the range of infrared transmission to cover more area. 3. Use of Optical Concentrator By using Optical Concentrator at the Transmitting end, the IR Power gets concentrated and ahigher volume of the music and a better quality of music can be obtained.Wireless IR Headset Page 24
    • College of Eng: Munnar Dept. of ECE 6. PCB Design and Fabrication Nowadays the Printed Circuit Board here after mentioned as PCBs makes the electronic circuitmanufacturing as easy one. In olden days vast area was required to implement a small circuit toconnect the leads of the components and separate connectors were needed. But PCBs connectsthe two by copper coated lines. In the single sided PCBs the copper layer is on both sides. Somecases middle layer is also possible than the two sides. In our project we have done the PCB design with the help of OR-CAD software. The differentsteps in the PCB design and how the same was done by us are explained below.6.1 BOARD TYPESThe most popular board types are: 1. Single-sided boards: They are mainly used in entertainment electronics wheremanufacturing costs have to be kept minimized. 2. Double-sided boards: Double sided PCBs can be with or without plated through holes. Theproduct of boards with plated through holes is fairly expensive. We have used double-sided board here taking into account the size of the board and ease ofinstallation. Figure 5.1a is the bottom layer and figure 5.1b is the top layer.6.2 MANUFACTURING PROCESS The different steps involved in the design and fabrication of PCB are explained below. We,observing the necessary precaution during the entire fabrication period have been carefullyfollowed these steps.6.3 LAYOUT APPROACHES The first rule is to prepare each and every PCB layout as viewed from the component side.Another important rule is not to start the designing of a layout unless an absolutely clear circuitdiagram is available, if necessary with components list. Among the components the larger onesare placed first and the space between is filled with smaller ones. Components requiringinput/output connections come near the connectors. All components are placed in such a mannerthat de-soldering of other components is not necessary if they have to be replaced. The layout for our circuit was obtained with the help of OR-CAD software. For this, as the firststep we drew our circuit with the help of the software obtaining the required components fromthe library files. These components have been properly placed avoiding a large number ofinterconnections and crossovers. To develop the layout at first the schematic of the circuit is donewhich is then converted into a single layered board design to obtain the layout.Wireless IR Headset Page 25
    • College of Eng: Munnar Dept. of ECE6.4 BOARD CLEANING The cleaning of the copper surface prior to resist applications is an essential step for any typesof PCB process using etch or plating resist. Insufficient cleaning is one of the reasons most oftenencountered for difficulties in PCB fabrication although it might not always be recognized as this.But it is quite often the reasons of poor resist adhesion, uneven photo-resist films, pinholes, poorplating adhesion etc. The cleaning of the board was done with just a sink with running water, pumice powder,scrubbing brushes and suitable tanks.6.5 SCREEN PRINTING The screen-printing process is very simple. For this reason fabric with uniform meshes andopening is stretched and fixed on a solid frame of metal or wood. The circuit pattern is thenphotographically transferred onto the screen, leaving the meshes in the pattern open, while themeshes in the rest of the area are closed. In the actual printing step, ink is forced by movingsqueegee through the open meshes onto the surface of the material to be printed.6.6 PLATING The plating was done expecting the circuit board to retain its solder ability for long periods ofseveral months so that reliable solder joints can be produced during assembly. Plating of a metalcan be accomplished on a copper pattern by three methods. They are: 1. Immersion plating 2. Electro less plating 3. Electroplating.6.7 ETCHING This was done manually by immersing the board into a solution of formic chloride andhydrochloric acid and finally cleaning the board y soap. The copper pattern was formed byselective removal of all unwanted copper which is not protected by an etch resist. Factors likeunder etching and overhang which complicate the matter especially in the production of fine andhighly precise PCBs have been carefully dealt with. This can also be done using a spray typeetching machine.Wireless IR Headset Page 26
    • College of Eng: Munnar Dept. of ECE6.8 COMPONENT PLACING In the circuit, components having considerably more connecting points than the others havebeen placed first and remaining ones were grouped around them. This will result in a minimumoverall conductor length. This was done aiming to get shortest possible interconnections. Thebending of the axial component leads was done to guarantee an optimum retention of thecomponent of the PCB while a minimum of stress is introduced on the solder joint. Horizontallymounted resistors have to touch the board surface to avoid lifting of solder joints along with thecopper pattern under pressure on the resistor body. Vertically mounted resistors should not beflush to the board surface to avoid strain on the solder joints as well as on the component leadjunction due to different thermal expansion coefficients of lead and board materials, wherenecessary resilient spaces have to be provided.6.9 DRILLING Drilling was done by mechanical machining operation in PCB production processes. Holes weremade by drilling wherever a superior hole finish for plated through hole processes is required andwhere the tooling costs for a punching tool cannot be justified. Therefore drilling is applied by allthe professional grade PCB manufacturers and generally in smaller PCB production laboratories.6.10 SOLDERING Soldering is a process for the joining of metal parts with the aid of a molten metal(solder),where the melting temperature is suited below that of the material joined and wherebythe surface of the parts are wetted, without then becoming molten. Soldering generally implies that the process occurs at temperature below 450 degreecentigrade. Solder wets and alloys with the base metals and get drawn, by capillary action into thegap between them. This process forms a metallurgical bond between the parts of the joint.Therefore solder acts by 1) Wetting of base metal surfaces forming joint. 2) Flowing degree centigrade. Solder wets and alloys with the base metals and gets drawn bycapillary action into the between these surfaces, which result in a completely filled space betweenthem. 3) Metallurgical bonding to these surfaces when soldered.If the basic constituents in making a soldered joint are represented in a diagram, it will look asfollows:Wireless IR Headset Page 27
    • College of Eng: Munnar Dept. of ECE Figure 6.1: Soldering Joint Constituents Soldering was done by placing the components at the right position, wetting these surfaceswith molten solder and allowing the solder to cool down until it has been solidified. During thissoldering operation, an auxiliary medium, flux, was used to increase the flow properties of moltensolder and to improve the degree of wetting. Following characteristics are required in the flux: It should provide a liquid cover over the materials and exclusive air up to the solderingtemperature. It should dissolve any oxide on the metal surface or on the solder and carry such unwantedelements away. It should be readily displaced from the metal by the molten soldering operation. Residues should be removable after completion of the soldering. To achieve a soldered joint,the solder and the base metal must be heated above the melting point of the solder used. Themethod by which the necessary heat is applied among other things depends upon: Nature and type of the joint Melting point of the solder Flux Generally applied soldering methods are iron soldering, torch soldering, electrical soldering,furnace soldering etc. of which we have gone for iron soldering. Components are mounted on onlyone side of the board. In double sided PCBs, the component side is usually opposite to the majorconductor pattern side, unless otherwise dictated by special design requirements. The performance and reliability of solder joints give best result covered with solder andherewith contributing to the actual solder connections. However, lead cutting after soldering isstill common in particular in smaller industries where hand soldering is used. With the soldered PCB, many contaminants can be found which may produce difficulties withthe functioning of the circuit. The problems usually arise at a much later than during the finalfunctioning testing of the board in the factory. Among the contaminants, we can typically find flux,chips of plastics, metals and other constructional materials, plating salts, oil greases,environmental soils and other processing materials. At the end, a cleaning procedure with an appropriate cleaning medium was done. Thefollowing performances are expected from the cleaning procedure:Dissolution or dissolving of organic liquids and solids, Eg. oils, greases, resin, fluxRemoval of plating salts and silicone oilsDisplacing of particulate and other insoluble matters, e.g., chips, dust and lintWireless IR Headset Page 28
    • College of Eng: Munnar Dept. of ECE No severe attacks on boards and components to be cleaned, no alteration of ink or paintnotations and last but not the least, compatibility with healthy environmental working conditions.7. PCB Layout TransmitterReceiverWireless IR Headset Page 29
    • College of Eng: Munnar Dept. of ECE8. List of Components Sl. No COMPONENTS QTY PRICE (Rs) 1 Audio Transformer 1 10 Transistors BC547 1 1 2 BC549 2 1 BD139 1 7 BD140 1 7 3 IR Photo transistor 1 80 4 IR LED 2 2 5 LED 1 1 Resistors 3 22k 1 10k 1 4.7k 3 6 2.2k 1 2.7k 1 100R 1 10R, 1W 1 470R 1 Potentiometer 2 100k 1 7 10k 1 Capacitors 12 2200uF, 16V 1 8 0.1uF 2 0.01uF 2 47pF 1 9 Battery 9V 2 40 Total 155Wireless IR Headset Page 30
    • College of Eng: Munnar Dept.of ECE 9. Result and Inference9.1 RESULT:The IR Cordless headphones were successfully built and a detailed study of theWireless IR Communication was carried out. The range of the system wasincreased by using array of LEDs. Also optical concentrators were used toimprove the power ratings, the amplification and quality of the music received.Diffusers were also used successfully to increase the angular range.9.2 FUTURE WORKIn future we plan to study and work more on the IR systems. The IR systemsprovide a potential for future research work for short range communicationbecause of its inherent advantages. We plan to work on increasing the bit ratetransfer of the IR systems so that they can be used effectively in future forfaster communication. 10. Reference:1. Electronic Devices And Circuit Theory-Robert L.Boylestad,Louis Nashelsky2. Electronic Devices And Circuits-J.B Gupta3. Electronics for You4. http://en.wikipedia.org5. http://www.alldatasheets.com/Wireless IR Headset Page 31