Rabu, 04 Oktober 2017

inverter as a sine energy generating function using direct DC signal and IC 555 to CD4047 AMNIMARJESLOW GOVERNMENT 91220017 LOR EL TRANS SIGNAL EL ENERGY LCLAR 02096010014 XWAM $$ '


                                                   GENERATOR  INVERTER
                                  dasar inverter,dc to ac inverter,inverter dc ke ac,Square Wave Inverter,Square Wave dc to ac Inverter,pengertian dc to ac inverter,teori dc to ac inverter,dasar dc to ac inverter,ilustrasi dc to ac inverter

                                        Basic Concept of Square Wave Inverter
     

inverter as a sine energy generating function using DC direct signal and IC 555 in everyday life not infrequently we want to change the frequency of AC signal as well if power outages and remote area that does not enter AC power source then we use batteries or batteries through or through inverter to turn on load at home or electric machine that works in AC signal (back and forth) examples of machine lamps pump washing machine etc


Inverter is a circuit that serves to change the input voltage direct current (DC) into a voltage output voltage back and forth (AC) a large voltage and the frequency can be adjusted as desired. In industrial applications, inverters are widely used such as the adjustment of AC motor speed, industrial heating, or uniterruptible power supply (UPS). Here is a basic concept of a simple square wave inverter.
The basic concept of Square wave DC to AC inverter basically as in the picture above. If the position S1 and S2 on A, the load L gets a positive voltage, and vice versa if S1 and S2 in B, L load gets positive voltage from different direction. Thus if switching switches S1 and S2 alternately will generate alternating voltages, with amplitude determined by the size of the source, and the frequency is determined by the switching of the switch 
 
   Simple Inverter circuit IC NE555 
 
  


Component Parts List:
R1 = 10K
R2 = 100K
R3 = 100 ohm
R4 = 50K Linear Potensiometer
C1,C2 = 0.1uF
C3 = 0.01uF
C4 = 2700uF
Q1 = TIP41A, NPN, or equivalent transistor
Q2 = TIP42A, PNP, or equivalent transistor
L1 = 1uH
T1 = Filament transformer, your choice
This simple 12VDC to 220VAC inverter circuit produces an AC output at line frequency and voltage. The 555 is configured as a low-frequency oscillator, tunable over the frequency range of 50 to 60 Hz by Frequency potentiometer R4. The 555 feeds its output (amplified by Q1 and Q2) to the input of transformer T1, a reverse-connected filament transformer with the necessary step-up turns ratio. Capacitor C4 and coil L1 filter the input to T1, assuring that it is effectively a sine wave. Adjust the value of T1 to your voltage.
The power output (in watts) is up to you by selecting different components, expecially for the transistor and the transformer.
Input voltage is anywhere from +5V to +15Volt DC, adjust the 2700uF capacitors working voltage accordingly.
Replacement types for Q1 are: TIP41B, TIP41C, NTE196, ECG196, etc. Replacement types for Q2 are: TIP42B, TIP42C, NTE197, ECG197, etc. Please feel free to use another type of similar specs

In this DC To AC Inverter circuit the NE555 IC is set to an astable multivibrator with an output frequency of 50Hz. The astable multivibrator is a multivibrator that has two states but is unstable in one state for a moment and then moves to another, where the astable multifibrator settles for a moment before moving back to its original state. This state of motion in the continuous astable multivibrator output produces a rectangular wave with a very rapid rise time. Since no input signal is required to obtain an output, the astable multivibrator is sometimes called a free running multivibrator.
The output of the NE555 is used to provide input power inverters consisting of NPN transistors and PNP TIP41 and TIP42. The two transistors work in turn, and are called Push Pull Transistors. The effect of this transistor makes the oscillation motion on the transformer causing the movement of alternating current. Then, using the Step Up transformer the magnitude of the voltage on the primer will be amplified (raised) on the secondary part of the transformer, then the 220v AC voltage is formed


                  Hasil gambar untuk inverter ic cd4047


     

Simple Inverter Circuit using IC 555

    Inverter Circuits are very helpful during the power cuts and for portable power source. If the load connected to the inverter circuit is very small means we don’t need pure sine wave inverter or bulk inverter with high power. We can create simple small inverter circuit to handle low power devices.
    Inverter Circuit using IC555
    Inverter circuit using IC 555
    Construction & Working
    The timer IC555 is used as a switching pulse oscillator and it is the main part in this circuit, IC 555 configured as Astable Multivibrator to give continuous switching pulse, two switching transistors TIP41A (NPN) and TIP42A (PNP) drives the transformer T1 according to the pulse input at the base. The transformer T1 is 230V primary to 9V secondary but connected in reverse, So it can react as step up transformer. We can apply +5V to +15V DC bias to this circuit and get 110V to 230V AC with 50Hz to 60Hz frequency but output may not pure sine wave as the PWM inverter output, it gives only pulsated AC.
    The output frequency of this circuit can be varied by varying VR1 resistor.
    IC 555 timer formula
    Use this formula to calculate the output AC supply and frequency, here R2 = R2+VR1 from given circuit. Use heat sink for Transistors to avoid over heat, Use 1 A to 1.5A transformer.

    How Switching Inverter works?

    how inverter works
    Lets consider the transformer with less primary and more secondary winding, for example 230V AC primary to 9V AC secondary used in reverse now less winding side becomes primary and more winding side becomes secondary. DC bias is applied in one terminal and -Ve or ground connected in another pin through switching device, when the switch is ON primary winding gets DC bias, when the switch is OFF primary winding disconnected from the DC bias, by the way 50Hz switching pulse drives the switching device so the winding gets discrete DC bias, magnetic flux produced from the primary winding induces more coil secondary so the high voltage EMF induced at secondary.
 

    Selasa, 03 Oktober 2017

    audio and video electronic schematic and circuit Inter dimension human AMNIMARJESLOW GOVERNMENT 91220017 LOR LINTER DIMENSIONS LCLAR ELMOVE SPACE ELFORM 02096010014 XWAM $$ '

       


                              
                                     
          humans as one of the users of life on earth have taste equipment that is categorized in two forms: 20-20Khz audio form and visual form in the order of GHz upwards; the position of man on earth is tangible to the body; this embodiment is manifested in the field of electronics as sound waves and waveforms; humans move in space and time within the two boundaries of waves: sounds and shapes that move in space and time; human image in dimension is a picture of various kinds of wave form that exist in the earth while outside the solar system there are many other forms of wave users according to the situation conditions of tolerance and the range of life form inter dimensional shape; schematic and electronic audio and video circuits are human advocates across the distance and time as well as the need for rapid information for humans as part of the dimension itself

                         
                         Hasil gambar untuk audio and video electronic schematic and circuit 
                                              Human to communication electronic


                                            Multi-Channel Surround Sound Systems




    Multi-channel Audio

    Multi-channel audio systems are widely used in modern sound devices. The term “multi-channel audio” means that, the audio system can be capable of handling multiple audio channels (usually called audio tracks) to rebuild the sound on a multi-speaker setup.
    Usually two digits separated by a decimal (.) point (2.1, 4.1, 5.1, 6.1, 7.1, etc.) are used to classify the various kinds of speaker set-up, this number basically depending on how many audio tracks are used. Some audio systems only have a single channel (called monophonic sound or single channel audio) or two channels (stereophonic sound or 2.0 channel sound)
    The first digit shows the number of primary channels (called satellite units), each of which are reproduced on a single speaker (these speakers are capable for handling the frequency range from 100Hz to 22Khz), while the second (decimal digit) refers to the presence of LFE (Low Frequency Effect), which is reproduced on a subwoofer.
    Stereo Setup
    Stereo Setup
     
    Surround Sound System
    Surround sound is a term used to describe a type of audio output in which the sound appears to “surround the listener” by 360 degrees –  that is, the technology gives the impression that sounds are coming from all possible directions.
    Surround sound is a way to provide a more realistic and engaging experience. All technical aspects aside, surround sound works because multiple audio channels are received through speakers that are positioned at various locations in the room. This is programmed into the source and the sound tracks are decoded when the source is played.

    The Surround Sound Setup

    The main component of a surround sound setup is a multi channel or digital coaxial/optical audio decoder. Using a DVD/HVD movie, the audio is encoded when the DVD/HVD is produced by packing multiple audio channels into a compressed format for storage.  When you play the DVD movie, your DVD player or A/V receiver (commonly called a home theatre receiver) decodes the encoding scheme (i.e. Dolby Pro Logic II or DTS for example). Decoding capabilities of an A/V receiver are built in. Most A/V receivers today can decode Dolby Digital and Digital Theater Sound (DTS) (DTS channel usually a coaxial or optical audio channel. It is a single channel digital pin that multiplexed with several channel. The decoder decodes the DTS sound from single channel to multiple channels), while higher-end receivers may also include DTS-ES or THX Surround.

    Multi-channel Surround Sound Systems

    • 5.1 Surround Sound Systems
    5.1 Surround sound systems are one of the widely used surround sound setup in home theater systems. Usually- Dolby Digital and DTS encoded in a DVD are 5.1 channel audio formats.  5.1 surround sound technologies produces five channels of sound in the left, right, center, left-surround and right-surround positions. These five channels are the minimum required to produce 5.1 surround sounds. The dot decimal (.1) represents the channel for LFE (low frequency effects), which is usually sent to a subwoofer. Other 5 units are capable for handling the frequency range except low frequency(Usually they are capable of  handling  the frequency range from 100Hz to 22Khz and no need for any other higher frequency component like tweeter). These five units are usually called satellite units. The arrangements of a 5.1 surround sound setup shown in the picture below.
    5.1 surround sound
    5.1 surround sound
    • 6.1 Surround Sound Systems
    6.1 multichannel sound technologies is the advanced version of 5.1 surround sound technology. 6.1 technology uses the same set-up as a 5.1 system, but it has the addition of a sixth speaker that takes the rear-center surround position (or back surround position) to provide a more 3-D realistic surround sound effect. 6.1 surround sound uses extended surround sound formats, such as THX Surround EX, Dolby digital ES and DTS-ES. The 6.1 channel surround sound setup is shown in the picture.
    6.1 Surround Sound Systems
    6.1 Surround Sound Systems
     
    • 7.1 Surround Sound Systems
    7.1 channel audio systems is the modified version of 6.1 channel and also provide more realistic experience than 6.1 setup. In this system splits the single rear-center speaker into individual left- and right-rear surround. These systems are not a true discrete 7.1 channel system as 7.1 formats don’t currently exist. In a true discrete 6.1 surround system, the back center surround position is separate from the surround left (SL) and surround right (SR) positions. A 7.1 channel system uses   matrixes extended surround where the left-back and right-back (rear-center surround) multichannel are blended together and stored. The structure of a 7.1 setup is given in the Picture below.
    7.1 Surround Sound Systems
    7.1 Surround Sound Systems
     
    • 10.2 Surround Sound Systems
    10.2 channel surround is the future surround sound technology that Developed by THX corporation, the name itself, 10.2 is an advanced version of 5.1 technology but 10.2 is twice as good as 5.1. In a 10.2 surround sound 14 channels are used. This includes five front speakers, five surround channels, two LFE and two heights, plus the addition of a second sub-woofer. This technology is considered as future TRUEHD.The Diagram of a 10.2 TrueHD setup is shown below.
    10.2 Surround Sound Systems
    10.2 Surround Sound Systems
     
    So far we talked about latest sound systems and the technologies behind. Often this type of technology is found in high end sound bar home theater speakers. Now lets take a look at surround sound formats.

    Common Surround Sound Formats

    • Dolby Surround
    Dolby surround is the consumer version of Dolby analog film decoding. This technology was introduced in 1982 which is capable of handling stereo and hi-fi audio. This audio format is commonly found in VHS and stereo hi-fi systems. In this surround format, the multichannel audio multiplexed into two audio channels (left and right channels)and decoded by using Dolby pro logic decoder ,then it recreates the four channel Dolby surround experience.
    • Dolby Digital
    Dolby digital is the standard surround sound format which provides high quality and highly realistic experience. This audio is developed by Dolby Corporation. Dolby digital audio is also known as Audio Codec-3(AC3). This audio format provides a high quality 5.1 surround experience. Normally this audio format used for the creation of DVD and Blue ray movies. Some video games and play station units are also available in this surround sound format.
    • Dolby Digital EX
    Dolby Digital EX is the modified version of Dolby digital audio. This extended format contains an additional surround sound unit (called center surround channel) for creation of more realistic experience. Dolby digital EX needs Dolby EX decoder. This surround effect also support 5.1, 6.1, 7.1 channel playback. This audio format usually available on DVD, HVD, blue ray, play stations, DTV broadcasts, etc .
    • Dolby Pro Logic IIx
    Dolby Pro Logic IIx is an advanced version of Dolby Digital EX technology. By using this technology, we can expand the 5.1 channel Dolby surround system into 6.1, 7.1, 10.2 channel surround. The Dolby digital prologic usually use three modes for listening (movie, music and game modes).This surround technology provide more rich  and depth surround sound effect   than conventional surround sound system. This audio is normally encoded in DVD, HVD, BRD HDTV, play stations,  etc.
    • Dolby True HD
    Dolby True HD surround sound is an advanced version surround sound that provides incredible High Definition experience to the listener. This surround sound format is also known as next generation surround sound format. Dolby True HD format only support HD based media and this technology provides 100% lossless audio encoding, bit rate up to 18Mbps and support 8.1 or higher channel with 24 bit/96Khz audio. This format also supports HDMI. Normally BRD and HVD are used for encoding this true surround.
    • DTS
    DTS is another digital surround format developed by DTS Corporation. It is a Multichannel digital surround format widely used in both consumer and commercial applications. The DTS audio system must have a DTS decoder and optical/coaxial digital decoder for decoding this surround. DTS is normally available in a single channel multiplexed format (2.1 to 11.1 channel surround sounds can be multiplexed into a single optical digital or coaxial output format).DTS format  is also available on DVD,HVD and BRD’s.
    • DTS-ES
    DTS-ES (digital theater sound –Extended Surround) is an advanced version of normal DTS. This surround system is usually available in 6.1 or higher channels. This provides us with more true digital experience than conventional DTS system. This unit also requires an additional DTS-ES decoder for the creation of a back-surround effect. The system is compatible with all current extended surround formats and an auxiliary surround channel is also provided for other applications.
    • TruSurround-XT
    TruSurround XT is the next generation of SRS TruSurround. The main advantage of this surround system is that it’s capable of handling 2.1 channel surround to 10.2 channel surround (support head phone media too).Audio is encoded in multiplexed format. and require DTS true surround decoder. This audio usually encoded in BRD’s and HVD’s

                                                             

    What is an Amplifier?

    We see amplifiers in almost all the electronic equipments around us. Though we usually relate them to stereo equipments they are also found in TV’s, computers, MP3 players and so on. All these devices have a speaker which is used to reproduce the original sound 
     
    Therefore an amplifier can be device that is used to change the amplitude of a signal. This increase in amplitude can be calculated by a factor known as transfer function, which is actually the ratio between the output and input given to the amplifier. The magnitude of this transfer function is called the gain of the amplifier.
    When referring to electronic circuits, the signal used in an amplifier is mostly either current or voltage. A sound is said to be amplified, when the device makes the sound louder than usual with the same clarity.  The amplifiers are divided according to the source that is supposed to be amplified, the driving device, the frequency of the signal and the type of signal.
    The source can be an electric guitar and the driving device can be a head-phone amplifier. The frequency of the signal is defined in its range like audio, IF, RF, VHF and so on. The type of signal refers to two parameters – inverting and non-inverting. Another major classification is in the device that is used to design the amplifiers. The most commonly used devices are Field-Effect transistors, and valve.

    Role of an Amplifier

    The amplification process is similar to the way in which the human receives the sound from our surrounding. When a voice is made it starts to vibrate in the atmosphere, thus beginning to move the air particles in hits. This causes more air particles to be hit and thus creates a vibrating pulse in the air. When it reaches our ears, they will be received as an air pressure and will be converted to the appropriate signals by our brain. We can define the working of amplifiers in the same sense.
    Sound waves will be sent through a microphone. The diaphragm of the microphone moves it in a peculiar motion and converts it into electrical signals. This fluctuating electric signal will be represented as compressions and rarefactions of the original sound.
    The electric signal will be encoded by the recorder and stored in a tape, CD and so on.
    A player for the particular recorded signal interprets the electrical signal and is given to the speaker which turns the cone back and forth. The same variation in pressure will be reproduced by the speaker as it was in the beginning. The basic block diagram of an amlifier is given below.
     
    How Amplifiers Work
    How Amplifiers Work
    From the above method you must have understood that translators play a major role in the working. That is, from a sound signal to electrical signal and vice versa.  The main translators here are the microphone and the speaker. The microphone diaphragm has to be designed in a careful manner so as to make it highly sensitive to even the smallest pressure variations the sound produced. Thus, its design will be slim in nature and will produce a small electric current as it can move only a very small distance. The design of the other translator, the speaker is a little more difficult. The cone of it has to move backwards and frontwards and for this you need its input signal to be high so that it maintains a large current so as to keep the manner of charge fluctuation constant. This role can only be done by the amplifier. That is, the weak electric signal from the microphone has to be amplified by the amplifier before producing it to the cone of the speaker.

    Basic Elements of an Amplifier

    Though the basic explanation of an amplifier was explained above, the making of it is far more complex. We know that there are two signals generated during the process. They are the input signal and the output signal.  The input signal is completely different from the output signal. Thus we can consider the generation of these signals as two separate electronic circuits. The input signal circuit is the signal recorded in a tape. It is designed as to modify the output signal circuit with its load. This is done by changing the resistance to the output circuit so as to make new voltage fluctuations of the original sound signal. But this load is very high when compared to the original sound. So, the sound must be first boosted with the help of a pre-amplifier. This will help in making a much more strong output signal as the input to the power amplifier. There is no much difference in the working of pre-amplifier compared to amplifier. A change in resistance is given by the input circuit to the output circuit, through the power supply. The design and number of pre-amplifiers in an amplifier varies according to the manufacturer.
    The output circuit is generated by the power supply of the amplifier. The power supply helps in drawing the required energy from an external battery or power outlet.
    Mostly the main power supply will be in ac form. It will be changed to dc and then given to the amplifier. The power supply also helps in making an uninterrupted signal by making the current smoother. This load will then be given to the cone of the speaker.
    For all this to work together a combination of many electronic circuits will be needed. The designer has to make sure that each and every part of the audio signal is correctly represented.

    Basic Components of an Amplifier

    One of the most basic components of an amplifier circuit is the transistor. The materials of the components used for an amplifier, must be able to conduct electric current in a varying manner. That is why the transistor is often used. The working of an N-P-N transistor is given below.
    We know that N-type semiconductors carry electrons and P-type semiconductors carry holes. In an N-P-N transistor, the P-type semiconductor will be kept in between two N-type semiconductors. This is illustrated below.
     
    Working of transistor in an Amplifier
    Working of transistor in an Amplifier
    From the left, the first N-type semiconductor is called the emitter. The middle P-type semiconductor is called the base and the end N-type semiconductor is called the collector. The output circuit which is supposed to drive the speaker is connected between the collector and the emitter ends. The input circuit will be connected between the emitter and the base terminals.
    The N-type electrons and the P-type holes start to get attracted. But, the number of free electrons is way higher than the number of holes. This will result in the combination and the filling up of holes. As a result of this combination depletion holes will be created at the boundaries of the N-type and P-type. This will cause the semiconductor material to switch back to its insulating state. Thus the charges get accumulated with no other place to go. Thus the depletion zones get heavier. Thus the movement of charge from the emitter to the collector reduces, even if there is a huge difference in voltage between the two electrodes. This situation has to be overcome.
    For the problem to be solved, a high voltage supply must be given to the base terminal. As the input current controls the base terminal its flow will cause the base terminal to have a higher positive charge and thus attracts the electrons from the emitter terminal. This in turn reduces some holes and thus reduces the size of the depletion region. This will help in an easier movement of the charges from the emitter to the collector. All these actions cause a natural increase in the conductivity of the transistor.
    In short, the voltage given to the base terminal decides the amount of conductivity of the transistor and the size of the depletion region. Here is the diagram of the working of a transistor as an amplifier.
     
    Working of Amplifiers-Step 1
    Working of Amplifiers-Step 1
    Working of Amplifiers-Step 2
    Working of Amplifiers-Step 2
    Working of Amplifiers-Step 3
    Working of Amplifiers-Step 3
    Working of Amplifiers-Step 4
    Working of Amplifiers-Step 4
    The above shown figure is just one stage of an amplifier. In order to get the sound signal boosted up in the form of an electrical signal, there has to be a lot more stages. Anyhow, the final stage of amplification will be the speaker driver.
    The output power produced in an amplifier depends on the necessity of its use. If it is used in some huge hall, the amplifier must produce an output power of at least a thousand watts. On the other hand, if it is used in a home theatre stereo amplifier, it may just need a few hundreds of watts as the output power. If it is in a speaker phone, the output will be the least of half a watt.
    Whatever the power may be, an amplifier must produce the least amount of distortion as possible. On the same time, the boosting of the sound must be high in the final driving stage and a high replica of the original sound must be produced. For these characteristics to occur accurately, the parameters like power rating, input impedance, output impedance and also fidelity must be varied accurately.
    By the concept of amplifiers we always think of amplifying sound. But, the same process can be done for amplifying radio signals and video signals as well.
                                                             
      power supply for motional feed back amplifier 
     
     
     
     
    A preamplifier operating on a single supply and suitable for use with high impedance type crystal pickups is shown here.The circuit is basically a non-inverting AC amplifier in which the gain is dependent on the feedback resistor R4.The smaller is the R4,the lower will be the gain.The low frequency roll off characteristics are decided by C3.
    Voltage divider network comprising of R1,R2 and R5 provide a DC bias of about half the supply voltage R5 and C2 from a supply line filter to reduce the hum level as well as to reduce the chances “growling” when the preamplifier is operated from common power supply.
    Circuit diagram with Parts list.
    crystal-pickup-_preamplifier-circuit.JPG
    Notes.
    • Assemble the circuit on a good quality PCB or common board.
    • Use mono sockets for connection input and output.
    • The IC1 should be mounted on a holder.
    • The supply voltage can be up to 24V DC .I prefer 12V DC.
                                                     waveforms on GPS
     
     

    Introduction

    Global Positioning System (GPS), has found itself as a gateway for the cutting edge technology for this century. It was designed and developed by USA during the late 19th century after recognizing its importance in military applications. Due to its accurate positioning capabilities and navigation and timing services it was later open for civilian uses as well.
     

    Working of GPS

    A GPS system consists of
    •             A GPS enabled product like a GPS phone or a GPS Receiver
    •             A plan for the extent of GPS data. Some plans provide all information’s about the locality you are in. While other plans are used only to track your position.
    •             A service plan to provide the phone’s location.
    •             Satellites around the Earth which provides your exact position using “Trilateration”.
    Basically a GPS receiver comprises of a receiver, and the help of the 27 earth-orbiting satellites, which rotates in the medium earth orbit. Out of these 27 satellites only 24 are in use and the rest is kept as backup for any failed satellite. Suppose you want to know your exact position using GPS, the receiver determines the exact locations of a minimum of 3 satellites above you and also your position with respect to the satellite. Then a method called “Trilateration” is used to find your exact location. These satellites make two complete rotations around the Earth everyday. So, a minimum of 4 satellites are assured to receive the GPS signals. 
     

    Trilateration Method

    When the receiver sends the signal to locate itself, it finds out three nearest satellites of known positions. The receiver then calculates the distance between one satellite and the receiver. If the distance is “X”, then it draws an imaginary sphere with “X” as the radius from the receiver to the satellite and also the satellite as the centre. Similarly, the same process is repeated for the next two satellites. Thus three spheres are drawn with just two possible positions. Out of these one point will be in space and the other will be the location of the receiver. Thus the exact position of the receiver is found out. Usually the receivers try to locate more than four satellites so as to increase the accuracy of the location. The Earth is made as the fourth sphere so that two points converge with the imaginary spheres of the other three satellites. This method is commonly called 3-D Trilateration method.
    Just as phones use radio signals, the satellites also use low power, high frequency radio signals so as to compute the location of it with respect to the receiver. They are also used to compute the distance between the device and the satellites. The distance is calculated by knowing the time it took to reach the receiver.
    Trilateration Method
    Trilateration Method

    Methods for calculating Distance and Location of the Satellite and Receiver

    As explained earlier, to find the distance and locations of the satellite and receiver, the parameter time is computed.
    At a time ‘t’, a pseudo-random code is transmitted from the satellite. At the same time the receiver also starts running the same pseudo random digital pattern. But there will be a time-lag, when the signals from the satellite reaches the receiver. The signal’s travel time will be equal to the length of this delay. When this time is multiplied by the speed of light, the distance between the satellite and receiver is obtained.
    For this method to work properly, accurate clocks that can read a small time as nanosecond is required in both the receiver and satellite. But these type of atomic clocks are rather expensive and so cannot be bought by all types of consumers.
    The only problem to this solution is to use a quartz clock and an atomic clock. The atomic clock will be mounted on the satellite. The quartz clock will be used in the GPS. he speciality of this quartz clock is that it constantly resets. Thus, when multiple signals from multiple satellites reaches the GPS the clock in the GPS will gauge its own inaccuracy. Thus only one current value will be used by the receiver, which causes the incoming signals to contradict at a single point in space. That time value is held by the atomic clocks in all satellites. Thus the time value of the receiver clock and satellite clock will be the same. Though this method is not as accurate as keeping two atomic clocks you will get almost 99% accuracy. Thus you get the distance between the satellite and receiver.
    Getting the location of both the satellite and receiver is easier. This is because the satellites travel at much predictable orbits. So, the GPS has an “ALMANAC” which stores the data referring to where a particular satellite is positioned at a particular time. Though the positions change with respect to the pull of the moon and sun, this is monitored by the Department of defence and is updated to the GPS receivers.

    Differential Global Positioning System (GPS)

          
    Though all these methods are used there may still be an inaccuracy of (5-10) meters. This can be reduced only by upgrading the satellites. This is because, the radio signals from these satellites will be affected by the ionosphere. But, this accuracy (5-10)meters was obtained only because of Differential GPS.
    Differential GPS is essential because of the following factors
    • Though the radio signals are known to have the speed of light, it will be reduced as it goes through the ionosphere and the troposphere.
    • The radio-signal delay can also depend on your position.
    • Bad data from the satellite itself.
    Using Differential GPS all these errors can be corrected. For this a stationary receiver is introduced. This receivers location is also known and is used to gauge the inaccurate data. This corrected signal is then provided to all the other Differential GPS equipped receivers and thus the signal is corrected.
    Differential GPS (DGPS) helps correct these errors. The basic idea is to gauge GPS inaccuracy at a stationary receiver station with a known location. Since the DGPS hardware at the station already knows its own position, it can easily calculate its receiver’s inaccuracy. The station then broadcasts a radio signal to all DGPS-equipped receivers in the area, providing signal correction information for that area. In general, access to this correction information makes DGPS receivers much more accurate than ordinary receivers.
    Differential GPS
    Differential GPS
    The raw data output from the GPS is mostly in latitudes and longitudes. But this is further converted into map data with the help of map files stored in the memory of GPS.

    Advantages of GPS

    Apart from our location GPS also helps us to find the distance we have travelled from one point to your current position. It can also tell the time you took to reach that distance. It can also act as a speedometer, and display your average speed.
    The size of the circuitory of GPS receivers are very small and so can be taken to any place.

    Future of GPS

    Though the satellites are capable of providing the GPS service for all countries, most countries prefer to stay independent. Most countries are on the verge of launching their own satellites. India is launching a satellite called IRNSS by 2012. Russia has its own satellite called GLONASS. Europe will launch their famous Galileo system by 2013. This is a clear indication that GPS has been accepted all around the world. 
     
     
                                                  Working of DVD Player 
     

    Parts of a DVD Player

    The DVD player is not only used for playing the data present in a DVD, but also to write the content onto a DVD. To know this process it is essential to know the basics of a DVD.
    As told earlier, DVD’s have pits and bumps in their track which holds the information that is required to be played. This information can be a video, audio or a mixture of both. When a DVD player reads this data, the smooth surface is usually taken as a ‘0’ and pits are usually taken as a ‘1’.
    In order to create as well as read these data, a red laser with a wavelength of 600 nanometers. This is about 180 nanometers lesser than the wavelength of CD, which enables it to have a higher density of pits. Thus the size of the DVD increases. Though the first released DVD’s were only a single layer, 2 layered discs have been released nowadays. Single layer can hold only up to 4.7 GB of data while double layered DVD can hold up to 17 GB of data. The DVD design is similar to a CD a reflective silver layer in the centre and a semi-transparent gold layer on the top of it.
    A DVD does not have the capacity to hold hi-def movies. So a MPEG-2 compression system is introduced. As this is used, the data will be encoded onto the DVD as elements of the changing frames. This has to be successfully decoded and decompressed by the DVD player.
    Thus the parts of a DVD player are

    1. Disc drive mechanism

    The disc drive mechanism consists of a motor that will drive the disc in a circular motion. The mechanism will also have a disc feed – a loading tray that is used to accept the DVD from the user. Thus the entire disc drive is basically a spindle that holds the disc and a motor that is used to circle the disc. The spindle is held in its position with the help of small gears and belts that are attached internally. Some players have an automatic feed system in which, there will be no tray. Instead the disc will be automatically recognized after inserting a part of it.

    2. Optical system

    The optical system mainly consists of the laser beam, lenses, prism, photo-detectors and also mirrors. The output of this mechanism will be the input for the disc-drive. The laser beam will be a red laser diode which works at a wavelength of 600 nanometers. The optical system also requires a motor to drive it. The laser system and photo-detector is placed together on a single platform. The laser diode as well as other diodes is made with the help of glass.

    3. Printed Circuit Board

    The PCB is similar to that of any other electronic circuits. The electronic outline must be drawn on the PCB with the correct placement of all the IC’s resistors as well as capacitors. After the outline has been drawn, the components must be soldered to their respective places. All this must be done in a very clean environment so that the board does not become contaminated by dust. All the primary components of the electronic circuit should be made out of silicon.

    Working of DVD Player

    Take a look at the basic block diagram of how a DVD player works.

    Block Diagram of DVD Player
    Block Diagram of DVD Player
    DVD Player-Block Diagram
    DVD Player-Block Diagram
    The pits and bumps in the DVD are hit by the laser from the optical mechanism of the DVD player. This laser will be reflected differently according to the change of pits and bumps. Though the laser hits a single spot, the DVD moves in a circular motion so that the entire area is covered. Mirrors are also used to change the spot.
    These reflected laser beams are then collected by a light sensor (eg. photo-detector) which converts the different signals into a binary code. In short, the optical system helps in converting the data from the DVD into a digital code.
    The binary signal is then sent to a Digital to Analog converter which will be setup in the PCB. Thus the corresponding analog signal of the DVD is obtained. The PCB also has amplifiers which amplify the signal and then sends it to the graphic and audio systems of the computer/TV. Thus, the corresponding audio/video signal is obtained. The basic working of a DVD player is shown below.
    Working of DVD Player
    Working of DVD Player

    Assembling a DVD Player

    As the different parts of the DVD player are all complicated electronic circuits, they are all manufactured by different people. They are later brought together and assembled at one place. During the assembling, the PCB will be connected to the rest of the machine and all the components are placed in the right positions. The whole package is then placed inside an outer plastic housing with a front panel with the buttons for various operations. This DVD player is then sent to a packaging station where they are placed safely inside boxes along with the respective power cords, operating manual, installing disks and so on. They are then taken by the distributors to various shops and then sold to customers.

    Cautions while assembling a DVD Player

    A DVD player will only be satisfactory to a customer only if it has a high performance. The degree of quality varies according to the flaws in the assembling process. Thorough inspections in both the visual as well as electrical divisions must be done most of the time. Flaws in the positioning of the different components can also cause the player to become faulty. After manufacturing the DVD also, the working performance is tested. To see the adverse effects of these players in different temperatures, the tests will be carried out in excessive heat as well as humidity. Since most of the parts of a DVD player is made by suppliers, they rely on other companies for good quality. The DVD assemblers will set a minimum standard for the supplies that they buy from outside. This specification must be met by them. The lenses and mirrors should be highly polished and cleaned before placing them.


                                         Working of Digital Versatile Disc (DVD) 
     

    Working of DVD
    Working of DVD
    What is a DVD?

    A Digital Versatile Disc/Digital Video Disc [DVD], is an optical disc storage medium like a compact disc [CD], but with greater data storage and high quality audio and video formats. The clarity, when comparison with a CD is almost six times higher.
    A DVD can be termed in different ways according to their applications.
    • If they are used for storing data that can only be used to read and cannot be written, it is called a DVD-ROM, where ‘ROM’ stands for ‘Read Only Memory’.
    • If a DVD is used to record data [audio, video or a combination of both] and then work as a DVD-ROM, it is termed as DVD-R, where ‘R’ stands for ‘recordable’. In a DVD-R, the data is can be inputted only once.
    • If a DVD can be read and again be written over it, it will be called a DVD-RW, where ‘RW’ stands for’re-writable’. The data in a DVD-RW can be erased and re-written and also can be written on the remaining space in a DVD.
    TAKE A LOOK : WORKING OF DVD PLAYER

    Specifications of DVD

    • DVD has a total capacity of 4.7 GB.
    • It can run a high-quality video for a maximum of 133 minutes.
    • DVD has a video compression ratio of 40:1 with an MPEG-2 compression.
    • DVD can use subtitles in almost 32 languages with a soundtrack in 8 languages.
    • Wavelength of a DVD is almost 650 nanometres laser diode light.
    • DVD’s can be written at a speed of almost 18x to 20x. [1x = 1318 Kbps].

    Advantages of DVD

    • The picture quality is far better than a CD.
    • Most DVD’s have Dolby Digital or DTS. Thus the clarity of the sound will be nearly equal to that in a theatre.
    • Though the technology of CD is gone, they were made with a compatibility with audio CD’s.
    • The DVD has a special on-screen index quality which helps you to take a closer look at important scenes of a movie which was earlier indexed by the publisher of the movie. This method is not common.
    • Unlike a CD player, the DVD player is specialised in taking you to the correct part which you prefer to see. Thus, there will be no need of fast-forwarding.
    • The format of a DVD can be changed according to the type of view you need. It can be a standard TV size format and also a wide-screen TV format.

    Structure of a DVD

    The manufacturing methods and materials used for manufacture as the same as that of a CD. The DVD has a number of layers of plastic pieces with a total thickness of 1.2 millimetres. Clear poly-carbonate plastic is basically used for making these layers. Apart from the original plastic, there will be some impressions of microscopic bumps on the layers. Naturally, with the formation of bumps, there will also be pits. Thus a long spiral of data can be created which is together called a track. The track in any DVD is only 740 nanometers thick. There are several tracks in a DVD. Thus the bumps will be smaller than the track with a width of 320 nanometers, a length of 400 nanometers a height of and 120 nanometers. Although the bumps are often mistaken for pits, it should be noted that they only appear as pits when seen from the aluminium side.  They are actually bumps when read from the laser side.
    DVD-Pits
    DVD-Pits
    At the inner layers of the plastic, the bumps and pits are covered with the help of a reflective aluminium layer. But their outer layers are protected with the help of a very thin layer of semi-reflective gold. Thus the lasers that hit the DVD are made to completely focus on the outer and also into the inner layers. On top of all these layers a coating of lacquer is also put. The lacquer is strongly bonded with the help of infrared light.
    There are DVD discs which are single-sided as well as double-sided. For the former, the outer label is silk-screened onto the side that is not readable. For the latter there are no labels except at the area which is not readable near the middle hole.
    In the case of DVD’s that are writable, each track in the DVD is spiral and has data stored in it. These tracks also have a unique direction. For single-sided discs, the circling will be from the inside to the outside. Take a look at the diagrams illustrated below.
    DVD structure
    DVD structure
    Thus, it is clear why DVD’s are capable of storing more data than a CD. The high density of tracks and smaller size of the pits and bumps is the main reason. In a CD, a lot of valuable space is simply wasted in codes, so as to avoid errors in the information. These codes are actually a repetition of the information that is already present in the disc. This shows that the method is not only efficient, but a wastage of storage space as well. But DVD’s does not need such error correction codes.
    TAKE A LOOK : WORKING OF DVD PLAYER

    DVD Video Format

    It must be noted that a movie video can never be stored in a DVD without being compressed. The movies are usually compresses with the help of MPEG-2 format, which is accepted internationally. Though the coding is done to compress the video, it also has to be decoded, which is actually done by the DVD.
    Decrease in Data size using MPEG-2 Format
    When a movie is being filmed, they use either a PAL format or a NTSC format. These formats are distinguished according to the number of frame rates that are displayed on a movie screen for a particular second. For NTSC format the frame rate is 30 and for NTSC the frame rate is 50. Thus, it is clear that there will be a difference in the resolution as well. Thus the MPEG-2 format must be compatible to both the above said formats.
    While using an MPEG format, each frame is carefully studied by the compressing file and a possible solution of encoding is finally decided. There are mainly three ways of encoding a file.
    1. One method is called the intra-frame format. This format contains all the image data for that particular frame. This type of coding provides lesser compression than the other two.
    2. The second method is the predicted frame format. The most recently displayed frame [either intra-frame or predicted frame] will be shown to the DVD player and will be told to predict the frame based on it.
    3. The third method is called bi-directional frame, in which a method of interpolation is carried out in such a way that the exact position and colour of each pixel is given from the nearest frames. For this frame the help of the other two frames are needed.

    DVD Audio Format

    The audio and video formats in a DVD are completely different. Audio DVD discs are not much in sale because, to play such a disc you will need a 192 kHz/24-bit digital-to-analog converter (DAC) compatible DVD player. This is rarely sold. Our usual DVD players have only a 96 kHz/24-bit DAC.
    Though an audio DVD is not as perfect as the original sound, it is far better than the sound from an audio CD. Whether it is a DVD or an audio CD, each bit is represented by a digital response from the DAC according to the voltage level it needs to output. As the sound is sampled at different frequencies, it is sure to lose small pieces of data and hence the difference.
    To get the best sound from an audio DVD, you will have to use a 5.1 home theatre along with a Dolby digital decider implanted receiver.
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