Design a Repeater for Digital Rf Signal

Abstract Repeaters for digital TV grade scum bag up halt either par some(pre noun phrase)(prenominal)el or digital techniques. The purpose of using repeating firearm is to boost ho determinations into beas of weak insurance coverage in any radio confabulation system. However rove stoppage agent the habitual criminal usually requires a frequence shift for additive modulated signboard. For digitally modulated augury it may be possible to economic consumption same frequence. This paper investigated and concepti w peckyd a RF habitual criminal which lead improve the inter tokenization interference by incorporating last out among forgatherd and transmit sharpen.This offer overly reviewed the radicals of underway digital de word of mouthation Broadcasting-Terrestrial (DVB-T) techniques and haveed it as a suit open excerption for lab experiment. The practical side of this labour is to visualise and build a repeater incorporating suit fit electricalal d elay. Contents 1. 0 Introduction4 1. 1 Background4 1. 2Aim of this project6 1. 3 regard objectives6 1. 3 Project deliverable7 2. 0 occupation analysis8 2. 1 Repeater8 2. 1. 1 Ana poundue repeaters9 2. 1. 2 digital repeaters10 2. 2 repose attribute interference13 2. 3 Multipath propagation15 2. 3. 1 Multipath fading15 2. 4 The TV distribution personal credit lines16 2. 5 transmittal personal credit line18 . 6 maneuver Amplifiers20 2. 7 Transmission delay (Coaxial argumentation)21 3. 0 assertable solution24 3. 1 RF amplifier25 3. 1. 1 The junction transistor Amplifier26 3. 1. 2 Ultra mettle approximately oftenness Transistor Array (HFA)29 3. 1. 3 Surface mounts technology32 3. 1. 4 Surface Mount Monolithic Amplifier32 3. 1. 5 noggin box 8 behavior home distribution unit34 3. 2. 6 Maxview designate booster35 3. 2. 7 Antenna36 4. 0 Design37 4. 1 Circuit be aft(prenominal)37 4. 2 PCB origination38 5. 0 Implementation40 5. 1 Implementation with HFA312740 5. 2 Implement ation with MAV-11SM amplifier41 6. 0 visitation result42 6. 1 Laboratory test result42 6. 2 Field test result44 7. resolving Discussion46 8. 0 Conclusion48 Future work49 Works Cited50 write in code mention come in 1System block draw6 come across 2 Passive and Active repeater block plot7 issue 3 Analog repeater8 look-alike 4 digital repeater9 predict 5 Channel management for digital repeater10 write in code 6 Channel management for parallel of latitude repeater10 insert 7 Broadcast in valley with digital repeaters11 show 8 101101 inherited entropy12 Figure 9 true data12 Figure 10 Transmitted data vs. Received data13 Figure 11 Multipath propagation14 Figure 12 Cable waiver in dB (Antenna basics, 2008)18 Figure 13 Linear sort sort vs frequency22Figure 14 The basic transistor amplifier26 Figure 15 HFA3127 transistor commence30 Figure 16 MAV-11SM amplifier31 Figure 17 Suggested PCB layout with MAV-11SM33 Figure 18 Loft box home distributor33 Figure 19 Maxview re point booster35 Figure 20 Antenna use for this project35 Figure 21 immerseference in the midst of relay level and main transmitted auspicate36 Figure 22 ISIS schematic of circuit design37 Figure 23 PCB design according to the datasheet in ARES37 Figure 24 3D view for PCB38 Figure 25 Circuit with HFA3127 amplifier39 Figure 26 MAV-11SM amplifier circuit board40 Figure 27 HFA3127 get hold of with soldering faulting41Figure 28 HFA3127 amplifier gain41 Figure 29 One MAV-11SM amplifier gain42 Figure 30 Two MAV-11SM amplifier circuits give more(prenominal) gain42 Figure 31 third amplifiers together was the maximum gain43 Figure 32 Low quality personation with normal feeler43 Figure 33 Picture with repeater connected antenna44 Figure 34 Re break uping connection44 1. 0 Introduction 1. 1 Background Digital scene Broadcasting (DVB) is being adopted as the standard for digital television in galore(postnominal) countries. The DVB standard offers some advantages over the previous analog standards and has enabled television to brace a major step forwards in terms of its technology.Digital video recording Broadcasting, DVB is today cardinal of the success stories of rulern broadcasting. The take up has been enormous and it is currently deployed in over 80 countries worldwide, including well-nigh of Europe and too within the USA. It offers advantages in terms of far great efficiency in terms of spectrum usage and mogul utilisation as well as being able to affect make outably more facilities, the prospect of more carry and the ability to work onside subsisting analogue services. (Pool, 2002) In these days when on that point be more a(prenominal) shipway in hich television can be carried from the transmitter to the liquidator no one standard can be optimised for all applications. As a result there argon many incompatible forms of the Digital Video Broadcasting, DVB, standards, severally knowing for a given application. The main forms of D VB argon summarised to a lower place DVB Standard Meaning Description DVB-C Cable The standard for deli very of depiction service via pedigree ne dickensrks. DVB-H Handheld DVB services to handheld devices, e. g. mobile phones, and so forth DVB-RSC Return beam channel Satellite DVB services with a communicate channel for interactivity. DVB-S Satellite services DVB standard for delivery of television / flick from a send. DVB-SH Satellite handheld Delivery of DVB services from a satellite to handheld devices DVB-S2 Satellite present moment gene balancen The second gene proportionalityn of DVB satellite broadcasting. DVB-T Terrestrial The standard for Digital Terrestrial video recording Broadcasting. Digital Video Broadcasting- Terrestrial (DVB-T) The common perception of digital television these days is of broadcasts emanating from emblem towers, bouncing off satellites, and being beamed to home receivers.This is the magic ofsatellite contagious disease, and it is un questionable as long as the view of those satellites is non obscured. However, this is non the honorable way in which television sign ups ar transmitted. Another popular mode of transmitting housesdigital video broadcasting quotidian (DVB-T). When broadcasters employ this method, the digital luffs do not leave the earth. The prognosticates transmitted usingDVB-Tdo not travel via cable, though rather, they go fromantenna to aerial antenna, from steer blaster to home receiver. Digital signals are routinely transmitted using terrestrial methods.The transmission method has different names in different separate of the world. DVB-Tis the name used in Europe and Australia. North American customers receive these signals using a set of standards approved by the Advanced Television Systems Committee (ATSC). In Japan, it is cognise as Integrated Services Digital BroadcastingTerrestrial (IDSB-T). DVB-Tbroadcasters transmit data using a mat digital audio-video stream, with the who le serve establish on theMPEG-2 standard. These transmissions can entangle all kinds of digital broadcasting, includingHDTVand other advanced-pitched-intensity methods.This is a vast rise over the old analog signals, which required separate streams of transmission. Oddly enough, just aboutDVB-Ttransmissions take place over analog networks, with the antennas and receivers getting some subservient technological upgrades along the way. (Pool, 2002) 1. 2 Aim of this project The aim of this project is to investigate the design of a repeater for DVB-T system but incorporating a delay surrounded by receives and transmits signals to avoid bury Symbol Interference (ISI). It is useful to use a repeater to boost the signal into areas of weak coverage in any radio wave communication system.However wave interference means the repeater usually requires a frequency shift for analogue modulated signals. For digitally modulated signals it may be possible to use the same frequency. The pro ject will review the basics of current digital systems such as DVB (Broadcast TV) and WLAN and to identify a suitable choice for a lab experiment. The practical side will be to design and build a repeater incorporating suitable transmission delay. 1. 3 Project objectives 1. Investigate and gip Inter Symbol Interference effect on received signal. 2.Investigate and learn the delay effect on received signal and earn of the delay. 3. Investigate and learn Multipath propagation and Doppler shift of the frequencies. 4. Investigate and learn more or slight Digital Video Broadcasting (DVB) techniques. 5. Investigate and learn about transmission delay of coaxial cable. 6. Investigate and learn about different type of Amplifier. 7. Designing repeater circuit. 8. Implementing circuit. 9. Testing the circuit. Figure 1System block diagram 1. 3 Project deliverable * System design * Circuit design * Documentation 2. 0 Problem analysis . 1 Repeater Repeaters ply an efficient solution to acce ssion the coverage of the broadcasting networks. In the broadcasting networks, the network operators usually primary put high power transmitters at the strategic points to readily ensure an attractive coverage and then, in a second step, increase their coverage by placing low-power repeaters in the dead make love or phantasma areas, such as a tunnel, valley or an indoor area. A repeater is simply a device that receives an analogue signal or a digital signal and regenerates the signal along the next leg of the medium.In DVB-T networks, there are two different kinds of repeaters. They are supine repeaters, which are overly called as gap-fillers and active repeaters that are withal called as regenerative repeaters. A reachive repeater receives and retransmits a DVB-T signal without ever-changing the signalling culture bits. The signal is totally boosted. An active repeater can pull up the incoming signal, perform error feely and then re-modulates the bit stream. The produce of the error recovery can even be connected to a local re-multiplexer to enable insertion of local programmes.This means that the entire signal is regenerated. The building blocks of the passive and active repeater configurations are shown in Figure 1. Figure 2 Passive and Active repeater block diagram In a first step, DVB-T broadcasters, as all broadcasters, launch their networks with high power transmitters in strategic point in effectuate to quickly insure an attractive coverage to TV operators and then, in a second step, increase their coverage by placing low power repeaters in shadow area. To repeat a DVB-T signal, two solutions can be used An analogue repetition in this case, repeaters use well-known techniques such as pass conversion, filtering, up conversion and amplification. The signal is only boosted. * A digital repetition this new type of repeater uses a professional DVB-T receiver to recover the programme stream (and correct all errors) carried in the RF channel, p erforms a new modulation followed by an up conversion and amplification. It means that the entire signal is regenerated. 2. 1. 1 Analogue repeaters In case of analogue repetition, the widening signal signal quality cannot exceed the quality of the received signal be hunting expedition the signal is not regenerated.Figure 3 Analog repeater Furthermore, being a passive process, it degrades the signal the cast hinderance of the local oscillator involves a degradation of the human body noise of the received signal and creates an inter-modulation. The local oscillator phase noise adds to the phase noise of the received signal. In these conditions, what are the performances of analogue repetition for intonation Error Ratio (MER) and Carrier to Noise ratio (C/N)? Of course, performances are cerebrate to the technology but analogue repetition cannot be insured ad infinitum. And, if one link in the analogue repetition chain is weak, all the system is deficient. Trolet, 2002) 2. 1. 2 D igital repeaters In case of a digital repetition, the entire signal is regenerated it means that repeaters, as transmitters, insure the quality of the broadcasted signal as long as it is able to demodulate it. Figure 4 Digital repeater The create signal quality is independent of the stimulus signal quality * Phase noise is linked to the local oscillator only, * A weak link, in a digital repetition chain, is erased by the next repeater, * Several digital repeaters can be cascaded without any cumulative degradation.Drawback of Digital repeater The delay inside a digital repeater is taller than the withstand interval. So, the signal cannot be repeated on the frequency of the main transmitter main transmitters and repeaters cannot pass in a Single frequency meshwork (SFN) even with 8K letter carriers and a guard interval of 1/4. (Trolet, 2002) Figure 5 Channel management for digital repeater The delay inside an analogue repeater is lower than the guard interval and allows main tr ansmitters and repeaters to operate in SFN mode. Figure 6 Channel management for analogue repeaterBut, with such technique, carrefour in the midst of repeater cells and transmitter cell cannot be optimised/adjusted. Analogue repeaters piddle not the possibility to buffer the signal they cannot add delay to bear on the overlap zone. To optimise single frequency network with this technique, two solutions * apparent movement the repeater that means you agree to find new broadcasting site. * ignore the output power of your repeaters and forbid overlap. So, to build an efficient Single Frequency Network (SFN), Broadcasters have benefits in using transmitters * Means more license for defining the size of the cells Means more freedom for defining the repeater locations Benefits of Digital Repeater * As long as the repeater is able to demodulate the RF channels, signal quality is independent of stimulant signal quality. * Output MER 33 dB (Trolet, 2002) * In theory, thanks to the forward error correction (FEC) and the output signal quality, digital repeaters can be cascaded ad infinitum. It is an efficient solution to broadcast in valleys. TV viewers and hostile repeaters share the broadcasted signal. Figure 7 Broadcast in valley with digital repeaters The demodulation process, trim down to the programme stream, allows broadcasters to insert a local multiplexor in order to customize the content for a local broadcasting. More and more, local communities cite their local programmes. Digital repeaters offer a flexible solution to the network. * iniquity area can be covered by several repeaters. Repeaters operate together in SFN mode without any external references (10 megacycle per second and 1 PPS) (Trolet, 2002). In their internal memory, digital repeaters can buffer the signal so as to optimise overlaps. 2. 2 Inter image interferenceInter- image interference (ISI) is an required consequence of both wired and wireless communication systems. Morse first noticed it on the transatlantic telegraph cables transmitting messages using dots and dashes and it has not gone way since. He handled it by just slowing down the transmission. bounty Time Figure 8 101101 transmitted data Figure 8 shows a data sequence, 1,0,1,1,0, which wish to be sent. This sequence is in form of square pulses. Square pulses are nice as an abstract but in practice they are hard to create and also require far too much bandwidth. Amplitude TimeFigure 9 Received data Figure 9 shows each symbol as it is received. It also shows what the transmission medium creates a tail of energy that lasts much womb-to-tomb than intended. The energy from symbols 1and 2 goes all the way into symbol 3. Each symbol interferes with one or more of the subsequent symbols. The circled areas show areas of large interference. Amplitude Time Figure 10 Transmitted data vs. Received data Fig. 3 shows the actual signal markn by the receiver. It is the sum of all these perverted symbols. Compa red to the transmitted signal, the received signal looks quite indistinct.The receiver does not rattling this signal it sees only the little dots, the value of the amplitude at the clock instant. Symbol 3, this value is approximately half of the transmitted value, which makes this particular symbol is more susceptible to noise and incorrect interpretation and this phenomena is the result of this symbol delay and smearing. This spreading and smearing of symbols such that the energy from one symbol do the next ones in such a way that the received signal has a higher probability of being interpreted incorrectly is called Inter Symbol Interference or ISI.ISI can be caused by many different reasons. It can be caused by filtering effects from hardware or frequency selective fading, from non- unidimensionality and from charging effects. Very few systems are immune from it and it is near always present in wireless communications. Communication system designs for both wired and wireless n early always need to incorporate some way of controlling it. The main problem is that energy, which is been wishing to confine to one symbol, leaks into others. So one of the simplest things can be done to reduce ISI is to just slowing down the signal.Transmitting the next pulse of information only after allowing the received signal has damped down. The term it takes for the signal to die down is called delay spread, whereas the original time of the pulse is called the symbol time. If delay spread is less than or equal to the symbol time then no ISI will result, otherwise yes. (Charan, 2002) Slowing down the bit rate was the main way ISI was controlled on those initial transmission lines. Then faster chips came and allowed to do signal processing controlling ISI and transmission fixtures increased accordingly. . 3 Multipath propagation Multipath propagation is caused by multipath receptions of the same signal. in city environment or within signal travels along different path from transmitter (Tx) to receiver (Rx). * Signal elements received at just about different propagation (delay) * These components are unite at Rx * Results as a signal that varies widely in amplitude, phase or polarization 2. 3. 1 Multipath fading When the components add destructively due to phase inequalitys amplitude of the received signal is very bitty.At the other times the components add constructively the amplitude of received signal is large. This amplitude variations in the received signal called signal fading, are due to the time-variant peculiaritys of the channel. Relative feat between Tx and Rx (or surrounding objects causing e. g. reflection) causes random frequency modulation. Figure 11 Multipath propagation Each multipath component has different Doppler shift. The Doppler shift can be calculated by using fd=V? cos? V is the fastness of the terminal ? is the spatial angle between the taperion of motion and the wave ? is the wavelengthThe three most important effe cts of multipath fading and moving scatters are * Rapid changes in signal strength over a piddling travelled distance or time interval * Random frequency modulation due to varying Doppler shifts on different multipath signals. * Time scatter (echoes) caused by multipath propagation 2. 4 The TV channels Hertz(Hz) meanscycles per second. (Heinrich Hertz was the first to build a radio transmitter and receiver art object beneathstanding what he was doing. )KHz means vitamin C0 Hertz, megahertz means 1,000,000 Hertz, and GHz means 1,000,000,000 Hertz The radio frequency spectrum is carve up into major bandsFrequencyWavelength(in meters) VLFvery low frequency3 KHz 30 KHz 100 Km 10 Km LFlow frequency 30 KHz three hundred KHz 10 Km 1 Km MFmedium frequencyccc KHz 3 MHz 1 Km 100 m HFhigh frequency 3 MHz 30 MHz 100 m 10 m VHFvery high frequency30 MHz 300 MHz 10 m 1 m UHFultra high frequency300 MHz 3 GHz 1 m 100 mm SHFsuper high frequency 3 GHz 30 GHz 100 mm 10 mm EHF pas sing high frequency 30 GHz 300 GHz 10 mm 1 mm (Antenna basics, 2008) The UK uses UHF for terrestrial television transmissions, with both PAL-I analogue broadcasts and DVB-T digital broadcasts sharing the band. The following table is a adroit channel/frequency conversion table showing the E channel number, PAL-I vision and sound carrier frequencies, and the centre frequency for digital tuning. The frequency plan for the UK involves each channel having an 8MHz bandwidth the space in the spectrum that each channel is allotted. The PAL-I standard specifies a video bandwidth of 5. 0 MHz and an audio carrier at 6 MHz.The DVB-T transmissions moldiness fall within this channel plan, resulting in each digital channel also having a bandwidth of 8 MHz. conflicting PAL-I, the digital channel (carrying a multiplexed signal) utilises the entire bandwidth available to it simultaneously, transmitting 2048 carriers (in 2k mode). For tuning purposes, a centre frequency is used (Table is admitd in appendices). (digital spy, 2009) Decibels Decibels (dB) are commonly used to describe gain or red in circuits. The number of decibels is found from get together in dB = 10*log(gain factor)or (Antenna basics, 2008) In some situations this is more complicated than using gain or loss factors. But in many situations, decibels are simpler.For use, depend 10 feet of cable loses 1 dB of signal. To ascertain the loss in a longer cable, just add 1 dB for each 10 feet. In general, decibels let add or subtract sort of of multiply or divide. Noise Whether a signal is receivable is determine by thesignal to noise ratio(S/N). For TVs there are two main sources of noise 1. Atmosphere noise. at that place are many types of sources for this noise. A light switch creates a radio wave every time it opens or tight fittings. Motors in some appliances produce nastyRF(radio frequency) noise. 2. murderer noise. Most of this noise comes from the first transistor the antenna is attached to. ne arly receivers are quieter than others. 2. Transmission cable Twin lead (ribbon cable) used to be common for TV antennas. It has its advantages. But due to its unpredictability when positioned near alloy or dielectric objects, it has fallen out of favour. Coaxial cable is recommended. It is amply shielded and not affected by nearby objects. Transmission cable has a feature called itscharacteristic resistor, which for TV coax should always be 75 ohms. Although rated in ohms, this has nothing to do with ohmic resistance. A resistor converts electric energy into heat. The 75 ohms of a coaxial cable does not cause heat. Where it comes from is mathematically complicated and beyond our scope here.But coax also has nondescript resistance (mostly in the center conductor) and thus loses some of the signal, converting it into heat. The meter of this breakup (loss) depends on the frequency as well as the cable length. guinea pigCentre conductorCable diameter RG-5920-23 cypher0. 242 in ches RG-618 gauge0. 265 inches RG-1114 gauge0. 405 inches Figure 12 Cable loss in dB (Antenna basics, 2008) The above map is only approximate. There are many cable manufacturers for each type and there is no enforcement of standards. If the mast-mounted amplifier gain exceeds the cable loss then it shouldnt matter what cable you use.But there are two problems with this * Some cable has incomplete shielding. This is most common for RG-59, some other reason to avoid it. * When the cable run is longer than 200 feet, the low-numbered channels can become too strong relative to the high-numbered channels. In this case, RG-11 or an ultra-low-loss RG-6 is recommended. (These alternatives are expensive. )Alternatively, frequency overlayd amplifiers will work. 2. 6 Signal Amplifiers There are two types of signal amplifiers Preamplifiers(Mast-mounted amplifiers)These should be mounted as destruction to the antenna as possible. Usually the amplifier comes in two parts 1. The amplifier.This is an exterior unit that is normally bolted to the antenna mast. It must have a very low noise figure, and enough gain to overcome the cable loss and the receivers noise figure. 2. The power module (power injector). This is an indoor unit that commonly lies on the floor behind the TV. It is inserted into the antenna cable between the amplifier and the TV. This module injects some power, usually DC, into the coaxial cable where the amplifier can use it. The power injector is the amplifiers power supply. Distribution amplifiersThese are simple signal boosters. They are much necessary when an antenna drives multiple TVs or when the antenna cable is longer than 150 feet.Distribution amplifiers dont need to have a low noise figure, but they need to be able to handle large signals without over adulterateing. Commonly, distribution amplifiers have multiple outputs. (Unused outputs usually do not need to be terminated. ) Never feed an amplifier output right off into another amplifier. T here should always be a long cable between the preamplifier and the distribution amplifier. Placing the two amplifiers close together can cause overload and/or oscillation. A mast-mounted amplifiers most important characteristic is its noise level, usually specified by thenoise figure. But many manufacturers dont take this number seriously. If it is given at all, it is often wrong. If all makers dont do them right then comparison-shopping is not possible.The author is inclined to rate amplifiers for their noise figures as follows 0. 5 dBsuperb (anything better runs into thermal atmospheric noise) 2. 0 dB excellent 4. 0 dBfair 6. 0 dBpoor 10 dBawful 2. 7 Transmission delay (Coaxial cable) Transmission lines are described by their two most important characteristics the characteristic impedance Zo and the delay. For instance, a short (say 0. 01 wavelength) piece of coaxial cable such RG-58U has been taken and measured its capacitance with the other end open. A one backside length yie lds more or less 31. 2 pF. The inductance also has been measured with the other end shorted. It yields 76. 8 nH. The impedance may now be computed as Zo=LC Zo=76. ? 10-931. 2? 10-12=49. 6 ohms Here L and C are measured for the same length. The delay may also be computed Delay= L? C Delay= 76. 8? 10-9? 31. 2? 10-12=1. 55 nSec For an ideal line, the delay increases linearly with its length, while its impedance remains constant. afterwards that it has been computed the velocity in foot per second V=lendelay V=11. 55? 10-9=6. 46? 108 foot per second or meters/second 8 10*966. 1 This is less than the speed of light. The ratio of the above speed to the speed of light gives the velocity factor Vf Vf=1. 966? 1082. 998? 108=0. 666 or 66. % of the speed of light As mentioned earlier, the delay increases linearly with the line length. For a given length, the phase difference between the commentary and output will increase with the frequency ? =2? f? delay Here the phase ? is in radians and t he frequency f is Hertz. Converting the phase from radians to degrees requires multiplying by 3602? In this case if frequency is 900 MHz so phase delay will be ?deg=f? 360? delay=900? 106? 360? 1. 55? 10-9? 502. 2 This length that gives 90 degrees of phase shift is also known as a quarter wavelength. Figure 13 Linear change phase vs frequency Figure-13 An ideal transmission line gives a linear change of phase versus frequency.The distributed inductance and capacitance are the basic transmission line line of reasonings. From these, it can be calculated the line impedance, the delay in terms of time and phase, the speed of propagation and the velocity factor. The inductive component has an additional component at the lower frequencies which slows the signal somewhat. This occurs around 100 KHz for small coax and lower for larger cables. For frequencies above 1 MHz, the dielectric constant of the cable is probably responsible for the subside in the delay. Measuring the delay of cable s can reveal some hidden properties that could make it unsuitable for some applications, such as carrying wideband data. (Audet, 2001) 3. 0 workable solutionThe main component of a repeater is amplifier. There are many types of amplifier can be used for this job. RF amplifiers are electronic devices that put up a varying stimulation signal and produce an output signal that varies in the same way as the commentary, but that has larger amplitude. RF amplifiers generate a completely new output signal establishd on the foreplay, which may be potential difference, current, or another type of signal. Usually, the comment and output signals are of the same type however, separate circuits are used. The input circuit applies varying resistance to an output circuit generated by the power supply, which smoothes the current to generate an even, uninterrupted signal.Depending on load of the output circuit, one or more RF pre-amplifiers may boost the signal and send the stronger output to a RFpower amplifier(PA). Other types of RF amplifiers include low noise, pulse, bi-directional, multi-carrier, buffer, and limiting amplifiers. Detector log video amplifiers (DLVAs) are used to amplify or measuresignals witha wide dynamic pasture and wide broadband. Successive detection logvideo amplifiers (SDLVAs)are log amplifiers that can operate over a wider dynamic rove than DLVAs, while extended site detector log video amplifiers (ERDLVAs)areDLVAs that can operate with a wider operating frequency. (Global Spec, 2008) * Military / Defense * Mobile / radio receiverSystems * Plasma / Electron Laser * RF Induction Heating * microwave radar SystemsAmplifier typeface Applications * Low Noise Amplifier * Power Amplifier * Bi-directional Amplifier * Multi-carrier Amplifier * Multiplier (RF amplifier, 2008) 3. 1 RF amplifier Selecting RF amplifiers requires an analysis of several performance specifications. Operating frequency is the frequency range for which RF amplifiers meet a ll guaranteed specifications. Design gain, the ratio of the output to the input power, is normally expressed in decibels (dB), or Gdb= 10 * log (Po/Pi) Output power isthe signal power at the output of the amplifier under specified conditions such as temperature, load, electromotive force standing wave ratio (VSWR), and supply potency.Gain flatness indicates the degree of the gain variation over its range of operating wavelengths. Secondary performance specifications to consider include noise figure (NF), input VSWR, output VSWR, and monolithic microwave integrated circuit (MMIC) technology. The noise figure, a measure of the amount of noise added to the signal during normal operation, is the ratio of the signal-to-noise ratio at the input of the component and the signal-to-noise ratio measured at the output. The NF value sets the lower limit of the dynamic range of the amplifier. Input VSWR and output VSWR are unit-less ratios ranging from1 to infinity that express the amount of reflected energy. Global Spec, 2008) There are several physical and electrical specifications to consider when selecting RF amplifiers. Physical specifications include package type and connector type. computer software types includesurface mount technology (SMT),flat pack, and by with(predicate) hole technology (THT). RF amplifiers may also beconnector ezedor use waveguide assemblies. Connector types include BNC, MCX, Mini UHF, MMCX, SMA, SMB, SMP, TNC, Type F, Type N, UHF, 1. 6 / 5. 6, and 7/16. Important electrical characteristics include nominal operating voltage and nominal impedance. Operating temperature is an important environmental parameter to consider. (Global Spec, 2008) 3. 1. 1 The Transistor AmplifierIn the prior section explains the internal functionals of the transistor and will introduce new terms, such as emitter, base, and gatherer. Here it discusses the boilers suit operation of transistor amplifier. To understand the overall operation of the transistor amp lifier, it must have to only consider the current in and out of the transistor and through the various components in the circuit. Therefore, from this point on, only the schematic symbol for the transistor will be used in the illustrations, and rather than thinking about majority and minority carriers that mean it will be only emitter, base and accumulator register current. Before going into the basic transistor amplifier, there are two terms it should be familiar with AMPLIFICATION and AMPLIFIER.Amplification is the process of increasing the strength of a SIGNAL. A signal is just a general term used to refer to any particular current, voltage, or power in a circuit. An amplifier is thedevicethat provides amplification (the increase in current, voltage, or power of a signal) without appreciably altering the original signal. Transistors are frequently used as amplifiers. Some transistor circuits are sure amplifiers, with a small load resistance other circuits are designed for VOLT AGE amplification and have a high load resistance others amplify POWER. By inserting one or more resistors in a circuit, different methods of predetermineing may be achieved and the emitter-base battery eliminated.In addition to eliminating the battery, some of these biasing methods compensate for slight variations in transistor characteristics and changes in transistor conduction resulting from temperature irregularities. observe in figure 2-12 that the emitter-base battery has been eliminated and the bias resistor RBhas been inserted between the collector and the base. resistance RBprovides the necessary forward bias for the emitter-base junction. accredited flows in the emitter-base bias circuit from ground to the emitter, out the base lead, and through RBto VCC. Since the current in the base circuit is very small (a few hundred microamperes) and the forward resistance of the transistor is low, only a few tenths of a volt of positive bias will be felt on the base of the trans istor.However, this is enough voltage on the base, along with ground on the emitter and the large positive voltage on the collector, to mightily bias the transistor. (Intregrated Publishing, 2002) Figure 14 The basic transistor amplifier With Q1 properly biased, direct current flows continuously, with or without an input signal, throughout the entire circuit. The direct current flowing through the circuit develops more than just base bias it also develops the collector voltage (VC) as it flows through Q1 and RL. Notice the collector voltage on the output graph. Since it is present in the circuit without an input signal, the output signal starts at the VClevel and either increases or decreases.These dc voltages and currents that exist in the circuit before the application of a signal are known as quiescent voltages and currents (the quiescent state of the circuit). Resistor RL, the collector load resistor, is placed in the circuit to keep the safe effect of the collector supply vol tage off the collector. This permits the collector voltage (VC) to change with an input signal, which in turn allows the transistor to amplify voltage. Without RLin the circuit, the voltage on the collector would always be equal to VCC. The union optical condenser (CC) is another new addition to the transistor circuit. It is used to pass the ac input signal and block the dc voltage from the preceding circuit. This prevents dc in the circuitry on the left of the coupling capacitor from touching the bias on Q1.The coupling capacitor also blocks the bias of Q1 from reaching the input signal source. The input to the amplifier is a sine wave that varies a few millivolts above and below zero. It is introduced into the circuit by the coupling capacitor and is applied between the base and emitter. As the input signal goes positive, the voltage across the emitter-base junction becomes more positive. This in effect increases forward bias, which causes base current to increase at the same r ate as that of the input sine wave. Emitter and collector currents also increase but much more than the base current. With an increase in collector current, more voltage is demonstrable across RL.Since the voltage across RLand the voltage across Q1 (collector to emitter) must add up to VCC, an increase in voltage across RLresults in an equal decrease in voltage across Q1. Therefore, the output voltage from the amplifier, taken at the collector of Q1 with respect to the emitter, is a minusalternation of voltage that islargerthan the input, but has the same sine wave characteristics. During the negative alternation of the input, the input signal opposes the forward bias. This action decreases base current, which results in a decrease in both emitter and collector currents. The decrease in current through RLdecreases its voltage drop and causes the voltage across the transistor to rise along with the output voltage.Therefore, the output for the negative alternation of the input is apo sitivealternation of voltage that islargerthan the input but has the same sine wave characteristics. By examining both input and output signals for one complete alternation of the input, we can see that the output of the amplifier is an exact reproduction of the input except for thereversal in polarityand theincreased amplitude(a few millivolts as compared to a few volts). The PNP version of this amplifier is shown in the upper part of the figure. The primary difference between the NPN and PNP amplifier is the polarity of the source voltage. With a negative VCC, the PNP base voltage is slightly negative with respect to ground, which provides the necessary forward bias condition between the emitter and base.When the PNP input signal goes positive, it opposes the forward bias of the transistor. This action cancels some of the negative voltage across the emitter-base junction, which reduces the current through the transistor. Therefore, the voltage across the load resistor decreases, a nd the voltage across the transistor increases. Since VCCis negative, the voltage on the collector (VC) goes in a negative direction (as shown on the output graph) toward -VCC(for example, from -5 volts to -7 volts). Thus, the output is a negative alternation of voltage that varies at the same rate as the sine wave input, but it is opposite in polarity and has a much larger amplitude.During the negative alternation of the input signal, the transistor current increases because the input voltage aids the forward bias. Therefore, the voltage across RLincreases, and consequently, the voltage across the transistor decreases or goes in a positive direction (for example from -5 volts to -3 volts). This action results in a positive output voltage, which has the same characteristics as the input except that it has been amplified and the polarity is reversed. (Intregrated Publishing, 2002) 3. 1. 2 Ultra High Frequency Transistor Array (HFA) The HFA3046, HFA3096, HFA3127 and the HFA3128 are Ul tra High Frequency Transistor Arrays that are fabricated from Intersil Corporations complementary bipolar UHF-1 process.Each swan consists of five dielectrically isolated transistors on a common monolithic substrate. The NPN transistors face a fT of 8GHz while the PNP transistors provide a fT of 5. 5GHz. twain types exhibit low noise (3. 5dB), making them ideal for high frequency amplifier and mixer applications. (HFA3127, 2003) The HFA3046 and HFA3127 are all NPN arrays while the HFA3128 has all PNP transistors. The HFA3096 is an NPN-PNP combination. Access is provided to each of the terminals for the individual transistors for maximum application flexibility. Monolithic construction of these transistor arrays provides close electrical and thermal matching of the five transistors. Features * NPN Transistor (fT) . . . . . . . . . . . . . . . . . . . . . . . . 8GHz * NPN Current Gain (hFE). . . . . . . . . . . . . . . . . . . . . . . . 130 * NPN Early Voltage (VA) . . . . . . . . . . . . . . . . . . . . . . . 50V * PNP Transistor (fT). . . . . . . . . . . . . . . . . . . . . . . . . 5. 5GHz * PNP Current Gain (hFE). . . . . . . . . . . . . . . . . . . . . . . . . 60 * PNP Early Voltage (VA) . . . . . . . . . . . . . . . . . . . . . . . .20V * Noise Figure (50? ) at 1. 0GHz . . . . . . . . . . . . . . . . . 3. 5dB * aggregator to Collector Leakage . . . . . . . . . . . . . . . . . .30 dB) and this transistor amplifier gain was not enough for rebroadcasting signal, this project select another amplifier MAV-11SM from supervisor suggestion. One MAV-11SM amplifier gives around 10dB gain what has been shown in examen section. At last two MAV-11SM amplifiers and one HFA3127 has been used to get more than 30dB gain. It has been tested in network scalar analyzer. For field test, a TV card, three TV aerials have been used. The amplifier circuit has been connected with one aerial. It was working very well when it was directly connected with TV card. That it can be sa id that the repeater was amplifying signal.But when another aerial with long transmission line was connected with amplifier and tried to rebroadcast the signal with 5v 1A power supply, TV enter quality was not improving expectedly. Digital repetition is an innovative concept, which helps to increase the DVB-T coverage while maintaining the highest quality and providing a greater flexibility. In bruise of failure, this project was a high level platform to learn about signal and signalling. Future work As this project is unsuccessful at that certain point, this project will try to solve the rebroadcasting problem. And the transistor array will be a great option to amplify signal if all five transistors are been used. From HFA3127, it is possible to get min of one hundred twenty dB gain if it is soldered perfectly. Works CitedAntenna basics. (2008, October 12). Retrieved May 5, 2011, from http//www. hdtvprimer. com/ANTENNAS/basics. html. Audet, J. (2001). Coaxial Cable Delay. Charan , L. (2002). Inter symbos Interferance (ISI) and Raised Cosine filters. Retrieved December 5, 2010, from http//www. complextoreal. com/chapters/isi. pdf. Datasheet. (2005, December 21). Retrieved February 20, 2011, from http//www. intersil. com/data/fn/fn3076. pdf. digital spy. (2009). Retrieved April 10, 2011, from http//www. digitalspy. co. uk/digitaltv/information/a12613/uhf-channel-and-frequency-guide. html. Global Spec. (2008). Retrieved April 10, 2011, from http//www. globalspec. om/learnmore/telecommunications_networking/rf_microwave_wireless_components/rf_amplifiers. HFA3127. (2003). Retrieved January 18, 2011, from http//www. intersil. com/products/deviceinfo. asp? pn=HFA3127. Intregrated Publishing. (n. d. ). Retrieved April 4, 2011, from http//www. tpub. com/neets/book7/25c. htm. Monolithic Amplifier. (2002). Retrieved January 14, 2011, from http//www. minicircuits. com/pdfs/MAV-11SM+. pdf. Pool, I. (2002). Digital Video Broadcasting. Retrieved April 13, 2011, from http// www. radio-electronics. com/info/broadcast/digital-video-broadcasting/what-is-dvb-tutorial. php. Power Amplifier design. (1998). RF transmitting transistor and power ampli? er basics . RF amplifier. (2008).Retrieved April 10, 2011, from http//www. globalspec. com/learnmore/telecommunications_networking/rf_microwave_wireless_components/rf_amplifiers. sub-TV. (2006, October 13). Retrieved April 20, 2011, from http//www. sub-tv. co. uk/antennatheory. asp. Trolet, C. (2002). SPOT filling gaps in DVB-T networks with digital repeaters. Presented by Gerard Faria, scientific Director, Harris Broadcast Europe at BroadcastAsia2002 International Conference, Available at http//www. broadcast. harris. com. Gantt chart APPENDICES Frequency Allocation for DVB-T in UK Band IV Channel PAL-I sight (MHz) PAL-I Sound (MHz) Centre (MHz) 21 471. 25 477. 25 474 22 479. 25 485. 25 482 3 487. 25 493. 25 490 24 495. 25 501. 25 498 25 503. 25 509. 25 506 26 511. 25 517. 25 514 27 519. 25 525. 25 522 28 527. 25 533. 25 530 29 535. 25 541. 25 538 30 543. 25 549. 25 546 31 551. 25 557. 25 554 32 559. 25 565. 25 562 33 567. 25 573. 25 570 34 575. 25 581. 25 578 35 583. 25 589. 25 586 36 591. 25 597. 25 594 37 599. 25 605. 25 602 38 607. 25 613. 25 610 Band V Channel PAL-I Vision (MHz) PAL-I Sound (MHz) Centre (MHz) 39 615. 25 621. 25 618 40 623. 25 629. 25 626 41 631. 25 637. 25 634 42 639. 25 645. 25 642 43 647. 25 653. 25 650 44 655. 25 661. 5 658 45 663. 25 669. 25 666 46 671. 25 677. 25 674 47 679. 25 685. 25 682 48 687. 25 693. 25 690 49 695. 25 701. 25 698 50 703. 25 709. 25 706 51 711. 25 717. 25 714 52 719. 25 725. 25 722 53 727. 25 733. 25 730 54 735. 25 741. 25 738 55 743. 25 749. 25 746 56 751. 25 757. 25 754 57 759. 25 765. 25 762 58 767. 25 773. 25 770 59 775. 25 781. 25 778 60 783. 25 789. 25 786 61 791. 25 797. 25 794 62 799. 25 805. 25 802 63 807. 25 813. 25 810 64 815. 25 821. 25 818 65 823. 25 829. 25 826 66 831. 25 837. 25 834 67 839. 25 845. 25 842 68 847. 25 853. 25 85 0