G.H.RAISONI COLLEGE OF ENGINEERING, NAGPUR Department:-Electronics & Communication Engineering Branch:- 7th Semester[Electronics & Telecommunication] Subject:- Television Engineering List of Experiments CYCLE -I 1. To study picture tube of monochrome television. 2. To study in detail, circuit of RF tuner section through various test points, the fault simulation and step-by-step fault finding. 3. To observe the composite video signal at the output of VIF section 4. To study in detail, circuit of SIF and video section through various test points, the fault simulation and step-by-step fault finding. 5. To study the Horizontal oscillator section through various test points and to study the fault simulation and step-by-step fault finding. CYCLE-II 6. To study the Horizontal output section and vertical oscillator section and to through various test points and to study the fault simulation and step-by-step fault finding. 7. To study the detail circuit of video and chroma section through various test points and to study the fault simulation and step-by-step fault finding. 8. To study the detail circuit of System Control Section through various test points and to study fault simulation and step-by-step procedure. 9. To plot the radiation pattern of single dipole and folded dipole antenna using antenna trainer kit. 10. (a)To setup an active satellite link and to demonstrate link fail operation. (b) To establish an audio/video satellite link between transmitter and receiver. The effect of voltages on the screen and the control grid is such a that the electrons converges in the space between these two grids. Cathode: It consists of a thoriated oxide of tungsten which is heated by a heater wire placed closed to the cathode but without touching it electrically. Control Grid 1: The element next to cathode is the control grid. The material between the heater and the cathode is a thermal conductor. Focusing Grid: This grid provides the required the electrostatic field to prevent spreading of the electron and help in producing a sharp spot on the screen. It uses the phenomenon of fluorescence and scanning. which allows the electrons to pass through. Screen Grid 2: It is a metallic cylinder of nickel. It is therefore also called as accelerating grid. Such a cathode known as indirectly heated cathode. This controls the brightness of the screen. The grid bias is –30 to –50V variable.Monochrome Television trainer kit. and focusing the electrons. housing an electron gun to produce a sharply focused electron beam and a fluorescent screen to produce light when the electron beam strikes the phosphor element on the element.Experiment No. The functions of various of picture tube are discussed below: Electron Gun: It produces a well-focused electron beam. which is kept at positive potential with respect to cathode. Apparatus: . This grid accelerates the electron in the beam.1 Aim: .To study picture tube of monochrome television. Control grid is kept at negative potential with respect to cathode. using thermionic emission of electrons from a Cathode and few grids for controlling. Theory: Picture tube is a transducer to convert electrical video signals varying with time into variations of light in space to reproduce the original picture. Also there are devices to deflect the electron beam horizontally and vertically to enable it to scan the screen through width and height to reproduce the original picture. . Negative grid bias enables the control grid to controls the space charge of the electron coming out of the cathode. and has a small aperture. but it is an electric insulator. Monochrome picture tube consists of an evacuated glass envelope. It is a metallic cylinder of nickel. accelerating. Result: . The mounting block containing deflection coils is called as yoke. called EHT. which is coated to a long conducting coating of aquadag inside the wide bell of the tube. The saw tooth currents flow in the horizontal and vertical deflection coils which produces the magnetic fields which deflects the beam in the picture tube. What is the function of aquadag coating? 3.Final Anode: To cause fluorescence in the phosphor material. At what potential all the grids maintained? . The glass is 1.Cross-sectional view of the picture tube is studied. Also the aluminum coating stops the ions to reach the phosphor coating. the electrons should strike the screen with great velocity. Deflection Coil: Electron beam is deflected by magnetic deflection. Fluorescent screen: It consists of rectangular faceplate made of an optically flat glass of high quality. Viva Question:1. The required high velocity is imparted by the final anode. which permanently damages the screen. There is a very thin aluminum coating on the back of the phosphor surface. The aquadag coating extends from the screen to the narrow neck. It is given a very high potential. It improves the brightness by reflecting the light from back to front. Why electrostatic focusing is preferred over electromagnetic focusing? 2.5 cm thick to withstand the outside air pressure against the internal vacuum. The Balun transformer is used to match the twin wire ribbon feeder impedance of 300 ohms to the 75 ohms input impedance of RF amplifier. The tuner is enclosed in a compact shielded box.9Mhz Sound IF=33. The function of the local oscillator is to tune the desired station.Monochrome TV trainer kit. The receiver uses the superheteordyne principle as used in the radio receivers. The fine-tuning control is varied to obtain exact picture & sound IF. amplify it and mix it with the continuous wave output of the local oscillator. mixer and local oscillator and is normally mounted on a separate sub-chassis. RF amplifier Picture IF=38. CRO. Adjusting the tuned circuits of all the three stages does channel selection. Each tuned circuits consists of a coil and a capacitor. called the ‘Front end’ or ‘RF tuner’. CRO probes. Block Diagram: Balun Trap Ckt. Theory: - .4Mhz Mixer AGC signal Local Osc. The function of tuner is to select a single channel signal form the various signals picked up by the antenna. Apparatus: .To study detail circuit of RF tuner section through various test points and to study the fault simulation and step-by-step fault finding. The IF signal form the tuner is coupled to the first picture IF amplifier through a coaxial cable.Experiment No: . The AGC line is connected from the main circuit to the tuner circuit. AFT signal This section consists of RF amplifier. and multimeter.2 Aim: . Balun Transformer: The tuner must have input impedance equal to the characteristic impedance of the antenna for maximum signal transfer to avoid reflections on the line. RF tuner consists of RF amplifier. The resonating capacitance consists of a distributed capacitance of the circuit and small fixed ceramic capacitors. The purpose of the tuner unit is to amplify both sound and picture signals picked by the antenna and to convert the carrier frequency and their associated bands into intermediate frequencies and their sidebands. local oscillator and mixer. It receives the signals like AGC and AFT from other sections of the receiver. The LO frequency is changed whenever a different channel is selected to maintain difference equal to the IF between the LO frequency & the tuned channel carrier frequency. Mixer Stage: The function of the mixer stage is to convert the incoming RF signal frequency from different channels into a common IF pass band of the receiver. VHF Tuner 2. 2. 3. What is the function of BALUN transformer? 2. What is the use of ganged tuning? 3. Simulate the fault using the jumper arrangements provided on the kit. RF amplifier prevents radiation from local oscillator & rejects image frequency signals. Following are the factors on which design of tuner depend: 1. Observe the various signals at various test points provided on the kit. Need for an RF amplifier stage. Result: .HP Filter and Trap circuits: Unwanted signals which lie in the IF band of 32 MHz to 42 MHz are rejected by the two trap circuits connected on either side of the HP filter. It converts the input signal into IF signal. Choice of IF & local oscillator frequencies. Coupling networks. RF Amplifier: The RF amplifier provides adequate gain to weak signals. UHF Tuner Procedure: (1) (2) (3) (4) Study the circuit diagram of RF tuner. The mixer stage & LO in combination can be considered as frequency converters. The HP filter has a cut-off frequency of 45 MHz. How is combined IF of the signal? . There are two types of tuner: 1. station and rejects all the other stations. It maintains high signal to noise ratio at the mixer.The RF tuner is the first block of the TV receiver which select a particular Viva Question: 1. Local oscillator: The Local oscillator generates an unmodulated sinusoidal voltage in the mixer with the incoming RF signal to affect its frequency translation to the IF band. Go with the step-by-step procedure to detect the fault as given in the trainer kit manual. The white level is referred to as pedestal. The repetition rate of horizontal blanking pulses is equal to the line scanning frequency of 15625 Hz.Experiment No.5 % of the maximum value of the signal. the picture tube is biased to ensure that a received video voltage corresponding to about 10 % modulation gives complete whiteness on the screen. the receiver can not follow the changes in the brightness. the scanning circuits produces retraces. Theory: Composite video signals consists of a camera signal corresponding to the desired picture information. Apparatus: . This level is called as peak. . CRO.Monochrome TV trainer kit. CRO probes. and multimeter. The composite video signal contains blanking pulses to make the retrace lines invisible by raising the signal amplitude slightly above the black level during the time.To observe the composite video signal at the output of VIF section. At the receiver. The composite video signal contains the vertical and horizontal blanking pulses to blank the corresponding retrace intervals. Detail description of each and every parts of composite video signal. The lowest 10% of the voltage range is not used to minimize noise effects. Horizontal and vertical sync pulses must have same amplitude to get higher efficiency of the picture signal transmission but their duration should be different so that they can be separable at the receiver. 3 Aim: . The level of the video signal in the composite video signal corresponds to the maximum whiteness of the signal transmitted. blanking pulses to make the retrace invisible & synchronizing pulses to synchronize the transmitter and receiver scanning. Similarly the frequency of vertical blanking pulses is equal to the field frequency of 50 Hz. Thus the picture information may vary between 10% to 75 % of the composite video signal depending on the relative brightness of the picture at any instant. which is fixed at 10 to 12. In the absence of DC component.white level. Composite video signal has an average value or DC component corresponding to the average brightness of the picture. The theory should cover following points. The darker the picture. The sync pulses that are added at 75 % level called as blanking level. higher will be voltage within those limits. and the black level corresponds to about 72%. Detail diagram of Composite video signal. A horizontal synchronizing pulse is needed at the end of each active line period whereas a vertical sync pulse is required after each field is scanned. Define pedestal height? 2. The horizontal and vertical sync. The blanking pulses are used to blank the screen during horizontal and vertical retrace. Give the significance of P/S ratio. and the blanking pulses.1)Search the test point in the VIF section at which you can observe the composite video signal. Why sync pulses are added at the blanking level? . The composite video signal consists of video signal corresponding to picture details. 2)Observe each and every part of composite video signal and draw it in the practical file. Procedure: - Result: - Viva Question: 1. 3. synchronizing pulses. pulses are used to achieve the horizontal synchronizing and vertical synchronizing between the transmitter and receiver. and audio pre amplifier. CRO probes. Which IC is used in sound section of the monochrome TV trainer kit? 2. The sound output section consists of sound driver and sound output subsections. CRO. FM detector section. audio pre amplifier section.To study the detail circuit of SIF and video section through various test points and to study the fault simulation and step-by-step fault finding.The SIF section consists of the SIF amplifier.Experiment No: -4 Aim: . The carrier frequency SIF signal is termed as audio signal. Go with the step-by-step procedure to detect the fault as given in the trainer kit manual. The amplified SIF signal is given to the in built SIF detector (FM detector) section. and electronics attenuator for volume control. Observe the various signals at various test points provided on the kit. Simulate the fault using the jumper arrangements provided on the kit. The amplifier section amplifies the audio signal and passes it to the volume control sub section. The SIF signal is separated from the composite video signal is given to the SIF amplifier. The theory should cover following points. Why FM is used for sound transmission? 3. and multimeter. The main function of this section is to separate the carrier frequency from the SIF signal. The purpose of the volume control is to control the audio signal. Result: . This audio signal is then fed to the audio amplifier section. In the video section the signal is processed before giving it as an input to the picture tube for reproduction of the received signal. Viva Question: 1.Monochrome TV trainer kit. The amplified version of the audio signal is further sent to the audio output section. Theory: The SIF section consists of various subsections such as SIF amplifier section. Procedure: 1) 2) 3) 4) Study the circuit diagram SIF section and video section. FM detector. List the audio amplifier IC known to you? . The purpose of the sound driver is to amplify the signal. This controlled audio signal is given to the sound output section. Audio output section amplifies the audio signal up to peak level. Apparatus: . Detail circuit of SIF and video section Description of the circuit in detail. and multimeter. Detail circuit of horizontal oscillator section. CRO. After this separation. The horizontal section generates the saw tooth current of frequency 15625Hz to move the electron beam in the horizontal direction.Experiment No: -5 Aim: -To study the Horizontal oscillator section through various test points and to study the fault simulation and step-by-step fault finding. and Horizontal oscillator amplifier section. Define: Front porch. 3)Simulate the fault using the jumper arrangements provided on the kit. Theory: The Horizontal section consists of following subsections. The theory should cover following points. 4)Go with the step-by-step procedure to detect the fault as given in the trainer kit manual. 2. vertical sync signal is given to the vertical section and simultaneously horizontal sync signal is given to the AFC section. The oscillated signal is amplified by the horizontal amplifier and given to the driver section. which separates the horizontal sync signal and vertical sync signal from the original amplified sync signal. Apparatus: . sync separator. 2)Observe the various signals at various test points provided on the kit. This section generates the horizontal line signal of 15625 Hz. Back porch. What’s the significance of front porch and back porch . Description of the circuit in detail. the sync amplifier. This AFC signal flows to the horizontal oscillator section. The amplified sync signal is given to the sync separator section. AFC section. The sync amplifier amplifies the sync signal. CRO probes. Result: . Viva Question: 1. AFC section controls the phase level of the horizontal sync signal and converts it into DC control voltage termed as AFC. sync separator.Monochrome TV trainer kit. The sync pulses separated from the composite video signal are fed to the sync amplifier.The horizontal section consists of sync amplifier. Procedure: - 1)Study the circuit diagram of horizontal oscillator section. horizontal oscillator section. AFC section. 3) Simulate the fault using the jumper arrangements provided on the kit. The horizontal output section is also called as EHT section. The oscillated vertical signal of 50 Hz is now synchronized along with vertical sync signal. which is given as the input to the internal aquadag coating of the picture tube.Experiment No: -6 Aim: -To study the Horizontal output section and vertical oscillator section various test points and to study the fault simulation and step-by-step fault finding. 3. Detail circuit of horizontal output and vertical oscillator section. This is known as HV or EHT supply. Apparatus: . This control mechanism is termed as vertical hold control. To obtain such a high voltage by stepping up the main voltage with a transformer is almost impossible and prohibited in cost. The vertical oscillator section generates the saw tooth current of frequency 50 Hz that is fed to the vertical deflection winding to achieve the vertical movement of the beam inside the picture tube. 2) Observe the various signals at various test points provided on the kit. Procedure: - 1) Study the circuit diagram of horizontal output section and vertical oscillator section. At what time the sync pulses are added during the scanning process? . CRO probes. How much is the frequency of horizontal scanning & vertical scanning? 2. Result: - Viva Question: 1. Theory: The vertical sync signal obtained from the sync separator section is given to the vertical oscillator section. During the retrace intervals of horizontal scanning. To maintain the vertical signal of 50 Hz generated by vertical oscillator section. 4) Go with the step-by-step procedure to detect the fault as given in the trainer kit manual. A different method of this high voltage generation is used. CRO. This section now generates the vertical signal of 50 Hz. The output of the rectifier is filtered to provide required dc voltage.Monochrome TV trainer kit. The horizontal section generates the EHT voltage. and multimeter. one control mechanism is connected. An anode voltage of the order of 15 KV is needed for sufficient brightness in black and white picture tubes. These are step up by an autotransformer winding of about 10 to 15 KV and fed to a high voltage rectifier. Specify the timing required for horizontal scanning & vertical scanning. Description of the circuit in detail. The theory should cover following points. high voltage pulses of amplitude between 6 to 9 KV are developed across the primary winding of the horizontal output transformer. Saturation The hue and saturation of a colour together is called as chrominance. Theory: - Procedure: (1) (2) (3) (4) Study the circuit diagram of video and chroma section. CRO probes. Give the significance of chromaticity diagram. Viva Question: 1. Any colour has three characteristics.Experiment No. These are: 1. and multimeter. Define Hue. luminance signal and sub carrier frequency is observed in the video and chroma section. Go with the step-by-step procedure to detect the fault as given in the trainer kit manual.Colour TV trainer kit. Observe the various signals at various test points provided on the kit. colour killer detector. Apparatus: . Luminance 2.7 Aim: . Hue or tint 3. Result: . 2. Saturation and Luminance. From the composite video signal the Y signal is detected and it goes to Y amplifier.To study the detail circuit of video and chroma section through various test points and to study the fault simulation and step-by-step fault finding. matrix. The signal corresponding to red green and blue colour is separated in this section.The colour composite video signal. colour oscillator. Simulate the fault using the jumper arrangements provided on the kit. The theory should include following points Detail circuit of video and chroma section. Description of circuit diagram in detail. The chroma section consists of chroma amplifier. and luminance signal amplifier. . CRO. The TV trainer has IC 901 FONDA 4ST for system control purpose. 2 and 3 are used for band switching purpose. Theory: - Procedure: 1) 2) 3) 4) Study the circuit diagram of system control section. The pin 28 is stand by input pin power ON/OFF signals are obtained here. Description of circuit diagram in detail. The remote control enables the TV viewer to operate from a distance. The pin 38 is brightness control pin. and multimeter. channel selection etc.Experiment No. The pin 5. 21 and 22 are the key matrix pins. Keyboard is used for selecting one function from the front panel. Observe the various signals at various test points provided on the kit. CRO probes. Whenever we store any channel or put it into memory the memory signals are stored in the memory IC with the help of these pins. contrast adjustment etc. then what may be the probable causes for such condition? 2. These pin transfers the signal to the tuner section. Pin 39 is volume control pin. If the remote control is not working. Viva Question: 1. contrast. In almost all the TV receivers the circuits are provided to adjust volume.Colour TV trainer kit. brightness control. Go with the step-by-step procedure to detect the fault as given in the trainer kit manual Result: - The system control section controls all the operations of the receiver such as channel selection. The signals are obtained first at this pin for any function from remote switches. Pin 36 is the colour control pin. Apparatus: . So signal work inside the IC for which remote key was pressed. What do you mean by chrominance? . Pin 11 is connected to the pin 5 of the memory IC. This eye recognizes the signal and amplifies it and gives to pin 34. 6. 7. Pin 34 is infrared remote input pin ON pressing the remote switches. Most of the controls provided on the front panel are also provided on the remote control. The theory should include following points Detail circuit of System control section. CRO. Simulate the fault using the jumper arrangements provided on the kit. brightness. which are connected with the keyboard.To study the detail circuit of System Control Section through various test points and to study fault simulation and step-by-step procedure. Pin 1. For various system control purposes either remote control or front panel control is provided. The remote provides the infrared waves which falls on sensor EYE ON front panel. It is dual in line package 40 pins IC that controls all the sections of the TV trainer. 8 Aim: . Theory:The antenna is a reciprocal device. The radiation pattern is usually measured in the two principal planes. Procedure: - 1. The radiation pattern of an antenna is peculiar to the type of antenna and its electrical characteristics as well as its physical dimensions. In other words the radiated power is normalized to the power at bore sight. cables etc. pipes. It is measured at a constant distance in the far field. The radiated /received dB is plotted against the angle that is made with the bore sight direction. 9 Aim: -To plot the radiation pattern of single dipole and folded dipole antenna using antenna trainer kit.000 times less than the power on the bore sight which. means it radiates or receives electromagnetic energy in the same way. at the position of maximum radiated power.5 m and align both of them. Apparatus:. If the antenna is not physically symmetrical about each of its principal planes. means that the scales would have to be very large in order to cover the whole range of power values. the power in all other positions appears as a negative value. The power at bore sight. single dipole and folded dipole antenna. thus. Keep detector assembly away from main unit approximately 1. Keep the main unit on the table and connect power cord. Keep detector level control in the center approximately 7. Thus although the radiation pattern is identified with an antenna that is transmitting power. 6. Bring the detector assembly near to main unit and adjust height of both transmitting and receiving antenna same. Mount simple dipole (λ /2) on the transmitting mast. The radiation pattern can be plotted using the polar or the rectangular / Cartesian co-ordinates. the same properties would apply to the antenna even if it was receiving power. Ensure that there are no reflector sort things in the vicinity of the experiment such as steel structure.Experiment No. The main reason for using dB instead of linear power is that the power at the nulls is often of the order of 10. The antenna radiates the greatest amount of power along its bore sight and also receives power most efficiently in this direction. 4. i. Keep the RF level and FS adjust to minimum and directional coupler switch to FWD. Any difference between the received and radiated powers can be attributed to the difference between the feed networks and the equipment associated with the receiver and transmitter. than one can also expect its radiation pattern in these planes to be unsymmetrical. namely. the azimuth and the elevation planes.Antenna trainer kit. 3. is usually plotted at zeros degrees. 5.e. Increase RF level gradually and see that there is deflection in the detector meter . Check the mains voltage and switch on the unit. The radiation pattern of an antenna is usually plotted in terms of relative power. 2. Viva Question:- 1.8. 12. c) Gain of the antenna Result:The radiation pattern of simple dipole antenna and folded dipole antenna is as shown in graph. 9. Start taking the reading at the interval of 5 or 10 degree. Align arrow mark on the disk with zero of the goniometer scale. 10. with the help of the conversion chart given at the end of this workbook. Convert the uA readings of detector assembly in to dB’s. Adjust RF level and detector level so that the deflection in the detector meter is approximately 30-35 uA. Calculate the following with the help of graph. Which type of antenna is used for commercial purpose and military purpose? 2. 13. a) Beam width b) Front / Back ratio. 11. What is the significance of side lobes in the radiation pattern? . Plot the polar graph in degrees of rotation of antenna against level in the detector in dB’s. Switch On the transmitter by mains switch and frequency display will come on.Experiment No. 6. 3. Downlink Transmitter. Connect the satellite uplink transmitter to AC mains. The transmitter ON-OFF toggle switch will switch on off the transmission. Connecting cables. 4. and so they appear to be stationed over one spot on the globe. . The various application of Satellite are: Satellite Television Direct Broadcast Satellites Cable TV Direct Home Reception Telephone Service via satellite Data communication services Data broadcasting using Satellite Interactive data communication Procedure: - 1. Connect X1 antenna to uplink transmitter to maximum. These satellites are basically repeater stations. Communication satellite appears to hover over given spots above the equator. Set the o/p gain of uplink transmitter to maximum. one for receiving and one for transmitting the signal. Dish antennas. they have same angular velocity as the earth. this prevents interference between the uplink and the downlink. These satellites are also known as Geosynchronous satellite. These stations are stationed at a specific angle and direction from the earth. The satellite communication is essentially a microwave link repeater. The satellites are always stationed in round or elliptical orbit. 2. There are mainly two types of antenna on the satellite. Theory: Satellite communications is one of our most rapidly growing and evolving technologies bringing with it a multitude of business opportunities in the decades to come.(a) To setup an active satellite link and to demonstrate link fail operations.10 Aim: . The transmitting frequency can be selected by UP-DOWN switch. It receives the energy beamed up at it by an earth station and amplifies and return it to earth at a frequency of about 2 gigahertz away. Elliptical orbits are not good because the speed gets varied. This is to say. The speed of the satellite is same as the earth. Satellite Transponder (b) To establish an audio/video satellite link between transmitter and receiver. Apparatus: Uplink Transmitter. The frequency can be changed from 1200-1250-1300 MHz. 5. 11. Align both the transmitter and receiver antenna’s in line. Keep the downlink receiver to 1100MHz. Keep downlink frequency of transponder to 1100Mz. Place a satellite transponder between transmitter and receiver at a convenient distance of 5-7 m. The downlink receiver on-off toggle switch will switch on off the receiver. The receiver side of the satellite transponder has an on off toggle switch. Adjust transmitter uplink frequency to 1300 MHz and transponder receiver frequency to 1300MHz. 9. 15. 24. Similarly on off toggle switch on the transmitter side will switch off transmitter of satellite. The downlink receiver can be changed from 1100 – 1150 – 1200 MHz. Result:- The above shows that a successful satellite communication link has been set up between transmitter and receiver. 19. Connect the downlink receiver to the AC main and switch it on by mains switch. 14. 18. What do you mean by passive satellite? 2. Connect the satellite transponder to AC mains and switch it on by mains switch. Why microwave frequency is used for satellite communication? . 22.7. Attach R2 antenna to the downlink receiver with BNC – BNC lead. 21. which will switch off the receiver of the satellite. 13. 17. 20. The downlink receiver also has tuning potentiometer. which can be used to tuned any frequency from 950 – 1500 MHz. This is a test link for active satellite communication. 16. 8. What is transponder? What are their different functions? 3. Keep the tuning pot fully anti-clockwise 12. 23. Keep the downlink voice switch in the on position & you will be able to hear tone in the speaker of receiver. 10. Now connect a tone output to tone input of the uplink transmitter by patch cord. Viva Question:- 1. Place downlink receiver at a convenient distance of 5-7 m. Connect any other audio signal to the audio II of uplink transmitter and you will hear the music in the speaker of downlink receiver.