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T ELEVISION - 2 1Communication Systems (EC-326). EC 326 COMMUNICATION SYSTEMS UNIT - III T Srinivasa Rao Dept. of ECE Bapatla Engineering College.

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Presentation on theme: "T ELEVISION - 2 1Communication Systems (EC-326). EC 326 COMMUNICATION SYSTEMS UNIT - III T Srinivasa Rao Dept. of ECE Bapatla Engineering College."— Presentation transcript:

1 T ELEVISION - 2 1Communication Systems (EC-326)

2 EC 326 COMMUNICATION SYSTEMS UNIT - III T Srinivasa Rao Dept. of ECE Bapatla Engineering College

3 Part 1 Vision characteristics and scanning systems, Composite video signal. Part 2 Camera tubes: Principle of operation, Image Orthicon, Vidicon, Plumbicon. Part 3 Block diagram of broad cast TV transmitter Block diagram of broadcast TV receiver. 3Communication Systems (EC-326)

4 Simplified cross-sectional view of a Vidicon TV camera tube 4Communication Systems (EC-326)

5 Elements of a picture tube 5Communication Systems (EC-326)

6 Signal transmission paths illustrating compatibility between colour and monochrome TV systems. R, G and B represent three camera tubes which develop video signals corresponding to the red, green and blue contents of the scene being televised 6Communication Systems (EC-326)

7 A Rectangular Picture Tube 7Communication Systems (EC-326)

8 Monochrome Picture Tube  One Electron Gun  Continuous phosphor coating Colour Picture Tube  Three electron beams  Three phosphors. 8Communication Systems (EC-326)

9 9

10 Electron Gun Control Grid Accelerating Grid Focusing Grid 10Communication Systems (EC-326)

11 11Communication Systems (EC-326)

12 12Communication Systems (EC-326)

13 13Communication Systems (EC-326)

14 14Communication Systems (EC-326)

15 15Communication Systems (EC-326)

16 16Communication Systems (EC-326)

17 17Communication Systems (EC-326)

18 18Communication Systems (EC-326)

19 19Communication Systems (EC-326)

20 Vidicon camera tube cross-section 20Communication Systems (EC-326)

21 Circuit for output signal from a Vidicon camera tube 21Communication Systems (EC-326)

22 Leaky Capacitor Concept 22Communication Systems (EC-326)

23 THE PLUMBICON Target Details Output Signal Current Characteristics 23Communication Systems (EC-326)

24 24Communication Systems (EC-326)

25 A sync generator driving several camera units Switcher for selecting any camera output to one monitor. 25Communication Systems (EC-326)

26 26 Block diagram of a drive and sync pulse generator

27 Communication Systems (EC-326)27 Block Diagram of a Television Transmitter

28 Rear view of a black and white receiver with the back removed 28Communication Systems (EC-326)

29 Block diagram of a monochrome television receiver 29Communication Systems (EC-326)

30 30Communication Systems (EC-326)

31 CHOICE OF INTERMEDIATE FREQUENCY IN TV (i) Image Rejection Ratio (ii) Pick-up Due to Local Oscillator Radiation from TV Receivers (iii) Ease of Separation of Modulating Signal from IF Carrier at the Demodulator (iv) Image Frequencies Should Not Lie in the FM Band (v) Interference or Direct Pick-Up from Bands Assigned for other Services (vi) Gain 31Communication Systems (EC-326)

32 V S B CORRECTION 32Communication Systems (EC-326)

33 VIDEO DETECTOIN 33Communication Systems (EC-326)

34 Detector and filter circuit of a radio receiver 34Communication Systems (EC-326)

35 REQUIREMENTS (a) The detector load must provide a suitable impedance as seen through the diode, at input of the detector to tune and damp secondary of the last IF coupling circuit correctly. (b) The detector load must remove from the output, the IF content in the signal as much as possible. For this purpose the load usually includes one or two low-pass filter sections. (c) The detector load should have a trap circuit (a series rejector circuit) for separating the intercarrier sound signal. (d) The detector load must also include a provision to boost the higher video frequencies to compensate for the loss due to input capacitance of the video amplifier. 35Communication Systems (EC-326)

36 FUNCTIONS OF THE COMPOSITE VIDEO SIGNAL 36Communication Systems (EC-326)

37 SOUND SIGNAL SEPARATION 37Communication Systems (EC-326)

38 Block diagram of AGC system 38Communication Systems (EC-326)

39 High Voltage (EHT) Supply 39Communication Systems (EC-326)

40 Deflection Circuits 40Communication Systems (EC-326)

41 41Communication Systems (EC-326)

42 Operating Controls of a T V Receiver  Channel Selector  Fine Tuning  Volume  Tone  Contrast  Brightness  Vertical Hold  Horizontal Hold. 42Communication Systems (EC-326)

43 Next… Colour Television… 43Communication Systems (EC-326)


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