T ELEVISION - 2 1

Simplified cross-sectional view of a Vidicon TV camera tube 2Communication Systems (EC-326)

Elements of a picture tube 3Communication Systems (EC-326)

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 4Communication Systems (EC-326)

A Rectangular Picture Tube 5Communication Systems (EC-326)

Monochrome Picture Tube  One Electron Gun  Continuous phosphor coating Colour Picture Tube  Three electron beams  Three phosphors. 6Communication Systems (EC-326)

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Electron Gun Control Grid Accelerating Grid Focusing Grid 8Communication Systems (EC-326)

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Vidicon camera tube cross-section 18Communication Systems (EC-326)

Circuit for output signal from a Vidicon camera tube 19Communication Systems (EC-326)

Leaky Capacitor Concept 20Communication Systems (EC-326)

THE PLUMBICON Target Details Output Signal Current Characteristics 21Communication Systems (EC-326)

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A sync generator driving several camera units Switcher for selecting any camera output to one monitor. 23Communication Systems (EC-326)

24 Block diagram of a drive and sync pulse generator

Communication Systems (EC-326)25 Block Diagram of a Television Transmitter

Rear view of a black and white receiver with the back removed 26Communication Systems (EC-326)

Block diagram of a monochrome television receiver 27Communication Systems (EC-326)

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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 29Communication Systems (EC-326)

V S B CORRECTION 30Communication Systems (EC-326)

VIDEO DETECTOIN 31Communication Systems (EC-326)

Detector and filter circuit of a radio receiver 32Communication Systems (EC-326)

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. 33Communication Systems (EC-326)

FUNCTIONS OF THE COMPOSITE VIDEO SIGNAL 34Communication Systems (EC-326)

SOUND SIGNAL SEPARATION 35Communication Systems (EC-326)

Block diagram of AGC system 36Communication Systems (EC-326)

High Voltage (EHT) Supply 37Communication Systems (EC-326)

Deflection Circuits 38Communication Systems (EC-326)

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Operating Controls of a T V Receiver  Channel Selector  Fine Tuning  Volume  Tone  Contrast  Brightness  Vertical Hold  Horizontal Hold. 40Communication Systems (EC-326)

Next… Colour Television… 41Communication Systems (EC-326)