PAL-D Colour TV Receiver – Block Diagram | New Topic

In this note, we are going to know about PAL-D Colour TV Receiver and Block Diagram of PAL-D Colour TV Receiver. Welcome to Poly Notes Hub, a leading destination for engineering notes.

Author Name: Arun Paul.

What is PAL-D Colour TV Receiver?

The PAL-D Colour TV Receiver is a television system that uses the Phase Alternating Line (PAL) standard, specifically the PAL-D variation, which is widely used in China, India, and portions of Eastern Europe. It uses the VHF and UHF frequency bands to receive analog television transmissions in the PAL format.

Significances of PAL-D Color TV Receiver

• Video System: PAL (Phase Alternating Line)
• Audio System: FM Modulation
• Carrier Frequency: Video – 38.9 MHz and Audio – 33.4 MHz
• Channel Bandwidth: 7 MHz or 8 MHz (depending on region)
• Number of Lines: 625 lines per frame
• Frame Rate: 25 frames per second (fps)
• Sound Carrier Separation: 5.5 MHz
• Color Subcarrier Frequency: 4.43 MHz
• Tuner Frequency Range: VHF (Very High Frequency) – 48.25 MHz – 230 MHz and UHF (Ultra High Frequency) – 470 MHz – 862 MHz
• Intermediate Frequency (IF): Picture IF – 38.9 MHz and Sound IF – 33.4 MHz
• Power Supply: Voltage – Typically 110V – 240V AC and Frequency – 50Hz / 60Hz
• Aspect Ratio: 4:3 or 16:9 (depending on model)
• Tuning System: Manual or Auto Tuning (Analog)
• Audio Output: Mono or Stereo (A2 or NICAM standard, depending on model)
• Connector Ports: RF Input, AV (Audio/Video) Input/Output, SCART (in some models)
• Screen Type: CRT (Cathode Ray Tube) or Early LCD Models

PAL-D Colour TV Receiver Block Diagram

Here is the block diagram of PAL-D Colour TV Receiver –

Types of Colour System in PAL-D Color TV Receiver

1. NTSC: In this system, the weighted colour difference signals, called I and signals are present on each line simultaneously and maintain in mutual phase difference of +90°. Modulation technique is AMSC. In this system, phase error if any produces a different colour (and for this reason Americans jokingly call their system as ‘Never The Same Colour’.
2. PAL: In this system, the weighted colour difference signals are called U and V signals. They maintain a phase difference of 90° between each other, but on one scanning line, V is +90° away from U, and on the next line, it is -90° from U thus, both signals are present simultaneously on each line, but with a different phase difference. This eliminates phase error automatically. Due to requirement of automatic phase channing switch, the PAL system is costlier than NTSC system. Modulation is AMSC type as in NTSC. India uses PAL system.
3. SECAM: In this system, the weighted color difference signals are called DB and DR. They do not appear simultaneously on any line. If DB appears on one line, then DR appears on the next line. So, the question phase difference and hence phase error does not arise. The modulation technique is FM. It is the cheapest system, but the resolution is reduced to 50%. For colors, high resolution is not needed.

In PAL system, the weighted color difference signals are called U and V signals. They maintain a phase difference of 90° between each other, but on one scanning line, V is +90° away from U, and on the next line, it is 0-90° from U, thus, both signals are present simultaneously on each line, but with a different phase difference. The eliminates phase error automatically. Due to the requirement of an automatic phase-changing switch, the PAL system is costlier than the NTSC system. Modulation is AMSC type in NTSC. India uses the PAL system.

The significance of various blocks (in the block diagram depicted above) are discussed below –

• Tuner: It selects bend and channel. It tunes the selected amplify VHF/UHF signals, convert into IF.
• VIF Sub-Section: It amplifies IF signals, provides input for A circuit, separates 5.5 MHz inter- carrier FM sound signals etc.
• Sound Section: Inter- carrier 5.5 MHz FM sound signal is separated sound take off circuit, then SIF amplifier, FM detector, de- emphasis, and amplifier and loud speaker for sound.
• AGC Sync Separator and Deflection Circuits: AGC is used to control the gain of various amplifying sections automatically. The sync separator filters out H & V sync signals from composite video signal and the deflection circuits used to modify the signal to drive the H & V deflection circuits used to modify the signal to drive the H & V deflection plate assembly.
• Luminance Section (Y Channel): Composite color video signal recovered by video detector includes – a) horizontal and vertical blanking pulses, b) horizontal and vertical sync pulses, c) Luminance signal Y, d) Colour burst, and e) Chromo signal.
• PAL-D Decoder: It recovers U & V signals which are applied to matrix. I adding U, V and Y signals in definite proportion, matrix recovers R, G, signals. These are amplified and applied to cathode to drive picture tube.
• Raster Section: It provides vertical and horizontal deflection circuit for deflection yoke at the neck of picture tube.