Rabu, 09 Maret 2011

Working Principle Television (TV)

Working Principle Television (TV)

TV RECEIVER BLOCK DIAGRAM


Block Diagram of Black & White TV Receiver



Colour TV Receiver Block Diagram

Before we study the working principles of a TV receiver, it is worth knowing a little about the journey of the object image that we usually see on TV. Images that we see is the production of a camera. The object image captured camera lens will be separated into 3 primary colors of red (Red), green (Green) and blue (Blue). Results will be emitted by the TV transmitter (Transmitter) in the form cromynance signal, luminance signal and syncronisasi.

Besides pictures, television transmitters also carry voice signals are transmitted along with the picture signal. Images transmitted by the system of amplitude modulation (AM), while the sound with a system of frequency modulation (FM). Both systems are used to avoid the noise (noise) and interference.



Objects Into Television Distribution


TV CHANNELS AND STANDARD TRANSMITTER

The group assigned to the transmission frequency signal is called channel (channel). Each has a 6 MHz channel in one field frequencies (bands) are allocated to commercial television broadcasters, namely:

a) The field of low frequency VHF channels 2 to 6 (54-88 MHz).

b) the field of high-frequency VHF channels 7 to 13 (174-216 MHz).

c) UHF channels 14 to 83 (470-890 MHz)

There are 3 TV transmitter systems are as follows:

a) National Television System Committee (NTSC) used in USA

b) Phases Alternating Line (PAL) used in the UK

c) Sequential Couleur a'Memorie (SECAM) used in France

While Indonesia's own use PAL system B. Thing that distinguishes these systems is the image format, the carrier frequency range image and sound carriers.


WORKING PRINCIPLE OF TV RECEIVER

Model and TV series block type varies, depending on the brand of TV used.

Broadly speaking, the block has the following functions:

a) Antenna Television

Antenna TV capture RF signals from television transmitters. Antennas are classified based on its construction is 3, ie:

1) Yagi Antenna

2) The period of logarithmic antenna

3) Antenna Loops

Another classification based on the received wave frequency bands are:

1) VHF Low Channel

2) High VHF Channel

3) UHF Channel...


Low VHF Antennas


VHF Antenna Height


UHF Antenna


Antenna Period logarithmically


Loop Antenna


Tuning circuit (tuner)

This circuit consists of booster high frequency (HF amplifier), mixer (Mixer) and local oscillator. Tuning circuit functions to receive the incoming TV signal and convert it to IF frequency signal.
Tuner

The amplifier circuit IF (Intermediate Frequency)

The series serves as a signal booster up to 1000 times. The resulting output signal tuner (Tuner) is a weak signal and very dependent on the distance transmitter, receiver and landscape position. Red circle indicates that some of the IF circuit inside tuner.
IF amplifier

Detector Video Series

Functioning as a composite video signal detection that comes out of the picture IF amplifier. It also serves to muffle the sound signal which will result in poor image quality.

Video amplifier circuit

The series serves as a reinforcement signal from the detector original video so it can run a picture tube or CRT (Catode Ray Tube).

The series of AGC (Automatic Gain Control)

AGC circuit serves to stabilize its own input television signal's changing so that the output becomes constant. Red circle indicates the component that resides in some of AGC and some tuner IC.
AGC circuit

Stabilizer circuit TV Receiver Waves.

Stabilizer circuit TV wave receiver such as AGC and the AFT. Automatic Fine Tuning function set the picture carrier frequency of the IF amplifier automatically.

Synchronization Deflection circuit

This series consists of four blocks namely: synchronization circuit, a series of vertical deflection, horizontal deflection circuit and high voltage generator circuit.
Horizontal deflection circuit

Voice circuit

The voice we hear is the work of this series, the sound IF carrier signal is detected by the frequency modulator (FM). Previously, this signal is separated from the carrier signal image: Rock On.

Series Power Supply (Power Supply)

Power Supply Series

Function to convert AC into DC current which then distributed throughout the circuit.

In the figure, the power supply circuit is limited by the white line and red boxes. Areas within the white line is a series of inputs which is a region of high voltage (Live Area). Meanwhile, the area within the red box is the output power supply which then distributes the DC voltage to the entire TV series.

Amplifier Krominan

This amplifier strengthens the signal frequency of 4.43 MHz for krominan are modulated in the signal V (RY signal) and signal U (BY signal). 2 MHz bandwidth amplifier.

Color Synchronization

In a series of sincronisasi color, the color synchronizing burst signal is removed from the composite color video signal.

Automatic Color Control (ACC)

If the explosion signal amplitude rises, the ACC issued a steering voltage to minimize the strengthening in the color.

Color Killer (which create color)

The circuit is useful to suppress the color amplifier, when it is no krominan incoming signal. It happened at the reception is a black and white.

Phase Switching circuit 180 (splitting Color)

From krominan amplifier, the signal is fed to the color. Splitter (splitting color). It separates the color splitting the modulated signal with the signal V from the modulated signal with the signal U. Splitting the color of PAL switch and some resistors. At the end of each line, during the withdrawal line PAL then rotated 180 V signal. U did not experience signal phase rotation.

Color demodulation

Using a color demodulator, then the color difference signals in demodulation of the signal U and V. Because the transmitter, the signals were modulated with a carrier system suppressed / eliminated and only the second sub-carrier side line (side band sub carrier) that exist. In order to demulation carrier signal into the original color back, then needed a sub carrier 4.43 MHz with phase and the exact same frequency as the transmitter

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