معالجة الحزم الجانبية لاشارة اللون .. كتاب التلفزيون الملون والعادي

20-6 Processing of side bands of the color signal:

There are several ways to process the color signal - one of these ways is to use the complete I and C signals, as in the box diagram in Figure (13-20).

Processing my 1-Q signal:

The entire color signal is taken from the visual stage and fed to a bandpass amplifier
(Band pass). A tab pulse is also applied to this pass beam amplifier, which shuts down the amplifier by applying a pulse directed from the horizontal deflection output transformer, and this pulse arrives only during the horizontal return period when the color pulse signal passes in this sector. By removing the splash of color from the beam amplifier, we prevent the return of the color signal from disturbing the balance of the screen valve. This imbalance can be increased if the continuous composite recalls are installed in the coloration channel above the color streams, with more than the natural color signal. The DC bias voltage coming from the color killer circuit also reaches the beam amplifier. This circuit is located in the color synchronization sector in the future, and the function of the color killer circuit is to make the amplification circuit bias stop its work when there is no color signal, i.e. when receiving a signal in black and white only. This is to prevent color signals from appearing on the screen during monochromatic reception. These color signals result from interference or black and white signals that reach rates 1 and 2. At the output of the beam amplifier, there is a beam filtering circuit to allow the passage of signals with a frequency of (304-5.4) MHz. It suppresses the strength of other frequencies, and this filtering circuit separates the signal of the side beams of color from the signal that contains black and white information, which is the luminance signal (Y).

Color setting:

The bandpass filter is connected to the Chroma Control switch, and by means of this switch the color signal can be obtained at the amount we see fit to reach the next detectors. This setting determines the saturation of the colors

(color depth) on the screen. This key is located on the front of the device and has multiple names such as (Color), (Chroma), (Color Saturation) or (Color Intensity).

7-20 Color reagents:

After the stage of enlarging the side beams of color and adjusting them with the (color intensity) key - the signal is fed equally to the color detectors (1) and (Q) - and a signal (4.43 MHz) reaches these detectors. It is the missing color sub-carrier signal that must be superimposed or combined with the color signal in the detectors. This is so that the original (1 and Q) signals can be detected. Both sections (1 and Q) receive a signal voltage
(4.43 MHz) - The only difference between them is that one of them differs from the other by an angle of (90). This characteristic of the page difference between the two signals is necessary because the color signal has been modified in the transmitter in an opposite way. Receiving the color signal leads to the work of the color section and channel. It represents the output of the two detectors
The original signal (I) and Q) sent by the station after its modulation. The (1) signal is then inserted into a bandwidth filter whose range is from 1.5MHz to a time delay line of about 05 microns (seconds) - and it may pass through additional amplification stages before it reaches the collector or (matrilex) with positive and negative polarity. Dual polarity (I) signals are required downstream to generate red, green and blue voltages. The single phase separator secures the negative and positive signals of (1).

Transmission of the Q signal in the narrow pass bandwidth 0 - 0.5 MHz. The Y signal is delayed by 1 microsecond for the same reason. The delay difference between the luminance signal Y and the 1 signal is due to the difference in the characteristics of the two circuits. In the (Y) channel, the beam-pass of the circuit is between (0-3.5 or 4 MHz), while in the (I) channel, the beam-pass is from 0 to 1.5. MHz - This narrower range causes some delay and requires less additional delay to slow the I signal further
of the Q signal - In the Q channel the exposed signal passes through a bandpass filter having a bandpass of 0.5 megahertz (MHz). It reaches the phase separator to produce the negative and positive Q signal, which is capable and valid for the work of the matrix.

Signs 1,Y,Q:

The signals reach (1) to the matrix (the matrix), and by installing these three signals, the voltages of the three colors - red - green - blue - are installed in the transmission to generate signals 1, Y, Q - and a circuit of simple resistors connected as in the figure can be used

(20 - 13). At the output of the matrix, the voltages of each color are amplified separately and, after passing through the DC rectifiers, are led to the special networks in the three-bucket colored LED.