SU985975A1 - Device for colour synchronization of secam system receiver - Google Patents

Description

(5k) DEVICE 1№THET80Y TELEVISION RECEPTION SYNCHRONIZATION "(A SYSTEM

The invention relates to a color television technique and can be used in television receivers or video monitoring devices of a color image of a SECAM system.

A device for generating a color synchronization signal in de. an SECAN system encoder containing a delay unit whose input is connected to the second input of the switch, two outputs of which are connected to the inputs of frequency detectors of two color difference channels, the output of the first frequency detector through a serially connected normally open switch, an integrator, a color switch, an OR element connected to the control input of the first frequency detector, through a second normally open key connected in series, a filter for the frequency of 7.8 kHz and a symmetric trigger connected en to the control input of the switch CECAM

the torus, the frame extinguishing frame driver, the output of which is simultaneously connected to the inputs of both yutches, the OR element, and the second control input of the CO switch. The disadvantage of this device is low noise immunity due to the fact that when the color recognition channel is unlocked for momentum

10, the effect of interference especially increases when the transmission of color synchronization signals is stopped, and the color recognition channel remains open. At these time intervals, the receiver is not protected from the effects of interference, which are unobstructed by the color recognition trigger, which leads to a malfunction of the switch and, consequently, to incorrect color reproduction. ..

Another disadvantage of the known device is the relatively long time required for the identification channel to operate, approximately 450 µs during which the color synchronization signals are transmitted. This also leads to a relatively long time during which interference can affect the desired signal and disrupt the correct color rendition.

The purpose of the invention is to improve noise immunity.

For this purpose, in the color synchronization device of the SECAM system television receiver, containing a switch, the first input of which is connected to the input of the delay unit, and the second input is connected to the output of the delay unit, two switch outputs are connected to the inputs of two frequency difference detectors of color difference channels, the control inputs of which are connected to the output adder (a, integrator, the output of which is connected to the first input of the three-input element I, and two control inputs of the switch, respectively, are connected to two outputs of the symmetric The first trigger, the first input of which is a horizontal reversal pulse input, a color recognition trigger, a clock selector, whose input is connected to the input of the delay unit and is an input of a chrominance signal, is entered in series with the equalizing pulse selector, control pulse generator, memory trigger. TI and an EXCLUSIVE OR element whose output is connected to the first input of the adder, the second input of which is connected to the second input of the three-input element AND, and the second output of the driver the right output pulses, the third output of which is connected to the second input of the EXCLUSIVE OR element, the fourth output is connected to the first input of the color recognition triggera, the output of which is connected to the third input of the three-way element And whose output is connected to the second input of the symmetric trigger, the second trigger input the memory and the second input of the color recognition trigger, where the outputs of two frequency detectors of the color difference channels are connected, respectively, to the two inputs of the integrator, and the fifth output of the driver The pulses are connected to the second input of the equalizer pulse selector, the first input of which is connected to the output of the sync pulse selector, in addition, the third input of the equalizer selector selector and the second input of the control pulse generator are connected to the first input of the symmetric trigger.

The equalizing pulse selector is made in the form of two consecutive triggers, the first and third inputs of the equalizer selector are the inputs of the first trigger, the second input is the second input of the second trigger, and the output of the control pulse selector is the output of the second trigger.

Fig. 1 shows the structural electrical circuit of the proposed color synchronization device of the SECAM system receiver; in fig. 2 - voltage diagrams at various points of the proposed device.

The color synchronization device of the television receiver of the SECAM system contains selecto e 1 sync pulses, a selector 2 equalizing pulses, a shaper 3 control pulses, a three-input logic element And k, a color recognition trigger 5, a trigger 6 memory. An EXCLUSIVE OR 7 logic element, an adder 8 and a color electronic switch 9, which contains a symmetric trigger 10 (control unit), a delay block 11, a switch 12, frequency detectors 13 and I of two color difference channels and an integrator 15 made in the form of a filter tuned to frequency

FCTP / 2.

The selector 2 equalizing pulses made in the form of two series-connected triggers 16 and 17.

The shaper of control pulses is made, for example, in the form of a five-bit counter 18 and —I-19 (first), 20 (second), 21 (third) and AND-22 (1) and 23 (second).

The device works as follows.

Claims (2)

The chrominance signal, for example, from the output of the intermediate frequency amplifier of the television receiver image is fed to the selector. 1 sync pulses and to the input of the color electric switch 9, the delay unit .1 1 and switch 12, from the output of which alternately to the signal inputs of the frequency detectors 13 and I. Selected by the selector 1 sync pulses, the horizontal and frame sync pulses are input to 3 of the equalizer pulses , the counting input of the trigger 16, and to the installation input of the latter receives a pulse reverse flyback line. At the same time, at the output of the selector 2 of the balancing pulses, a personnel damping pulse is generated, the leading front of which is unlocked and the initial shaping of the driver 3 of the control pulses. The formation of the leading edge of a quenching extinguishing pulse takes place with the following procedure. The trigger 16 is opened at the counting input by the first equalizing impulse of a personnel extinguishing pulse, which follow with a double horizontal frequency. The output voltage of the trigger 16 is supplied to the installation input of the trigger 17, opens it, and, at the output of the trigger 17, it extracts a vertical damping pulse from the frame. The control pulse generator 3 generates five control pulse signals, the pulse duration of which is a multiple of the horizontal frequency repetition period, and their timing is determined by the time position of the color burst signal. The operation of the former 3 control pulses will be considered on the example of the SECAM-III system. Counter 18 opens for the duration of a frame extinguishing pulse and operates from horizontal retrace pulses. The required duration of the control pulses at the outputs of the imaging unit 3 and their arrangement in time is obtained by properly connecting the output signals of the counter 18 to the AND 19-21 elements and the AND-OR .22 and 23. At the fifth output of the imaging unit 3 using the first AND element 19, a pulse is selected that coincides in time with the 22nd line of the chroma signal (Fig. 2q, 6). This pulse is applied to the setup input of the trigger 17i closes it, thus forming the trailing edge 5 of the frame extinguishing pulse, which stops the counter 18 of the former 3. At the second exit of the former 3, a pulse is emitted, which overlaps the time interval the seventh to 15th lines, during which the color burst signal is transmitted in the chroma signal (Fig. 2). At the fourth output of the imaging unit 3, using the second element I 20, an impulse coinciding in time with the seventh row (Fig. 22) is extracted. This pulse is used to install memory trigger 6 into the initial (zero) state (Fig. 2e). At the third output of the imaging unit 3, using the second element AND-OR 23, a pulse is selected that overlaps the time interval from 1b to 21st line (Fig. 2e) and is fed to one of the inputs of the element EXCLUSIVE OR 7. In the initial state, a three-input the element AND Q is closed and opens when Logic 1 is simultaneously present at its three inputs. At the output of the AND Q element there appears a negative voltage drop (Fig. 2), which switches the memory trigger 6 into one state (Fig. 2n ), produces a phase correction symmetrically trigger 10, switches the color recognition trigger 5 (Fig. 2), which negatively closes the three-input element 4, stopping the color synchronization signal passing through it, which is fed to the first input of the element i i from the integrator output 15 (fig. 2l); During the time interval from 1bth to 21st LINE, both inputs of the EXCLUSIVE OR 7 element have a logic level (Fig. 2e, i), while at the output of the EXCLUSIVE OR 7 element, a logical O (Fig. 2o), which is applied to the first input of the adder 8, to the second input of which at the same time - logical O (Fig. 2-6). At the output of the adder 8 there is also a logical O (Fig. 2k), which closes the frequency detectors 13 and I. Thus, in the time interval from the 15th row corresponding to the end of the color synchronization signal transmission, to the 22nd line corresponding to the frame HR damping, the color recognition channel will be closed again for interference. During the forward course of the vertical sweep, the frequency detectors 13 and 1 are open. This is achieved by the fact that after termination of the frame extinguishing pulse at the third output of the imaging unit 3, and therefore, at the second input of the EXCLUSIVE OR 7 element, a logical form is generated. 2e), i.e. at the output of the EXCLUSIVE OR 7 element there is a logical 1 (Fig. 2k). The received signal through the adder 8 keeps the frequency detectors 13 and 1A open. In black and white transmission, when there are no color synchronization signals in the television signal, logical 1 is formed at the output of the color recognition trigger 5 (Fig. 2n which goes to the third input of the three-input element And k, but does not contain color synchronization signals at its first input) element i i in the closed (single) state and therefore at the output of memory trigger 6 there is a logical O (fig. 2m), which is fed to the first input of an EXCLUSIVE OR element 7, to the second input of which logical o (Fig. 26), as well as a logical O (Fig. 2n), which, through the adder 8, keep the frequency detectors 13 and 1A in the closed state. Therefore, during the forward run through the frame (after the 22nd line, the voltage locking the color channel corresponds to a logical zero, i.e., the color channel with black and white transmission is closed for any kind of interference signals (Fig. 2o) Using the invention, it is possible to increase the noise immunity of the color recognition circuit compared to the prototype. In the proposed device, an exact temporal reference of the beginning of the frame damping pulse to the leading edge of the first equalizing pulse of the color signal is carried out during the formation of a frame damping pulse in the device, which allows closing the color recognition channel for H0G signals, including for interference for the time exactly corresponding to the front and rear pads of the personnel extinguishing pulse, i.e. time intervals free from color burst signals. For the CEKAM-III system, these intervals correspond to the sections of the color signal from the seventh row and from the 1st to the 22nd rows. The accuracy of temporal anchoring, temporal separation of color synchronization signals is provided by the introduction of a selector of equalizing pulses and gating with the help of elements of computer technology. In addition, in the proposed device, the color recognition channel is locked after the first burst of the color burst signal is extracted, due to which the interference signal affects the integrator as well as in known devices and is present at the input of the three-input element AND, it does not open as it is covered by a color recognition trigger signal. At the same time, the switch works correctly by synchronizing with the selected color burst signal packet, which ensures correct color rendition. The proposed device can be performed on the basic elements of the TTL series in the form of an integrated circuit, which reduces the size of the device and increases the reliability of its work. Claims 1. A color synchronization device for a SECAM television receiver containing a switch, the first input of which is connected to the input of the delay unit, and the second input connected to the output of the delay block, two outputs of the switch connected to. inputs of two frequency detectors | Color difference channels, the control inputs of which are connected to the output of the adder, the integrator, the output co-jpporo connected to the first input of the three-input element I, and two control inputs of the switch respectively connected to the two outputs of a balanced trigger, the first input of which is the input of a pulse reverse horizontal sweep, color recognition trigger, selector. sync pulses, the input of which is connected to the input of the delay unit and is the input of the color signal, different TeK, h then, in order to improve noise immunity, sequentially connected equalizer pulse selector, control pulse generator, memory trigger and ELEVATOR OR element, whose output is connected to the first input of the adder, the second input of which is connected to the second input of the three-input element AND second, are included in it control pulse generator output, the third output of which is connected to the second input of the EXCLUSIVE OR element, the fourth output is connected to the first input of the color recognition trigger, the output of which is Inen with the third input of the three-input element And, the output of which is connected to the second input of the symmetric trigger, the second input of the memory trigger and the second input of the color recognition trigger, and the outputs of two frequency detectors of the color difference channels connected to the second input of the selector equalizing pulses, the first input of which is connected to the output of the clock pulse selector, in addition, v the third ahrd of the selector is equalized | x The pulses and the second input of the control pulses are connected to the first time of the symmetric trigger. 2. The device according to claim 1, wherein the equalizing pulse selector is made in the form of two series-connected triggers, the first and third inputs of the equalizer selector puller being the inputs of the first trigger, the second input is the second input of the second trigger, and the output of the selector equalizing pulse is the output of the second trigger. Sources of information taken into account during the hex test. 1. Khokhlov B.N. Decoder color TV receivers. M., Holy Hour, 1973, p. 93-95, fig. 9-15 (prototype). Fig.1 LlyJy g1 || fЦУ | UЦyU 1 // f / til i: ln 3 tn r and P t / // tu t П П П П П 7 LЯJULJlJlJ P t, -I