SU1239891A1 - Generator of clock pulses - Google Patents

Abstract

The invention relates to television and can be used to work with a video recorder. The stability of the frequency and phase of the generated clock pulses increases. To obtain clock pulses of the frequency of 17625 MHz, the device contains a crystal oscillator (KG) 8 and an LC generator 23. KG 18 is connected to a pulsed phase-locked loop (SIFAP) circuit consisting of a counter 12, a sawtooth voltage generator (L

Description

13, a phase detector (PD) 4, a repeater 16, and a low-pass filter 17. The LC generator 23 is included in a CIFPCH consisting of a counter 14, a sawtooth generator 15, a PD 5, a repeater 21, and a low-frequency output 22. The horizontal pulses necessary for maintaining both digital CIFAPs are extracted from the input signal by the horizontal pulses extraction unit 1, are formed by the shaper of 3 horizontal pulses and are fed to the other inputs of PD 4 and 5. The capture in the CIFAPCH quartz oscillator 18 is determined by the capture recorder CG 6, which impulses come from ormirovatel 3 lowercase

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The invention relates to a television engineering technique and is an integral part of the synchro generator of a digital time distortion corrector, designed to work with video recorders.

The purpose of the invention is to increase the stability of the frequency and phase of the shape of the clock pulse,.

Fig. 1 shows a structural electrical circuit of a clock pulse generator; FIG. 2 is a circuit diagram of the capture generator of the quartz oscillator, the capture recorder of the LC generator, the first integrator, the second integrator, the capture generator of the quartz oscillator, the capture generator of the LC generator, the switching unit and the capture indication generator,

The clock pulse generator contains a block of lowercase pulse extraction, the first input of which is the input of the clock pulse former, and the second input is connected to the output of the detector of 2 pulses. The first output of the lowercase pulse extraction unit 1 is connected to the former of 3 lowering pulses, and the second output is connected to the input detector 2 pulses. The first exit shaper 3

39891

pulses from the counter 12. The signal from its output through the integrator 8 is fed to the formatter 9 of the capture signals. From its output, a signal indicating the presence or absence of synchronism in this CIFAPCH enters the switching unit 19 and the display signal generator 24. Similarly, the capture of the CIFAPC LC generator 23 is fixed. The signal from the imaging signal generator 24 is used to switch the clock pulses to the output either from KG 18 / or from the LC generator 23 or from the autonomous KG.20-depending on the frequency stability of the input pulses. 2 Il.

line pulses connected to the first input of the first phase detector 4 and the first input of the second phase detector 5 The second output of the imaging unit 3 horizontal pulses connected to the first input of the capture generator section 6 of the quartz oscillator and the first input of the capture generator module LC. The output of block 6 registration capture quartz oscillator through the first integrator 8 is connected to the input of the imaging unit 9 capture signal of the quartz oscillator. The output of the LC generator capture register 7 via the second integrator 10 is connected to the input of the capture generator signal 11 of the LC generator. The first output of the first counter 12 is connected via the first saw voltage generator 13 to the second input of the first phase detector 4.

The first output of the second counter is 14 I

A second generator 15 of the sawtooth voltage is cut to the second input of the second phase detector 5. The second output of the first counter 12 is connected to the second input of the quartz oscillator registration unit 6, and the second output of the second counter 14 is connected to the second input of the LC generator capture unit 7. p output of the first phase detector 4 through serially connected

the first repeater 16, the first low-pass filter (LPF) 17, the crystal oscillator 18 is connected to the first input of the switching unit 19 and to the input of the first counter 12. The second input of the switching unit 9 is connected to the output of the autonomous to the Var 20 generator The output of the second phase detector 5 through The second repeater 21, the second LPF 22 and the LC generator 23 are connected in series with the third input of the switching unit 19 and the input of the second counter 14, the output of the capture signal generator 11 The LC generator is connected with the fourth input of the switching unit 19 and with the first the shaper 24 signal capture indications. The output of the imaging unit 9 of the quartz oscillator signal is connected to the fifth input of the switching unit 19 and to the second input of the imaging sensor 24 of the capture indication, the output of which is connected to the sixth input of the switching unit 19 and to the input of the autonomous quartz oscillator 20. The output of the clock pulse generator is the output of the switching unit 19,

Shaper clock pulses works as follows.

To obtain clock pulses of frequency 17.625 MHz, synchronous with the input signal, the device contains a crystal oscillator 18 and an LC generator 23, each of which is included in its own pulse phase automatic frequency control (IFAP) circuit.

The IFAPCH crystal oscillator 18 consists of the first counter 12, the first sawtooth 13 generator 13, the first phase detector 4, the first repeater 16 and the first low-pass filter 17, the IFAPCH circuit 23 of the LC generator 23 consists of the second counter 14, the second generator 55 of the sawtooth eg the second phase detector 5, the second repeater 21 and the second low pass filter 22,

The horizontal pulses, which are not required to drive both IFAP lines, are separated from the input video signal in the horizontal pulses extraction unit 1, are formed by the former 3 horizontal pulses and are fed to the inputs of the first phase detector 4 and the second phase detector 5,

The first phase detector 4 compares the frequencies of the input horizontal pulses and the reference signal of the crystal oscillator 18. The reference signal in the IFAPF circuit is a sawtooth voltage generated by the first sawtooth voltage generator 13 from the output of the first counter 12, in which division is made clock pulses of the crystal oscillator 18 to the line frequency. At the output of the first phase detector 4, an optic signal is formed, the magnitude and sign of which correspond to the frequency detuning between the input signal and the odor signal, which through the first repeater 16 and the first low-pass filter 17 enters the control input of the quartz oscillator 18, changing its oscillation frequency.

In the second phase detector 5, the frequencies of the input horizontal pulses and the reference signal of the LC generator 23 are also compared. The reference signal in the IFEPH circuit is a ramp voltage generated by the second ramp voltage generator 15 of the pulses from the output of the second counter 14 in which is used to divide the clock pulses of the LC generator 23 to a horizontal frequency. At the output of the second phase detector 5, an error signal is generated, the magnitude and sign of which correspond to the frequency detuning between the input signal and the reference signal, which through the second repeater 21 and the second low-pass filter 22 enters the control input of the LC generator 23, changing its oscillation frequency

To determine the capture in the input1 chains, the additional blocks that form the control signals by which the reference sources of clock pulses of the clock pulse generator are switched depending on the frequency stability of the input video signal source. Block 6 of registering the capture of a quartz oscillator, made on trigger 25 (FIG. 2), detects the capture in an IFAP circuit by reading the pulses of the first counter 12 supplied to the C input of the trigger 25, input pulses to the D input of the trigger 25 from the output of the imager 3 lower case pulses.

From the outputs of the trigger 25 of the registration unit 6 for capturing a quartz oscillator, the control signals in the form of DC voltages are fed to the first integrator 8, made by resistors 26 and 27 and capacitors 28 and 29 and providing a smooth change of the control signal with a predetermined time. From the output of the first integrator 8, the signal is fed to the driver 9 of the capture signal of the quartz oscillator, consisting of a key circuit made on transistors 30; and 31 and the resistor 32 and the trigger 33, In this case, the outputs of the key circuit are connected to the R and S inputs of the trigger 33, ensuring its switching. Thus obtained, at the outputs of the trigger 33 of the driver of the capture signal of the quartz oscillator, the control signals in the form of constant voltages indicate the presence or absence of synchronization in the IFAPH circuit with the quartz oscillator 18.

The formation of the control signal of the LC generator is carried out using a block for registering the capture of the LC generator 7, performed on the trigger 34, the second integrator 10, performed on the resistors 35 and 36 and connectors 37 and 38, and the driver P of the capture signals of the LC generator , performed on the transistors 39 and 40, the resistor 41 and the trigger 42.

The interconnection and operation principle of the blocks are similar to those described for an IFAPCH with a quartz oscillator 18. The control signals in the form of constant voltages obtained at the outputs of the trigger 42 of the former 11 capture signals of the LC generator of the LC generator indicate the presence or absence of synchronism in the IFAPCH circuit with the LC generator 23

The control signals from the output of the capture generator 9 of the quartz oscillator and the capture generator 11 of the LC generator signal arrive at the capture indication signal 24 of the capture indicator HE 43, the output of which produces a signal of the presence of capture in the form of a constant voltage at the capture one of the IFAP lines or in both at the same time

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capture, that in the absence of capture in both circuits of the EPRI or the absence of an input signal. This signal is used to switch various video recorder systems, as well as to switch on an autonomous quartz oscillator 20,

Vph; od1-1e signals from the output of the generator 9 of the signal and the capture of the quartz oscillator, the generator 11 of the signal capture LC-generator and the former 24 of the signal indicating the capture and are the control unit 19 switching, performed on three logic elements And 44-46 ( 2) in which the switching frequency clock frequency of 625 MHz is switched from the crystal oscillator 18, the LC generator 23 and the autonomous, crystal oscillator 20 in the following sequence depending on the frequency stability of the input video signal source.

When the frequency of the input pulses is stable, both generators 10: the crystal oscillator 18 and the LC generator 23 are in the capture mode, and a clock frequency of 17, 625 MHz with a high temporal stability from the slave quartz oscillator passes to the output of the switching unit 19. generator 18,

When the frequency of the input pulses is of the order of 10-10 and there is no capture in the IFAPCH circuit with a quartz oscillator 18 and there is a capture in the IFAPCH circuit with an LC generator 23, the clock pulses of 17,625 MHz from the slave LC- pass through the output of switching unit 19 generator 23,

When the frequency of the input pulses is less than 10 and the IFPCH has not captured in both circuits, the clock pulses from the LC generator 23 and the crystal oscillator 18 are turned off by the circuit of the pickup generator 24 of the capture signal, and in this case the frequency clock 17 passes to the output of the switching unit 19 , 625 MHz from an autonomous quartz oscillator 20,

In the absence of the input video signal in the pulse detector 2, a control signal is generated that turns off the input pulses on the IFAPH circuit, and there is no capture in both IFPCH circuits.

and the output of the switching unit 19 is the clock pulses of the frequency 17.625 MHz with high temporal stability from the autonomous quartz oscillator 20.

Due to the presence of integrators 9 and 10 in the IFAPH circuits, the switching of control signals and, consequently, the output clock pulses in the switching unit 19, when synchronization is established in the IFAPH circuits or its disruption, occurs smoothly without jumps, ensuring the stability of the reproduced image.

Claims (1)

Invention Formula A clock pulse shaper, comprising a row pulse extraction unit, the first input of which is the clock pulse shaper input. The pulse detector, whose input is connected to the first output of the horizontal pulse output unit, the horizontal pulse generator, whose input is connected to the second output of the horizontal pulse extraction unit, the first phase detector, the first input of which is connected to the first output of the horizontal pulse generator, the first sawtooth generator the output of which is connected to the second input of the first phase detector, the first counter, the first output of which is connected to the input of the first sawtooth generator, the first repeater, the first low pass filter, the crystal oscillator and the switching unit, the first repeater input connected to the output of the first phase detector, and the output of the switching unit is the output of the clock generator, connected in series to the second low pass filter and the LC generator, an autonomous quartz oscillator, the output of which is connected to the second input of the switching unit, is so that, in order to increase the stability of the frequency and phase of the generated clock pulses, is led block of Registration I quartz oscillator capture, capture LC generator registration unit, first and second integrators, quartz oscillator capture signal former, LC oscillator capture signal generator, second counter, second saw unit, shaped voltage, second phase detector, second repeater, the driver of the capture indication signal, with the output of the pulse detector connected to the second input of the horizontal pulse extraction unit, the first output of the horizontal pulse generator connected to the first input of the second phase detector, and the second output to the first input of the capture generator register of the quartz oscillator and to the first input of the capture generator register of the LC generator, the second output of the first counter is connected to the second input of the capture recorder of the crystal oscillator, and the input of the first counter is connected with the output of the crystal oscillator, the first output of the second counter through the second generator of the sawtooth voltage connected in series, the second phase detector and the second repeater are connected to the input of the watt cerned lowpass filter, the generator output is connected to the third input of the switching unit and the input of the second counter, the second output of the second counter is connected to the second input of the LC generator capture registration unit, the output of which is connected through the second integrator and the capture generator signal of the LC generator is connected to the fourth input of the switching unit and the first input unit of the capture indication generator, output of the capture generator register through the serial the first integrator and the capture generator of the quartz oscillator are connected to the fifth input of the switching unit and to the second input of the indicating signal generator capture, the output of which is connected i with the sixth input of the switching unit and the input of an autonomous quartz oscillator. cznr lg1 jV 72 Ib 2 2 / f | 27 II Lrzljt  l iitLL { fel five" | 1 AND n and 11 36 t  and „: ICjL 7 33 J one //. Compiled by Fedotov Editor A.Sabo Tehred O.Sopko Proofreader E.Roshko Order 3411/58 Circulation 624 Subscription VNIIPI USSR State Committee for inventions and discoveries P3035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, - st. Project, 4