SU415831A1 - - Google Patents

Description

PAL color synchronization consists of 10 oscillations of the frequency of the color subcarrier, which changes the phase shift relative to the axis V-V from line to line by ± 45 °. The selected signal is fed to the input of the phase detector 4 gated by the horizontal frequency pulses, as well as through phase shift 1, 5th puppy 5 pa to the delay line 6. Moreover, the delay time of line 6 is chosen to be shorter than the color synchronization signal duration. At the time of occurrence of the color synchronization signal at the output of the delay line 6, and hence at the input 7 of the phase detector 4, the latter opens for a time equal to the difference between the duration of the color synchronization signal and the delay time of the delay line 6. During this time, the horizontal frequency pulses are phase the detector 4 produces an error voltage, the value of which depends on the phase difference of the signals at its inputs, which after a day of control 8 is supplied to the phase shift, to its chain 5, by adjusting the phase c A signal passing through the delay line 6. From the output of the delay line 6, the signal also goes to the input of a positive feedback circuit containing a compensating amplifier 9 that is open for the duration of the active part of the line and closed at the time of arrival of the color synchronization signals. Passing the noise amplifier 9 to compensate for the losses in the delay line 6, the signal is fed back to the input of the phase-shifting chain 5, and the processes are repeated until the next color burst signal arrives. This allows the input of the feedback circuit, and thus the input of the single-pole switch 10 of the phase recovery circuit of the PAL color sub-carrier, to be a color subcarrier during the active part of the line. The phase of the color burst signal changes from line to line, so to get a single-pole switch 10 at the input of a reconstructed sub-network with a phase corresponding to the phase of the color synchronization signal of the defined string n, it is necessary to interrupt the generation of the one-carrier that has the phase one. The latter is accomplished by turning off the gated amplifier 9 for the time of arrival of the color burst signal. The recovered subcarrier, which is from the line: to the line is a phase shift of + 45 ° with respect to the axis V-Y, it is connected to the input of a single-pole switch 10, the outputs of which by a half-line frequency meander supplied to the control values 11 are connected to one of the two phase-shifting chains during each line 12 and 13 (± 45 °). With proper synchronization of the single-pole switch 10 at the outputs of the phase-shifting chains 12 and 13, and hence at the input of the phase-shifting chain 14, a continuous subcarrier with a phase corresponding to the B-Y axis. This subcarrier is then supplied to the input of the synchronous detector 15 directly, and to the input of the synchronous detector 16 through the phase-shifting chain 17. When receiving SECAM signals, the output of the gated horizontal frequency pulses of the amplifier 3 produces oscillations of a certain frequency that occur during the entire line. The oscillation frequency varies from row to row from 4.25 MHz to 4.4 MHz, so the signals supplied from the output of amplifier 3 to the frequency detector 18 result in the appearance of half-line frequency meanders at its paraphase outputs. Taking into account the fact that the oscillation frequency at the output of amplifier 3 determines the type of color difference signal that goes during the next line, it is possible to connect the paraphase outputs of the frequency detector 18 to the control circuit 19 and 20 of the switch 21 in a definite way and thus provide color synchronization of the decoder devices when receiving signals SECAM. When receiving signals PAL device works as follows. Consider the 1st line carrying color information on the PAL system. During the duration of the color synchronization signal, the output of the amplifier 3, which is gated with the horizontal frequency pulses, appears to signal 22, with a phase shift equal to -f45 ° relative to the V-V axis (Fig. 2). This signal, having passed through the phase-shifting chain 23 (Fig. 1) (-f45 °) with phase 24 (Fig. 2), is fed to the input of the phase detector 25 (Fig. 1). At its other input, as well as at the input of the switch 10 and the outputs of the phase-shifting chains 12 and 13, the signals 26, 27 and 28 (Fig. 2) are missing. Therefore, the voltage and the outputs of the phase detector 25 are absent. Suppose that the switch 10 is in such a state that its input is connected to the input of the phase-shifting circuit 12 (+ 45 °). Moreover, the switch is designed in such a way that to transfer it from one state to another it is required that the voltage applied to the AND control circuits be higher or lower than a strictly defined threshold. After a time equal to the duration of the color burst signal, the signals 29 and 30 will appear over the entire length of the line at the input of the switch 10 and the output of the phase-shifting chain 12 (Fig. 2). The signal 31 (Fig. 2) at the input of the phase decuctor 25 will be shifted by -45 ° with respect to the signal at the input of the phase shifter 14, which gives the phase shift of -45 ° at the frequency of the PAL color carrier. At the time of arrival of the next line P, the duration of the color synchronization signal at the output of the gated pulse of the horizontal frequency amplifier 3 turns on the signal 22, which has a different phase shift relative to the axis V-Y than in the previous line. This signal, having passed through the phase-shifting chain 23 (+ 45 °) {plot 24 of FIG. 2) arrive at the input of the phase detector 25. The other input of this detector continues to receive the signal of the previous line, i.e., the phase of the signals during the duration of the line II color synchronization signals at the input of the switch 10, the phase-shifting chain 14 and the detector 25 (plots 26, 27 and 28 of Fig. 2) are similar to the phases of the signals of the previous line I at the same points (plots 29, 30 and 31 of Fig. 2). As a result of the interaction of two signals arriving at both inputs of the phase detector 25 (plot 32, Fig. 2), a well-defined potential is obtained at its output (say, for a given phase shift of 45 °, it is positive), which is fed through control circuit 11 to a single-pole commutator 10. Since the potential has a well-defined polarity, then the switch 10 will be translated by it into a well-defined state. We assume that the positive notional occurring on the switch control circuit corresponds to its state when the input of switch 10 is connected to the input of the phase-shifting chain 12, and the negative one corresponds to co10 with the input to the input of the switch 1U to the phase-shifting chain 13. So A positive signal in control circuit 11 keeps switch 10 in a state where the input of switch 10 is connected to the input of the phase-shifted cenochka 12. This will result in the end of the color signal 40 minutes synchronization stro- ki II (during its duration) to the switch 10, phase-shifting circuit 14 and the input of the phase detector 25 will be a signal having the phase shown in FIG. 2 (plots 29, 30 and 31). During the next line III, the processes are repeated, but in this case the phase shift of the signals arriving at the phase detector 25 for the duration of the color-locked signals is 135 °. In this connection, the 50-volt voltage at the output of the phase detector 25 will change from the previous line to the opposite one, which will result in switching of the single-pole switch 10 (the input of the switch 10 55 is connected to the input of the phase-shifting chain 13). The constant time of the output circuit of the phase detector 25 and the trigger threshold of the single-pole switch 10 are selected so that the transition of the latter from one state to another occurs at the time of the end of color synchronization pulses, i.e., at the time of the transition of the gated horizontal frequency pulses to the locked state condition. 45 65 In the following, the processes described above are repeated, which leads to the presence of a phase-shifting chain 14 of a continuous subcarrier 30 having a phase coinciding with the S-Y axis (Fig. 2, lines II, III, IV, etc.). ). This sub-loop occurs during the entire time the PAL signal is received and is used to demodulate the chroma signals. In addition, it is fed through the circuit 14, introducing a phase shift of -45 °, to the input of the phase detector 25 (Fig. 2, plot 31), and a second signal is supplied to its second input, changing the phase from line to line by 90 ° ( Fig. 2, plot 22). Therefore, at the outputs of the phase detector 25, semi-linear frequency meanders arise, controlling the operation of the switch of the color difference channels 21, including limiters 33 and 34 (SECAM), as well as a matrix 35 (PAL). FIG. 3 shows the phases of the signals occurring at different points in the circuit, for the case when at the output of the gated pulse of the horizontal frequency of amplifier 3 a signal appears with a phase shift of + 45 ° relative to the main VB, the input of the unipolar switch in the initial state With the input of the phase shifting circuit 12. Phases of signals occurring at different points in the circuit, for the case when the output of the gated and horizontal pulses of the amplifier 3, appear signals with a phase shift of -45 ° to the X-axis axis, and when input switch 10 is connected either to the input of the phase-shifting chain 12 or to the input of phase-shifting circuit 13 are shown in FIGS. 4 and 5. The operation of the device for the cases shown in FIG. 3, 4 and 5, is similar to that considered. When receiving a black and white program, synchronous and frequency detectors 15, 16, 36 and 37 are closed. When PAL signals are received at the output 38 of the frequency detector 18, a constant potential is formed, which through the filter 39, which does not allow a half-line frequency, passes through separation resistance to the synchronous detectors 15 and 16 and opens them. In this state, the detectors are held for non-transmitting PAL signals. The meander of the half-line frequency formed at the output 40 of the phase detector 25 by the filter 41 is not passed to the frequency detectors 36 and 37, and they remain in the closed state. Upon reception of the SECAM signals, the output 38 of the frequency detector 18 forms a square wave of the half-line frequency, which is not passed by the filter 39, and the synchronous detectors 15 and 16 are closed. At the same time, at the input of the phase-shifting chain 14, a subcarrier takes place, changing from line to line frequency and phase NOT ± 45 °. This subcarrier passes through the phase-shifting circuit 14, which is designed in such a way that when it passes EDN from the subcarriers corresponding to, for example, signal V-Y, the latter receives a phase shift of + 45 °, and when passing another () -45 °. Moreover, the single-pole switch 10, controlled by a meander from the output 42 of the frequency ектораtector 18, works as follows: The total |) basic shift of the subcarrier at the input of the phase detector 25 obtained from the phase-shifting chains 12 and 14 or 13 and 14 is always + 45 ° 1L ratio to the signal of the other input of the phase detector 25. In connection with this, the product of the signals pushed onto the phase detector 25 will give a completely constant potential, which, when passing through the filter 41, which does not let through the half-line frequency, and the separation resonance opens Detectors 36 and 37. Subject of the Invention 1. A SECAM-PAL color television receiver decoding device containing an electronic switch controlled by color-synchronization signals with a SECAM color subcarrier recovery unit and a PAL system color subcarrier phase, to the outputs of which are connected in parallel the color channels of the SECAM system signals, each consisting of a limiter / silitel and a frequency detector, and PAL system signals — with an input matrix connected to synchronous detectors, are The control inputs of which are connected to a single-pole switch of the phase recovery unit of the color subcarrier on a PAL system controlled by half-line frequency pulses, characterized in that, in order to increase the reliability of the device when receiving SECAM signals, the color subcarrier recovery unit and the electronic switch are on an additional frequency detector, the signals from the paraphase outputs of which are fed to the control inputs of the electronic switch. 2. The device according to claim 1, characterized in that, in order to increase the reliability of the device when receiving PAL system signals, between the outputs of the subcarrier recovery units and the color subcarrier phase through additional phase shifters a phase detector with paraphase outputs is turned on, the signals from which are supplied to control inputs of an electronic switch. 3. The device according to PP. 1, 2, characterized in that, in order to automatically switch color channels to one of the standards and turn them off when receiving black and white television signals, one of the paraphase outputs of the aforementioned additional frequency detector and phase detector are connected via synchronous filters to narrowband and frequency detectors color channels.

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