FI74856B - TIDSSEKVENTIELLT TELEVISIONSOEVERFOERINGSSYSTEM, SAERSKILT FOER EN VIDEOAPPARAT. - Google Patents

Abstract

1. A time-sequential transmission system wherein a first signal and a second signal are compressed in time at the transmitting end, transmitted time-sequentially and again expanded in time at the receiving end, characterised in that, at the transmitting end, the first signal and the second signal each contain a marking signal (12, 13) at defined moments, which marking signals are in a defined relationship to one another and that, at the receiving end, a correction signal is obtained by comparison of the marking signals (12, 13), for the correction of the first and/or second signals.

Description

! 74856

PERIODIC TELEVISION TRANSMISSION SYSTEM, ESPECIALLY FOR VCRs

When recording a color television signal with a magnetic tape recorder, it is known (radio nentor elektronik 1973, pp. 343-345) that the tal-5 fly the luminance signal by frequency modulating the image carrier and the color signals with a color carrier below the frequency spectrum taken by the image carrier. For this purpose, the frequency of the quadrature modulated color carrier is reduced from 4.43 MHz to a value of 0.53 10 MHz, and when reproduced it is reset to 4; 43 MHz, respectively.

This type of recording has the disadvantage that, due to the nonlinearities of the recording carrier, crosstalk occurs between the luminance signal and the color carrier. In order to keep the effect of the 15 color carriers on the luminance signal small, the amplitude of the color carrier must be significantly reduced with respect to the image carrier, which reduces the interference interval in color reproduction.

It is also known (DE-A-20 56 684) to reduce the luminance signal and the color signal in time, to store them sequentially in time during the line period and to expand them in time and to make them available again simultaneously. The color signal then takes up, for example, about 20% and the luminance signal 80% of the line drawing time. In this solution, since the luminance signal and the color signal are never stored simultaneously, but in chronological order, crosstalk between these signals is avoided with certainty. In addition, the control range of the sound carrier can be fully utilized for both signals.

30 In this type of recording method known as "timeplex" (Fernseh- und Kino-Technik 1983, No. 5, pp. 187--196, especially page 193-194), a time-reduced color difference signal (BY) is first transmitted alternately in a line after a line synchronization pulse. and then a time-reduced luminance signal Y 2 and in the next line first a time-reduced color difference signal (RY) and a time-reduced luminance signal Y. at a different pace.

Thus, in such a system, the color difference signal and the luminance signal in one line at a time are reproduced again in time to the length of the line drawing time, and are thus available simultaneously in image reproduction.

In practice, it has been found that there are temporal shifts in the reproduction between the luminance signal and the color difference signal, which cause falsifications in color reproduction. The shift between the two small signals at 1 jjs means a shift of the order of 10 mm on a screen with an image diagonal of 65 cm, as a result of which strong color tone defects and so-called color blurring can occur at the vertical edges.

In the transmission of time-shifted time-reduced signals, other errors may occur in the repetition, such as phase amplitude and / or group time differences between the two signals.

However, it is possible in each case to adjust the repetition circuit so that the two signals required for repetition, e.g. the snow-nance signal and the color difference signal, are in proportion to each other, i.e. in particular, they are temporally consistent and have the correct amplitude ratio. However, this consistency is no longer guaranteed for playback with another playback device or also for dubbing in a tal-30 flight system.

It is an object of the invention to further develop the time-varying system shown so that said deviations between the two 3,74856 small signals are avoided in the reproduction, in particular with respect to the temporal position, amplitude and phase.

This object is solved by the invention set out in claim 1. Preferred embodiments of the invention 5 are set out in the subclaims.

The invention is based on the following idea. Both similar signals on both signal paths are on the transmission side in a defined relationship to each other, especially in terms of temporal position and amplitude. Preferably, both signaling signals are identical in that, e.g., at specified times, the first signal passes through its own signal path in addition to the signal path of the second signal. For this reason, all the errors in the time reduction, transmission and time extension also affect the marking signals 15 so that they have a time shift with respect to each other, e.g. Thus, by comparing the marking signals on the receiving side, a correction signal can be generated indicating the errors generated in the transmission. This correction signal can then be used to eliminate the errors 20 by affecting the first signal or the second signal on the receiving side.

The invention can be used very advantageously when transmitting or recording a color television signal according to said "time-plex" recording method. This is based on the following 25 ideas and information:

In time extension playback, all pulses depend on the front ramp of the line-sync pulse. Since the contraction factor of the luminance signal and the synchronous signal are the same, the tolerances and time shifts in playback on the VCR are automatically equalized. The color signal, on the other hand, passes through a different signal path. Due to the higher contraction and expansion factor, the time deviations are observed significantly more strongly than in the path of the luminance signal.

When there is a time error between recording and playback, 4 74856, this occurs when the color signal and expansion factor are magnified.

In one embodiment of the invention, a marking pulse is consciously provided for the time of the line defined by the luminance signal and the color signal. Any time shifts in the reproduction of the snow nance signal and the color signal then also affect the time position of both of these signal pulses. By interpreting the temporal position of both marking pulses with respect to each other, i. the deviation of this time position from the predetermined hold value in the recording, so that a setpoint can be obtained which shows the amount of time shift between the luminance signal and the color signal. With this setpoint, one of these signals can thus be transmitted in time so that the marking pulses and thus necessarily the luminescence signal and the color signal are in line in each case in line with respect to their temporal position.

The marking pulse 11a can take various forms, since it has to essentially mark only a certain time of the line. The Mie-20 plum is a marking pulse called a black / white jump to take advantage of the full control range. The marking pulse may also consist of several successive individual pulses. The repetition then compares the temporal position between the nth pulse of the luminance signal path and the nth pulse of the color signal path. A pulse already present in the signal, e.g. a line synchronization pulse, can also be used as the marking pulse. This should then be added to the color signal in addition. As the marking pulse, it is also possible to use an achromatic value pulse in the path of the color signal, which has the same position with respect to the line period and indicates the achromatic value with the amplitude, i.e. (R-Y) = 0 and (B-Y) = 0 and recognizes in duration the color difference signal in question, i.e. B-Y or R-Y.

It is also possible to connect the signal of the first signal path sig-35, e.g. the luminance signal Y, to the second signal path 5 of the color signal C, after which a correction signal is derived from the signal difference of both channels on the receiver side.

The transmission of the marking pulses preferably takes place in the field extinguishing opening in the region of the check lines, e.g. in lines 17 and 18 5 and in lines 330 and 331. As such, it is sufficient when the signal pulses are transmitted on both signal paths in only one line. Preferably, the marking pulses are transmitted on both signal paths in two consecutive lines, because due to the characteristic of the "timeplex" system, the luminance signal from line n-1 and the color difference signal from line n occur simultaneously in the repetition.

It is sufficient when the marking pulses are transmitted periodically over a larger interval, because there are relatively slow errors in the transmission of the signals. The resulting correction setting-15 variable changes in practice relatively slowly.

Preferably, the transmission of the marking pulses takes place at the beginning of the half-picture, so that in the reproduction of the half-picture the time deviation of the luminance signal and the color signal is measured, possibly a change in the setpoint and a reduction in the time deviation.

In repetition, the setpoint basically causes a temporal transmission of another such signal. It can control, for example, an electronically controlled delay line in the path of the signal.

25 Preferably, a set variable is used to move the read rate from the memory for time expansion, because this read rate determines the time position of the signals expanded during that time. In any case, the memories required for time expansion can thus be used by means of additional control to change the time position of another such signal.

The invention will be explained with reference to the drawing by means of a recording example of a "timeplex" signal.

6 74856

In the drawing: ·

Fig. 1 shows a simplified block diagram of recording and playback ·,

Fig. 2 shows curves for explaining the operation of the block diagram 5 of Fig. 1;

Figure 3 shows an enlarged block diagram of the storage side, and

Figure 4 shows an enlarged block diagram of the playback side.

In Fig. 1, the luminance signal Y from point 1 is fed through the sun image 2 to the time compressor 3, which reduces the luminescence signal (BAS signal) by a factor of 0.8 to 80% of its original duration. The time-reduced luminance signal is thus fed to the toggle switch 4. The color signal-15 li C, which contains the color difference signals B-Y and R-Y alternately from line to line, is fed from the pin 5 through the adder stage 6 to the time compressor 7, which reduces the color signal by 0.2. 20% of its original duration. This reduced color signal C is applied to the second input of the changeover output 20.

The synchronization pulses S of the luminance signal Y synchronize the "timeplexM time control circuit 8."

The pacing pulses 3 further control the pulse stage 11, which includes a counter and a keying pulse generator. The stage 11 produces in the lines 17 and 18 and 330 and 331 the marking pulses 12, 13 in each case, which are connected in the buzzer stages 2, 6 to the signals Y and C. The marking pulses 12, 13 have a defined position with respect to the line duration.

7 74856

In playback, a signal Y is applied to the time expander 16 and the signal C to the time expander 5 17 and the signal C to the time expander 5 17, respectively. 5. At pin 18, signal Y and at pin 19, signal C then again have the original duration.

In addition, the signals Y and C are fed to a reference stage 10. In stage 20, the time-selective interpretation compares the marking pulses 12, 13 with respect to their temporal position. Thus, a setpoint Us is obtained which indicates an undesired temporal transfer between signals Y and C. The setpoint Us affects the control circuit 15 and the reading rate of the expander 16, 17 so that the temporal transmission between the signals Y and C is equalized and these signals Y and C are temporally consistent in the pins 18, 19.

Fig. 2a shows the structure of a time-reduced "timeplex" signal at the output of the change-over switch 4 or at the input of the change-over switch 14. The signal in each case after the line synchronization pulse Z in the line n first a time-difference color difference signal BY, in line n + 1, first the time-reduced color difference signal RY and then the time-reduced luminance signal Y.

Fig. 2b shows the marking pulses 12 during lines 17 and 18 in the luminance signal Y; 2c shows the marking pulses 13 in the same lines in the color signal C. These pulses 30 12, 13 are identical in time position, duration, amplitude and pulse shape and in each case extend from the black level to the white level.

Figs. 2d, e show the marking pulses 12, 13 at the inputs of the reference stage 20, due to the operation of the timeplex repetition circuit β 74856, the marking pulse 12 from line n-1 and the marking pulse 13 from line n coincide. When the signals Y and 5C have shifted, which signals could cause said image disturbance, the front ramps are temporally shifted by Atr with respect to each other, so that a setpoint Us corresponding to this shift At occurs. The setpoint depends on the amount of time shift and the sign of the setpoint depending on the direction of the transfer, for example, the setpoint is positive when Y is ahead of C and negative when Y is behind C so that the correction is made by the right amount and in the right direction.

In Fig. 3, the counter 35 is controlled by field frequency pulses 15a V and line frequency pulses H. The counter 35 produces in the lines 17, 18 and 330 and 331 an extinguishing pulse 20 for the duration of the line drawing. The pulse 20 turns off the signals Y and C through the extinguishing stages 21 and 22 to eliminate the signal in these lines in order to produce the marking pulses. The pulse 20 controls the pulse stage 21, which produces the marking pulses 12, 13 according to the stage 11 shown in Fig. 1. These are connected to the signals Y and C as in Fig. 1 in the adder stages 2, 6.

In Fig. 4, the pin 24 again shows a time-alternating, time-25 reduced signal C, Y from the video recorder 10, which corresponds to the signal at the output of the changeover switch 4 shown in Fig. 3. At the synchronization difference stage 25, the pulses V and H are again obtained from the Y signal and fed to the counter 26. This produces by counting the lines 17, 18 and 330, 331 30 the keying pulses 27 which connect the signals Y and C in these rows to the counter 30 via the gates 28, 29. 30 receives at each of its inputs the recording pulses 12, 13 stored in said parts. The left input of the counter 30 is formed as a start / stop input and the right input of the counter 30 35 is formed as a stop / start input. A voltage is generated at the output of the counter 30 94856, the magnitude of which depends on the time deviation of the marking pulses 12, 13 at both inputs of the calculator 30, and its sign depends on the direction of this deviation. This voltage ver * 5 is orbited in the reference stage 31 to the holding value of step 32. Thus, the setpoint Us is again obtained in line 33. This acts on the "timeplex" control circuit 15 via a low-pass filter 34, as in Figure 1, so that the time deviation of the marking pulses 12, 13 is equalized and thus the signals Y and C of the signals 10 are time-congruent at the outputs of the circuit. the adjustment takes place slowly gradually and has, for example, a time constant of 100 ms, which can be dimensioned relatively large, because the time deviation-15 mass is only a slowly changing error.

The marking pulses 12, 13 do not necessarily have to be similar in time in the recording, but they can also already have a time shift in it. The adjustment can then take place in the second setting with the setpoint Us so as not to adjust the time deviation 0, but to adjust the determined final deviation in the time position of the marking pulses 12, 13 at the inputs of the counter 30.

Figures 1-4 illustrate the operation of the invention with respect to the time error between the two signals. Similarly, other errors can be corrected by the marking signals or marking pulses so that, for example, the set variable obtained by comparing the marking signals affects the amplitude or phase of the second signal.

The invention is not limited to television signals, but can also be used in stereo signals, radio signals.

Claims (17)

10 74 8 5 6 A time-alternating transmission system, in which the first signal and the second signal are reduced in time on the transmission side, transmitted in time and expanded on the reception side again in time, characterized in that on the transmission side the first signal and the second signal each contain a signal (12, 13) at defined times. , which are in a defined relation to each other, and that a comparison of the marking signals (12, 13) on the receiving side gives a correction signal for correcting the first and / or second signal. A system according to claim 1, characterized in that on the transmitting side the first signal passes through the signal path of the second signal at defined times in addition to its own signal path and in that on the receiving side similar signals from both signal paths are initially compared and a phase amplitude or group time difference is obtained, which affects another signal path. A system according to claim 1, characterized in that it acts as a transmission system for color television signals. System according to Claim 3, characterized in that it functions for phase correction of the luminance signal (Y) 25 and the color signal (C). System according to claims 2 and 3, characterized in that the first signal is a luminance signal (Y) and the second signal is a color signal (C). System according to claims 2 and 3, characterized in that the first signal is a color signal (C) and the second signal is a luminance signal (Y). n 74856 A system according to claim 4, characterized in that on the transmitting side a time stamping pulse (12, 13) arranged for each predetermined line period time is connected to the luminance signal (Y) and the color signal (C) and on the receiving side between the two marking pulses (12, 13). the time interval (At) gives a setpoint (Us) for adjusting the correct time position between the luminance signal (Y) and the color signal (C). System according to Claim 7, characterized in that a synchronizing pulse or an achromatic plane pulse present in the signal is used in each case as the marking pulse. System according to Claim 7, characterized in that the marking pulse (12, 13) has voltage values of black 15 and white. System according to Claim 7, characterized in that the two marking pulses (12, 13) have the same time position, duration, shape and / or amplitude. A system according to claim 7, characterized in that the marking pulse (12, 13) consists of a plurality of individual pulses and a single pulse having a certain sequence number is used to produce a set variable (Us). A system according to claim 7, characterized in that the marking pulse (12, 13) is transmitted during an empty line or a check line during field extinguishing. System according to Claim 7, characterized in that the marking pulse (12, 13) is transmitted in each case in two time-successive lines (17, 18, 330, 331). 12 74856 System according to Claim 7, characterized in that the setpoint (Us) is obtained by interpreting the ramps of the marking pulses (12, 13). System according to Claims 7 and 12, characterized in that a filter element (34) having a time constant such that the deviation from the correct time position is reduced from half-image to half-image in small degrees is in the path of the setpoint (Us). A system according to claim 7, characterized in that the setpoint (Us) controls the travel time element in the path of the second signal (B-Y, Y). A system according to claim 7, characterized in that the setpoint (Us) controls the reading rate of the memories (16, 17) operating for temporal expansion. 13 74856