DE2615451C2 - Transmission system for color television signals - Google Patents

Description

5 The invention relates to a transmission system , for color television signals according to the preamble of the main claim.

Such a transmission system, which z. B. from the Dutch patent application DE-OS 14 62 473 is known, has the advantage that it is for during The timing errors introduced in the transmission are particularly insensitive. This is of particular importance when recording a color television signal on a record carrier, e.g. B. a magnetic tape or a

2-Ί optically readable optical disc, or when playing back of such a signal from such a record carrier. In these systems, timing errors are, among other things. by changes in the speed of the recording medium and, in the case of an optical disc, also by a

jo existing eccentricity introduced. If with such Recording systems record the chrominance signal in a known manner as a quadrature signal is, i.e. on two carrier waves shifted by 90 ° in phase with the same frequency as in amplitude are modulated with two chrominance signals, these time errors are expressed in the reproduced chrominance signal, namely as an error in the color tone, which is particularly annoying.

In the case of a transmission system of the type mentioned at the outset, these timing errors are much less common disturbing influence because these separate carrier waves modulated signals, in particular FM-modulated Carrier waves, much less sensitive to the time errors mentioned than the one mentioned above in quadrature are modulated signal.

DE-AS 10 25 932 discloses a line sequence color television system known, in which two monochromatic components one after the other in a single line jump and are displayed alternately at the line frequency and one complete scanning cycle consists of four vertical scans. Such a system can be called a line sequential transmission system are called because the main feature of a line sequential transmission system lies in the fact that a particular chrominance component does not transmit in every period of the line deflection but for example only during every other period of the line deflection, such as this for example is the case with the SECAM system.

A disadvantage of such a system of the type mentioned, however, is that it is necessary for changes in the transfer characteristic is particularly sensitive. A change in the transfer characteristic leading to The result can be that the second and third signal components no longer have the same transfer function are subjected, leads to an error in the color tone in the reproduced chrominance signal, which, as already mentioned, is particularly annoying.

The aim of the invention is to create a transmission system of the type mentioned, in which under Maintaining the stated advantages this problem is largely resolved. The invention is thereby designed characterized in that the two chrominance signals added to the first and second color subcarrier waves are mutually exclusive be exchanged line-sequentially.

The inventive measure is first achieved that when playing from a Record carrier provided with a color television signal thus composed which in a color television receiver set up for the reproduction of a color television signal according to the PAL standard taking place averaging of the color over two lines is used. This averaging becomes then namely an error in the color that has arisen as a result of mutual differences in the transfer characteristic automatically balanced for the second and third signal components. This also applies in relation to on differences in noise and bandwidth of the transmission channels for this second and third Signal component. It is also achieved that the same recording medium can also be sent to the SECAM color television system adapted player can be played back without this mutual Differences in the transfer characteristic lead to color errors.

The system according to the invention is also particularly suitable for use with recorded recording media, d. H. Recording media that have already been provided with a program by the manufacturer. Of course, the first thing to think about is the now extremely interesting video disc. Of course It is advantageous if such a recorded recording medium is as large as possible Has distribution area. In Europe the problem arises that two different color television standards can be used, namely PAL and SECAM, whereby a recorded record carrier that specifically suitable for one of these standards, is not played in an area without further measures by applying the other standard. The transmission system described is in this one Universal, because the second and third signal components contain two elementary chrominance signals can, from which with the help of coding circuits in the player simply one after the PAL or SECAM standard composite color television signal can be obtained. So this means that for the One and the same recording medium is sufficient for the entire PAL-SECAM area without this being too significant Consequences in particular with regard to the increase in the cost price for the player

Finally, it turns out that the transmission system according to the invention is particularly advantageous in the above-mentioned optical disks, namely in delayed or accelerated reproducing a _draw: th program, which will be explained in more detail below.

Some embodiments of the invention are shown in the drawing and will be described in more detail below described. It shows .

. F i g. 1 a frequency spectrum of the transmitted. Television signal in a transmission system according to the Invention,

2 shows a diagram to explain this spectrum,

3 shows a first embodiment of a recording or sending device,

F i g. 4 shows a first embodiment of a reproducing or receiving device for use in FIG a system according to the invention,

F i g. 5 and 6 two diagrams to explain the mode of operation,

F i g. 7 and 8 show two other embodiments of the recording or transmitting device for use in a system according to the invention,

F i g. 9 a diagram to explain the mode of operation of the same,

F i g. Finally, a further embodiment of the reproducing or receiving device for use in a system according to the invention,

F i g. 11 is an associated diagram, and

12 schematically shows an embodiment of a Logic circuit for use in the receiving device.

F i g. 1 shows, for example, a frequency spectrum of a color television signal as it can be transmitted by the transmission system according to the invention. The luminance signal is added as a frequency modulation to a carrier wave F _y and has a frequency deviation of f _s (synchronization pulse) = 6.7 MHz to f _w (maximum white) = 8.4 MHz. It is assumed that the first signal component Ey, which in addition to the frequency deviation also includes the first-order sidebands, occupies a bandwidth of 4.2 to 11.4 MHz. The frequency spectrum also contains a second signal component £ Ί, which contains a first chrominance signal as modulation of a first chrominance carrier wave Fi, and a third signal component £ 2, which contains a second chrominance signal as modulation of a second chrominance carrier wave F2 Frequency bands of 1.2MHz around the two carrier frequencies from 1.8 to 3.2 MHz. A fourth signal component Eg, which consists of a carrier wave F _g that is FM-modulated with the audio signal, is also given to complete the process.

It should first be noted that the invention in no way relates to the positions selected in FIG various signal components within the available bandwidth limited the positioning these signal components in the frequency spectrum is not at all essential for the invention. So could they second and third signal components also within that occupied by the first signal component Frequency band are positioned, such as. B. in the Dutch patent 1 06 695 is described or one of these signal components could be below and the other above that of this first Signal component occupied frequency band are positioned.

It should also be noted that the way in which the first and second color carrier waves Fi and F ₂ are modulated by the two chrominance signals is not of essential importance for the measure according to the invention. B. be thought of an amplitude modulation or a frequency modulation. For other reasons, including the greater insensitivity to noise, frequency modulation of these color subcarrier waves is preferably used, which is why only this frequency modulation will be discussed in the further discussion.

Finally it should be noted that the composition of the chrominance signals is not of direct importance though is the application of color difference signals

(RY) and (BY) have the most advantages. In the following, these two color difference signals (R-Y) \ ind (B- V ^ are selected as modulation signals for the two color subcarrier waves Fj and Fi.

According to the measure according to the invention, the two signal components E \ and Ei no longer continuously contain the same chrominance signal, but these two chrominance signals are added line-sequentially alternately as modulation signals to the two chrominance carrier waves Fi and Fz. Based on (RY) and (B- V ^ chrominance signals, this is shown schematically in FIG. 2, in which, as a function of the line number L _n , it is indicated which chrominance signal in the second signal component E \ and which chrominance signal in the third. signal component Ej is included. it can be seen that the signal component e \ contains, however, in opposite phase alternately alternately from line to line, the two chrominance signals (RY) and (B-Y) and the signal component £ 2, the same chrominance signals, that is, the color signals mutually alternately are transferred to the two subcarriers Fi and F2.

3 shows a first embodiment of a device with which such a color television signal can be obtained on the transmitter side or in the receiving device for a recording medium. This device initially contains a transcoder 2 which splits a color television signal fed to a terminal 1 into a luminance signal and two color difference signals (RY) and (BY). The structure of this transcoder is naturally determined by the composition of the color television signal fed to terminal 1. If this color television signal is a signal built up according to a standard (z. B. PAL), this transcoder 2 can z. B. correspond to the decoding devices used in receivers for the standard color television signal in question. Any known transcoder which delivers the three desired signals (R-Y), (B-Y) and K can be used.

The separated luminance signal Y at the terminal 6 is frequency-modulated in an FM modulator 14, which results in the first signal component E _y. The two chrominance components (RY) and (BY) are fed to the two input terminals 4 and 5 of a commutator 3. This commutator 3 contains a two-pole coupled switch that can occupy two positions, namely a first position in which a connection is established between the input terminal 4 and an output terminal 10 on the one hand and the input terminal 5 and an output terminal 11 on the other hand, and a second position , in which a connection between the input terminal 4 and the output terminal 11 on the one hand and the input terminal 5 and the output terminal 10 on the other hand is established. This Schaher, which will naturally be trained electronically in practice, is controlled by a control signal at a control terminal 8 of the commutator 3. B. the output terminal 7 of the transcoder 2, which control signal by a symmetrical rectangular signal with the. half the line frequency is formed. This ensures that the commutator 3 is controlled in such a way that the chrominance signals (RY) vmä (BY) are available at its output terminals 10 and 11 in phase opposition from line to line, in accordance with the circuit diagram according to FIG. 2. The signal at terminal 10 is fed to a frequency modulator 12, in which this alternating chrominance signal is modulated onto a carrier wave Fi, which results in the second signal component £ 1. The signal at terminal 11 is fed to a frequency modulator 13 in which this alternating chrominance signal is modulated onto a carrier wave F2 , which results in the third signal component E _2. These second and third signal components E 1 and E 2 are summed with the aid of a summator 15.

This sum signal (E \ + Ei) then has to be combined with the first signal component E _y and an audio signal E _g , possibly added as frequency modulation of a carrier wave F ^ of 0.5 MHz, for example, that of a terminal! is supplied, are assembled. A simple way of achieving this assembly is described in German Patent 23 43 456. The relatively low-frequency signal components (E] + E2) and E _{g are added} to the first signal component E _y , which has finely steep edges, and the sum signal (E _y + E \ + E ₂ + E _g ) is fed to a limiter 18 . In this way, a rectangular signal is obtained at the output terminal 19, the frequency of which contains the luminance information and in which the color sum signal (E \ + E ₂ ) and the sound signal E _g are contained as pulse width modulation, which signal is particularly suitable for use as a recording signal suitable for an optical readable image disk.

Fig. 4 shows an embodiment of the device for receiving or reproducing a color television signal transmitted or recorded in this way. From an input terminal 21 supplied color television signal z. B. is read with the help of an optical read-out system from an image plate, the first signal component Ey is separated by means of a high-pass filter 24, from which the luminance signal is ydemodulated by means of an FM demodulator 27.

The second and third signal components E _{1 and E 2} are separated by means of two bandpass filters 22 and 23, after which the chrominance signals are recovered from these signal components with the aid of two FM demodulators 25 and 26. These chrominance signals are fed to the two input terminals 29 and 30 of a commutator 28. This commutator has the same structure as the commutator 3 on the transmitter side and therefore has two input terminals 29 and 30 and two output terminals 32 and 32, between which connections alternate as a function of a control signal at a control terminal 33. This control terminal 33 receives a control signal from a logic circuit 34. This logic circuit 34 in turn has three input terminals 35, 36, 37, of which terminal 35 receives a control signal from a command device 38, terminal 37 a control signal from an identification circuit 39 and terminal 36 can receive a control signal via a switch 51 from a detector 40.

The mode of operation of the command device 38 and the characteristic circuit 39 is explained in more detail below. First, it is specified how the original chrominance signals can be recovered by means of the commutator 28. For this, the switch 51 must be in position / f (PAL) in which the horizontal synchronization pulses detected by the detector 40 from the luminance signal Y reach the input terminal 36 of the logic circuit 34. These

As a result, logic circuit 34 supplies control terminal 33 of commutator 28 with a symmetrical one rectangular signal with half the line frequency, reducing the position of the commutator switch by line to line is implemented. This has the in the block diagram of FIG. 5 specified sequence.

This F i g. 5 indicates for three consecutive lines n, n + 1, n + 2 of a television picture which chrominance signal is present at the inputs 29 and 30 and the outputs 32 and 31 of the commutator 28 during the relevant lines. The indices in this chrominance information indicate via which signal component Ei or E ₂ this chrominance information is transmitted. It is assumed that the input 29 of the commutator 28 receives the chrominance signal which is transmitted as modulation of the first color subcarrier wave Fi, and that the input 30 receives the chrominance signal which is transmitted as a modulation of the second color subcarrier wave F _2. Both inputs 29 and 30 thus receive the (RY) and (B-Y) chrominance signals alternately from line to line, but in opposite phase.

If it is now assumed that during the line η the commutator 28 produces the connection pattern shown with the full lines, the output 31 receives the (R- Y) _r chrominance signal from the input 29 and the output 32 the (BY) ₂ - Chroma signal from input 30. During the next line, the commutator establishes the connection pattern indicated by the dashed lines and output 31 accordingly receives the (RY) ₂ chrominance signal from input 30 and output 32 the (B- V? I chrominance signal from Input 29. The output 31 of the commutator 28 thus continuously supplies the (R-Y) chrominance signal, but this chrominance signal comes line-sequential alternately from the FM demodulator 25 and the FM demodulator 26. In the same way, the output 38 now continuously supplies the (B- V / signal.

In order to reassemble these two color difference signals (RY) and (BY) into a standard chrominance signal according to the PAL standard, both chrominance signals must be modulated in a known manner in quadrature (orthogonal modulation) of a carrier wave of 4.43 MHz. For this purpose, it may be desirable to add synchronous color strobe pulses to the two chrominance signals in two adding circuits 41 and 42. These color sync strobe pulses can be derived from the horizontal sync pulses detected by detector 40 and are used in a known manner to obtain the desired color sync signal when modulating the chrominance signals onto the carrier wave of 4.43 MHz at the rear shoulder of the retrace period. If these synchronous color strobe pulses have already been added to the chrominance signals at the transmitter end, these adding circuits 41 and 42 can optionally be omitted, which is indicated in the figure with the dashed connections between the outputs 31 and 32 of the commutator 28 and the AM modulators 43 and 44. The necessity the generation of these color sync strobe pulses in the receiving device depends on any interference in the transmitted color sync strobe pulses. It should be noted that in a PAL receiver, by averaging over two lines, a certain compensation also occurs with regard to any interference in these color sync strobe pulses

The chrominance signal (B-Y) provided with color sync strobe pulses is fed to a first amplitude modulator 43 which receives a 4.43 MHz signal with a fixed phase (+ sin) from an oscillator 45 as a carrier wave. The chrominance signal (R - Y) provided with color sync strobe pulses is fed to an amplitude modulator 44, which also receives a 4.43 M Hz carrier signal from this oscillator 45, but the phase is 90 ° with respect to the carrier wave fed to the modulator 44 is shifted and also carries out a phase jump of 180 ° from line to line (± cos). By adding these two modulated chrominance signals to one another in an adding circuit 47, a quadrature (orthogonally) modulated color signal is then obtained which is constructed according to the PAL standard. This color signal is added to the demodulated luminance signal Y in an adding circuit 48, as a result of which a PAL standard color television signal is available at an output terminal 49 which can be fed to a standard receiver.

In order to demonstrate the effect of the measure according to the invention, refer to FIG. 5 and refer to the vector diagram shown in FIG. In FIG. 5, the PAL-ID column indicates which PAL phase is added to the (R- Y> signal of the relevant line in the AM modulator 44, while the PAL chroma column shows the final vector composition of the PAL color signal the relevant line is specified.
If it is now assumed that by any-

Before the cause of the transfer characteristic of the second signal component £ \ has a greater gain factor than the transfer characteristic of the third signal component E ₂ , the chrominance signals (B- V ^ and (R- Y) \ are always too large a value im

Compared to the chrominance signals (B-Y) ₂ and (RY) ₂ . The effect of this difference in the gain factor is illustrated in FIG. 6 described.

It is assumed that the chrominance signal transmitted via the third signal component E _{2 has} the correct value. During the line η , the (β-y) ₂ color signal is therefore equal to the desired value (BY) _c . The (Λ - ^ - chrominance signal ^is π However while this line is too large, that is greater than the desired signal (R -Y) ^ This has ge to r Fol as ß sta tt

of the correct color vector Ü _r "= (B = T) _1. + (R ~ = Y) _C while this line η the color vector C ^ (BY), + (Ä-y) f is obtained. This color vector C" forms a Phase error A Ψ with the desired vector C ", which means that a deviation in hue

so occurs, which is particularly annoying.

Due to the measure according to the invention, however, the color vector C ⁺¹ during line n + 1 ^{is now composed of the (λ-y) i +} 'color signal and the (RY) Y ¹ chrominance signal, with the (R- y) ₂ Signal has the correct value (R - Y) _c and the (By) i signal is too large by the same factor with respect to the desired value as it is with respect to the (Ä-y) i signal during line η was the case. The n + 1 for this row are de Far bvek tor C ⁺¹ thus consists of C ⁺¹ = (.S = Y) P * - (/ p7) "on the minus sign. the negative PAL phase (-cos) present during this line n + 1 can be traced back. In a PAL receiver, however, the vectorial sum of the color vectors obtained is determined from two successive lines, with the previous one relating to the negative PAL · phase (-cos ) Corresponding vector C ^{+1 is positioned} in mirror image with respect to the (2? -Y) axis, which sum vector is the final one

reproduced chrominance signal. The vector C "* ¹ is thus initially arranged in a mirror-inverted manner with respect to the (BY) ^{axis, which results in the vector CP +1} , which is then added vectorially to the vector Ü" , whereby the vector Ü "+ ÜP" ^{+ i} is obtained. It can be seen from the figure that this sum vector is quite correct with regard to its phase compared to the desired color vector C _c , so that no error occurs in the hue. The only remaining error is an error in the color saturation, because this sum vector is larger than twice the desired color vector 2 C _c , but which is much less disturbing than an error in the hue.

The transmission system according to the invention has additional advantages that are based on the already described embodiment according to FIG. 4 will be explained in more detail. It has already been mentioned that the Transmission system according to the invention in recorded recording media is particularly advantageous because in the playback device very easily one for a PAL receiver or one for a SECAM receiver suitable color television signal can be obtained. The generation of the PAL color television signal was described above already described, so that it will not be discussed in more detail.

To obtain a SECAM color signal, it is sufficient to put switch 51 in position 9. A SECAM color signal contains the (RY) and (B- V ^ color signal alternating from line to line. When the switch 51 is set to position S, the logic circuit 34 no longer receives any horizontal synchronization pulses from the detector 40, which likewise the control terminal 33 of the commutator 28 does not receive a control signal and the commutator switch remains in a fixed position. This means that the two outputs 31 and 32 are continuously connected to a fixed input 29 or 30. At each of these two outputs the ( RY) -.., and (B ^ -Farbartsignal on one of these outputs, for example the output 31, so a line sequential color signal Fsecam can then be removed, which is at an output terminal 50 available to it a complete SECAM color television signal to received, this color signal Fsecam only needs to be modulated onto the standard color carrier waves and then added to the luminance signal K. In order not to unnecessary the block diagram To make it complicated, this obvious step is not detailed

Another advantage of the transmission system according to the invention results in particular in the case of a plate as a recording medium, although this system is also useful when using a tape-shaped recording medium For details on the use of an optically encoded disk as a Reference is made to US Pat. No. 3,854,015 for recording media. The video information is in generally recorded in a spiral track on such an optical disc in such a way that that a complete television picture is just recorded per revolution of this disk To achieve a still image of this type of image plate, it is only necessary after each revolution of this plate Scanning spot with which the information is read out, move back over a lane distance, so that the same television picture is displayed in each case. When playing a PAL television standard recorded signal there arises a problem due to the alternating phase of the PAL color signal (see DE-OS 24 33 330 of the applicant). Since a television picture according to the PAL standard is 625 Contains lines, the first and last lines of a PAL color television signal have the same PAL phase.

However, this means that when a still image is obtained, the line-sequential switching of this PAL phase is always interrupted at the beginning of the picture, causing disturbances in the reproduced color signal may occur.

When using the transmission system according to the invention, this does not pose a problem because the alternating PAL phase is only added to the chrominance signal in the read-out device, namely during the modulation of the (R- ^ chrominance signal on the standard color carrier wave (4.43 MHz) with alternating Phase (± cos) in modulator 44. However, in order to continuously maintain the (R-Y) chrominance signal in the case of a still image at output 31 of commutator 28, the commutator switch must perform an additional switch after each rotation of the image plate. The first and the last Lines of one and the same recorded television picture contain the same chrominance signal, e.g. (R - Y), due to the odd number of lines, which means that without additional switching, output 31 becomes the (R - Y) chrominance signal during one picture period and during the following picture period would contain the (B-Y) chrominance signal, etc. Due to the additional frame rate switching of the commutator switch, di avoided it.

This additional switchover can be effected very easily with the aid of the command device 38. This command device 38 will already be present in the readout device and will be the control desired movements of the scanning spot to achieve this still image. So it's very easy this command device 38 also emits an additional pulse when the scanning spot is reset to be fed to the input 35 of the logic circuit 34, whereby this logic circuit 34 is the commutator 28 supplies an additional alternating pulse. It should be obvious that everything here in was mentioned with reference to still images, also for other deviating playback speeds, such as in slow motion or images played backwards, applies.

Finally, in FIG. 4 there is also a characteristic circuit 39

shown. This code circuit 39 is used to check in PAL playback whether the output 31 of the commutator actually contains the (R - ^ color signal and the output 32 the (B - V ^ color signal If confusion had occurred, this characteristic circuit 39 delivers an additional pulse to an input 37 of the logic circuit 34 using an identification signal recorded in the video signal, e.g. color sync strobe pulses, whereby the commutator switch performs an additional switchover. the adding circuits 41 and 42 must be arranged upstream of cancellation circuits in order to cancel the transmitted color sync strobe pulses.

F i g. 7 and 8 show two further embodiments

an arrangement for converting a color television signal constructed according to the PAL standard into a color television signal can be converted, as it is transmitted in the system according to the invention.

In the arrangement according to Fig. 7 it is assumed that that one terminal 51 is the hue component

of the color television signal is supplied according to the PAL standard. This color tone signal contains a quadrature (orthogonally) modulated chrominance signal on a chrominance carrier wave of 4.43 MHz. In order to derive the two chrominance signals (RY) and (BY) therefrom, an oscillator 52 is provided, which supplies two chrominance carrier waves with a frequency of 4.43 MHz derived from a color sync signal, but which are mutually shifted in phase by 90 ° (sin and cos). One of these carrier waves is fed to a phase switch 53, which changes the phase of this carrier wave by 180 ° line-sequentially Outputs 54c and 54 </ are connected to two amplitude demodulators 56 and 57 with inputs 566 and 576, whose inputs 56a and 57a are also supplied with the original color signal at terminal 51. This commutator 54 receives at its control input 55, like the phase switch 53, a control signal from a detector 62 which detects the line pulses from the luminance information of the PAL color television signal fed to a terminal 69, so that both the phase switch and the commutator are switched line sequentially , while this detector 62 also ensures that the phase switch 53 assumes the correct position corresponding to the PAL phase of the color signal offered.

If it is assumed that the commutator 54 assumes the position indicated by full lines, the (B- V ^ color signal is derived in the AM demodulator 56, which is available via a low-pass filter 58 at a terminal 60. At the same time, the AM- Demodulator 57 receives the (R-Y) chrominance signal that is available via a low-pass filter 59 at a terminal 61. During the next line, the cos signal of the 4.43 MHz carrier wave is fed to the AM demodulator 56, see above that the (R- V ^ color signal is generated at terminal 60, while at the same time the (BY) chrominance signal is available at terminal 61. The two desired chrominance signals (RY) are therefore alternating line-sequentially at the two terminals 60 and 61 and (BY) are available to be transmitted over separate frequency bands.

8 shows a second embodiment of a device with the help of which, starting from a PAL standard color signal, which receive the color signals desired for the transmission system according to the invention will. Corresponding elements are given the same reference numerals as in FIG. 7 designated. That PAL color tone signal is fed back to an input terminal 51, which is now connected to a delay line 63 is connected, which delays this hue signal over a line period. The delayed hue signal becomes on the one hand directly and on the other hand via an inverter 64 the two inputs 65a and 656 one Commutator 65 is supplied, which receives a symmetrical square-wave signal at its control input 66, which is supplied by the line pulse detector 62, whereby this commutator is line sequential Location changes.

In order to clarify the effect of this device, refer to the block diagram according to FIG. 9 referenced. The signals present at different points in the device are indicated for five consecutive lines L _n . The PAL color tone signal at terminal 51 is shown as alternating Lf- V and U- V in order to indicate the alternating PAL phase, where U is the ( By> chrominance signal modulated to 4.43MHz, and V das (R- IT chrominance signal, modulated to 4.43MHz, The indices denote the line during which the color tone signal is offered. The output signals A and B of the commutator 65 will be over a line period

ίο contain delayed color tone signal, the polarity of which changes from line to line as a result of the inverter 64.The output signal A is added to the undelayed color tone signal in an adding circuit 67, which results in the color tone signal indicated in column 67, while signal B is added in an adding circuit 68 is added to this undelayed hue signal, which results in the signal indicated in column 68, it being assumed that the chrominance components of two successive lines are only slightly different. From these two columns 67 and 68 it can be seen that at the outputs of the two adding circuits 67 and 68 there is primarily always only a single chrominance component of phase errors identical.

The hue signals supplied by the adder circuits 67 and 68 are supplied to the AM derhodulators 56 and 57, respectively, which also receive the carrier waves C and D , which are transmitted to an oscillator 52 with the aid of a phase switch 53 and the commutator 54 in the same manner as in F i G. 7 can be taken. This results in the chrominance signals indicated in columns 60 and 61 at terminals 60 and 61. It can be seen from this that the desired color sequence occurs again at both terminals. The difference with the device according to FIG. 7 is that the chrominance signal available during a given line, e.g. B. (B-Y) n, equal to the mean value of the chrominance signals (BY) \ and (BY) ₂ , that is, the two chrominance signals of two consecutive lines. This is naturally due to the use of the delay line 63. The advantage of the device according to FIG. 8 in comparison to that according to FIG. 7 is that the requirements to be placed on the AM demodulators 56 and 57 are less stringent.

FIG. 10 shows another embodiment of a reproduction device for the transmission system according to the invention, the signals occurring in the diagram according to FIG. 11 are shown. Corresponding elements are denoted by the same reference numerals as in FIG. The read-out color television signal is again split up into the signal components E \, Ez and Ey with the aid of bandpass filters 22 and 23 and the low-pass filter 24. These signal components are demodulated with the aid of the FM demodulators 25, 26 and 27. At the outputs of the two FM demodulators 25 and 26, the chrominance signals (R-Y), (BY) , etc., alternating in a line-sequential manner, are again obtained. These two chrominance signals are now added in the adding circuits 41 and 42, synchronous color strobe pulses. Since the two alternating chrominance signals (R-Y) and (B-Y) pulse pulses of opposite polarity belong, a commutator 71 is required, the two outputs of which are connected to the adding circuits 41 and 42 and both inputs are connected to the line pulse detector 40, the

both the probe pulses with positive and the probe pulses with negative polarity, with the detected This commutator 71 supplies a line pulse in the luminance signal y coupled to this commutator 71 is via a control input 72 from the logic circuit 34, which in turn receives a control signal from the detector 40

In this way, the correct color sync key pulses are always added to the demodulated chrominance signals. These two chrominance signals, provided with key pulses, at the outputs of the two adding circuits 41 and 42 (columns 41 and 42 in FIG. fed to inputs 43a and 44a ^ These two AM modulators (inputs 430 and 44b, respectively) are also fed two carrier waves E and F with a frequency of 4.43 MHz, the phase of which is switched line-sequentially Oscillator 52 is assumed to be 4.43 MHz, which supplies two carrier waves (sin and cos) shifted in phase by 90 °, while one of these carrier waves also changes its polarity line-sequentially (± cos). These two carrier signals are fed to a commutator 73 , which receives a control signal from the logic circuit 34 at its control input 74 and thereby changes its position line-sequentially which the chrominance signals (R-Y) and (BY) always modulate a carrier wave with the correct phase. At the outputs 43c and 44c of the two AM modulators, alternating chrominance signals are still generated line-sequentially, but these are now modulated onto carrier waves at a frequency of 4.43 MHz and therefore, as in FIG. 9 with U and V are indicated. By adding these two chrominance signals in the adding circuit 47, a color signal (column 47 in FIG. 11) is produced which fully corresponds to the PAL standard and which, when added to the luminance signal Y in the adding circuit 48, produces a complete PAL color television signal VpAL at the output terminal 40 leaves.

FIG. 12 finally shows schematically an embodiment of the logic circuit 34 including the identification circuit 39. The identification circuit 39 receives z. B. the chrominance signal from the output 32 of the commutator 28 (Fig. 4). This signal is fed to a switching transistor 80 which, at its control electrode 81, receives such pulses derived from the horizontal synchronizing pulses that this switching transistor is conductive during the time intervals in which the transmitted synchronous color pulses occur in this chrominance signal at output 32. These transmitted color synchronous strobe pulses are fed to a capacitor 82. As is known, the key pulses added to the (R ^ color signal are positive and the key pulses added to the (Ώ - V ^ color signal are negative.) Depending on the chrominance signal present at output 32, the voltage across capacitance 82 will be positive or negative is forwarded via an amplifier 83 and an integrator 84 with an integration time of, for example, 200 line periods to an input of a comparator 85, the second input of which is at ground potential , which again corresponds to the presence of the (RY) chrominance signal at the output 32 of the commutator 28. But if the switching phase of this commutator 28 were incorrect and the (B-Y) chrominance signal would appear at the output 32, the comparator would do so 85 applied signal positive, whereby this comparator flips over. With the help of a monostable multivibrator 86 a suitable pulse a n the terminal 37 of the logic circuit 34 is supplied

This logic circuit also contains a terminal 35 which is connected to the command device 38 Both terminals 35 and 37 are through a differentiating network, which consists of a capacitor 87, one

ίο Capacitance 88 and a common resistor 89 is coupled to an amplifier 90 which delivers a pulse of a desired duration as soon as one of these terminals 35 and 37 receives a pulse. The logic circuit 34 also contains a D flip-flop 91, the set input S of which is connected to the amplifier 90. The outputs Q and Q of this D flip-flop are connected to the J and K inputs of a JK flip-flop 92. The Q output of this JK flip-flop is connected to an input of an AND gate 94 and the Q output is connected to an input of a NOT AND gate 93. These two gates 93 and 94 receive at their other input the line synchronization pulse series supplied by the detector 40, which is also supplied to the Γ input of the JK flip-flop 92. The output of the gate 93 is connected to the reset input R of the D flip-flop 91 and the output of the gate 94 is connected to the T input of a JK flip-flop 95. The J and / f inputs of this JK flip-flop 95 are connected to a common terminal 95, while_die

Signals at one or both outputs Q and Q can be used as switching signals for the commutator 28.

The operation of the circuit is as follows. By the feedback via the gate 93 to the reset input R of the D flip-flop 91 results in a more stable condition by a logical "0" is present at the Q output a logical "1" and the (^ output. This is also the Q - and a logical "1" or "0" is present at the Q output of the JK flip-flop 92.

The UN D gate 94 consequently lets the line synchronizing pulse series of the detector 40 through to the Γ input of the JK flip-flop 95 in this state. If the color signal offered to the display device has to be converted into a standard PAL signal, a logical "1" is offered to terminal 96, whereby the two outputs Q and Q change the logical value line-sequentially as a result of the line synchronizing pulse series at the Γ input, whereby the Position of the commutator is also switched line-sequentially.

If a pulse is now offered to one of the terminals 35 or 37, the set input S of the D flip-flop receives a pulse and the position of this D flip-flop changes, that is, the (^ output is a logical "0" and the Q- The output supplies a logical "1". Since these two outputs are connected to the / - or AT input of the JK flip-flop, the position of this JK flip-flop also changes when the next line synchronization pulse appears at the Γ input Output then delivers a logic "0" to AND gate 94, which means that the second subsequent line synchronization pulse is not passed to the Γ input of JK flip-flop 95 and this flip-flop does not cause its output signals to be switched -Output of the JK flip-flop 92 supplies a logical "1" to the N ICHTUN D gate 93, the said second line synchronization pulse is fed to the reset input R of the D flip-flop,

whereby after this second line sync pulse the stable state is restored

A pulse at one of the terminals 35 and 37 thus finally ensures that the outputs of the JK flip-flop 95 available line-sequentially alternating control signals for the commutator 88 during two line periods in one and be held in the same position, whereby this commutator 88 during these two line periods in remains in the same position, as a result of which the desired phase reversal of the commutation is achieved it can be seen that under the phase reversal of the commutation mentioned in the introduction to this description both the failure of one of the line syn-

chronising pulse series prescribed switching as well as the implementation of an additional commutation, z. B. during the retrace period are to be understood. The execution of the Logic circuit in no way limited to the illustrated embodiment. Also in relation to that Modulation method by which the three signal components are recorded on a record carrier various modifications are possible. This modulation method is natural for the invention not essential. For illustration, reference is only made to German patent applications P 25 40 6682 and P 25 42 523.4 of the applicant.

See S sheet drawings

Claims (12)

Patent claims: 1. Transmission system for a color television signal, in particular a system for recording on it Recording medium and for reproducing from such a medium, in which transmission system in addition to a first signal component containing the luminance information, a second, a signal component containing a first color subcarrier wave modulated with a chrominance signal and a third one containing a second chrominance subcarrier wave modulated with a chrominance signal, Signal components are transmitted, these second and third signal components being separate Occupy frequency bands and each of the two color subcarrier waves during each line period is only modulated with one of the two chrominance signals, characterized in that that the first color carrier wave alternates line-sequentially with a first and a second The chrominance signal of the two chrominance signals is modulated and the second color carrier wave in the same cycle alternating with the second and the first chrominance signal of the two chrominance signals is modulated 2. Transmission system according to claim 1, characterized in that the first and the second chrominance signal are formed by color difference signals (RY and BY). 3. Transmitting or recording device for use in a transmission system according to Claim 1 or 2, characterized in that the device has a first commutator (3) a first and a second input (4 and 5, respectively) j5 and a first and a second output (10 and 11, respectively) is provided, which as a function of a Control signal line-sequentially alternating a parallel and cross-wise coupling between on the one hand said first and second input (4 and 5 respectively) and on the other hand said first and second output (10 or 11) can produce around the line-sequential confusion of the first and the second color subcarrier wave added chrominance signals. 4. transmitting or recording device according to claim 3, characterized in that the first input (4) of the first commutator (3) receives the first chrominance signal (R- V ^ and the second input (5) the second chrominance signal (BY) while the first output (10) with a first modulation circuit (12) for modulating an offered signal onto a first color subcarrier wave (F]) and the second output (11) with a second modulation circuit (13) for modulating an offered signal onto a second color subcarrier wave ( Fj) is coupled (Fig. 3). 5. transmitting or recording device according to claim 3, in which it is assumed that a color television signal constructed according to the PAL standard, t> o, characterized in that the device is provided with a first and a second amplitude demodulator (56, 57), each of which contain: a first input (56a. 57a) to which a color signal derived from the PAL color remote sehignal supplied to an input terminal (51) is fed, a second input (566,576; connected to the first or second output (54c, 54d ) of the first commutator (54) is coupled, and an output (56c, 57c) for supplying the second and third signal components, respectively, while the device further includes an oscillator circuit (52, 53) for supplying two carrier waves to the first and second input (54a , 546; of the first commutator (54), which two carrier waves have a frequency equal to that of the PAL color subcarrier wave and a mutual phase difference that alternates line-sequentially e is + 90 ° and -90 ° (Fig. 7). 6. transmitting or recording device according to claim 5, characterized in that the first and the second chrominance signal by the full color signal present in the PAL color television signal are formed. 7. Transmitting or recording device according to claim 5, characterized in that the device further comprises a delay device (63) coupled to the input terminal for delaying the color signal by one line period of an inversion circuit (64) connected to the output of the delay device (63) Inverting the output signal thereof is coupled, and a second commutator (65) is provided, either a coupling between a first input (65a,} and a first output (65c) and between a second input (656; and a second output (65d)) or a coupling is established between the first input (65a; and the second output (65d) and between the second input (656, J and the first output (65c)) and which switches line-sequentially as a function of a control signal supplied by a control circuit (62), wherein the first input (65a; with the output of the delay device (63) and the second input (65b) with the output of the In version circuit (64) is coupled, while there are further provided: a first adding circuit (67) having a first input (67a; coupled to the input terminal (51), a second input coupled to the first output (65c) of the second commutator (65) (676; and an output coupled to the first amplitude demodulator (56) output (67c, and a second adding circuit (68) having an input coupled to the input terminal (51) first input (68a ;, one to the second output (65d) of the second commutator (65) coupled second input (686; and an output (68c; Fig. 8) coupled to the second amplitude demodulator (57). 8. receiving or reproducing device for use in a transmission system according to claim 1 or 2, characterized in that the device with a first commutator (28) with a first and second input (29 or 30) and a first and second output (31 or 32) is provided which, as a function of a control signal, can produce a parallel and a cross coupling between the first and second inputs (29 and 30) on the one hand and the first and second output (31 and 32) on the other hand, alternating line-sequentially, whereby the two inputs (29, 30) are coupled to two separate color channels, which supply the second and third signal components (E \ or E ₂ ), while the outputs (21, 22) are coupled to two separate output channels, the control signal from a logic circuit device (34) supplied horizontal synchronizing signal can provide a rectangular control signal. 9. receiving or reproducing device according to claim 8, characterized in that the Device includes an identification circuit (39) coupled to at least one of the output channels and is set up to detect which chrominance signal is in the relevant output channel is present, and which, if the wrong chrominance signal is detected, a pulse to one second input (37) of the logic circuit (34) for effecting a phase reversal of the change in the Coupling between the two inputs (29, 30) and the two outputs (31, 32) of the first Commutator (28) yields (Fig. 4). 10. Playback device according to claim 8 or 9 for reproducing a color television signal recorded on a disk-shaped recording medium, characterized in that it is equipped with a command device (38) for controlling the Readout is provided, which is also provided with a third input (35) of the logic circuit (34) is coupled to a phase inversion of the alternation of the coupling between the two inputs (29, 30) and the two outputs (31, 32) of this first commutator (28) so that the PAL change phase in a playback sequence of the recorded television pictures that is different from the recording sequence deviates, is maintained (Fig. 4). 11. receiving or playback device zt * r application in a transmission system according to claim 1 or 2, characterized in that it has a first demodulator (25) for demodulating the chrominance signal modulated on the first color carrier wave, a second demodulator (26) for demodulating the second color carrier wave modulated «! Chrominance signal, a first and a second, each with a first input (43a, 44a) coupled to the first and second demodulator (25, 26) of an oscillator circuit (45) for supplying two carrier waves with a frequency equal to that of the PAL color subcarrier wave, but line-sequentially shifted alternately by + 90 ° and -90 ° in phase, and a first commutator (73) with two inputs (73a, 73b) and two outputs (73c, 730 ^ which as a function of one of a logic circuit (34 ) supplied control signal alternating line sequentially a parallel and cross-wise coupling between these two inputs (73a, 73b) and the two outputs (73c, 73d) is provided, the first and second output (73c, 73d) of the commutator (73 ) is coupled to a second input (436, 44i> ^ of the first or second amplitude modulator (43, 44), the outputs (43c, 44c ^ of which are coupled to an adder circuit (47) (FIG. 10). 12. receiving or reproducing device according to claim 11, characterized in that the Device contains a first and a second adding circuit (41,42), which color sync strobe pulses via a second commutator (71), of which two outputs with the separate Addersclialtungen (41, 42) are connected and of which two inputs are two line frequencies Receive pulse trains, one of which is positive and the other is negative Contains polarity, which second commutator (71) is also controlled by the logic circuit (34), a parallel and cross-wise coupling between the two inputs, alternating line-sequentially and to produce the two outputs, these first and second adding circuits (41, 42) furthermore as input signals the demodulated by the first and the second demodulator (25, 26) Received chrominance signals and coupled via their outputs to the first and the second amplitude modulator (43,44) are (Fig. 10).