DE2550102A1 - System for reproducing video signals recorded on magnetic medium - has read out units, synchronous detector imparted with reference carrier signal - Google Patents

Abstract

System for reproducing information signals such as video signals, so as to obtain an improved signal to noise ratio when the signals are played back from a magnetic recording medium. The video signal contains a balance, modulated luminance signal on a carrier, with the synchronisation signals section having a larger amplitude than the other signal sections. The system contains a magnetic read-out unit for the video signal, a synchronous detector for the balanced, modulated, luminance signal and a circuit for supplying the synchronous detector with a reference carrier signal which is controlled in phase by a signal with a suppressed carrier, during the period of the synchronisation signal of the modulated luminance signal.

Description

Circuit for reproducing a video signal The invention relates to a circuit for reproducing information signals to be recorded or reproduced, especially of video signals. An object of the invention is to provide an improved Signal-to-noise ratio achieved when such signals are on a magnetic Recording material can be recorded and subsequently reproduced.

According to the state of the art it is for the recording of television signals has been common on a magnetic recording material, a relatively high-frequency one Carrier-frequency signal with aem iiuminanzsignal of the composite television signal to modulate and then the resulting frequency modulated signal onto the magnetic material to record. The signal-to-noise ratio of the reproduced signal can be then be relatively high.

With frequency modulation, however, there is a relatively wide frequency change or stroke is required to achieve the best signal-to-noise ratio. In the event of recording a frequency-modulated signal on magnetic tape accomplishes this to the further requirement that the bandwidth of the information signal is limited or that a large amount of magnetic recording material, e.g. B. tape, plate or film is to be used. When recording video signals on magnetic tape it is common to use a drum with a rotating magnetic head, wherein at least a portion of the tape is wrapped around the circumference of the drum If a broadband signal is to be recorded, the rotation of the rotating Magnetic head can be enlarged in relation to the tape and it is accordingly big drums have been needed for broadband recording.

Another disadvantage of using frequency modulation is that such signals form a number of harmonics which a circuit for filtering out require the same.

Another difficulty that occurs when a video signal is from a known device is recorded on a magnetic tape is that the signal usually recorded in a number of adjacent tracks that are separate from each other are at a distance, with an area occurring as a protective strip between adjacent recording tracks is used.

Such protective strips require additional tape and it is one A number of technologies have been developed to reduce the width of protective strips to be able to. However, it has been difficult to remove or remove the beat signal. exclude that are generated by the interaction of adjacent tracks, if the protective strips are made too narrow or have been omitted entirely.

It is an object of the present invention to provide a circuit for Recording and / or a circuit for reproducing magnetically recorded or to find reproduced video signals that have an improved signal-to-noise ratio of the reproduced signal is guaranteed or

guarantee. In particular, with the to be found circuit a video signal can be generated for playback, in which synchronization disturbance components are essentially eliminated, even if the speed of the for the Drive of the magnetic recording medium provided device fluctuates. In a circuit according to the invention for reproducing a video signal, a modulated luminance signal by means of a stabilized reference signal synchronously be demodulated.

The disadvantages of the prior art discussed above and the object on which the invention is based are provided with a circuit for Playback solved as indicated in the claims. According to the present In accordance with the invention a circuit for reproducing a video signal is provided, wherein a signal is generated which contains the video information primarily in only one sideband detected with the carrier at a relatively low frequency within the usual Videotape, as it is before modulation, lies.

The carrier may originally have a frequency above the Band of the video signal that is modulated onto it.

The carrier can be converted in frequency to allow the carrier to respond is shifted a relatively low frequency value.

This requires that at least substantially all of one sideband is eliminated. In the case of a color television signal, the chrominance signal is frequency-converted, so that it occupies an even lower frequency band than the converted luminance signal Has.

In the following description, the expression "Dräger frequency" used to designate the frequency the carrier would occupy, albeit with some modulation methods the carrier is completely suppressed.

A part of the circuit according to the invention for low-temperature gas is that penetration and distance losses due to the distance or gap between occurring between the recording head and the recording medium can be reduced. In addition, when the Sigaal is reproduced, the influence of the losses in the (magnetic) head becomes largely reduced or eliminated, taking these losses otherwise lead to frequencies occurring in the transmission characteristic which the amplitude of the output signal is reduced to üjull, due to of the gap of the head, this being in the higher frequency range of the recorded Signal occurs. In addition, with the invention there is the influence of self-demagnetization of a recorded signal and the influence of its recording demagnetization and the like

greatly reduced. This means that using the Invention, d. H. when recording and / or reproducing signals with an inventive Circuit that maintains an excellent signal-to-noise ratio.

The losses that are mentioned above occur as a result of the Recording and / or reproduction characteristics of the magnetic tape and the transducer on. These characteristics make themselves dependent on the change in amplitude the frequency, noticeable and show a peak or maximum value at a relative low frequency, e.g. B. is about 1 MHz. At this frequency is the efficiency or

the sensitivity of recording and playback combined quite high. In a circuit like the one according to the invention, however, the carrier frequency is of the signal to be recorded are set so low that they are close to this The maximum range of the sensitivity curve is, with which the signal-to-noise ratio of the reproduced signals is improved.

A circuit according to the invention allows signals to be sequentially in record adjacent tracks that have no protective strip between them and which even partially overlap in practice. Despite this fact is the quality and fidelity of the signal reproduced from such overlapping tracks very high. This means that using a circuit according to the invention for Reproduction with the reproduced signals Hifi quality achieved can be used if amplitude modulation or phase modulation is used in recording is and when the phases of the carrier signal of adjacent tracks to neither Position of the tracks are correlated to one another. Because of the special feature of an inventive Circuit that its carrier frequency is low, the phase deviation is small, even if there is a time or phase deviation in the T carrier signals @adjacent tracks occurs during recording, the result is, d next small eeinfluence due to beating interference of the signal level, caused by crosstalk between adjacent tracks. The consequence is that the reproduced signals are not degraded in quality This is in contrast to the fact that when a signal is frequency modulated becomes, the alignment of the carrier z-iris see adjacent tracks is difficult, so that protective strips are necessary. Since then the record with the present en invention using amplitude modulation or phase modulation can take place in traces that have no protective strip between them and thus If an increased density of the recording can be achieved, the tape can be saved and / or reduce the belt speed, compared to previous practice. However, even frequency modulation with subsequent filtering to the essential part of the one sideband, and then frequency converting to Bringing the carrier to a low frequency still leads to that of the invention Advantage of lower losses in the magnetic head.

Since in the present invention the video signal is used to Modulating the amplitude or phase of a carrier can be the frequency range or the bandwidth of the resulting modulated signal is kept relatively narrow and the speed of the rotating heads can be related to the tape speed be kept low. A result of this is the diameter of the drum for the head, within which the head rotates, can be reduced.

In summary, Brfinl-Inb can be used as a cloning or as a process for recording and / or subsequent playback of video signals on or from a magnetic recording material can be outlined as being a modulated Signal is generated in which the video or image information is primarily only is detected by a sideband of the carrier, which in certain nodulation methods can also be suppressed. The frequency of the carrier is within the band that was taken up by the video signals before they were modulated. The carrier can originally be a higher frequency carrier and to the one mentioned above Be implemented frequency that is also within the frequency band that has the maximum the playback characteristics or

-sensitivity of a magnetic recording and / or reproducing system includes. With certain modulation methods, the carrier is phase and frequency controlled, around recorded between aul adjacent tracks of the magnetic recording material Eliminate any interference that occurs in the signals.

A more specific embodiment of the general principle of the invention can be outlined as a circuit or as a method that provides modulation a carrier with the video signal (for black-and-white images) or the luminance component (with color picture). A push-pull modulator can be used as a modulator, in whose output signal the carrier is suppressed It can also be an amplitude or phase modulator can be used. The modulated signal is filtered in such a way that that most or the major portion of one side ligament has been removed. The filter can be a vestigial sideband filter with an attenuation of 6 dB at the Carrier frequency.

The carrier frequency must be at least as high as the highest modulating Be frequency. The suppressed sideband is the upper sideband and the lower one Sideband (YC in Figure 8C) is maintained. This sideband becomes frequency wise implemented to bring the carrier frequency to a frequency value that is lower than the other sideband frequencies (YD in Fig. 8D).

It should be noted that the converted carrier frequency is within of the tape or area of the highest sensitivity to recording and Playback lies. This keeps the noise in the reproduced signal to a minimum brought, the chrominance signal need not be used to modulate a carrier will. It is simply converted into a frequency band because @ below the frequency converted Luminance signal (CS in Fig. 8D). The frequency-converted chrominance carrier lies at about 0.5 EEz. The frequency-converted carrier of the vestigial sideband luminance signal is around 1 IHz.

Low frequency cracks make it easy to phase the carrier to be controlled in such a way that the recording can take place in such tracks that are mutually are immediately adjacent without beat interference occurring, which then would be difficult to eliminate if the carrier that modulates with the luminance signal is, would have high frequency.

An improved signal can also be obtained with a frequency-modulated video signal Achieve signal-to-noise ratios. With amplitude and phase modulation the carrier can be compared between adjacent tracks in such a way that that protective strips can then be omitted.

The present invention may be summarized as a circuit or as a Method for reproducing files recorded on a magnetic recording material Signals are described, this recording as a modulated signal with suppressed carrier, the video information is primarily from only one Sideband is included and the frequency of the suppressed carrier in that band that has been taken up by the video signals before they are modulated. Synchronization failure or jitter components are substantially eliminated from the reproduced signals or is the picture shake-free.

As described in particular in connection with Figs. 16A-E, are solved with the invention those problems with speed fluctuations of the drive motor of the recording material are connected. Such fluctuations namely, generate synchronization disturbances or tremors in the reproduced picture. This type of interference causes those signals and especially those signal frequencies, which are marked with "in FIGS. 16A-E.

Synchronization disturbances are eliminated by deriving the frequency-converting Signal of frequency c "" from the frequency conversion of the stable signal of the in the Circuit contained stable oscillator and the signal f "," which is the undesirable Contains sync interference or jitter components.

If the signal of the frequency fC "is used to generate the signal C" implement, the sync component drops out and the implemented The chrominance signal is jitter-free or free from synchronization disturbances. If that Luminance signal YD "containing synchronization disturbance at frequency fC" in YF "is implemented, it still contains some synchronization interference component then the signal YF "in synchronism with the signal fB" is demodulated which is the same Has sync component, becomes a sync-free Signal reached and the result is the pure luminance signal YA With a frequency doubler is the frequency of the coming from the reproduction converter 51 Signal produced by push-pull modulation of a carrier with an information signal YA was generated, doubled. With push-pull modulation, in which the carrier suppresses a different type of envelope is generated than is the case with normal amplitude modulation is present. The effect is comparable to switching the signal YA around the AC zero line, which is denoted by e in FIG. 5A. The part TB the signal YA, the upper one the line, generates the same envelope as usual amplitude modulation. The negative part TA produces the same envelope when TA is folded around the line e will. This places the synchronization peaks at the points of maximum amplitude.

The effect of the folding around the axis e is such that to each Point in time at which the modulation signal passes through the axis e, the phase of the modulated Signal jumps by 180 °.

This can cause phase problems in the synchronous detector, however by doubling the frequency of the signal R in the frequency doubler by eliminating the sudden phase jump have been resolved.

A new phase problem is based on the fact that the signal Q of a variable frequency oscillator has a frequency fL which is the fourth Part of the frequency of a signal Z is. With the signal Z one could change the Synchronize the oscillator at each of the four locations.

However, the synchronizing signal has a frequency 2fL and becomes In one Gate switching controlled. The signal controlled in the gate circuit only has a half as high in frequency as the signal Q and is also used to control the phase of the Signal Q used. For the signal 0- this gives the possibility that only two phase conditions are present. In the following description of an exemplary embodiment is still mathematically proven that the synchronously demodulated signal in hoid cases or in each case the same or

is the same.

Further explanations of the invention and further achievable advantages go from the description given below with reference to the figures of individual preferred Embodiments emerge.

Figures 1A and 1B show graphs of the output characteristic of a conventional Magnetic tape recorder in order to explain the present invention.

Figure 2 shows a view of signals recorded on a tape.

FIG. 3 shows a block diagram of a first circuit according to the invention for signal recording.

Figures 4A to 4G show a series of frequency spectra used for Explanation of a circuit according to FIG. 3 are used.

FIGS. 5A to 5E show a series to explain the invention of waveform graphs.

Figure S shows a block diagram of an embodiment of an inventive A playback circuit which corresponds to the circuit of FIG.

FIG. 7 shows a block diagram of another exemplary embodiment a circuit according to the invention for recording.

Figures 8A to BH show a number of frequency spectra for illustration the mode of operation of a circuit according to FIG. 7.

Figures 9 to 11 show block diagrams of other embodiments a circuit for playback.

Figures 12A to 12G show a number of fresuence spectra for explanation a circuit according to FIG. 11.

Figure 13 shows a block diagram of another embodiment of a circuit according to the invention for re-gases.

Figures 14 and 15 show block diagrams of further embodiments a circuit according to the invention for recording.

FIG. 16 shows a number of frequency spectra for explanation A-E of the Reduction of synchronization disturbances in the circuit according to FIG. 7.

FIG. 17 shows a block diagram of a circuit according to the invention for playback.

Figure 18 shows waveforms produced in the operation of a circuit according to Fig. 17 occur.

The description of exemplary embodiments according to the invention preceded by The graphs of Figures 1A and 1B are discussed first in order to the issues related to magnetic recording and reproduction which make the present invention so useful.

1t shows a diagram of a frequency curve, the losses can be seen makes that occur in connection with the recording head or in this. on the abscissa are the frequency values of a signal to be recorded or are fourth the ratio of the belt speed to the wavelength is plotted.

In a logarithmic scale, the amplitude values are on the ordinate plotted against the output voltage of the reproduction. It is known that in a relative low-frequency range the amplitude of the reproduced by a reproduction transducer Voltage increases linearly with frequency with an increase of 6dB per octave. However, as the frequency increases further, the flow of the recording is no longer linearly proportional the recording current. There is some power loss in the winding of the recording head based on core and copper losses. The sensitivity or the frequency response Curve a representing it falls and reaches the value zero at point P. From it it can be seen that there is a range of frequencies available for video or image recording is not fully usable.

Fig. 1B shows a graph of the voltage of the playback signal, depending on the frequency. On the abscissa is again the frequency of the recorded Signal and on the ordinate is the amplitude on a logarithmic scale plotted against the voltage of the playback output signal.

The curve of the voltage of this playback signal should ideally be a straight line b. In fact, however, this curve deviates from the straight line Line b and runs in a frequency band of about 1 IMHz from to higher frequency values towards, according to curve c, due to such factors as losses in the (magnetic) head, penetration and distance losses, the gap effect, Recording demagnetization and self-demagnetization and the like. These losses can occur during the magnetic recording or afterwards.

From a discussion of the curves of FIGS. 1A and 1B it can be seen that that. because of the overall frequency dependency that occurs, a maximum value at occurs at a frequency of approximately 1 MHz. So it would be useful to send the signals in such a way that the carrier to be modaxed by the video signal is at a frequency of approximately 1 N4Iz. Usually a wearer must have a such a signal can be modulated, which is a comparative to the frequency of the carrier has a much lower frequency. Therefore it would not be possible to use a 1 ttEz carrier modulating a video signal directly, which up-converts frequencies that are even higher than 1 MHz.

Fig. 2 shows a short piece of magnetic tape M on which in a number Tracks T1 - T6 video signals are recorded. These tracks are a little sloping shown, but in practice they are inclined to a far greater extent, so that they are almost parallel to the longitudinal direction of the belt, which are the same in FIG the horizontal is. In a simplified way, the tracks T1 - T3 show a frequency relationship, which can be present when signals having the same carrier frequency in a each of the tracks are recorded and the carrier frequency is relatively low, which is represented by waveform d. Those occurring in tracks T1 and T2 Waves are in phase with each other. However, there is a phase difference between the Waves of tracks T2 and T3. Due to the fact that the carrier frequency is low, the phase shift is related to the period of the carrier signal small. Thus, beat interference or crosstalk occurs between neighboring ones Tracks do not appear even if a reproducing head h follows the track T2 is supposed to reach part of the track T3. The low frequency of the carrier makes it easy for the wearer align between adjacent tracks or to adjust, even if there is a synchronization problem should.

In the tracks T4-T6, the carrier signal d 'according to the status of the Technology much higher frequency. One consequence of this is that there is a synchronization problem or a similar effect, significantly larger phase changes or phase differences causes, so that one can look at an amplitude-modulated or phase-modulated high-frequency Carrier can only carry out the phase control or correction with the close spacing between adjacent tracks would be possible. If the playback head h 'partially passes over to a second track, as shown, can be a beat signal and / or a crosstalk signal occurs. However, since according to the present Invention the frequency of the carrier has the value of approximately 1 NHz, the adjustment is of the carrier is much easier than it used to be with frequency-modulated carriers was much higher carrier frequency. The tolerance for synchronization disturbances can be relatively large when using the invention and / or there can be a synchronization disturbance eliminating servo circuit can be implemented in a simple manner.

When the carrier signal is push-pull modulated, i. H. Amplitude modulation is present with suppressed carrier, the degree of modulation being compared to usual amplitude modulation is larger, the carrier signal can be considered an imaginary one Consider the carrier signal. The alignment described above for the carrier is in the case of a push-pull modulator, this is equivalent to an adjustment of the sideband components, whose frequencies are close to the frequency of this imaginary carrier. I. E.

in other words that because a usual television signal is relative has many frequency components around 1 MHz, signal components that are close to the above frequency range lie, can be compared or used for the comparison.

Fig. 3 shows an example of a system for recording a black-and-white video signal. The video signal is applied to an input connection 1, which passes through a low-pass filter 2 is connected to a push-pull modulator 3. The carrier is controlled by an oscillator 4 generates and has the Frequency value f. The oscillator 4 is also connected to the modulator 3. The output of the push-pull modulator 3 is via a The remaining sideband filter 5 is connected to a frequency converter or converter 6. An oscillator 7 supplies a signal of the frequency fC and is connected to the frequency converter 6 connected. The converted output signal passes through a low-pass filter 8 into an amplifier 9. The output of the amplifier 9 is applied to a recording head 10 at.

The operation of a circuit of Figure 3 will be discussed below in context with the frequency spectra of FIG. 4 and the waves or pulse representations of Fig. 5 described. The signal appearing at the output of the low-pass filter 2 in FIG is designated as signal YA and has a frequency spectrum as shown in Fig. 4A and a waveform as shown in Fig. 5A. The upper limit frequency of the signal YA is identified as frequency fA in Figure 4A and is approximately 3.5 MHz. This Signal YA is fed to push-pull modulator 3.

The carrier fed to the modulator 3 has a frequency fB of 4 MHz. The frequency spectrum resulting from the push-pull modulation taking place in the modulator 3 is indicated in Fig. 43 by the signal YB. The waveform of this signal is shown in Fig. 5B, from which it can be seen that the modulated signal YB has a component MH which corresponds to the synchronization signal SK that is in the signal YA of Fig. 5 is included. The proportion Mm has compared to the other proportions of the signal YB has a larger amplitude value.

The video signal YB modulated by the modulator 3 (FIG. 3) becomes the residual sideband filter 5 supplied. This has such a frequency (response) characteristic or transmission behavior, that the amplitude of the signal at the carrier frequency is reduced by 6dB. In order to Most of the upper sideband is eliminated and it primarily remains only nor the lower sideband YC, which is shown in Fig. 4C. This lower sideband YC is sent to the frequency converter 6, together with the signal f0 of the oscillator 7, supplied.

The signal fC has a frequency of approximately 5 MHz, so that the output signal of the converter 6 has two bands, as shown in Fig. 4D. One band is through the signal YD and the other 3and thereby represents the signal YE. Although the The frequency band of the signal YD is below that of the signal YE, is nevertheless its carrier frequency at its lower wind at frequency fD. This frequency results as D = - fB = 1 MHz. As it is common for upper sideband signals, Having the wearer near or below the bottom of their band will do that Signal YD addressed as an upper sideband signal. The carrier frequency fE des Signal YE, on the other hand, is given by fE = fC + f3 = 9 14Hz.

The upper sideband signal YD is desirable. This is done by the frequency converter 6 transmitted signal passed through the TiefpaB filter 8, which only the from the signal YD passes frequencies occupied and the signal YE filters away.

The spectrum of the output signal of the filter 8 is shown in Fig. 4E. The modulated video signal YD is amplified by means of the recording amplifier 9 and given to the magnetic recording head 10 to set this signal to an appropriate one record magnetic material.

6 shows a block diagram of a system for reproducing signals, recorded by a system of FIG. This playback system has a playback head or playback transducer 11, which is connected to an amplifier 12 is connected, from which an amplified signal is supplied to a frequency converter 13 will. An oscillator 14 with a variable frequency and an oscillator 15 with a fixed Frequency supply signals to another frequency converter 16. The output signal of the converter 16 is given to two filters 17 and 18. The output of the filter 18 is connected to the frequency converter 13. The output of the frequency converter 13 is via a low-pass filter 19 with a synchronous detector; or 20 tied together, to which a signal from the filter 17 is also fed. The output of the detector 20 is connected to a terminal 21.

The output signal of the low-pass filter 19 is also sent to a gate circuit 22 and given to an envelope detector 23. The outcome of the latter is with a separation stage or an amplitude filter 24 connected for a synchronization signal, which gives signals to the gate circuit 22.

The output signal of the gate holding 22 goes to a phase comparator 25, to which signals from the filter 17 are also fed. The comparator delivers an output signal used to control the operation of the variable oscillator 14 will.

The operation of a system shown in Fig. 6 is as follows in connection with the frequency spectra indicated in FIG. 4 and those in FIG. 5 waveforms shown. The magnetic head 11 becomes that shown in Fig. 4E Signal YD reproduced. This signal is from amplifier 1? reinforced and that Frequency converter 13 supplied. From the oscillator 14 with variable frequency generates a signal at approximately 0.5 MHz and another signal at a frequency of 4.5 MHz is supplied by the oscillator 15. When the latter two signal are fed to the frequency converter 16, an output signal is generated which both has a sum frequency component and a difference frequency component. the Difference frequency component has a frequency fB of 4 MHz and passes through the filter 17 through.

The sum frequency component has a frequency c of 5 MHz and goes through the filter 18 to be fed to the frequency converter 13. From it it follows that the converter 13 supplies an output signal which has two as shown in FIG. 4F has bands. The lower sideband is marked with and has an imaginary one Carrier frequency fB, which results from fB = fC f fD = 4 MHz. The upper sideband has an imaginary carrier frequency fG, which results from fG fC + fD = 6 MHz. Just the lower sideband is desired and accordingly it will The output signal of the frequency converter 13 is passed through the low-pass filter 19, to obtain the signal YF shown in Fig. 4G.

This signal YF is similar to the signal YC obtained from the residual side bana filter 5 of the recording system shown in Fig. 3 is provided. To get the signal YF to demodulate, it is given in the synchronous detector 20, together with the difference frequency signal, which has a frequency of 4 MHz. The resulting Detector signal receives d at output terminal 21 and it is essentially the same with the signal YA of Fig. 4A.

The modulated video signal to be obtained at the output of the filter 19 YF has a waveform as shown in Fig. SB with a component MH which is the synchronizing signal is equivalent to. This portion MH has a larger amplitude, in comparison on any other part, in the same way as the modulated one Video signal YB to be obtained from the push-pull modulator 3 of FIG. The on Output of the filter 19 to be obtained modulated video signal YF is in the synchron Gate circuit 22 controlled by a gate signal from the envelope detector 23 and the amplitude sieve 24 is to be obtained. This gate signal (which controls the gate circuit) of the output of the amplitude filter 24 is the signal PH and shown in Fig. 5D the signal controlled by the gate signal that occurs at the output of gate circuit 22, corresponds to the signal component M11 with a frequency B = 4 MHz and is shown in FIG. 5C shown. This signal component MH is given to the phase comparator 25 to to compare it with the signal that also has a frequency of 4 TEz and comes from the filter 17. Any phase difference between the signal MH and the The signal of the filter 17 is fed as an error signal to the variable oscillator 14, to control this.

The output signal of the frequency converter 16 is thus controlled. The output of this variable frequency oscillator 14 is shown in Fig. 5E shown as signal Q with a continuous waveform.

Because the oscillation frequency and the phase of the changeable in frequency Oscillator 14 is controlled or monitored, is also the output signal of the filter 18 controlled so that a compensation of synchronization disturbances is achieved.

Depending on whether the original video signal shown in Fig. 5A YA is above or below line e, which in turn is on a middle or is an intermediate level between the white and black levels, and accordingly depending on whether the video signal YA is in an interval TA or in an interval Q £ (where it is assumed that the video signal has a sawtooth shape), this becomes supplied by the filter 17, serving for synchronization in the synchronous detector 20 synchronized Carrier signal phase-synchronized with the 4 MiHz signal component M11, which occurs during the Synchronlsierintervalls occurs. This is true even if the push-pull modulated signal B and Accordingly, the modulated video signal that is obtained after the filter 19 are opposite in phase or reversed in phase. Therefore, on Output terminal 21 a predetermined video signal which is equal to the signal YA, obtained from the filter 2 of the recording system of FIG.

Fig. 7 shows a block diagram of a magnetic recording system of color video signals or color image signals. The composite signals are given to an input terminal 31, from which they pass through a low-pass filter 32 in a push-pull modulator 33 arrive. An oscillator 34 with a variable frequency and an oscillator 35 of relatively fixed frequency are connected to each other and provide signals to a frequency converter 36. At the output of the converter 36 two bandpass filters 37 and 38 are connected. The output of the filter 37 is connected to the push-pull modulator 33 as a carrier signal.

The output of the modulator 33 is sent to a vestigial sideband filter 39 and the resulting vestigial sideband signal goes into a mixer 40. The input terminal 31 is also through a band pass filter 41 connected to the mixer 40.

The composite or mixed signal of the mixer 40 arrives to another frequency converter 42, which also has the output signal of the filter 38 is fed. The frequency converted signal supplied by the converter 42 goes to a low-pass filter 43 and the correspondingly filtered signal arrives in an amplifier 44 from which it is amplified to the recording transducer or head 45 is given.

The input terminal 31 is also provided with a sync signal separator 46 connected, the output of which is connected to a phase comparator 47. the Frequency of the output signal of the oscillator 34 is variable frequency divided in a frequency divider 48 and sent to the frequency or phase comparator 47 given, thus generating an output signal that is fed back to the Operation of the oscillator 34, which has variable frequency, to control.

The output of the band pass filter 41 is in addition to the connection connected to the mixer 40 also to a color burst gate circuit 49. The output signal of the separation stage or of the amplitude filter 46 goes to a waveform forming circuit 50, which in turn sends a signal to the burst signal gate circuit 49 supplies. The output signal of the color synchronous gate circuit goes to the oscillator 35 to control its frequency.

The operation of the circuit of FIG. 7 is explained together with the in Fig. 8 described frequency spectra shown. The luminance component of the color signal, which is applied to the input terminal 31 can pass through the low-pass filter 32 and appears as the luminance signal YA shown in Fig. 8A.

Its frequency band extends from approximately 0 Hz to one Frequency f B = 2.99 iIHz. This signal goes as Modulating signal to the push-pull modulator 33.

The variable modulator 34 generates a signal of frequency = 2n + 1fH, where fH is the line frequency of the video system 2 and n is a positive integer, z. B. n = 37. In this case fL = 75 fH = 0.59 MHz. The oscillator 35 generates 2 a signal with a frequency fc = 3.58 MHz If the signals and fS the frequency converter 36 are supplied, an output signal is generated which is a component in the Difference frequency fB = fS- fL = 2.99 MHz. Another component has the sum frequency fC = fS + fL = 4.17 MHz. The filter 37 allows the frequency B = 2.99 Mllz as a carrier signal to the modulator 33, where this carrier is push-pull modulated by the luminance signal YA will. The result is the signal Y shown in FIG. 8B. The one in the figures Signals A and YB shown in FIGS. 8A and 8B have waveforms similar to those of the figures 5A and 5B. The modulated luminance signal YB has a component YH that of the synchronizing signal SH of the luminance signal A corresponds. This share thus has. an amplitude the is greater than any other portion of the signal YB.

After the modulated luminance signal YB as shown in Fig. 8B, has passed through the vestigial sideband filter 39 of Figure 7, one obtains a lower sideband signal YC.

The vestigial sideband filter 39 has such a frequency curve that the amplitude of the signal YC at the frequency fB = 2.99 MHz by 6 dB below the maximum level.

The signal YC is one of the signals fed to the mixer 40 will.

The band pass filter 41 leaves only the chrominance portion of the composite Signal that is present at the input terminal 31 through. This shown in Fig. 8C The chrominance signal aS has a carrier frequency fS = 3.58 SEz and is the other signal which is fed to the mixer 40 to be mixed with the modulated luminance signal YC to become. The resulting mixed or composite signal with the components and CS goes to the frequency converter 42 to deal with the Signal from the filter 38 to be implemented in frequency.

The latter signal has the sum frequency fC = 4.17 MHz.

As a result, the output of the frequency converter 42, as shown in FIG 8D, includes luminance components YD and YE that are symmetrical about the frequency fC and has chrominance components CL and CH, which are also symmetrical to the frequency fC lie. The imaginary carrier of the part B has the frequency close to the lower one End of the band of the signal YD As described above, the signal YD is considered to be an upper sideband signal. The frequency fD results from the Equation fD = fC-fB = (fS + fL) - (fS-fL) = 2fL = 1.18 MHz. The signal ye, which as a lower Sideband has a carrier frequency fE, which can be derived from the equation = fC + fB = 2fS = 7.16 MHz results.

The lower frequency chrominance signal CL has a carrier frequency fL, which results from the equation fL = fC-fS = 0.59 MHz. The higher frequency chrominance signal CH has a carrier frequency fH fC + f5 = 2fS = fL = 7.75 MHz. The whole in Fig. The signal shown in FIG. 8D is applied to the low pass filter 43 which only controls the frequencies passes below the frequency fC. The output of the filter 43 is in Fig. 8E. It comprises the chronological signal CL with the carrier frequency fL = 0.59 M11z and the upper sideband component YD of the modulated luminance signal, which has the carrier frequency fD = 1.18 MHz. The output of the filter 43 goes via a recording amplifier 44 for recording on a suitable magnetic Material to the magnetic converter or Kof 45 The synchronizing signal separator or the amplitude sifter 46 also receives the capture color image signal from the connector 31 1 ago.

The separated synchronization signal is sent to the phase comparator 47 to compare it with the output signal of the frequency divider 48. That The division ratio of this divider is the ratio between the frequency fL des variable frequency oscillator 34 and the (horizontal) line frequency f11. In the present example the ratio is 2/75 so that both input signals of the phase comparator 47 are at the line frequency fH. An error or a discrepancy with regard to the phase between these two signals generates an error or correction signal, which goes to the oscillator 34 in order to control or correct its frequency.

The separated synchronization signal also becomes the waveform forming circuit 50 modified so that it is used as a gate signal for controlling the The chrominance signal CS contained in the chrominance signal can be used from the filter 41 is available. The color synchronizing signal in the gate circuit is derived from the gate signal 49 controlled and is given to the oscillator 35 to control its frequency. The oscillator 35 has the same frequency 3.58 IMHs as the burst signal.

In Fig. 9 is a display system for displaying color television pictures recorded with a system of FIG. Some details of Fig. 9 are the same as those of Fig. 6 and correspondingly have the same reference numerals. In Fig.9, a reproduction converter 51 is via an amplifier 52 with a frequency converter 53 connected.

A variable frequency oscillator 54 and an oscillator 55 together give signals to a frequency converter 56.

The output of this converter 56 is connected to the filters 57 and 58, of which the filter 58 is connected to the frequency converter 53.

The output of the converter 53 is through a low pass filter with a Synchronous detector 60 connected. This also receives the output signal of the filter 57. The output signal of the detector 60 goes to a mixer 61, which also has output signals from the frequency converter 53 via the bandpass filter 62. The output of the mixer 61 is connected to an output terminal 63.

The output of the low pass filter 59 is also connected to the gate circuit 22nd and the envelope detector or envelope rectifier 23 is connected. The latter supplies signals to the synchronizing signal separation stage or amplitude filter 24, the or the again connected to the gate signal input terminal of the gate circuit 22 is. The output of the gate circuit 22 is connected to the phase comparator 25, which also receives the output signal of the filter 57.

In addition, to describe the operation of the system of FIG reference is also made to the frequency spectra shown in FIG. That at the exit The reproduced signal appearing in the amplifier 52 comprises the luminance signal and the chrominance signal CL as shown in Fig. 8E.

The chrominance signal has a carrier fL = 0.59 IHz and the luminance signal has a carrier fD = 1.18 MHz. These two signals are sent simultaneously in the frequency converter 53 frequency converted. The converting signal is by combining the output signal the variable oscillator 54, which has a frequency fL = 0.59 MHz, and the output signal of the oscillator 55, which has a frequency f5 a 3.58 MHz, in the frequency converter 56 generated. The latter generates an output signal that is an output signal with a Component of frequency B = fS + fL = 2.99 MHz, which is the difference frequency, and has another component that has the sum frequency = = SS + fL = 4.17 MHz. the the latter component passes through the filter 58 and reaches the frequency converter 53 to convert the frequency of signals CL and YD.

The resulting output signal of the frequency converter 53 is in 8F. It comprises a signal of frequency fC = 4.17 MHz with converted Chrominance signals and luminance signals, which are syrninetrically spaced above and lie below this frequency. The chrominance signals are labeled CS and CI and have the corresponding carrier frequencies fS = fC-fL = 3.58 MHz and fI = fC + fL = 4.76 MHz.

The luminance signals are still in modulated form and are ds Signal YF with a carrier frequency fB = 2.99 NHz and the signal YG with the imaginary Carrier frequency fG = fC + fD = 5.35 MHz. The low-pass filter 59 only lets the signal YF on the detector 60 therethrough. This signal is shown in isolation in Figure 8G. That Bandpass filter 62 leaves only the chrominance signal CS in the original chrominance frequency band with the original harmonic frequency f5 = 3.58 MRz. This signal does not require any further demodulation and can therefore be sent directly to mixer 61 will.

The luminance signal YF must be demodulated by the synchronous detector 60 and for this purpose the difference frequency fB = fS-fL = 2.99 MHz goes from the frequency converter 56 through has filter 57 to the detector 60. The processed by the detector or demodulated luminance signal then goes to mixer 61, where it is matched with the chrominance signal is combined to form the composite color image signal at the output terminal 63 obtain.

The circuits 22-25 operate in the same way as those 6 and control the operation of the oscillator 54 with variable frequency.

If the composite signal coming from the upper sideband of the modulated luminance signal YD, which has a relatively low frequency of a suppressed Carrier, and consists of the chrominance signal CL having a frequency that is lower than that of the suppressed carrier of the recording material is reproduced or played back, these signals are then according to the invention in the Frequency implemented. The frequency-converted luminance signal is demodulated synchronously and the frequency-converting and synchronous demodulating signals are through the the same signal derived from the reproduced signal.

The frequency and phase of the signal from the oscillator 54 can be varied Frequency (Fig. 9) are controlled and the result is that from filter 58 Frequency-converting signal is controlled to avoid synchronization disturbance of the chrominance signal to eliminate and to synchronize interference of the modulated luminance signal to decrease. Furthermore, the frequency and the phase of the synchronous demodulating Signal that comes from the filter 57, controlled or monitored at the same time to a to eliminate residual synchronization control of the modulated luminance signal.

The operation of the circuit of FIG. 9 to minimize Malfunction signals are discussed below in connection with Figures 16A-E described. Assume that the recording is made with a recording system according to Figure 7 has been made, with that relationship between the Carrier frequencies fL and fD, which results from fL = 1 / 2fD. The frequency-converted chrominance signal CL ub the modulated luminance signal YD as shown in Fig. 8E are on recorded on the magnetic recording material and contain synchronization disturbance components, the fluctuations or fluctuations of the drive motor, not shown during the signal reproduction or

-decrease based. The signal reproducing head 51 outputs a chrominance signal CLII with a carrier frequency fL "and an upper sideband signal YD" again that has a suppressed carrier frequency fD11. This is illustrated in Figure 15E. The index II indicates that these so-called signals have synchronization disturbance components contain. The chrominance signal CLII and the modulated luminance signal YD ", the both contain sync components go through the playback amplifier 52 to the frequency converter 53. In the meantime, the signal goes with the frequency fL "which contains synchronization disturbance from the variable frequency oscillator 54 and the interference-free signal goes with the frequency fS of the oscillator 55 to the Frequency converter 56 to a signal of frequency fB "= = fS - "and to generate a signal of the frequency fC" = fS + fL ". The filter 57 can the signal of frequency fC "" passes through. This signal from the filter 57 goes to the Frequency converter 53 to convert the reproduced signals YD "and CL" in frequency to convert it into a luminance signal consisting of a lower sideband signal YF "with a frequency fB" = fC "-fC" = (fS + fL ") - fD" = fS-fL "of a suppressed carrier and to derive an upper sideband signal v G "which has a frequency fG" = fC "+ fD" = (fS + fL ") + fD" = fS + 3fL " of an oppressed carrier. In addition, a chrominance signal is made up of it from a signal CS with a carrier frequency = = fC "- f" = (f5 + f ") - fL" = f5 and a signal CI "with a carrier frequency fI" = fC "+ fL" = (fS + fL ") + fL" = fS + 2fL " as shown in Fig. 16B.

These signals YF ", $ YG", $ CS and CI "are sent to the low-pass filter 59 to pass therethrough a modulated luminance signal YF "which has an imaginary frequency fB "= fS fS -" as shown in Fig. 16c. This modulated luminance signal YF "is given to the synchronous detector 60 in order to communicate with the Signal fB "= fS f fl" of the filter 57 to be demodulated synchronously, thus the luminance signal A is generated. The synchronization disturbance component is thus eliminated; how this can be seen in Figure 16E. The amplitude of the sync components, contained in the modulated luminance signal YD "are halfway through the frequency converter 53 and the filter 59 are reduced and are further reduced to zero by the synchronous detector 60. The signals YF ", YG," CS and CI "received from the frequency converter 53 come also go to the bandpass filter 62 to pass the chrominance signal CS, which has a carrier frequency f5 which does not contain any synchronization disturbance component, as shown in Fig. 16D.

Even though there is no color signal system as in the circuit of Fig. 4 is a common one generated by an analysis circuit (PLL) Signal with components 14 - 18 so adapted or suited to the Frequency converter 13 and the synchronous detector 20 to be supplied so that the Synchronization noise components shown in Fig. 4E in the modulated luminance signal YD can be eliminated in the same way. The syncronization disorder components, contained in the reproduced signal, and in other embodiments can be eliminated in the same way.

The embodiment according to FIG. 10 is similar to that according to FIG. 9 and it has a number of details that are related to each other have, and therefore again have the same reference numerals. The only one in Fig. 10, part not present in FIG. 9 is a delay circuit 101 connected between the amplitude filter 24 for the synchronization signal and the gate signal input of the Gate circuit 22 is. However, there are individual parts (of the circuit according to Fig. 10) connected in a different way than that described for FIG. In Fig. 10 is the signal to be controlled in the gate circuit is supplied from the output of the bandpass filter 62.

In FIG. 9, this signal is instead taken from the output of the low-pass filter 59 delivered. Instead of the output of the filter 57 with the phase comparator 25 is connected, here is also an output of the oscillator 55 with the phase comparator tied together.

How the circuit works according to Pig. 10 differs from on that of FIG. 9 in that the chrominance signal converted again in frequency CS with the carrier frequency fS = 3.58 MHz, i.e. the output signal of the bandpass filter 62, in the gate circuit 22 is controlled. In order to receive a gate signal at the right time, i. H. a gate control signal to obtain the burst signal To control in the gate circuit, the synchronization pulses of the amplitude filter 24 somewhat delayed in the delay circuit 101 so that they are at the time of burst signals occur on the rear black shoulder of the beam blanking signal, the one Forms portion of the chrominance signal C5. This is how the output signal exists the gate circuit 22 from color sync signals or pulses of oscillations of the Frequency f5 = 3.58 ritz. These are in the phase comparator 25 with the 3.58 MHz output signal of the oscillator 55 compared and any deviation or error generates a signal, that is used to control the operation of the variable oscillator 54 and thus to control the operation of the frequency converter 56. Let it be remembered that the sum signal with the frequency fC - S = fL, that from the frequency converter 56 ago passes through the filter 58, which is the signal that is used in the frequency converter 53 will. Thus, the frequency conversion in the whole system is controlled by Control of the operation of the variable oscillator 54 by means of phase comparison between the converted color sync signal and the output signal of the oscillator 55.

Fig. 11 shows another example of a reproducing system.

This includes a number of details that are already included with other embodiments have been discussed. These details have the same reference numerals in FIG. 11 as in the figures of the other embodiments.

In Fig. 11, the converter 51 is via the amplifier 52 with a high-pass filter 64 connected. The output of the filter 64 is one of the input terminals Frequency converter 65 and connected to a limiter circuit 66. The exit this circuit 66 is connected to an oscillator 67, which again around its output signal to a frequency converter 68.

An oscillator 69 is also connected to the frequency converter 68 and the output of the frequency converter 68 is through a filter 70 with a second input terminal of the frequency converter 65 connected. The output of frequency converter 65 is over a low-pass filter 71 is connected to the synchronous detector 60.

The output signal of the amplifier 52 is through a low-pass filter 72 also connected to a frequency converter 73.

A frequency divider 74 is connected to an output circuit of the oscillator 67 and its output circuit is in turn connected to a frequency converter 75. The latter receives the output signal of the oscillator 69 and the output signal of the Frequency converter 75 is connected to frequency converter 73 via a filter 76. The output signal of the frequency converter 73 goes through a bandpass filter 77 to the Mixer 61, which is also connected to the output of synchronous detector 60. The output terminal 63 of the system is connected to the mixer 61.

The operation of the system of FIG. 11 is described below at With reference to the representations of the frequency spectra of FIG. 12 described. That modulated luminance signal UD and the chrominance signal CL shown in Fig. 12A and reproduced by the converter 51 via the amplifier 52, it corresponds to the in Fig. 8E. They are means of signals with different frequencies implemented in their frequency. The luminance signal YD goes through the high-pass filter 64 and is from separated from the chrominance signal, as in Fig. 12B shown.

Since the carrier with its frequency fD near the lower edge of the tape which is occupied by the signal YD, this signal is considered an upper one Called sideband signal.

As already stated above, the frequency is D = 1.18 SEz.

The signal YD is given to the frequency converter 65 to convert a Signal to receive. The signal YD also goes through the limiter circuit 66, to synchronize the oscillator 67, which oscillates at a frequency of 1.18 1Hz.

The signal from the oscillator goes together with the signal from the oscillator 69 to frequency converter 68. The latter signal operates on the chrominance subcarrier frequency fD, which is 3.58 MH. The output of frequency converter 68 includes one Component fI with fI = fD + fS = 4.76 MHz. The output signal of the frequency converter 68 is sifted through filter 70 to take out only that signal that has the frequency f1 and which is fed to the frequency converter 65.

The result is that the output of the frequency converter 65 a component YC as shown in FIG. 12C with a carrier frequency f5 = 3.58 MHz Has. This signal goes through filter 71 which removes any other components and the signal YC goes to the synchronous detector 60 to be demodulated. Since the carrier frequency 9 of the signal YC is 3.58 MHz, the output signal of the Oscillator 69 can be used directly in the synchronous detector 60, the signal YC to demodulate and to restore the signal YA at the output of the detector 60, as shown in Fig. 12D.

The combined signals CL and shown in Fig. 12A also go on the low-pass filter 72, which only allows the signal CL to pass to the frequency converter 73. The signal CL has a carrier frequency fL = 0.59 MHz and this frequency is on 3.58 NHz implemented. To achieve this, the output of the oscillator 67 with a frequency of 1.18 MHz from the frequency divider 74 by a factor of 2 to the frequency 0.59 MHz divided. This signal goes along with the signal of the oscillator 69 of the frequency fS = 3.58 IGHz to the frequency converter 75. This shows that one of the output components of the frequency converter 75 has a frequency fC = fL + fS = 4.17 IMiz. This component is able to pass through the filter 76 into the frequency converter 73, to convert the frequency of the signal CL. The output signal of the frequency converter 73 comprises and has the converted chrominance signal C5 shown in Fig. 12F Subcarrier frequency f = 3.58 MHz. This signal can pass through the band-pass filter 77 get through to the mixer 61. It gets there with that shown in Fig. 12D Luminance signal A combined so that at the output terminal 63 the composite, in Fig.

12G occurs.

In the embodiments described so far, the video signals were black and white or the luminance component of the color image is modulated in push-pull mode. However, it can normal amplitude modulation can also be used instead of push-pull modulation. In this case the carrier signal, which is eliminated with push-pull modulation, remain in the modulated signal. In addition, angle modulation, e.g. B. phase modulation, be applied. In this case it can also be possible for the phase modulation having a signal that consists mainly of the lower sideband portion, at which the carrier frequency is near the upper portion or end of the band that is taken by this signal.

This lower sideband signal can then be frequency-converted, in order to produce a modulated signal that is mainly from the upper sideband with a low carrier frequency that is well within the band below that Curve c is in Fig.1B. Fig. 13 shows a reproduction system for reproducing a Color video signal or color picture signal in which the luminance component is phase-modulated and has a carrier frequency fD = 1.18 MHz.

The chrominance signal is in the low frequency range and is equivalent to z. B. the signal CX of Fig. 12A. It has a carrier frequency t = 0.59 EEz.

In the circuit of Fig. 13 a number of details are used, which have already been described for the preceding exemplary embodiments and which are therefore have the same reference numbers. The converter 51 is connected to the amplifier 52 one input terminal of the frequency converter 53 is connected. The changeable oscillator 54 and the oscillator 55, which are connected to the frequency converter 56, generate a signal which, after passing through the filter 58 and being fed into the frequency converter 53 has the desired frequency, the input signal output by the amplifier 52 to implement.

The output signal of the frequency converter 53 goes to the low-pass filter 59 and via the bandpass filter 62 to the mixer 61.

The filter 59 is via a limiter circuit 78 with a phase demodulator 79 connected, the output terminal of which is connected to another input terminal of the mixer 51 is connected.

The output of filter 62 is in addition to being connected to the mixer 61 is also connected to a burst signal gate circuit 80. Of the The output terminal of the phase demodulator 79 is connected to an amplitude filter 81, which in turn is connected to a waveform shaping circuit 82.

The output of this circuit 82 is connected to the dorsignal singing terminal of the burst signal gate circuit 80 and the output of the gate circuit 80 is connected to a phase comparator 83. The output of the oscillator 55 is also connected to the phase comparator 83 and the output of the phase comparator is connected to the variable oscillator 54.

When operating the circuit of FIG. 13, both the phase modulated Luminance signal as well as the frequency-converted chrominance signal in their frequencies implemented in the frequency converter 53. The variable oscillator 54 provides an output signal with a frequency t = 0.59 MHz. This signal will in the frequency converter 56 with the input signal of the oscillator 55, which has a frequency fS = 3.58 IIHz, combined so that an output signal fC results which is the sum of the frequencies and fS and that accordingly has a frequency of 4.17 MHz. This signal passes through the filter 58 and arrives at the frequency converter 53, where it the carrier frequency fD = 1.18 Nfjz of the phase-modulated luminance signal to a Frequency 2.99 MHz converts and where the carrier frequency = = 0. 59 IÇHz of the chrominance signal CL converts to a frequency f5 = 3.58 NHz. The chrominance signal CL is in itself converted to the original chrominance band so that it is again the signal CS. On the other hand, the luminance signal is still a phase-modulated signal and must be demodulated will.

For this purpose it goes through the limiter circuit j8 into the phase demodulator 79, from which it comes as a demodulated luminance signal, to be included in the mixer 61 to be combined with the reconverted chrominance signal. Thus, at the output terminal 63 a restored color image signal is available.

The output signal of the phase demodulator 79 is a luminance signal, which includes synchronizing pulses. These are in a synchronizing signal separator or the amplitude filter 81 is separated and fed to a wave-shaping circuit 82. This causes the pulses to be delayed and makes them suitable for use as color synchronous gate signals of the chrominance signal CS of the output of the bandpass filter 62 can be used. In the the burst signal gate circuit 80 controlled burst signals go from whose output to the phase comparator 83 in order to match the signals of the oscillator 55 to be compared.

This generates a signal that enables the operation of the variable oscillator 54 controls to correct its frequency in this way, or to the correct value keep that the converter signal for the frequency converter 53 is the correct frequency Has.

Fig. 14 shows a circuit which forms part of the circuit of Fig. 7 can replace. Details that correspond in Fig. 14 with details of Fig. 7, have the same reference numbers.

In the system of Fig. 7, when a composite color image signal is to be recorded, the lower sideband signal YC, which is from the residual sideband filter 39 comes here, and the chrominance signal cs coming from the bandpass filter 41, In are combined in the mixer 40 to give the composite signal YC + C5 form. This signal is then frequency-converted in the common frequency converter 42. In the modification of FIG. 14, the chrominance signal C5 and the modulated upper sideband signal YD separately implemented in terms of their frequency.

Fig. 14 shows an input terminal 31 which is provided with a low-pass filter 32 and a band pass filter 41 is connected. The output of the low pass filter 32 is connected to the push-pull modulator 33 which receives a carrier signal from the bandpass filter 37 receives.

Although not shown in Fig. 14, it is a band pass filter 37 connected so that there is a signal from the frequency converter shown in FIG 36 receives. The output of the modulator 33 is connected to the vestigial sideband filter 39, which is directly connected to the frequency converter 42.

This is in contrast to the circuit according to FIG. 7. The output of the Frequency converter 42 is connected to the low-pass filter 43. An oscillator 84 is connected so that it gives a signal to a frequency converter 85, which also receives a signal from the bandpass filter 41. The resulting in frequency converted signal is given to a mixer 86, which is also so connected is that it receives the output of the pass filter 43. The output of the mixer 86 is connected to converter 45 via amplifier 44.

The luminance signal C5 to be obtained from the band pass filter 41 and the frequency converter 85 is supplied, has a carrier frequency fS = 3.58 MEz. The oscillator 84 has a frequency fc = 4.17 z and the difference signal CL, which is on Output of the frequency converter 85 occurs, has a carrier frequency fL = 0.59 ICHz. This signal can be filtered and fed to one of the input terminals of mixer 86 are given.

The luminance signal of the low-pass filter 32 is sent to the push-pull modulator 33 given, which also receives a carrier signal from the bandpass filter 37. This carrier signal has a frequency = = 2.99 MHz, so the output signal of the push-pull modulator 33 is signal YB shown in Fig. 8B. The vestigial sideband filter 39 eliminated most of the upper sideband of this signal and it remains the vestigial sideband signal YC of Fig. 8C. This signal is in the frequency converter 42 implemented, for which purpose the signal of the bandpass filter 38 is fed. The latter signal has a frequency fC = 4.17 MHz, so that the modulated forming a lower sideband Buminance signal YC is an upper sideband modulated luminance signal YD, which has a carrier frequency fD = 1.18 MHz.

The signal is filtered in the low-pass filter 43 and in the mixer 86 combined with the frequency-converted chrominance signal CL, so that a Fig. 8E results in the corresponding output signal. This output signal is provided by the amplifier 44 amplified and sent to the Transducer 45 given.

In the embodiment of Fig. 15, the video signals, or im In the case of a color image signal, the luminance signals to the input terminal 1 and passed through the low-pass filter 2. With the filter 2 is an angle modulator 88 connected, and the output of this modulator is connected to a carrier generator or Carrier oscillator 89 connected whose output is through a vestigial sideband filter 91 connected to a frequency converter 92, with which a source 93 for a converting signal is connected. The output of the frequency converter is through a low pass filter 94 and an amplifier 96 with a recording converter 97 connected.

When operating a circuit according to FIG. 15, the generator or Oscillator 89 generated carriers have about 3.5 MHz. He can use the video signal with a frequency modulation or a stroke of t 0.5 1'iiiz be modulated. For example the peak sync signal can have a frequency. f1 of about 3.0 MHz and the peak white signal can drive a frequency 12 of approximately 4.0 MHz. Just the modulated lower sideband signal below 4.0 NHz is used in the converter 92 implemented by a signal with a frequency f3 of about 5.0 D; Ez. The filter 94 lets the sideband signal between the frequency f3-f2 = 1 14Hz des converted peak white signal and the frequency f3 - f1 = 2 MHz of the peak synchronization signal to amplifier 96 therethrough. From the amplifier the signal goes as to be recorded Signal to converter 97.

The chrominance signal can be separated in this way into a deeper one Frequency band are converted so that it does not pass through together with the luminance signal the modulator 88 must pass through. This can be done in a way as shown in FIG. The recorded frequency-modulated signal can can be reproduced by means of a reproducing circuit which is the same as the one after Fig. 13 is if the demodulator 79 is a frequency modulator.

17 shows an embodiment of a circuit according to the invention for playback. Some details are the same as those of the circuit of Fig. 9 and have the same reference numerals. The connections between these parts is therefore not described again. Details shown in FIG. 17 for the first time occur, are a high-pass filter 200, through which the output of the amplifier 52 with the detector 23 and a limiter 201 is connected. The output of the limiter is connected to a frequency multiplier, on the turn the variable frequency oscillator 54 is connected. Via a low-pass filter 203 is the output of the synchronous detector 60 with one of the level gears of the mixer 61 connected.

In the circuit according to FIG. 9, the portion of the gate circuit 22 MH of the push-pull modulated signal YF to be received by the filter 59 is. These signals are shown in Figures 5C and 5B. That of the control in the Gate circuit subject signal MH goes to the phase comparator 25 to there with to be compared to the signal coming from the filter 57, resulting in an error signal for controlling the phase and frequency of the output signal of the oscillator 54 can be generated with a variable frequency.

Such a phase comparison is only made during each (horizontal) line synchronization interval performed. The phase and frequency of the signal Q of Fig. 5E takes during the entire interval between the pulses PH of Fig. 5D does not remain constant. With a circuit according to FIG. 17, even more stability is achieved.

For a description of the operation of a circuit according to FIG. 17, let it is assumed that the signal reproduced by the converter 51 has a modulated luminance component YD, which is modulated onto a suppressed carrier with a frequency fD, and a Chrominance signal CL which has a carrier frequency fL as shown in Fig. 8E, where fD = 2fL. The signal YD goes through the filter 200 to the limiter 201. The frequency of the output signal of the limiter is determined in the frequency multiplier 202 doubled to a frequency 2fD = 4L = 2.36 MHz.

This signal is sent to one of the control inputs of the oscillator 54 given with changeable frequency. This oscillator 54 generates an output signal the frequency f.

The signal YD of the filter 200 is also sent to the gate circuit 22 and given to the envelope detector or envelope rectifier 23. The latter demodulates the envelope of the signal YE according to FIG. SB and generated an output pulse signal PH corresponding to the components with the highest amplitude. Even with signal convolution, which is typical for a push-pull modulated signal, step these proportions during the line sync intervals. The pulses will be PH separated by means of the circuit 25 or screened off and to the gate signal input given to the gate circuit 22 in order to pass the signal components MH of FIG. 5C allow.

The frequency of the oscillations during the parts MH is = - 2fL = 2.18 MHz. This signal is also sent to the oscillator 54 with a variable Frequency given to control the phase of its output signal.

Even though the push-pull modulated signal YB coming from the filter 59 is obtained, reverses in phase when eas nodulating signal YA after Fig. 5A passes from one side of the axis e to the other side, generated at this Arrangement of the frequency multiplier 202 with a signal of the frequency 4fL = 2.36 MHz a constant phase. The signal generated by the variable oscillator 54 the frequency fL = 59 ° 0.59 MHz can correspond to four different phase conditions be synchronized by means of the signal with the frequency 4fL. The changeable one However, oscillator 54 is also modulated by means of the signal 2fL = 1.18 MHz, which only allows two phase conditions. The synchronous detector 60 accordingly provides restores the original luminance signal A, although the phase of the modulated Lwninanzssignal YF coming from the filter is reversed as above is described.

The operation of this portion of the circuit of FIG. 17 is described below will be described with reference to the waveforms of FIG. The output signal R or R 'of limiter 201 is in Figures 5F and 17A with different time scales applied. This signal reverses the phase every time the modulating Signal Y of Fig. 5A the Passes through the zero line or axis e or crossed. When the signal R or R 'is given to the frequency multiplier 202, an output signal Z is generated which has the frequency 2fB = 4lL, so that the phase this output signal s is constant, as shown in Figures 5G and 18B is-t, and is independent of the phase of the output signal R or R 'of the limiter 201.

When the signal Z is given to the variable oscillator 54, can control the output signal Q of the variable oscillator in any of the four phase conditions Z1, Z2, Z3 and Z4 of the signal Z are kept phase-locked, as indicated by the Waves or curve Q1-Q4 of Fig. 18D is shown. However, the Si signal Q is also phase-locked with the two phase conditions m1 and m2 of the signal MH Figures 5C and 18C, this signal coming from gate circuit 22 has the Frequency 2fT, the result is that the signal Q with only one of the phase conditions Z1 or Z3 can be made phase-locked.

Even if the modulated signal YD from the synchronous detector 60 with a Signal is demodulated, which is obtained from one of the signals Q1 or Q3, can a predetermined luminance signal can be generated. That is, if the reproduced modulated luminance signal D is given as Ey cos (2 # L + p) t, the signal of the changeable Oscillator 54 given as cos (#Lt + and the signal from oscillator 55 as cos #St are.

The signal of the filter 57 appears as cos [(# S + # L) t + #] and the signal of filter 58 occurs as cos [(# S- # L) t. The modulated results accordingly Luminance signal that has been converted in frequency by the converter 53 and from Filter 59 has been filtered as cos [(W 5 £ L> L-p) t + #]. The luminance signal, demodulated by synchronous detector 60 and passed through filter 205, can be expressed as Ey cos (pt - 2).

if the phase # of the signal cos (# Lt + #) of the variable oscillator 54 is controlled so that there is e.ne phase or the inverted one Phase # 0 + ir, the demodulated luminance signal E cos (pt - 2), that of filter 203 korn.t, as Ey cos (pt - 20o) or as Ey cosLpt -2 (# 0 +) J = Ey cos (pt - 20o) express.

The result is that a predetermined luminance signal can be generated. A result is that a desired reproduced color image signal is present at the output terminal 63 can be obtained.

when a color image signal is recorded, the carrier frequency may of the modulated luminance signal as well as being recorded on a recording medium will be selected so that it is a multiple higher than the chrominance carrier frequency, which is converted into a frequency band that is lower in comparison to the luminance signal has been. If z. B. the chrominance signal has been implemented in such a way that its Carrier has a frequency fL = = 0.59 MHz, the subcarrier of the modulated luminance signal can be selected to have a frequency of about 1 NHz. Although with the preceding description of exemplary embodiments of the present invention the luminance carrier has been given a frequency of 1.18 MHz, the second Harmonic of the carrier frequency of the converted chrominance signal is not necessary that the ratio between these two carrier frequencies is an integer Is multiple. It is sufficient if the subcarrier is the modulated luminance signal is in a low frequency range, such that the spectrum of the modulated Buminance signal and the spectrum of the converted into an even lower frequency band Chrominance signals do not overlap with each other. Special frequencies to which reference is taken are e.g. B. suitable for use where television signals accordingly the N.T.S.C. standard. However, other frequencies can also be used there be used. Wherever television standards are used that differ from the N.T.S.C. standard differ, the frequencies can be correspondingly different from those be, to which reference has been made here or which have been mentioned here.

It is not necessary to record signals using a recording system according to the invention takes place on a magnetic tape and that the recording takes place in inclined tracks on the tape. The record can also be done on magnetic sheets, cards or discs.

It should be noted that the present invention does not the specific embodiments described above is limited and that the skilled person carry out further modifications within the scope of the inventive concept can.

Claims (29)

P A T E N T A N S P R Ü C H E Circuit for reproducing a sound on a magnetic recording material recorded video signal containing a luminance signal which is recorded on a carrier is push-pull modulated and a synchronization signal component with an amplitude ha-t, which is greater than that of other components of the signal, characterized by a magnetic Converter (51) for reproducing the video signal from the recording material through a Synchronous detector (60) for synchronous demodulation of the push-pull modulated luminance signal and by a circuit part (54,55,56,58) for supplying a reference carrier signal to the synchronous detector 60, the reference carrier signal during the synchronizing signal of the modulated luminance signal phase-controlled by a suppressed carrier signal will. 2. Circuit according to claim 1, characterized in that the Schaltstell (54,55,56,58) has a circuit (201-) for taking out a carrier signal, from this circuit (201) the suppressed carrier signal from the reproduced Video signal is obtained during the synchronizing signal component and that the circuit steeply an oscillator (54) with a variable frequency for generating a reference carrier signal has, wherein the oscillator (54) is connected to the synchronous detector (60) to to supply the reference carrier signal to the synchronous detector (60) and wherein the oscillator (54) is phase-controlled by the signal obtained with the circuit (201). 3. A circuit according to claim 1 or 2, characterized in that the Circuit part (54,55,56,58) also has a frequency multiplier (202), which is connected to the converter (51), which is the frequency multiplication of the push-pull modulated Buminance signal is used and that with the oscillator (54) with variable frequency connected is, around the frequency-multiplied signal to the oscillator (54) to enter its phase by means of the output signals of the circuit (2G1) to control the acquisition of the suppressed trigger and the frequency multiplier. 4. Circuit according to one of claims 1 to 3 for use in a A video signal that is the upper sideband signal of a carrier associated with the luminance signal has been push-pull modulated, the push-pull modulated signal being suppressed Carrier and has a low carrier frequency, characterized in that the circuit part (54,55, 55,58) connected to the transducer (51) do the carrier signal from this during the synchronizing signal interval of the modulated luminance signal. 5. A circuit according to claim 4, characterized in that the suppressed Carrier signal from the reproduced video signal during the synchronizing signal interval is obtained and in that the oscillator (54) with variable frequency supplied signal is a reference carrier signal and the oscillator (54) with variable Frequency is controlled with the suppressed carrier signal by means of the circuit (201) is obtained. 6. Circuit for magnetic recording of a video signal that has frequency components extending over a video tape, characterized by a circuit part (3, 5, 6; 33, 59, 42; 88, 89, 91, 92) for generating a modulated Signal that has a carrier frequency lying in the band and that essentially comprises no more than a sideband signal of the video signal, and through a converter (10;, 45; 97), which is connected to the circuit part (3, 5, 6; 33, 39, 42; 88, 89, 91, 92) for generating the modulated signal is connected and from which the modulated signal is recorded on a magnetic recording material. 7 ,. Circuit according to claim 6, characterized in that the circuit part (3, 5, 6; 33, 39, 42; 88, 89, 91, 92) to generate the modulated signal Contains amplitude modulator (3, 33). 8th . Circuit according to claim 6, characterized in that the. Circuit part (3, 5, 6; 33, 39, 42; 88, 89, 91, 92) for generation of the modulated signal contains a push-pull modulator (3; 33). 9 .. Circuit according to claim 6, characterized in that the circuit part (3, 5,6; 33, 39, 42; 88, 89, 91, 92) to diffract the modulated signal Phase modulator contains 10 ". Circuit according to Claim 6, characterized in that that the circuit part (3, 5, 6; 33, 39, 42; 88, 89, 91, 92) for generating the modulated signal contains a frequency modulator (88). 11. Circuit according to one of claims 6 to 10, characterized in that that the circuit part for generating the modulated signal includes a modulator (3; 33; 88) and an associated bandpass filter (5; 39; 91), of which the im essentially only a sideband signal from the modulator (3; 33; 88) is let through. 12. A circuit according to claim 11, characterized in that the bandpass filter (5; 39; 91) has an attenuation of approximately 6dB at the carrier frequency and a The rest of the other sideband of the modulator (3; 33; 88) lets through. 13. Circuit according to claim m or 12, characterized by a carrier circuit part (4; 34-37; 89) for supplying a carrier signal with a comparative to the video tape higher frequency, the modulator (3; 33; 88) with this carrier circuit part (4; 34-37; 89) is connected to modulate the carrier signal and by that the band-pass filter (5; 39; 91) passes a residual sideband signal which is substantially only the lower sideband signal of the modulated signal of the Uräger circuit part (4; 34-37; 89), and by a frequency converter circuit (6; 42; 92) for Conversion of the frequency of the modulated carrier signal in such a way that the frequency-converted Carrier is at a frequency within the band and that is below the sideband in an upper sideband is implemented. 14, circuit according to one of claims m to 13, characterized in that that a second filter (8; 43; 94) is provided which only allows one frequency band to pass through, whose frequencies are lower than the frequency of the one intended for frequency conversion Signals, this band comprising at least the residual sideband signal, and in that the frequency converter circuit (6; 42; 92) with this second filter (8; 43; 94) is connected to output signals from this frequency converter circuit (6; 42; 92) to feed this second filter (8; 43; 94). 15. Circuit according to one of claims 6 to 10, characterized by a circuit part or modulator (3; 33; 88) for modulating a carrier with a Video signal to generate a modulated signal that is essentially not more as a sideband signal by a frequency converter (6; 42; 92) a source (7; 34-38; 93) for a signal for frequency conversion, the signal the source (?; 34-38; 93) and the sideband signal to the frequency converter (6 ;, 42; 92) are fed to this sideband signal in such a frequency range implement that the carrier frequency fD of the resulting converted sideband signal YD essentially at the lower frequency end of the converted sideband signal YD and has a frequency value that is opposite to at least a portion of the frequency components of the video signal has a lower frequency value. 16. Circuit according to one of claims 6 to 15 for use for a color signal as a video signal, this having a luminance component and a chrominance component has, characterized by a filter circuit part (32, 41) with which the luminance component is separated from the chrominance component and the luminance component from the modulation of a carrier provided circuit part is supplied, wherein the luminance component represents the modulated signal, and through a mixer (40; 86) which is connected to the Modulation of a carrier provided circuit part is connected to a carrier to modulate and to obtain the one sideband signal, and that with the filter circuit part (41) is connected to obtain the chrominance component. 17. Circuit according to claim 16, characterized in that the frequency converter (42) is connected to the mixer (40; 86) in order to receive the output signal from the mixer (40; 86) to obtain that comprising a sideband signal and the chrominance component. 18 Circuit according to claim 16 for use with a color signal, whose chrominance component has a chrominance subcarrier, characterized in that, that the source for a frequency-converting signal is a circuit part (35) for generating of a first signal that has the same frequency like the subcarrier signal has a circuit part (34) for generating a second signal with a frequency, which is lower than the lowest frequency of the converted sideband signal, has a circuit part (37) for generating a third signal with a frequency which is equal to the difference between the frequency of the chrominance carrier and the Frequency of the second signal and a circuit part (33) for generating a fourth signal at a frequency equal to the sum of the frequency of the chrominance subcarrier and the frequency of the second signal, the third signal comprising the carrier, which is modulated by the video signal and where the fourth signal is the frequency converting signal includes. 19. The circuit according to claim 18, characterized in that the for Generation of the third signal provided circuit part (77) with that for modulation of the carrier provided circuit part (33) is connected, the third signal the carrier is. 20. The circuit according to claim 19, characterized in that the for Generation of the fourth signal provided circuit part (38) with the frequency converter (42), the fourth signal being the frequency converting signal. 21. A circuit according to claim 16, characterized in that the filter circuit part contains a low-pass filter (32) connected to the circuit part provided for modulation (33) is connected in order to supply this with the luminance component, and thereby that a Band-pass filter (41) is connected to the mixer (40) to this the chrominance component to feed 22. Circuit according to claim 16, characterized by a second frequency converter (85), which is connected to the filter circuit part (41), to the chrominance component and convert it into a frequency range that is lower is than that of the converted sideband signal, the mixer (86) with this second Frequency converter (85) is connected to the frequency-converted chrominance component to record. 23 circuit according to claim 16, characterized in that the converted Sideband signal and the converted chrominance component with each other in terms of frequency are nested. 24. Circuit for reproducing a video signal on a magnetic Recording material is recorded and has a sideband signal whose carrier frequency is essentially at the lower frequency end of the sideband signal, characterized by a magnetic transducer (11; 51) for reproducing that on the recording material recorded signal, by a frequency converter (13; 53; 65) with the Converter (11; 51) is connected and a frequency conversion of the sideband signal performs to find the frequency ratio between the carrier frequency and the rest of this To reverse or reverse sideband signal, and by a detector (20; 60; 79) with the frequency converter (13; 53; 65) for demodulating the frequency-converted Sideband signal is connected. 25. Circuit according to claim 24, characterized in that the detector a synchronous detector (20; 60) and that the circuit is circuit means (14, 15, 16, 17; 54, 55, 56, 57; 69) for generating a reference carrier signal has the are connected to the synchronous detector (20; 60), the reference carrier signal synchronous with the phase of the carrier in a predetermined proportion of the video signal is sated. 26. Circuit according to claim 25, characterized by a gate circuit (22), which is connected to the frequency converter, to convert a selected proportion of the applied sideband signal (according to a gate circuit) to control, and through a phase comparator (25) connected to the gate circuit (22) and with the circuit part (14, 15, 16, 17; 54, 55, 56, 57) for generating a reference carrier signal is connected to control the (carrier) phase of this reference carrier signal. 27. A circuit according to claim 26, characterized by an enveloping Detector or envelope rectifier (23) connected to the frequency converter is to get its converted signal and to generate a pulse signal, corresponds to the synchronizing pulses contained in the video signal, the enveloping detector (23) is connected to the gate circuit to the converted Sideband signal during the synchronization pulse intervals (according to a gate circuit) to control. .28 A circuit according to claim 26 for use with a color image signal as a video signal that contains bursts, characterized in that the Gate circuit includes a circuit part (101) to generate the color sync signals (according to a gate circuit) to control. 29. The circuit according to claim 24, characterized in that the detector (79) is an angle modulated signal demodulator.