DE2156305B1

DE2156305B1 - Device for recording and / or reproducing a television signal, in particular for an optical disc

Info

Publication number: DE2156305B1
Application number: DE19712156305D
Authority: DE
Inventors: Walter Prof. Dr.-Ing. 3000 Hannover Bruch
Original assignee: Licentia Patent Verwaltungs GmbH
Current assignee: Licentia Patent Verwaltungs GmbH
Priority date: 1971-11-12
Filing date: 1971-11-12
Publication date: 1973-04-12
Also published as: DE2156305C2

Description

Die vorübergehende periodische Amplitudenerhöhung kann keine Störung im Bild bewirken, weil zu dieser Zeit das Bildsignal nicht sichtbar wird und außerdem übliche Fernsehempfänger während dieser Zeit durch die Rücklaufaustastung dunkelgesteuert sind. Andererseits wird durch die Amplitudenerhöhung über die ganze Zeile betrachtet das Signal/ Rauschverhältnis verbessert. Wenn z. B. bei einer kontinuierlichen Aufzeichnung eines Hilfsträgers mit stark reduzierter Amplitude das Rauschen den Wert 1 hat und erfindungsgemäß während der Zeilenaustastzeit von 18°/o der Zeilendauer die Amplitude des Hilfsträgers so stark erhöht ist, daß das Rauschen verschwindet, so wird das Gesamtrauschen so verringert, als wäre es nur während 82°lo der Zeilendauer mit dem Wert 1 vorhanden, während jedoch das Nutz-Zusatzsignal während der ganzen Zeilendauer vorhanden ist. The temporary periodic increase in amplitude cannot cause a disturbance cause in the picture because at this time the picture signal is not visible and also Conventional television receivers are blanked out during this time by the return blanking are. On the other hand, the whole line is considered due to the increase in amplitude the signal / noise ratio improves. If z. B. with continuous recording of a subcarrier with a greatly reduced amplitude, the noise has the value 1 and according to the invention, the amplitude during the line blanking time of 18% of the line duration of the subcarrier is so much increased that the Noise disappears, so the total noise is reduced as if it were only during 82 ° lo of the line duration with the value 1 present, but during the useful additional signal during the whole Line duration is present.

Die Erfindung wird im folgenden an Hand der Zeichnung erläutert. Darin zeigt F i g. 1 Kurvenformen zur Erläuterung der Wirkungsweise, Fig.2 ein Frequenzspektrum für die Lage des Hilfsträgers und des Bildträgers, Fig 3 ein Blockschaltbild für die Aufnahme und F i g. 4 ein Blockschaltbild für die Wiedergabe. The invention is explained below with reference to the drawing. In it, F i g. 1 curve shapes to explain the mode of operation, FIG. 2 a frequency spectrum for the position of the auxiliary carrier and the image carrier, Fig. 3 is a block diagram for the recording and F i g. 4 is a block diagram for reproduction.

Dabei zeigen die kleinen Buchstaben, an welchen Punkten in den F i g. 3,4 die Spannungen gemäß F i g. 1 stehen. The small letters show at which points in the F. i g. 3.4 the stresses according to FIG. 1 stand.

F i g. 1 a zeigt ein Videosignal 1, das einem Träger in FM aufmoduliert wird. Dadurch entsteht ein FM-Träger 2 gemäß F i g. 1 b. Ein als Hilfsträger dienender Tonträger 3 gemäß F i g. 1 c wird mit einem Tonsignal in FM moduliert. Dabei ist die Amplitude des Tonträgers 3 während der Zeilenhinlaufzeit H gegenüber der Amplitude des FM-Trägers 2 stark abgesenkt, z.B. um 40db. Während der Zeilenaustastzeit A, während der das Videosignal 1 bei der Wiedergabe nicht sichtbar wird, ist die Amplitude des Tonträgers 3 jedoch -stark erhöht. Zur Aufzeichnung gelangen die addierten Träger2, 3 als Kurvenform gemäß Fig. 1 d. Bei der Wiedergabe wird der Tonträger 3 durch Frequenzselektion abgetrennt und in einem Begrenzer in einen Tonträger ohne Amplitudenerhöhung gemäß F i g. 1 e umgewandelt. Der Tonträger kann auch mit dem Tonsignal in AM moduliert sein. F i g. 1 a shows a video signal 1 which is modulated onto a carrier in FM will. This creates an FM carrier 2 according to FIG. 1 b. One serving as an auxiliary carrier Sound carrier 3 according to FIG. 1 c is modulated with a sound signal in FM. It is the amplitude of the sound carrier 3 during the line trace time H compared to the amplitude of the FM carrier 2 is greatly reduced, e.g. by 40db. During the line blanking time A, during which the video signal 1 is not visible during playback, is the amplitude of the sound carrier 3, however, greatly increased. The added carriers2 are used for recording, 3 as a curve shape according to FIG. 1 d. During playback, the sound carrier 3 is selected by frequency separated and in a limiter in a sound carrier without amplitude increase according to F i g. 1 e converted. The sound carrier can also be modulated with the sound signal in AM be.

Fig.2 zeigt die Frequenzlage des FM-Trägers2 und des Tonträgers3. Der Tonträger 3 liegt unterhalb des gesamten vom modulierten FM-Träger 2 eingenommenen Frequenzbandes 4. Fig. 2 shows the frequency position of the FM carrier2 and the sound carrier3. The sound carrier 3 is below the total occupied by the modulated FM carrier 2 Frequency band 4.

In F i g. 3 wird das Videosignal 1 in einem FM-Modulator 5 einem FM-Träger 2 aufmoduliert und dann einer Addierstufe 6 zugeführt. Ein Tonsignal 7 wird in einem FM-Modulator 8 einem Tonträger 3 aufmoduliert. Dieser Träger wird einem Verstärker 10 zugeführt, dessen Verstärkung durch eine Schaltspannung 1l während der ZeilenhinlaufzeitH einen verhältnismäßig geringen und während der ZeilenaustastzeitA einen erhöhten Wert hat. Dadurch entsteht an einer Leitung 12 ein während der ZeitA in der Amplitude stark erhöhter Tonträger 3 gemäß F i g. 1 c. Der FM-Träger 2 und der Tonträger 3 werden in der Addierstufe 6 addiert und einem Bildplattengerät 13 zugeführt. Auf diesem wird ein Signal gemäß F i g. 1 d aufgezeichnet. In Fig. 3 is the video signal 1 in an FM modulator 5 a FM carrier 2 is modulated and then fed to an adder 6. A beep 7 is modulated onto a sound carrier 3 in an FM modulator 8. This carrier will fed to an amplifier 10, the gain of which by a switching voltage 1l during the line trace time H a relatively low and during the line blanking time A. has an increased value. This creates a line 12 during time A. Sound carrier 3 of greatly increased amplitude according to FIG. 1 c. The FM carrier 2 and the sound carriers 3 are added in the adding stage 6 and an optical disk device 13 fed. A signal according to FIG. 1 d recorded.

In F i g. 4 wird das gemäß F i g. 3 aufgezeichnete und vom Gerät 13 entnommene Signal mit dem Frequenzspektrum nach F i g. 2 mit einem Hochpaß 14 und einem Bandpaß 15 in den FM-Träger 2 und den Tonträger 3 aufgespalten. Der FM-Träger 2 wird in einem FM-Demodulator 16 demoduliert, der an einer Klemme 17 wieder das Videosignal 1 liefert. In Fig. 4, according to FIG. 3 recorded and from the device 13 extracted signal with the frequency spectrum according to FIG. 2 with a high pass 14 and a bandpass filter 15 split into the FM carrier 2 and the sound carrier 3. The FM carrier 2 is demodulated in an FM demodulator 16, which is again connected to a terminal 17 Video signal 1 supplies.

Der am Ausgang des Bandpasses 15 stehende, in der Amplitude getastete Tonträger 3 wird einem Begrenzer 18 zugeführt, in dem die Amplitudenerhöhung während der ZeitA ausgeglichen wird. Der Begrenzer 18 liefert dann einen Tonträger mit begrenzter Amplitude, der in einem FM-Demodulator 19 wieder demoduliert wird. An einer Klemme 20 steht dann das demodulierte Tonsignal 7 zur Verfügung.The one at the output of the bandpass filter 15, which is sampled in amplitude Sound carrier 3 is fed to a limiter 18, in which the amplitude increase during the timeA is compensated. The limiter 18 then delivers a sound carrier with limited Amplitude which is demodulated again in an FM demodulator 19. On a clamp 20 the demodulated audio signal 7 is then available.

Durch die Amplitudenerhöhung während der ZeilenaustastzeitA entsteht im Signal eine zusätzliche zeilenfrequente Komponente. Deshalb kann es bei der Wiedergabe zweckmäßig sein, mit zusätzlichen Schaltungsmitteln, z.B. einem Filter, diese zeilenfrequente Komponente zu unterdrücken. Der Begrenzer 18 in Fig.4 kann weggelassen werden, wenn der FM-Demodulator 19 die Amplitudenerhöhung selber eliminieren kann, indem z.B. seine Ausgangsspannung von der Amplitude der Eingangsspannung hinreichend unabhängig ist. Die Beseitigung der Amplitudenerhöhung kann auch durch andere Schaltungsmittel, z. B. mit einem durch den Träger 3 synchronisierten Mitnahmeoszillator oder mit einer Verstärkerschaltung erfolgen, deren Verstärkung während der Austastzeit A verringert ist. The increase in amplitude during the line blanking time A results an additional line-frequency component in the signal. So it can be when playing be expedient with additional circuit means, e.g. a filter, this line frequency Suppress component. The limiter 18 in Figure 4 can be omitted if the FM demodulator 19 can itself eliminate the amplitude increase by e.g. its output voltage is sufficiently independent of the amplitude of the input voltage is. The removal of the amplitude increase can also be done by other switching means, z. B. with a synchronized by the carrier 3 driving oscillator or with an amplifier circuit, the amplification of which during the blanking time A is decreased.

Der Hilfsträger kann mit dem Signal auch in einer anderen Modulationsart, z.B. AM, moduliert sein. The subcarrier can also be used with the signal in a different type of modulation, e.g. AM, be modulated.

Zur weiteren Verringerung des störenden Einflusses des Hilfsträgers auf das Bildsignal kann es zweckmäßig sein, das Verhältnis von Phase oder Frequenz des Hilfsträgers zur Zeilenperiode für einen bestimmten, periodisch wiederkehrenden Signalwert, z. 3. den Tonsignalwert 0, auf einen konstanten Wert einzuregeln. Bei einer FM des Hilfsträgers hat dann z. B. der Hilfsträger für den Tonsignalwert 0 immer dieselbe Phasenlage relativ zur Zeilenperiode des Fernsehsignals.To further reduce the disruptive influence of the subcarrier on the image signal it can be useful to adjust the ratio of phase or frequency of the subcarrier to the line period for a specific, periodically recurring Signal value, e.g. 3. Set the audio signal value 0 to a constant value. at an FM of the subcarrier then has z. B. the subcarrier for the audio signal value 0 always the same phase position relative to the line period of the television signal.

Claims

Claims: 1. Device for recording and / or playback of a Television signal, in particular for an optical disc, in the case of which on a track of the recording medium an FM carrier frequency-modulated with the image signal and additively one with an additional signal modulated subcarrier are recorded and the amplitude of the subcarrier is much lower than that of the FM carrier, characterized in that at times (A), in which the image signal (1) is not visible during playback, the amplitude of the auxiliary carrier (3) is increased.

2. Apparatus according to claim, characterized in that the amplitude is increased during the line blanking time (A).

3. Apparatus according to claim, characterized in that the amplitude is increased during the vertical blanking time.

4. Apparatus according to claim 1, characterized in that the amplitude while the blank lines is increased in the vertical blanking time.

5. Apparatus according to claim, characterized in that the additional signal is a sound signal (7).

6. Apparatus according to claim 1, characterized in that the phase of Vibrations of the sub-carrier (3) regulated to a fixed ratio to the line period is.

7. Apparatus according to claim, characterized in that during playback the increase in amplitude is eliminated by a limiter (18) (FIG. 4).

8. Apparatus according to claim 1, characterized in that during playback by evaluating the amplitude increase, a switching signal for a periodic switchover is won.

9. Apparatus according to claim, characterized in that during playback by evaluating the amplitude increase, impulses to generate a pilot carrier be won.

10. Apparatus according to claim 1, characterized in that during playback Circuit means for suppressing the frequency component caused by the increase in amplitude are provided.

11. Apparatus according to claim 10, characterized in that at one Amplitude increase during the line blanking time (A) the circuit means on the Line frequency suppressing filter is.

12. Recording medium for a device according to Claim 1, characterized in that that the subcarrier during times when the picture signal is not reproduced is visible, is recorded with enlarged amplitude.

It is known to use an image signal, e.g. B. a television signal, as a frequency modulation of a medium on a recording medium. For recording devices, where only one for the signal only track is available, it is necessary In addition to the image signal, other signals such as an audio signal, a synchronization signal or to record a switching signal on the same track.

For this purpose it is known (German patent specification 1277900), the additional signal, z. B. modulate the audio signal to a subcarrier below that of the FM carrier occupied frequency bandwidth is. It is also possible to use the additional carrier above or within the frequency bandwidth of the image signal in a frequency range record in which there is no useful modulation of the image signal.

In such a recording, non-linearities mixed products between all recorded in the characteristic curves during recording and playback Frequencies arise, which results in additional modulation in the image signal.

The resulting disturbance is z. B. is that the sound signal becomes visible in the picture.

To avoid such disturbances, it is known to adjust the amplitude of the Subcarrier to reduce greatly compared to the amplitude of the FM picture carrier, z. B.

by 40 db. This can cause interference in the image signal from the subcarrier can be largely reduced.

However, this solution has the disadvantage that because of the strong decrease in amplitude the signal / noise ratio is significantly reduced.

The invention is based on the object of a device for recording and / or to provide playback in which the signal-to-noise ratio improves and still there is no interference from the additional carrier in the image signal.

This object is achieved by the invention specified in claim 1. Further developments of the invention are given in the subclaims.

The amplitude is preferably increased during the line blanking time, the vertical blanking time or the blank lines in the vertical blanking time.

The phase of the oscillations can be used to further reduce the interference of the sub-carrier must be adjusted to a fixed ratio to the line period.

This can be done e.g. B. achieve that the subcarrier in one Start / stop oscillator is generated, each by a line sync pulse triggered with constant phase to the line period and then with the additional signal is modulated. The increase in amplitude that occurs in the signal can occur during playback can be eliminated again by a limiter. By evaluating the amplitude increase can generate a switching signal for periodic switching during playback a time division multiplex system or other impulses for generating a pilot carrier or derived for synchronization.