DE1462401C - System for direct recording and playback of television signals with internal phase reversal - Google Patents

Description

adorned and costly additional measures required to achieve that the linear course 2 H 'of the Magnesind. reduction curve 2 - F i g. 2 ■ - the total amplitude

The invention is well covered below with reference to the area. Of course, drawings are thus explained in more detail. It also shows a corresponding reduction in S / N

Fig. 1 is a schematic representation of a bound with 5.

a tape recorder according to the prior art

recorded and reproduced television signal, television signal usually of different anyway the usual signal improvements, nen noise, which both from the tape system and

Fig. 2 is a schematic characteristic curve also produced by the amplifier system, showing the relationship between that on which _{10 is} superimposed. This problem could not be satisfactorily avoided in the previously recorded magnetic tape remaining magnetism, and an applied magnetic field in the case of FIG. 3 is a part of the regular television magnetic recording of a composite signal with a sampling period marked "L" image signal, for comparison with the corresponding distorted

F i g. 3 shows an enlarged schematic diagram, ₁₅ signal is shown schematically.

which contains a part of the television signal in the range of a natural-

vertical scanning period, shows a large proportion of low-frequency components

F i g. 4 is a block diagram showing a preferred component. If this signal is through a low frequency embodiment The recording system runs as part of the transmission system, the resulting Invention represents, show ao signal significant distortion, as it to-

FIG. 5 is a block diagram which a preferred one was described above with reference to FIG. Embodiment of the playback system as part of Although the invention is not limited to an entirely invention represents, correct type of signal inversion is restricted, is

Fig. 6A is a schematic diagram of the comparable worked in various preferred embodiments and assumed before equalization in the playback ₂₅ thereof, that the television signal in its stage occurring signal ^:: polarity at regular time intervals alternately H

6B is a schematic diagram that is reversed by 180 °.

worked signal, which is directly on the tape. From Fig. 4 it can be seen that a composite

is to be taken, television signal M, for example, as shown in FIG

F i g. 7 shows a modified embodiment of which in FIG. 30 an input 9 reaches a preamplifier 10. F i g. 5 playback system shown, the amplified television signal is from a two

F i g. 8 is a block diagram of a recording system 11 through two separate channel systems, further ones second embodiment and directed.

F i g. 9 a block diagram of the playback system. In the first system, the signal is sent to the synchro

the second embodiment. _iv 35 nisiersignal separator 12 supplied. The filtered out

Before a detailed description of the explanatory * synchronization pulses are passed on to a differentiating version of the invention, the execution circuit 13, which is sharply defined, the state of the lifting pulses according to FIG. 6A are generated first. Technique inherent and briefly mentioned above. These pulses are shown to a frequency divider 14, the disadvantages on the basis of FIG. 1 and 2 explained: ₄₀ leads, which has an oscillator and the signal in

In Fig. 1, a reproduced television signal, a half-frequency gate signal is converted to the as is applied in the aforementioned direct pickup and delay circuit 141. Direct playback occurs, shown schematically. The thus delayed square wave signals are on

According to this figure, the is processed two ways during the sampling period. The first way will »L« appearing signal part strongly distorted. 45 this signal via a connection point 15 a

With reference to Fig. 2, the problem of the noise on acquisition amplifier 16 is supplied, the amplkabstandes SIN, as it occurs particularly in the process of the output signal a magnetic recording direct recording, described. If a head 17 is fed in to use the incoming Im premagnetization, a tape T _{in FIG. 50} is recorded on a pulse on a first recording track of a magnetizable recording medium. In this case, there is a delay in the drawn in remanent magnetism, whereby the gate impulses of 0.1-3.8 seconds occur if the synibole "Ή" is to be understood as a magnetic quantity. Signal reversal is triggered at the rear. .,. A linear characteristic remains in the case of the. On the second way, the square-wave signals are

Magnetic conversion obtained when the applied via the connection point 15 and a line 28 magnetic field is within the range ± H ' . ₅₅ led to a connection point 18 and from there

The amplitude or the peak-to-peak value of the transmitted in two different ways, The signal 1 to be recorded should be within the range of one of the two paths.

± H ' limited range as large as possible, signals N to a gate circuit 19, while it is to keep the signal-to-noise ratio S / N on a second possible path via the line 26 to the phased value. However, the result is normal- 60 reverse circle 21 α are directed. In this circle, the square-wave signals are shifted by 180 ° during magnetic recording and re-recording - there would be a considerable loss of low-frequency signal shape S - and then fed into a gate switch component of the television signal, its alternation 22. ·

Stromachse is exposed to considerable fluctuations. At the same time, this is branched off from junction 11.

Therefore, the total amplitude swept-out television signal via a line 27 to the processor is considerably greater than the peak-to-peak value. Connection point 20 and from there in two different ways. For this reason, the peak-peak value should be further processed in different ways. In this case, that of the signal will be kept small compared to 2 H ' in order to input the signal once into the gate circuit 19 and

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on the other hand, a phase reversal circuit 21 is fed, the th arrangement of a playback head

in order from there as a signal form O to the gate circuit 22 to 50 from the second track on the tape T

reach. mene television signal in a preamplifier 51

The remote strengths emanating from circles 19 and 22 and at a point 52 on two different visual signals P and Q arrive in a mixer 23, further processed in 5 ways. In this form, the signals P and Q are combined, the signal has a specific form at certain intervals that correspond to the peak-to-peak amplitude of the generated horizontal scanning period, signal smaller than twice the polarities not processed on. The total original signal is. In the case of the special amplitude of the signal shown, which is less than twice that of the th embodiment, the two signals are combined to form the peak-to-peak amplitude of the untreated original, so that the blanking level of the signal P is the television signal.

essentially with the white level of the signal Q. On the first path, the signal arrives at one

coincides. The thus combined signal R becomes separating circuit 53 for separating the pulses at each

amplified in a recording amplifier 24 and polarity reversal of the signal. The severed

finally to a separate recording head 25 signal is then amplified in a preamplifier 54,

placed to on a second track of the same magnet whose output signal A is indicated and a

band T to be included. monostable multivibrator 55 for triggering

The signals recorded on the tape will let lead.

advantageously from a playback system, the width of the output from the multivibrator

as is shown by way of example in FIG. 5, reproductive ₂₀ pulses is selected, for example, to IH , where

adorn. As usual, "H" corresponds to 63.5 milliseconds.

According to FIG. 5 the output on the first track of the multivibrator 55

Band'des recorded signal from a first weighing signal B arrives at a connection point 56

The delivery head 30 removed and then in a front two different ways.

amplifier 31 reinforced. Its output signal M '25 is initially the signal of a gate circuit 57

is first processed and fed in the pulse shaping circuit 32, and at the same time it arrives via a phase

then branches at point 33. Inverse circuit 58 to a gate circuit 59.

On the one hand, the signal is sent via a line 46.Furthermore, the remote signal branched off from point 52 is

a gate circuit 34 is applied, on the other hand processed via a visual signal in the equalizer 60 and connected to a

Line 47 branches off to a phase reversal circuit 35 and ₃₀ connection point 61. On the first way

from there as a signal form N ' to a gate circuit 36, it is fed to the gate circuit 57, while it

directed. on the second way via a phase reversal switch

The device 62 located on the second track of the tape reaches the gate circuit 59. The respective signals are taken from a second playback head 37. Output signals are taken to a mixer 63. In a preamplifier 38 amplified ₃₅ conducts, and the two signals are thus processed together and in the equalizer 39. It is then guided that the white levels coincide. That then branches off the signal at a point 40. . The resulting combination signal is then converted into

First, the output signal O 'is passed to the gate circuit 163, applied to the circuit 34 and at the same time amplified in an amplifier 64 via a phase-closing circuit and fed to the gate circuit 36. The 40 borrowed signals P ' and Q, which are not masked out by the display, via an output 65 and which are output in the television receiver,
Circuits 34 and 36 have been processed, are combined in the mixer 42 in the embodiment described above. The combined processing is based on the negative polarity output signal i? 'Is then based on a black synchronization principle. The control circuit 43 can just as well be processed in order to use the direct current _{45, which is the} positive polarity synchronization principle, in place of the negative and low-frequency components, which may even be necessary. Finally, the fully reproduced television signal is amplified in an amplifier 44 to further improve the signal-to-noise ratio and can contribute to SIN.

via an output 45 to a receiver, for example in the case of positive polarity synchronization

wise a commercially available remote principle (not shown) would be the synchronization signals

visual receiver, headed. point to the white level, and the peak-to-peak value

In the described embodiment the signal would be compared to about 1: 1.8 the gate impulses are separated from the television signals in the corresponding case of negative polarity Track recorded and played back. Reduce the synchronization principle, if applicable However, according to the present 55 method, it is assumed that the amplitude of the processed Invention not absolutely necessary, and according to television signal in these two cases a certain one improved embodiment, this represents a constant value. Therefore, the separated Signal processing can be omitted, which would take place if from positive polarity synchronicity below will be described in detail. nization principle is assumed to be a

As can be seen from FIG. 6 A, the signal in front of 60 has approximately 1.8 times greater amplitude than in the case of the processing in the equalizer at the points of the negative polarity synchronization principle consisting of polarity reversal, which is shown in FIG . Therefore it can be used in a special beneficial way. For the exemplary embodiment, the signal-to-noise ratio S / N continues to be the same in FIG. 6 B can be improved by about 6 db by way of example and schematically if the synchronous form of the recorded signal is shown, where the signal pulses are converted into those with corresponding positive effects by the pulses shown in FIG. 7,
Realize the arrangement shown. In the last-mentioned embodiment, which

When playing with the help of the lh F i g. 7 shown in FIG. 7, the inverse is

7 8

caused them to be on a second track of the same at any rear black school-fed signal

tem. As a modification to this, the Um-Band T can be added.

reversal also with all front black shoulders In the corresponding in Fig. In an embodiment (not shown), the first track of the tape with the aid of a playback system can reproduce the gate pulses as they are picked up in the system according to head 104 . This signal, which is generated and processed in the manner of the invention, in the case of an amplitude-modulated signal, if necessary also with audio signals also modulated with audio signals, is incorporated into a preamplifier 105 . .,., is processed in an equalizer 106 and fed to the third in FIG. 8, a connection point 112 is created in order to further process the incoming television signal via paths in two examples. The shape of one input 70 , signal A " , fed to a preamplifier 71 , is shown schematically, the output signal of which is sent to a connection point 72. On the first path, the signal is passed to an amplitude limiter 107 , while it is fed to the From there the signal is reversed in phase - 15 second path an envelope detector 109 to stage 77 to a gate circuit 76. On a separation of the superimposed audio signals is fed, the second path passes the signal into a synchronizing signal separator 78 and from there to a Dif- 110 to an output terminal 111 and a non-referencing circuit 80, with which, as before, signals are routed to the loudspeaker shown. The shape of the output peaks are produced. This differentiated output signal B " is shown schematically in FIG. 9 signal is then drawn to a connection point 83 .

The output signal C "of the amplitude limiter

is working. 107 is in a differentiating circuit 108 in sharp

In one way, the signal is converted to a pulse that is sent to a frequency divider 114

Frequency divider 81 to which an unstable multivibrator 25 is applied. This has a square pulse

has so that the signal in a square wave signal of the generating oscillator to the frequency on the

half the frequency of the fed-in signal to reduce half the original frequency,

is delt. These square-wave signals are transmitted in the The square-wave signal arrives at a connection

Delay circuit 82 processed to a precise point 115 from which the signal on the following

the specified delay time compared to the signal 30 is further processed in both ways,

phase before processing. Then, on the first way, the signal goes into a gate

which the square wave signals are initiated at a connection point circuit 96, while it is on the second

74 forwarded, of which the signal is processed on two paths in a phase reversal circuit 99

is forwarded and processed in different ways. and then to gate circuit 98 .

In the first junction, the signal is in a 35 Das from the second track of the tape T of a

Gate circuit 73 is input while it is recorded on the playback head 93 television signal D "

second branch via a phase inversion circuit is in a preamplifier 94 and an equalizer

75 where the polarity of the signal is processed by exactly 180 ° and then to a connection point

is reversed, sent 113 to a gate circuit 76. This output signal of the equalizer 95

will. 40 is then used in the following two ways

On the other hand, this works from the connection point:

83 branched signal to control a bistable On the first path, the signal is used in a gate multivibrator 87 , from there to a series circuit 96 is input, while the signal on the of square-wave pulses with a frequency of the second path in a phase reversing circuit 97 is 15.75 kHz, which works with the horizontal and 45, the output signal of which is fed into a gate trap of the originally fed television signal 98 . The faded out held synchronization signal pulses synchro signals E " and F" are nized with one another. These output pulses are combined in a mixer 100 , so that the white levels of the amplitude modulator 90 are fed in, while signals E " and F" coincide. The output is equal to audio signals which are applied via a separate input 50 of the minimum stage to a black control 88 synchronous with the fed television signal stage 101 to restore the direct current, via an amplifier 89 to the amplification level of the synchronization pulses Vor- "tuden modulator 90 for amplitude modulation of the determined value. The signal processed in this way is given in the form of square-wave pulses described above, amplified to an amplifier 102 and then via an. The output signal of the modulator 90 is output 103 to the Given the television receiver, after it has been amplified by an amplifier 91 , it can be seen from the preceding detailed description, with the aid of a recording head 92, for example of the various special embodiments , of the invention recorded on a first track of the tape T that the main advantage is poor . in lies that the TV-Das fed into the tape recorder fades out e signal A 'of the gate circuit 73 60 signal is no longer subjected to frequency modulation and the signal B' of the gate circuit 76 is and is advantageously processed so that the aid of a mixer 84 is linked together, so the spectrum of the signal with a low frequency against that the peak-to-peak amplitude of the signal that is shifted to the higher, namely the outputting signal, is less than twice that of the original peak-to-peak amplitude of the original during the processing of the signal. TV signal is. Then there is a further tendency to avoid distortions which occur due to the transmission of the signal via a recording amplifier 85 deficiency in the low-frequency transmission characteristics to a recording head 86, which is used to produce the device according to the prior art. Further

9 10

the otherwise possible considerable shift due to the increasing fluctuation of the alternating current axis

AC axis caused by an excessive lack of low frequency components

change of the mean image brightness APL vet- shifting the low-frequency components according to

is caused to be significantly reduced to admissible and reasonable values above. The

are lowered so that the range of the linear magnetic 5 overall frequency range is correspondingly smaller, and the

table inversion characteristics fully peak-to-peak amplitude of the recorded

can be exploited. In this way the signal is used for a desired improvement in the

applied television signal is made larger without any distortion S / N.

tion of the low-frequency signal components, such as As a further advantage of the present invention

For example, the included synchronization io can interfere with lower frequencies, such as after

impulses, for perfectly sharp and stable speech the synthetic composition of signal com-

produce the image recorded and re-component in the case of magnetic recording and

are given. before the synthetic composition of the

From the description it follows that the assumed signal components arise in the

processing according to the invention of the television signal 15 avoids visual effect of the reproduced image

the contained frequency components that are smaller because the signal is in regular short

than 15m75 / 2 kHz (horizontal deflection frequency), time intervals, for example at intervals of 1 H, in the

converted to those of more than 15.75 / 2 kHz polarity is reversed. This eliminates the

can be, whereby a loss of the above kind in short and frequent time intervals.

frequency components in the course of the magnetic 20 in the reproduced image also in their

see recording and playback is avoided. Reversed polarity, thereby reducing the visual

In addition, an otherwise on- perception can hardly be perceived.

1 sheet of drawings

Claims (2)

1 2 signal is used for a longer period of time in the repat 1. System for direct recording and constant signal level provided. The experience has would have been shown by television signals with internal phase 5, however, that even with the application of a reversal and with a recording or re-such clamping circuit is extremely difficult that Gave magnetic head for a magnetic sliding by - distorted vertical sync signals in tape, characterized in that a satisfactory degree in the correct shape the polarity of the pickup head in the application. When such a reproduced signal, receiving system to be supplied television signal in itself io the largely distorted signal components low repetitive Time intervals alternating with the opposite frequency, such as vertical synchronism reversed is and that the reversed signal parts sierungssignale contains, fed to a monitor of the recorded television signal in itself occur when the synchronizing odor is separated repeating time intervals in the playback signal from the video signal considerable difficulty system are again reversed in such a way that 15 times on. As a result of the instabilities of synchronicity On the output-side television signals of the reproduction signals, the reproduced picture result system the input television signals on considerable fluctuations. of the recording system. Another notable and unavoidable one 2. System according to claim 1, characterized in that there is also a disadvantage of conventional comparison systems draws that the alternating polarity reversal 20 when using complicated circuits in tion in regular short time intervals a relatively small and thus debilitating he follows. S / N ratio given. This is through the wider voltage range of the video signal compared to the relatively narrow linear characteristic ; ' 25 see area of the magnetic recording medium at for example the magnetically coated recording tape. To improve the transmission behavior is it is the case with the magnetic tape recording of television 30 signals also known, the leading and trailing edges The invention relates to a system for direct viewing from a camera or a stabilization interrogation and playback of television signals with stronger received signal pulses Phase reversal and with an uptake or lift. At this time, the main signal is transferred to a magnetic reproducing head superimposed for a passing correction signal, its use and gnetband. ■ 35 amplitude from the amplitude change and the In the above system, the amplitude of the main signal occurs when the amplitude depends. The main of the immediate recording and the immediate signal can, for example, have considerable difficulties in stabilizing the synchronization correction signal in the form of a higher-frequency signal, which are superimposed on the reproduced television signal in order to better reproduce the signal. To ensure 40 signals recorded in this way,
It is to be sent in advance that in the following the essential object of the invention consists in In writing, the direct recording is referred to as "the creation of a system for direct recording and direct recording" and that this refers to the reproduction of television signals of the type mentioned, magnetic recording technology, with the frequency modulation, which is much more commonly used than in the prior art, continued - 45 is improved and has a simple structure. Dalassen is. Likewise, with the "Direktwieder- at are exactly reproduced synchronization gift meant" a magnetic reproduction technique in which signals and improved signal to noise ratio S / N erebenfalls commonly used frequency ^': be targetable to limited sharp and well stabilized modulation-demodulation omitted is. To receive television pictures. In the reproduction technology for television signals 50 the solution to the task at hand depends on one, as well as in the. The case of acoustic signals, · System for direct recording and reproduction of the reproduction means of magnetic reproducing heads of television signals with internal phase inversion and with ^'r from the voltage induced by the magnetic flux change a recording or playback magnetic head, which means that the magnetic re- - A magnetic tape sliding past is achieved in that there would be a differentiated aft. In order to counteract the distortion 55 of the polarity of the signal that is reproduced in the recording head, the television signal to be fed into the system is corrected in an equalizer circuit, which is reversed, for example, with alternating time intervals and is designed to have an attenuation of 6 db / oct. But and that the reversed signal parts of the recorded also with such a correction means, the nth television signal can be equalized again in the reproduction system in correspondingly again signal not over the entire frequency range spanning time intervals in the reproduction system. This imperfect cor- rection can be reversed in such a way that the output-side correction particularly affects the range of the signal television signals of the reproduction system, the input components with low frequency, and the resulting signal from the television signals of the recording system generally has considerable speaking. Deformations, especially in the vertical synchro- 65 The main advantage of the invention is therein too nization signals that look in the reproduced that with simple means a considerable Video signal are included. Known improvement of the transmission properties To correct the undesirably wavy television systems can be achieved without complicating