SU1412002A1 - Device for recording onto magnetic tape and reproducing a video signal - Google Patents

Description

vertically, the second input with the output of the sync selector, the first output with the second input of the identification signal generating unit, and the second output with the second inputs of the first blocks of the horizontal and vertical scanning.

and a frame recognition unit, the input of which is connected to the output of the sixth amplifier, and the output to the input of the inputted repetition unit, the output of which is connected to the second input of the fourth vertical scanning unit.

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The invention relates to radio engineering and can be used in the body, not zoonnyh with the themes

A fixed head recorder is known in which the video signal is recorded at a high frequency offset. The high frequency offset frequency is then selected to eliminate the occurrence of beats with the video signal, the audio signal can be recorded across adjacent tracks or with the video signal as a phase-modulated signal in the interval of horizontal absorbing pulses ij.

The main disadvantage of this device is the high speed of movement of the recording medium.

A fixed-head VCR connected to a television standard converter is also a known tape recorder and television signal reproducing apparatus comprising first, second, and third graphekons, with the deflection systems of the recording and reading sections of the first and second graphecons connected respectively, with the first and second blocks of the horizontal and vertical scanning, and the deflecting systems of the recording sections and the counts of the third gracnecon are connected to each other with the third and fourth blocks of horizontal and vertical scanning, the video recording head, auxiliary and scale signals, the video playback head, auxiliary and scale signals, a delay line whose output is connected to the first amplifier through the series-connected identification signal generating unit and the first amplifier.

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the output of which through the second amplifier is connected to the video signal recording head, the sync selector, whose input is connected to the output of the delay line, the third amplifier, the output of which is connected to the input of the second gracnecon, the output of which through the fourth amplifier is connected to the scale signal recording head , the first and second tape drives, connected, for example, through automatic control units, respectively, to the recording and playback heads of the auxiliary signal, the fifth amplifier, whose input is connected to the output of the video signal, and the output to the input of the third gracnecon, the output of which is connected to the input of the sixth amplifier, the seventh amplifier, whose input is connected to the playback head of the scale signal, and the output to the first input of the third horizontal scanner, the second input to which is connected to the playback head an auxiliary signal, wherein the output of each horizontal scanning unit is connected to the first input of the corresponding vertical scanning unit 2.

However, the known device does not allow to reduce the speed of movement of the magnetic carrier and to reduce its consumption in fixed-head video recorders.

The purpose of the invention is to reduce the speed of movement of the recording medium.

The goal is achieved in that the device for recording on a magnetic tape and reproducing a television signal containing the first, second, and third gracnecons, while the deviation of the recording and reading sections of the system of the first and second gracnecons are respectively connected to the first and second horizon blocks. horizontal and vertical scanning, and the deflecting systems of the recording sections and the frequency of the third gracnecon are connected to the third and, respectively. fourth blocks of horizontal and vertical scanning, video recording head, auxiliary and scale signals, video playback head, auxiliary and scale signals, delay, the output of which is connected to the first amplifier through the serially connected identification signal generating unit and the first amplifier the amplifier is connected to the video recording head, the sync selector, the input of which is connected to the output of the delay line, the third amplifier, the output otorrhea connected to the input of the second grafekona ,. the output of which is through the fourth, the amplifier is connected to the scaling signal recording head, the first and second tape drive motors connected, for example, via automatic control units, respectively, to the recording and playback heads of the auxiliary signal, the fifth amplifier, whose input is connected to the reproduction head video signal, and the output is to the input of the third gracnecon, the output of which is connected to the input of the sixth amplifier, the seventh amplifier, the input of which is connected to the playback head of the scale signal a, and output to the first input of the third horizontal scanning unit, the second input of which is connected to the playback head of the auxiliary signal, the output of each horizontal scanning unit connected to the first input of the corresponding vertical scanning unit, the phase discriminator is entered, the first and second inputs of which are connected respectively, with the outputs of the first and second vertical scanning units, horizontal and vertical definition control units, the inputs of which are connected to the output of the phase disc iminator, the scale signal generating unit, the first input of which is connected to the device input, the second input - to the output of the definition control block

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horizontals, and the output with the input of the third amplifier and the second input of the first horizontal scanning unit, the synchronous generator, the first input of which is connected to the output of the vertical definition control unit, the second input - with the output of the sync selector, the first output - with the second input of the signal conditioning unit recognition, and the second output - with the second inputs of the first blocks of horizontal and vertical scanning, and the frame recognition unit, the input of which is connected to the output of the sixth amplifier, and the output - to the input of the entered repetition unit, d is connected to the second input of the fourth vertical scanning unit. |

Figure 1 shows the block diagram of the device; Fig. 2 shows graphs illustrating a large-scale method of recording a television signal, with a tenfold change in time scale being considered.

On the graph, the lines of the television signal (Fig. 2a) are divided into two sections: AB — high frequency; Sun is a section with a slow signal change. The signal (fig. 2s), whose value depends on the frequency characteristic of the video signal - the BC section, has a large amplitude value. This signal is hereinafter referred to as a time scale signal or a scale signal. In a conventional magnetic signal recording, the unit of length on the record corresponds to a certain length of time, and this quantity, called the time scale, is constant (Fig. 2a).

If, while recording the indicated line (Fig. 2a), the time scale on the BC section is reduced, then the carrier consumption is reduced by S. In this case, a scaled signal (Fig. 2d) can be recorded on another track of the carrier, which, during playback, allows the original video signal to be restored.

The television signal contains frequencies from 50 to 6 MHz. Moreover, if in the section of the aircraft (fig. 2a) the high-frequency components of the video signal do not exceed 600 kHz, then as a result of tenfold compression of this section, the frequency band of the compressed video signal

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(Fig.2b) does not exceed the standard value. Thus, information in a compressed video signal is not lost.

To obtain a scale signal, a device is used — a scale signal generating unit comprising a frequency analyzer, the main element of which is a differentiator associated with a threshold element. The frequency analyzer has a specified frequency threshold value (frequency parameter), for this example, 600 kHz, resulting in

and reduce its consumption. To do this, the proposed device uses intermediate high-speed memory devices, such as gracones. An electron beam storage tube - a grafecone consists of a recording section and a reading section and has two deflection systems, with the help of which one electron beam continuously records incoming information and the other reads it. The video signal and the zoom signal are first recorded in graphecons with a repetition of the large-scale signal, at a variable speed of the recording beams, which is determined by the scale signal. The sections of the AV video signal and the scale signal are recorded at the same speed of the electron beams, and the parts of the sun are recorded at the reduced speed of the beams (for example, ten times, figure 2 & I). After a certain moment of time, both signals are found at a reduced constant speed of movement of the intersecting rays (Fig. 2a) and finally are recorded onto a magnetic carrier that moves at a reduced constant speed.

When playing, only a compressed video signal enters the storage device, and the massed signal changes the speed of the recording beam so that the reconstructed parts of the frequency are less than 600 kHz.

In small areas of a video signal, reducing the time scale is not rational, since this, without creating a significant positive effect, tends to reduce the number of transient processes, which complicates the signal and complicates the restoration of the original form of the video signal. Therefore, the scale signal generating unit operates in such a way that it allocates only significant low frequency portions that exceed a certain predetermined value in duration. Thus, the scale signal contains non-transmitted information and can be transmitted in a narrow frequency band.

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The scale signal generating unit of the original video signal has a control circuit with which you can change the frequency parameter (by changing the specified value for the threshold element). At the same time, if we increase the frequency parameter, then as a result of a tenfold compression of the selected sections, the frequency band of the compressed video signal exceeds the standard value. This excess is reduced in the video channel, therefore, in the restored video signal, the frequency band is reduced, which corresponds to a decrease in horizontal definition.

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Thus, a change in the frequency parameter of the scale signal shaping unit allows the degree of compression of the video signal to be varied by changing the clarity of the images.

A change in the time scale provides compression of the video signal, which makes it possible to reduce the speed of movement of the magnetic carrier during recording.

and reduce its consumption. To do this, the proposed device uses intermediate high-speed memory devices, such as gracones. An electron beam storage tube - a grafecone consists of a recording section and a reading section and has two deflection systems, with the help of which one electron beam continuously records incoming information and the other reads it. The video signal and the large signal are first recorded in graphens from the transcript of the original form of the video signal.

Nala The read beam moves at a constant speed and reads the already reconstructed video signal, which enters the video playback device.

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The device for recording on a magnetic tape and reproducing a television signal contains the first 1, second 2 and third 3 graphecons, the deflection systems of the 4 recording and reading sections of the first 1 and second 2 gracnecons being connected respectively to the first and second blocks 5, 6 and 7, 8 horizontal and vertical scanning, and the deflecting systems 4 of the recording and reading sections of the third grafecon 3, are connected respectively to the third and fourth blocks 9, 10 and 11, 12 of the horizontal and vertical scanning, the heads 13-15 of the video signal recording, all auxiliary and scale signals, a video signal reproduction head 16-18, auxiliary and scale signals, a delay line 19, the output of which through the serially connected block 20 of the formation of the identification signal and the first amplifier 21 is connected to the input of the first graph 1, the output of which through the second amplifier 22 is connected to the video signal recording head 13, a sync selector 23, the input of which is connected to the output of the delay line 19 ″, a third amplifier 24, the output of which is connected to the input of the second grachecon 2, the output of which is through the fourth amplifier 25 is connected to the scaling signal recording head 15, the first .26 and the second 27 tape motors, connected, for example, through the automatic control units 28 and 29 respectively to the auxiliary signal recording and reproduction heads 14 and 17, the fifth amplifier 30 the input of which is connected to the video playback head 16, and the output is connected to the input of the third gracheon .3, the output of which is connected to the input of the sixth amplifier 31, the seventh amplifier 32, whose input is connected to the playback head 18 of the scaler and the output to the first input of the third 9-horizontal scanner unit, the second input of which is connected to the auxiliary signal playback head, and the output of each horizontal scanning unit 5, 6, 9 and 10 is connected to the first input of the corresponding block 7, 8, 11 and 12 are vertical, the phase discriminator 33, the first and second inputs of which are connected respectively to the outputs of the first 7 and second 8 blocks of vertical scanning, horizontal definition control blocks 34 and vertical 35, whose inputs are connected to output f The basic discriminator 33, the scale signal generating unit 36, the first input of which is connected to the device input, the second input - to the output of the horizontal definition control unit 34, and the output - to the input of the third amplifier 24 and the second input of the first horizontal unit 5, sweep, synchronous generator 37, the first input of which is connected to the output of the vertical definition control unit 35, the second input to the output of the sync selector 23, the first output -.c with the second input of the unit

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20 generating the identification signal, and the second output - with the inputs t and the inputs of the first horizontal 5 and vertical 7 scanning units, and the frame recognition unit 38, the input of which is connected to the output of the sixth amplifier 31, and the output - to the input of the repetition unit 39, the output of which is connected to the second input of the fourth block 12 vertical.

The device works as follows.

The video signal from the source is fed to the input of the device, passes the delay line 19, the identification signal generating unit 20, is amplified in the first amplifier 21 and enters:; the recording section of the first gracone 1. The video signal also enters the scale signal generation unit 36, which outputs the scale signal. This signal is fed to the first input of the first horizontal scanning unit 5 and through the third amplifier 24 to the input of the second gracheon 2. The first horizontal scanning unit 5, which controls the deflection systems of 4 sections of the first 1 and second 2 graphs, provides a horizontal scan of the recording electron beams . At the same time, the speed of movement of these beams varies in accordance with the scale signal. Consequently, when recording a line of a television signal (phg.2a) in the segment of the EU, the speed of the rays decreases ten times, and this segment occupies a segment on the screen of the first gracnec ten times smaller than in a normal recording. In this case, the amplifiers 21 and 24 must provide the necessary correction associated with a change in the recording speed. The first vertical scanning unit 7 receives a control signal from the first horizontal scanning unit 5 and, by controlling deflection systems 4 vertically, provides a predetermined density of horizontal recording tracks on the screens of the first 1 and second 2 graphs.

The second blocks of horizontal scanning 6 and vertical scanning 8 control the deflecting systems of the first 1 and second 2 gracneck sections and provide reading at a reduced constant speed of compressed video and compressed May914

a staff signal, which are respectively amplified in the second 22 and fourth 25 amplifiers and recorded on magnetic tape with magnetic heads 13 and 1 5.

The automatic control unit 28 controls the motor 26 of the tape mechanism and generates an auxiliary signal containing information on the change in the speed of movement of the magnetic tape. This signal is recorded on a magnetic tape by a magnetic head 14 and is fed to the input of the second horizontal scanning unit 6, as a result of which the speed of movement of the reading electron beams is corrected in the first 1 and second 2 graphers, depending on the change in the speed of the magnetic tape.

With this method of recording a television signal, different frames can occupy segments of different length on a magnetic medium, however, on average, one segment has a segment of a certain length. If there are images with high redundancy, then each frame takes on a magnetic medium a segment smaller than the set one. In this case, it is possible, for example, to automatically provide pauses between frames or reduce the degree of compression. But upon receipt of images with low redundancy, each frame begins to occupy a segment longer than the set one. At the same time, it is necessary to increase the degree of compression of the video signal, which can be obtained by reducing the sharpness of the recorded images, and this process is ensured by the clarity control unit 40.

The read electron beam in the graph moves with some lag from the recording beam, and this delay, corresponding to the amount of recorded information in the gracone, is determined by the phase difference at the outputs of the first 7 and second 8 blocks of vertical scanning, which are connected respectively to the first and second inputs of the phase discriminator 33, the output of which is fed to the horizontal definition control block 34. This block changes the frequency parameter of the scale signal generating unit 36 and thus changes the horizontal clarity. On-.

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For example, if the frequency parameter (partial threshold value) is changed from 0.6 MHz to 1.2 MHz, then as a result of a tenfold compression of the video signal and a limitation of the bandwidth during recording, many parts experience a loss of high frequency components, which corresponds to a decrease in

o horizontal definition.

The vertical definition of change is made because it is possible in the gracnec to periodically ensure the omission of one field of the television frame, and during playback this frame is determined and this field is counted twice in the gracone. For this, the vertical clarity control unit 35, which receives the signal from the phase discriminator 33, puts the synchronous generator 37 into the mode of generating multiple frequencies. This device generates pulses of fixed frequencies.

5 corresponding to the frame rate, as well as corresponding to every second frame - every third, and every fourth. Due to the fact that synchronization is provided at

0 using the sync selector 23, the synchronous generator 37 controls the operation of horizontal 5 and vertical 7 blocks, turns off scanning and recording for the time of one field: at the beginning of every fourth frame, and with decreasing image redundancy of every third, second, and finally one decomposition field of each frame is recorded that matches

0 to decrease the definition vertically by a factor of 2. Frame sync pulses for such frames are marked with special identification signals by the identification signal generation unit 20,

5 which is controlled by a synchronous generator 37.

Thus, the clarity control unit 40 allows the degree of compression of the video signal to be adjusted to the required

The magnitudes for all kinds of images are due to the change in image clarity.

During playback, the compressed video signal is read by the magnetic head 16, amplified in the fifth amplifier 30, and fed to the input of the third grafecon 3. The compressed scale signal is read by the magnetic head 18, amplified in the seventh amplifier

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32 and is fed to the input of the third horizontal scanning unit 9, which, by controlling the deflecting system of the recording section of the third grafecon 3, will change the speed of movement of the recording electron beam in accordance with the scale signal, as a result of which on the form of the television signal. The third vertical scanning unit 11 receives the signal from the third horizontal scanning unit 9 and, controlling the vertical deflection system, provides a predetermined density of the horizontal recording tracks on the screen of the third grachekon 3. The fourth horizontal scanning blocks 10 and vertical 12 U1: equal to the deflecting systems the slichagan sections of the third gracnecon 3 and ensure that the reconstructed video signal is combined, which is amplified in the sixth amplifier 31 and arrives at the output of the proposed device -keeping.

Magnetic head 17 reads out the auxiliary signal entering the automatic control system 29 by the motor 27 of the tape mechanism and the third horizontal scanning block 9, as a result of which the speed of movement of the recording electron beam in the third grafcon 3 is corrected depending on the change in the velocity of the magnetic beam. tapes.

Frame recognition unit 38 detects the arrival of a frame sync pulse with a special identification signal and delivers a control signal.

pulse to repetition unit 39, which controls the operation of the fourth vertical scanner 12. At the same time, in the section of the third gracsecon 3, the scanning of the electron beam is changed so that after reading the first half of the frame, the return beam is returned to a certain segment along the vertical corresponding to one screen of the decomposition field, and the second half is obtained correct image. The amplifier 31 also receives the control pulse of the repetition unit 39 and provides the necessary change in the current of the reading beam of the gracone 3.

In the grafecone 3, at a low current of the reading beam, a mode of operation is possible where each frame can be read several times (up to 5000 times). Therefore, the repetition unit 39 using manual control also allows to obtain the playback mode Image slowdown, Image stop.

The device provides a reduction in the bandwidth of the video channel (Fig. 2 (.e)), which allows it to be used for transmitting a television signal. If it excludes the automatic regulating units 28 and 29 of the engines 26 and 27 and replaces the block 41 of the recording heads 13-15 the transmitting unit, and the block 42 of the reproduction heads 16-18 to the receiving unit, the device is a device for transmitting a television signal.

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Claims (1)

DEVICE FOR MAGNETIC TAPE RECORDING AND PLAYBACK OF A TV SIGNAL, containing the first, second and third grafcons, while the deflecting systems of the recording and reading sections of the first and second grafcons are connected respectively to the first and second blocks of horizontal and vertical scanning, and the deflecting systems of the recording and recording sections the third grafcon are connected respectively with the third and fourth blocks of horizontal and. vertical scan head, video recording head, auxiliary and large-scale signals, video playback head, auxiliary and large-scale signals, a delay line, the output of which through series-connected recognition signal generation unit and the first amplifier is connected to the input of the first grafcon, the output of which through the second amplifier is connected to a video recording head, a sync selector, the input of which is connected to the output of the delay line, a third amplifier, the output of which is connected to the input of the second afekona, the output of which through the fourth amplifier is connected to the recording head of the large-scale signal, the first and second tape drives, connected, for example, via automatic control units respectively to the recording and playback heads of the auxiliary signal, the fifth amplifier, the input of which is connected to the video playback head, and the output - with the input of the third grafcon, the output of which is connected to the input of the sixth amplifier, the seventh amplifier, the input of which is connected to the playback head of large-scale Ignal, and the output is with the first input of the third horizontal block, the second g input of which is connected to the playback head of the auxiliary signal, and the output of each horizontal block is connected to the first input of the corresponding vertical block, ^{On the one} hand, in order to reduce the speed of the recording medium, a phase discriminator is introduced, the first and second inputs of which are connected respectively to the outputs of the first and second vertical blocks, the control units are even horizontally and vertically, the inputs of which are connected to the output of the phase discriminator, a scale signal generating unit, the first input of which is connected to the input of the device, the second input is the output of the horizontal clarity control unit, and the output is with the input of the third amplifier and the second input of the first horizontal scan unit, a synchronous generator, the first input of which is connected to the vertical output of the clarity control unit tv zooziHns, the second input is with the output of the sync selector, the first output is with the second input of the block recognition signal, and the second output with the second inputs of the first horizontal and vertical blocks. and a frame recognition unit, the input of which is connected to the output of the sixth amplifier, and the output is to the input of the input repetition unit, the output of which is connected to the second input of the fourth vertical block.