SU803124A1 - Television signal recording and reproducing method - Google Patents

Description

(54) METHOD OF RECORDING AND PLAYING A TELEVISION SIGNAL

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The invention relates to radio engineering and can be used in a wide range of video equipment.

A known method of recording and reproducing a television (TV) signal, a signal from a rotating disk information carrier, for example, a focused beam of light, is that, before recording, a sound signal is extracted from the full TV signal, delayed and summed up with the non-held signal, mixed with the image signal and the received signal when recording modulate a beam of light, and during playback each turn is repeatedly read by a beam of light, the audio signals and the image signal are extracted from the read from each turn vayut image signal with one of the sound signals 1.

However, the known method uses almost extreme possibilities for compacting information and does not allow to increase the duration of TV programs without further significantly increasing the complexity of the recording and reading device, reducing the wavelength of the coherent light emitter (in optical recording systems), further

increasing the resolution of the recording layers of the carrier, etc.

The aim of the invention is to increase the duration of the recorded TV program and its reproduction without increasing the size of the disk medium.

To do this, before recording from the TV signal of each half-frame, the audio signal is extracted, delayed for the duration of the half-frame, summarized with the audio signal of the subsequent half-frame and mixed with the image signal of one of the half-frames of each frame, recorded during one half-frame, the TV signal of each frame, the recording medium is rotated at the doubled frame rate during recording and reading, and when playing back a sound signal from each half-frame is extracted from each signal read from a turn, the signal is mixed images with a delayed sound signal, and when the second reading of the same turn is mixed, the image signal is mixed with the non-held sound signal and transferred to the reading of the next turn.

FIG. Figure 1 shows schematically a part of a video disc of radius R with recording of video signals along a ring having width B for a known method and width B В B for the proposed recording method.

FIG. Figure 2 schematically shows, on an enlarged scale, a section of a video disc with coded recording of TV signals, for example, with frequency modulation of the carrier frequency by image and sound signals. Here, for comparison, the geometry of the elements of expansion of the line of the same frame is shown for a known recording method (elements 1, one after another at a distance of mechanical wavelength I, and occupying the active recording area S) and the proposed method of recording a TV program (elements 2 having a period of following A and area S), and with the same other

conditions

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The proposed method of recording and reproducing a TV signal is as follows.

The TV signal is recorded optically by modulating a coherent radiation source, such as a laser onto a rotating disk medium. The modulated laser beam forms, on a rotating disk carrier, a sequence of decomposing elements of a TV signal, having in particular the appearance of recesses.

Reading a recorded TV program is performed using a low-power laser, the beam of which is focused by a micro-lens on the working layer of a video plate in spot 3 (Fig. 2), having geometrical dimensions close to the size of the recorded decomposition elements 1 (2), 4 (Fig. 2 ).

The beam reflected from the video plate, which, as a result of the successive passage of a series of recesses on a rotating disk storage medium, is modulated, enters the photodetector, where it is converted into a sequence of electrical signals and demodulated according to previously recorded information.

In order to increase the duration (reproduction), they increase the angular velocity of rotation of the disk information carrier to a rotational speed corresponding to twice the frame frequency of the signal.

For K 1 (K - multiplicity of reproduction), one half-frame of the image and the soundtrack of the entire frame are recorded during one revolution, and then the modulator is closed during the next half-frame and the recording is not made at this time.

Sound is recorded through two channels: the sound of this half-frame is recorded through one of the iiHx and the half-frame through which the modulator is closed is recorded through the other.

At the same time receiving the soundtrack of two adjacent half-frames when recording the disc "of the original is carried out.

for example, using as a source of a TV program a video recorder in which one of its sound heads is shifted relative to the other by an appropriate distance.

Together with the rotation of the disk, the recording head is moved at such a speed that in two turns of the carrier it moves radially to the next turn.

When playing disc media

Information is also rotated at twice the frame rate. With the help of an opto-electronic reader, each turn of the information recorded on the video plate is reproduced twice a second.

the first playback of the half-frame sync pulse includes the first channel of the soundtrack, and the next sync pulse turns off the first channel and turns on the second channel.

For K 2, during one revolution, one half-frame of the image and the soundtrack of four consecutive half-frames are written, and then the modulator is closed for the next three half-frames.

J. In this case, each turn is reproduced 4 times. The image quality is the same as when skipping every second frame.

In order to obtain common television interlace scan reuse

0 the reading of one revolution is made with a shift in time equal to the half-integer value of the length of the lines relative to the initial one.

The proposed method of recording and reproducing a TV program reduces the internal radius of the recording (reproduction), which, together with the preservation of the playback time of one revolution and the distance between the coils, increases the duration of the recorded and reproducible program.

Claims (1)

Invention Formula 5 A method of recording and reproducing a television signal, a signal from a rotating disk information carrier, for example, a focused light beam, which means that, before recording, a sound signal is extracted from the full television signal, delayed and summed up with the non-held signal, mixed with the image signal and the recorded signal modulates a beam of light during the recording, and during playback each turn is repeatedly read by a beam of light, the sound signals and the image signal and Sewing an image signal with one of the sound signals, characterized in that, in order to increase the duration of the recorded television program and reproduce it without increasing the size of the disk medium, before recording, a sound signal is extracted from the television signal of each half-frame, it is delayed with the audio signal of the next half-frame and mixed with the image signal of one of the half-frames of each frame, the television signal is recorded for one half-frame each frame, and when recording and reading the disk, the disk is rotated at twice the frame rate, and when playing back a sound from each frame read from the turn, each half-frame is mixed, the image signal is mixed with the delayed sound signal, and at the second reading of the same turn the image signal with an unattached sound signal and is transferred to the reading of the next turn. Sources of information taken into account during the examination 1. Klimenko GK Video plate. M., “Energie, 1976, p. 19-20. (Prototype).