SU1739382A1 - Device for recording of tv signals - Google Patents

Abstract

The invention relates to the field of magnetic recording and can be used for recording-reproducing television signals. The purpose of the invention is to improve the quality of the television signal recording. The device contains a source 1 of the reference television signal, a unit 2 for changing the duration of television frames 2, a VCR 4, which includes an automatic gain controller 3, a selector 6 for frame sync pulses, a recording channel 5, a switch 11, systems 12 and 13 for automatic tape speed control and rotational speeds of the high-speed motor, control channel 14. In addition, the proposed device comprises a series-connected frequency detector 7, an integrator 8, a controlled delay device 9, and a constant delay device 10. During recording, a television signal with a variable frame duration is recorded on a magnetic tape. In this case, a sequence of frame sync pulses with phase errors occurs at the output of the selector 6, which with the help of blocks (7, 8, 9, 10) is converted into a sequence without phase errors, fed to the control systems 12 and 13 and to the control channel 14 of the video recorder. 2 Il. YO I CJ YO SA SA YO YOU

Description

FIG. one

The invention relates to magnetic recording and, in particular, can be used for recording-reproducing television signals.

The purpose of the invention is to improve the quality of the television signal recording.

FIG. 1 shows a functional diagram of the device; in fig. 2 - diagrams explaining the operation of the device (where 2a are pulses of the selector Vc; 26 is the output signal of the frequency detector V4; 2c is the output signal of the integrator Ui; 2g are the pulses at the output of the controlled delay V0; 2e are the pulses at the output of this delay V3).

The device contains a source 1 of a standard television signal (or a bus of a standard television signal) connected through a block 2 for changing the frame duration and an automatic controller 3 for amplification (AGC) of a video recorder (VM) 4 with channel 5 for recording. The output of the AGC 3 through the selector 6 HR clock pulses VM, frequency detector 7 and the integrator 8 is connected to the control input of the controlled delay unit 9, the output of which through the delay unit 10 is connected to the switch 11, the outputs connected to the blocks 12 (CAP-SL), 13 (CAP-LED) and the control signal channel 14, while the pulse input of the controlled delay unit 9 is connected to the AGC output 3.

The device works as follows.

The input of block 2 receives a standard television signal. Unit 2 is a random access memory (RAM) into which information containing in one television frame can be recorded. This block delays the standard television signal by an average of 10 lines, however, the instantaneous delay value periodically varies from 0 to 20 lines according to the harmonic law. This changes the frame duration from standard to increased or decreased by 10 lines, and the length of all lines in all frames remains unchanged.

The signal from the output of block 2 goes to the AGC, where its scope stabilizes and becomes equal to 1B. The output signal of the AGC is then recorded on a tape, previously processed in channel 5. At the same time, frame sync pulses Vc appear at the output of selector 6 (Fig. 2a), the phase of which varies relative to the mean value (indicated by a dotted line and has a period Tc 20 ms) by harmonic law. In order to compensate for the phase errors of the pulses, the frequency detector 7 produces a voltage V4 (Fig. 26) proportional to the change in the frequency of the pulses Vc, which is then integrated

unit 8. At the output of the latter, a voltage VH appears (Fig. 2c), which depends on phase errors A (Fig. 2a). This voltage is applied to block 9, the output of which produces pulses / and whose duration depends on the voltage / and, i.e. from phase errors. As a result of the action of voltage / and on block 9, sections C of the pulses V0 will have a constant period Tc (Fig. 2d).

The constant delay unit 10 is triggered by the action of slices C (Fig. 2d) on V0 pulses and produces Vs pulses with a period Tk, the action of which coincides in time with the action of the pulses that also follow the period Tk shown in FIG. 2a dotted line. V3 pulses no longer have almost phase errors A, so they, falling through the switch 11 on blocks 12-14, do not disrupt operation

systems of automatic control of the VM both during recording and playback.

Claims (1)

Invention Formula A television signal recorder containing a television reference source, connected through a signal duration change unit with a tape recorder selector input and through its automatic gain controller to a VTR recording channel, a switch whose outputs are connected to automatic speed control systems of speed and speed motor and control channel, characterized in that, in order to improve the quality of the television signal recording, serially connected frequency detector, integrator, a controllable delay and a constant delay unit connected between the output of the selector and the input of the video switchboard. 1GL  and