SU1727171A1 - Device for control of video tape recorder parameters - Google Patents

Description

the ability to measure the time interval between two adjacent pulses in a continuous sequence of pulses without prior processing of the latter.

The aim of the invention is to improve the noise immunity.

This goal is achieved by the fact that a device for monitoring and measuring the parameters of a VCR, containing a reference pulse generator, connected to one of the inputs of the coincidence circuit, the output of which is connected to the input of an instantaneous time interval counter, is additionally equipped with a selector and driver of counting clock pulses connected in series and connected to another input of the coincidence circuit, the first adder, the inverting input of which is connected to the output of the instantaneous counter, and the output to the first input of the first divider, the second input of which and the inverting input of the first adder are connected to the master output No, the output of the first divider is connected to the second input of the second divider via one input of the second input second adder and the second input of the second adder respectively to the Vo outputs and 1 setting device, the output of the horizontal sync pulse generator through the reset pulse shaper is connected to the inputs for setting the zero counter of instantaneous values of the first and second adders and about their divisors.

The output of the coincidence circuit through the average counter is connected to the non-inverting input of the third adder, the output of which is connected to the first input of the third divider, the second input of which and the inverting input of the third adder are connected to the output kNo of the setpoint controller, and the output of the video recorder through serially connected selector, comparator and driver half-frame pulses are connected to the inputs of the zero setting of the average counter, the third adder and the third and fourth dividers, and the first and second inputs of the fourth d divisor are respectively connected to the output kVoNo setpoint counter and the output average values.

The essence of the invention is as follows.

The video signal of a television image, in particular, contains lowercase SI, between which information is located. During recording-reproduction, this information is distorted (compressed or stretched over time). When playing a distorted video signal, image quality deteriorates. Distortion occurs for various reasons: instability of the carrier movement, deformation of the carrier, displacement of the video head from the track, change of the trajectory of the video head, etc.

To estimate the distortion of the reproduced video signal associated with the instability of the relative movement of the tape-to-head system, a device is proposed that allows measuring the relative average speed of movement of the carrier in the tape-to-head system on a recording line,

5 the instantaneous relative speed of movement of the carrier in the tape-head system and the measurement of time distortion.

Temporal distortion (VI) is a parameter that is calculated using the formula (Weida)

tb-ts

dt

T.Z.

(one)

five

0

five

where te is the duration of the recorded and reproduced time interval;

t3 - the duration of the recorded time interval.

When measuring In And we will use the following assumption: all recorded minima have the same duration - the duration of the reference time interval. This assumption is possible with high stability (-) of the reference generator.

Then the formula (1) takes the form

to-to atf

AT

to

I Ј-l.

where to - the duration of the time interval of the reference generator,

To increase the noise immunity of the device, the measurement of the duration of the time interval is made by purely digital methods, i.e. we translate the duration of the time interval into the number of reference pulses, and then into a binary code. The interference immunity of the device is increased as a result of the use of pulse width modulation, which is more noise-proof. than amplitude modulation,

In this case

dl ad-shp | r-grg AP, .. ni 1

tOnQTno no

(3)

where ni is the number of reference pulses in the recorded and reproduced reference time interval;

a swarm whose input is fed a continuous sequence of pulses from the generator

5 support impulses (fig, 2d).

At the output of the coincidence circuit 7, a burst of pulses of the reference generator 5 is produced, the number of pulses in which is equal to the duration of the measured time interval (Fig. 2e). The shaper 6 reset pulses produce short pulses (Fig. 2g), necessary for the initial installation and periodic reset to zero of the counter 8, adders 9 and 11, dividers 10 and 12 on the leading edge of the horizontal sync pulses (Fig. 26).

The duration of the reset pulses is selected from the maximum pulse duration necessary to zero the blocks 8-12. The instantaneous value counter 8 counts the number of pulses in the NJ burst. In the adder 9, the nominal number of pulses No is subtracted from this number, i.e. the number of pulses, which should be in the burst, if the recorded and reproduced signal is identical, and divider 10 normalizes the difference to No, and thus, at the output of divider 10, we get instantaneous time distortion values DT

Adder 11 adds to the instantaneous value of temporal distortion a unit whose value comes from setpoint 13, and divider 12 divides the value of the nominal instantaneous speed obtained from setpoint 13 by the value (A P + 1). Thus, at the output of divider 12, we obtain instantaneous values of the velocity Vi.

When the following line sync pulse appears at the output of the driver

A 6-pulse reset appears in the pulse, which produces zeroing of blocks 8-12, and the whole process of measuring the instantaneous values of temporal distortion and the instantaneous velocity begins anew.

Similarly, the device operates when determining the average (for the recording line) value of the time distortions АТср. The average counter 17 counts the number of pulses, the adder 18 takes the difference with the nominal average number of pulses obtained from the setpoint 13, and the divider 19 takes the ratio of this difference to the nominal average number of reference pulses per recording line. Since video recorders operating in VHS format are considered, the appearance of a half-frame pulse indicates the beginning of the recording line. Therefore, resetting the counter 17, the adder 18 and the divider 19 occurs synchronously with the appearance of the leading edge of the half-frame pulse (Fig. 2h) through the corresponding circuit blocks 14-16 by the pulse of FIG. 2k

Thus, information on the average value of temporal distortions for the period

the recording line is removed from the output of divider 19.

The definition of the average speed occurs when dividing by the number of pulses of the reference generator 5, calculated for

0 line recording counter 17 average values of the number kVoNo, obtained from the corresponding output of the setpoint 13 on the divider 20.

Information about the average speed per record line is removed from the output of divider 20.

Compared with a device of a similar purpose (prototype), the proposed device provides enhanced functional capabilities: measurement of instantaneous and average values of temporal distortions, instantaneous and average relative speeds of movement in a tape-head system, the ability to work with

5 by a continuous sequence of pulses, which makes it possible to increase the information content of the device. In addition, signal processing takes place in digital form, which significantly increases the noise immunity of the device.

The use of this device allows you to reduce the time control of the parameters of the video recorder by 15-20%, as well as significantly simplify the adjustment of the SAR BB and

5 UAR SAR.

Claims (1)

Apparatus of the Invention A device for monitoring the parameters of a video recorder, comprising a horizontal sync pulse selector, connected by an input to the output of a video recorder and connected by an output through a first comparator to the input of a first pulse generator, a coincidence element, connected by a first input to an output 5 of the reference pulse generator, the reset pulse shaper, the second comparator and the second pulse shaper, due to the fact that, in order to improve the noise immunity, 0 counter of the average values of the time interval and the counter of instantaneous values of the time interval connected by the inputs of the zero setting to the outputs of the second pulse former, respectively 5 and a reset pulse generator and connected by counting inputs to the output of a coincidence element connected by a second input to the output of the first pulse generator connected to the input of a reset pulse generator, an additional horizontal sync pulse selector connected to the output of the VCR and connected to the output through the second comparator to the input of the second formatter pulses, the first divider made with the output bus connected to its output of the average time distortion, the second an itel equipped with a medium speed output bus connected to its output, a third divider made with an instantaneous speed output bus connected to its output, a fourth divider, first, second and third adders and a parameter value setter, the first adder is connected with an output to the first input of the first divider connected by the second input to the first output of the parameter value setting device connected to the inverting input of the first adder connected by a non-inverting input to the output of the counter the bottom values of the time interval connected to the first input of the second divider, which is connected by the second input to the second output of the setpoint Parameters and connected to the input of the zero setting with the output of the second pulse generator connected to the inputs of the zero setting of the first adder and the first divider, and the third divider connected to the third output of the parameter setting handler connected to the fourth input of the second adder of the second adder the second input of the third divider and is connected by a second input to the output of the fourth divider connected by the first input to the output of the third adder and connected by the second input to p that parameter setting output, connected to the inverting input of the third adder, connected by a non-inverting input to the output of the instantaneous time counter, and connected to the installation input zero to the output of the reset pulse generator connected to the installation inputs of the second adder and the third and fourth dividers.