SU515996A2 - Device for measuring the speed of movement of magnetic media - Google Patents

Description

one

The invention relates to the field of instrumentation.

A device is known for measuring the speed of movement of a magical carrier by aut. St. No. 437015, containing a recording magic head associated with a pulse generator, and a reproducing magnetic head, the output of which is connected via a amplifier to the trigger, and one of the magnetic heads is made with two working gaps. Amplifier shaper connected to the counting input of the trigger. In addition, the device is equipped with a signal conversion unit, made in the form of a comparison circuit, one input of which through an integrator with fixation of the final link level with the trigger output, the second input through a series-enabled} differentiator, limiter, delay unit and sawtooth voltage generator connected to a pulse generator, and the output through the driver connected to the low pass filter.

The device makes it possible to measure the average speed of movement of the carrier and its unevenness in the process of reproduction, but it does not allow to measure the average speed of movement of the carrier and its unevenness in the process of recording the waveform.

The purpose of the invention is to measure the average speed of the carrier and its non2

uniformity in the process of recording waveforms.

The goal is achieved by introducing a low-pass filter into the device, the input of which is connected between the trigger output with the counting output and the integrator, and two parallel chains connected to the output of the low-pass filter and consisting of one of the series-connected DC amplifiers and a block of direct current indicators, a friend of an AC power amplifier, and a block of alternating current indicators.

FIG. 1 shows a block diagram of the proposed device; in fig. 2, a – d are time diagrams.

The device comprises a recording head, conjugated with a magnetic tape 1, for example, with two working gaps 2 and 3, and

the reproducing head 4. A pulse generator 6 is connected to the recording head through the pickup 5, an amplifier-former, for example, is connected to the reproducing head 4, for example,

connected to each other amplifier 7, cutout circuit 8, differentiator 9, driver 10; trigger 11 with a common counting input, an integrator with fixation of the final level 12 and a comparison circuit 13. The second input of the latter through sequentially

the included differentiating element 14, the limiter 15, the delay unit 16 and the geyrator of the sawtooth voltage 17 are connected with the pulse generator 6.

A registering device 20 is connected to the output of the comparison circuit 13 via a driver 18 and a low-pass filter 19. The driver 18 output is connected via a reset switch 21 to the input of the integrator 12. Trigger 11 is equipped with a zero-22 setting unit.

In addition to the output of the trigger 11 with a counting input, a low-pass filter 23 is connected, to the output of which a DC amplifier 24 and an AC amplifier are connected. 25. Both of them are connected to the blocks of indicators 26 and 27 of constant and alternating currents.

FIG. 2 shows timing diagrams of the signals at the output of the following elements: a) driver 10, b) trigger I, c) integrator 12, d) sawtooth generator 17, e) low pass filters 19, 23.

The operation of the device is as follows.

Two zones of pulsed magnetization with a distance equal to the distance between gaps 2 and 3, which does not depend on the speed of the carrier, are simultaneously recorded on a moving magnetic carrier with gaps 2 and 3 with a recording magnetic head. Recording is carried out using a recording amplifier 5 from a generator of 6 periodic pulse signals. A sequence recorded on the carrier in a series of two pulses is reproduced by a reproducing magnetic head 4. Their signal is amplified by an amplifier 7, the cutout unit 8 cuts out some symmetric about zero area, the level of which is chosen so that it would be possible to eliminate additive noise and spurious noise.

Cutout circuit 8 can serve two parallel semiconductor diodes connected in opposite polarity. The signal is differentiated by block 9, and zero or some close to zero level signal transitions are fixed by shaper 10 (Fig. 2, a). At the zero output of the trigger 11, which is preliminarily set to "O," pulses are received (Fig. 2.6). The duration of these imiuls is equal to the time interval for the passage of a pair of pulses recorded on the carrier 1 past the reproducing head 4. The time interval, i.e./i- / 2, on the sequence of a and b, contains information about the speed of movement of the carrier during playback, the period of the emulse sequence, t. e. the distance between the first impulse of the 1st pair and the first impulse) -H pair has information about the speed both during recording and playback. The rest of the circuit serves to extract information about the speed fluctuation only during recording. This is done by sequencing.

where the modulating function is rate fluctuation only during playback. The duration of the i- / 2 pulse trigger 11 determines the magnitude of the voltage on the integrator 12 (Fig. 2, c), which, at the end of the emulsion, is fixed and fed to one of the inputs of the comparison circuit 13. A second saw voltage is applied to the second input (Fig. 2, d) from sawtooth generator

voltage 17, which starts up 16 pulses delayed in a delay unit with

generator 6, passed through differential circuit 14 and limiter 15.

The maximum delay time / ass (FIG.

2, e) is determined by the minimum period of the read pulse and sequence, the maximum duration of the read pulse at the input of the trigger 11 and the discharge time of the integrator 12. The duration and duration of the pulse

ii- / 3 (fig. 2, c) from the moment the generator 17 starts up to the moment of equal voltage (generator saws 14 with voltage fixed to integrator 12) is proportional to the speed value during playback.

This time interval is formed by the formation unit 18, at the output of which it has a sequence (Fig. 2, e) modulated by speed fluctuations during playback. The modulated function is extracted by a low pass filter 19. Reset key 21 generates a pulse that discharges generator 12 and prepares it to capture information from the next series of two pulses.

The value of the average velocity and its oscillations during recording is directly separated by a low-pass filter 23 in proportion to the constant component and variable component of the voltage at its output during demodulation of output pulses from the output of trigger 11. This assumes that Megolocation of the f-ihar labels magnetization modularovio

write speed When playing the rth pair of labels, each of them is modulated in time by the speed of the carrier during playback, which ultimately manifests itself as a corresponding modulation of the leading and trailing edges of the trigger 11 (Fig. 2.0). In the spectrum of such a modulated sequence, there is no component of the frequency of the speed fluctuations during reproduction, but there is a component of the oscillations in the recording.

Lowpass Filter Output

23 amplified by a constant current amplifier

24 (information about the mean speed, which was only at the time of recording) and AC amplifier 25 (information about speed fluctuations, also only during recording) is recorded by blocks of DC and AC current indicators 26 and 27. At the same time, the output signal can be recorded.

Recording can be done with a single-gap head, but then a two-gap head with a common magnetic core should be used for measurements. The pulse frequency of the generator 6 is chosen such that their period is longer than the magnetic time of the distance between the gaps of the two-gap head.

The device is used when recording and reproducing time distributed for an unlimited time interval, with the joint or separate operation of the block diagram elements of the known and proposed devices. The device allows to measure the speed of movement of the carrier, which was at the time of recording the measuring magnetic marks, and the accuracy is almost independent of the speed of movement of the carrier at the time of reproduction.

Claims (1)

6 claims A device for measuring the speed of movement of a magnetic nosnel by aut. St. Law 437015, characterized in that, in order to measure the average speed of the carrier and its irregularity in the process of recording the waveform, a low-pass filter is inserted in it, the input of which is connected between the output of the trngger with the counting output and the integrator, and two narral chains connected to the output of A low-pass filter consists of one of a series-connected DC amplifier and a block of DC indicators, the other is from an AC amplifier and a block of AC indicators. one but / g L Jl