SU760181A1 - Tape recorder parameter measuring device - Google Patents

Description

The invention relates to the field of Instrumentation, in particular to the technique of magnetic recording, and can be used when setting up and end of tape recorders in high-volume and mass production.

A device for monitoring and adjusting a tape recorder, comprising a generator of sequences of signals of various frequencies, connected to the input of the tape recorder, and an oscilloscope connected to the output of the tape recorder is known.

In the process of recording, a repeatedly and repeatedly repeating sequence of signals of different frequencies comes from the generator to the tape recorder input, the reproduced signal is indicated on the oscilloscope screen, and the amplitude of the frequency characteristics of the tape recorders is measured by the amplitudes of the signals of different frequencies. The repetition frequency of the sequential “signals” ensures the absence of flickering of the image on the screen of the oscil-25 scanner. however, to control frequencies below 400 Hz, when working with this device, it is required to sequentially produce a recording and then follow the introduction of each of the low frequencies,

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which increases the time required for control.

It is also known a device for measuring the parameters of tape recorders, containing generators, waiting for multi-, vibrators, keys, an alternating voltage conversion unit, a controlled tape recorder, a clock generator, an oscilloscope, a switchboard and, according to the number of tested frequencies, chains from a series-connected gate forming unit, analog key, memory block and integrator. In this device, a repeatedly repeated sequence of signals of different frequencies of the checked frequency range (including low frequencies) is fed to the tape recorder's input. When playing, the amplitude of the signal of each recorded frequency is converted into a constant voltage. With the help of a switch, the clock is clocked, the received signals are sequentially input to the oscilloscope, forming on its screen a curve characterizing the amplitude-frequency characteristic of the tape recorder under study.

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For the operation of the device, it is necessary that at least at least several periods of the signal of each frequency be recorded on a magnetic tape. In the recorded sequence of signals of different frequencies, the total duration of all low-frequency signals is several times longer than the total duration of the signals of the remaining frequencies. In the reproduced signal, high frequencies are most susceptible to changes in amplitude due to the presence of spurious amplitude modulation. Since the repetition frequency of a sequence of signals of different frequencies is not great, the amount of information about the amplitudes of high-frequency signals / arriving over a certain time interval | Meny is also small. To improve measurement accuracy, it is necessary to average information about the amplitude of high-frequency signals for as long as possible, which, if there is a sequence of signals of different frequencies, with a longer total duration, leads to an increase in measurement time ...

The aim of the invention is to accelerate the measurement process (while maintaining its accuracy) by reducing the information about low frequencies.

This goal is achieved by introducing a pulse distributor into the device and according to the number of controlled low frequencies of the AND circuit, with the output of one of the waiting multivibrators through the two-input circuits AND connected to the control inputs of the corresponding switches and to the input of the pulse distributor whose outputs are connected to the second inputs of the circuits And, and the output of each of the individual waiting multivibrators is loaded to the input of a separate key, while the clock generator is connected to the control one — the input of the Switch, the outputs of which are connected to oscilloscope input, and an output unit converting AC to DC is connected to the control inputs of the analog switches. έ

The drawing shows a block diagram of the device.

The device contains generators 1, keys 2, standby multivibrators 3, pulse distributor 4, circuits And,

5, a controlled tape recorder 6, an alternating voltage to constant voltage converter 7, gating pulse shaping blocks 8, analog switches 9, memory blocks 10, integrators 11, switch 12, clock generator 13 and oscilloscope 14.

The proposed device works

in the following way.

At the outputs of the waiting multivibrators

3 impulses are shifted

on time relative to each other.

The pulses formed by the extreme barely * (by block diagram) waiting multivibrator 3 arrive at the inputs of the AND 5 'circuits and at the input of the pulse distributor 4, at the outputs of which the pulses are shifted relative to each other by the time determined by the pulse repetition frequency of this multivibrator 3. Pulse distributor 4 can be assembled on the basis of a pulse counter with a decoder, a shift register, etc. The pulses from the outputs of the distributor 4 are fed to the second inputs of the circuits And 5, the number of which is equal to the number of controlled low frequencies. The outputs of the circuits And 5 and the outputs of the rest of the waiting multivibrators 3 are loaded on the control inputs of the keys 2 connecting the generators 1 to the input of the monitored tape recorder 6. Thus, the input of the tape recorder 6 receives signal sequences of different frequencies, each of which consists of a signal one of the low frequencies and successive signals of other frequencies. For example, the first sequence of signals may contain 4-5 periods — with a frequency of 40 Hz and successive signals with frequencies of 400 Hz and above. The second sequence - signals with a frequency of 63 Hz, as well as signals of medium and high frequencies. Accordingly, the third sequence contains signals with a frequency of 80 Hz, the fourth — 125 Hz, and the fifth — again 40 Hz. Since low frequencies are practically not subject to parasitic amplitude modulation _{, it is} enough to receive information on the amplitude of low frequencies less often than information on the amplitude of medium and high frequencies. By forming a similar sequence of signals of different frequencies, the duration of this sequence can be reduced. repeatedly. Using the converter 7 AC voltage to DC, connected to the information inputs of analog switches and chains, the number of tested frequencies connected to the output of the tape recorder b and consisting of series-connected shaper pulsating pulses 8) analog key 9, memory 10 and integrator 11 receive a constant the voltage at the output of each integrator .11, proportional to the amplitude of the signal of the corresponding frequency, at the output of the tape recorder 6. These voltages are through the switch 12, controlled by · 'that striation ge- generators of 13 arrive at the input of the oscilloscope 14, forming on its screen multiply repeating sequence of pulses, the amplitude of each of which characterizes the course of the amplitude-frequency characteristic in a specific controlled point

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frequency range. Since the information about the amplitude of the high-frequency signals comes in several times more often than in a known device, the integrator time constant can be reduced, which speeds up the measurement process.

Due to the introduction of the pulse distributor and the circuits And the proposed device allows to increase the measurement speed of the amplitude-frequency response by 20-30%. At the same time accuracy of measurements is kept.

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Claims (1)

Claim A device for measuring the parameters of a tape recorder, containing generators connected via keys to the input of a tape recorder, the output of which is connected to the corresponding information inputs through chains of serially connected gating pulse shaping unit, analog key, memory block and integrator 15 20 switch and to the input of the AC voltage to DC conversion unit, as well as pending multivibrators, a clock oscillator and an oscilloscope, characterized in that, in order to avoid the measurement process by reducing the information about low frequencies, a pulse distributor has been entered into it And the frequency of the circuit, and the output of one of the waiting multivibrators through two-input circuits AND connected to the up-. equating the inputs of the corresponding keys and cr to the input of the pulse distributor, whose outputs are connected to the second inputs of the AND circuits, and the output of each of the other waiting multivibrators is loaded to the input of a separate key, while the clock generator is connected to the control input of the switch, whose outputs are connected with the inputs of the oscilloscope, and the output of the AC / DC converter is connected to the control inputs of the analog switches.