SU1278938A1 - Device for reproducing magnetic record with correcting time distortions - Google Patents

Abstract

The invention relates to magnetic recording and allows reducing information reproduction errors by correcting temporal distortions. To do this, after reproducing the magnetic head 2, the information and reference signals recorded together on a single record are reproduced and their information signal is converted into a digital code with a recording frequency that is a multiple of the reference signal frequency and stored in memory block 7, which is read out set by the clock generator 8, and is converted to analog form in a digital-to-analog converter 9. To improve the efficiency of correction 3 a wide range of frequencies of time distortions, the delay 16, leveling, phase characteristics of the information and reference signal circuits by introducing tracking feedback from the output of the device so that its operation is not disturbed during a deep parasitic amplitude modulation or complete loss of the reference signal, recording pulses are generated with a frequency of the synchronized generator 18 equal to the average recording frequency generated from the reference signal. 1 nl

Description

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The invention relates to magnetic recording, in particular, to devices for reproducing magnetic recording with time distortion correction.

The purpose of the invention is to reduce the error in reproducing information by improving the accuracy of correcting temporal distortions.

The drawing shows a functional diagram of a device for reproducing a magnetic recording with time distortion correction.

The device comprises a playback amplifier 1 connected by an input to a reproducing magnetic head 2 and an output to interconnected inputs of a first band-pass filter 3 and a low-pass filter 4 connected by an output to a first input of an analog-digital converter 5 connected by a second input through a pulse shaper 6 to the output of the first bandpass filter 3 and the output to the first input of the memory block 7 connected by the second input to the output of the clock generator B and the output through the digital-to-analog converter 9 - from output bus 10. In addition, a device for reproducing a magnetic recording with time warp correction includes a series-connected second band-pass filter 11, a frequency detector 12, an integrator 13, a detector 14, a first controlled oscillator 15 and a controlled delay element 16 connected between the output of the filter 4 low frequencies and a first input of an analog-digital converter 5, as well as series-connected voltage comparator 17 and a second controlled oscillator 18 connected between the output of the first band-pass filter 3 input of 6 pulses.

The device works as follows.

To eliminate inter-channel time errors due to static and dynamic carrier skews, the information and reference signals are recorded together on the same track. The reproduced magnetic head 2 information and reference signals are installed in the playback amplifier 1 and from its output go to the low-pass filter 4 and through the filter 3 to the input of the pulse shaping unit 6 to start the analog-to-digital converter 5.

The lowpass filter 4 has a bandwidth allowing the frequency spectrum of the information and reference signals to pass through it, and serves to prevent the input of the analog-digital converter 5 of the noise components beyond the frequency range of the information signal. The reference and information signals through a controlled delay element 16, used to equalize the transit time of the information and reference signals through the low-pass filter 4 and the band-pass filter 3, respectively, are fed to the inputs of an analog-to-digital converter 5, which converts them into a parallel digital code, which is written in block 7 memory The code is read from it at a stable frequency generated by a clock generator.

After reading from memory block 7, the code words are converted to analog form in a digital-to-analog converter 9.

The reference signal is separated by a bandpass filter 3 for the sum of the reference and information signals read from the carrier, and through the comparator 17 the voltage is fed to the synchronization input of the second controlled generator 18. The threshold of the comparator is set slightly higher than the noise voltage. Thus, when the reference signal disappears, caused by the action of a deep parasitic amplitude modulation, the generator 18 is not synchronized with a random njyMOBbiM signal and it continues to generate a signal at its average frequency equal to the sampling rate and recording in the memory block 7, which ensures the preservation of the device . From the output of the generator 18 through the pulse shaper 6, the analog-to-digital converter 5 is started. Since the analog-to-digital converter converts the information and reference signals, its starting frequency to satisfy the conditions of the Kotelnikov theorem is chosen above the upper frequency spectrum of the signal at the analog-digital input converter

The signal from the output of the digital-to-analog converter 9 through the second band-pass filter 11, the selection of the reference signal, is fed to the input of the frequency detector 12. From the output of the integrator 13, the signal, the law of change and the value of which is proportional to the residual temporal distortion at the device output, goes to the detector 14, at the output of which a constant voltage is formed, which is proportional to the magnitude of residual temporal distortions, which is fed to the control input of the generator 15, which is degraded by voltage. If a rms value detector is used as the detector 14, then a signal is generated at the output of the device, in which the minimum mean-square value of the time error is set, and if the detector is 14 peak, then the minimum amplitude value of the time error. A signal from the output of the generator 15 is fed to the control input of the delay element 16, providing the amount of delay at which the minimaly is caused by an error at the output of the device. In this way, the maximum effect of the correction of temporal errors is achieved.

Claims (1)

Invention Formula A device for reproducing a magnetic recording with temporal distortion correction, containing a reproduction amplifier connected by an input to a reproducing magnetic head and an output to interconnected inputs of a first band-pass filter and a low-pass filter connected by an output to a first input of an analog-digital converter connected by a second input through pulse generator to the output of the first bandpass filter and output to the first input of the memory unit connected by the second input with the output of the clock generator and the output through a digital-to-analog converter - with an output width, characterized in that, in order to reduce the error in reproducing information by increasing the accuracy time distortion corrections, a second band-pass filter, a frequency detector, an integrator, a detector, a first controlled oscillator, and a controlled delay element are introduced into it, connected between the output of the low-pass filter and the first input of the analog-to-digital converter, as well as the series-connected voltage comparator and the second controlled oscillator connected between the output of the first band-pass filter and the input of the pulse former.