SU711623A1 - Arrangement for compensating for distortions at reproducing signals from signals from magnetic carrier - Google Patents

Description

I

The invention relates to the field of instrumentation and can be applied in devices based on the principle of magnetic recording, in which frequency modulation is used.

The information signal received at the output of the playback channel has distortions arising from the cz-oa instability of the speed of movement of the magnetic carrier during recording and playback.

It is known a device that makes it possible to partially compensate for these distortions, which improves the quality of the reproduced signal, for example, a device implementing a method based on dividing the main signal by the error signal produced prior to extracting useful information flj.

However, this device does not eliminate distortion.

The closest to the invention to the technical essence is a device for compensating distortions during playback of signals from a magnetic carrier, comprising a frequency modulator and a carrier frequency generator, the outputs of which are connected to the corresponding inputs of the recording unit, a playback unit, one output of which is connected to the input of the first demodulator connected by its output to the first input of the first subtraction unit, and the second output of the playback unit is connected to the input of the second demodulator connected by its output with the second input of the first subtraction unit G2.

A disadvantage of the prior art compensation device is the incomplete compensation of distortion when reproducing signals from a magnetic carrier.

The aim of the invention is to eliminate distortions caused by the instability of the speed of movement of the magnetic carrier,

For this purpose, a second subtraction unit, a constant voltage source, a division unit and a multiplication unit are introduced into the known device, the first input of the second subtraction unit being connected to the constant voltage source, the second input to the output of the second demodulator and to the first input dividing unit, and the output to the second input of the dividing unit, the output of which is connected to the first input of the multiplication unit, the second input of which is connected to the first input of the first subtraction unit, and the output to the second input of the latter,

In the device before subtraction, the demodulated signal of the carrier frequency is distorted - c. (i-t-cJ)

Oh oh

S is the slope of the transformation

Where

during demodulation,: E is the carrier frequency,

 Vo

-

- - the ratio of the magnitude of the velocity deviation of the magnetic carrier from

the nominal value to the nominal value is subjected to the treatment consisting in subtracting the constant voltage U from it. equal to the product of the slope of the transformation during demodulation and the magnitude of the carrier frequency, in dividing the received signal by the demodulated signal of the carrier frequency Vo and multiplying by the distorted information signal

N 9 () o

where l i is the useful deviation of the carrier frequency.

When the information compensation signal is subsequently subtracted from the information signal, the signal is received without distortion

). Oh ..,. )

The following drawing shows a block-cf: em of the proposed device for distortion compensation when playing signals from a magnetic carrier.

Frequency modulator 1 and carrier frequency generator 2 are connected via their outputs to the corresponding inputs of recording unit 3.

The playback unit 4 with one of its outputs is connected to the input of the first demodulator 5, which is connected by its output to the first input of the first subtraction unit 6, and its second output to the input of the second demodulator 7.

The second subtraction unit 8 with its first input is connected to the constant voltage source 9, and the second input to the output of the second demodulator 7 and to the first input of the division unit 10. The output of the second subtraction unit 8 is connected to the second input of the division unit 10 connected to the first input of the multiplication unit 11 by its output. The second input of the multiplication unit 11

connected to the first input of the first block S subtraction, and i output - to the second input of the last,

In recording mode, the information signal is converted by frequency modulator 1 into FM oscillation. These oscillations and the carrier signal produced by the carrier frequency generator 2 are recorded on a magnetic carrier by means of a recording unit 3.

In the playback mode, the signals recorded on the magnetic media are reproduced using the playback unit 4, the FM oscillation is demodulated with the first demodulator 5, the output of which has a distorted information signal. The carrier signal is demodulated by a second demodulator 7, from which output a distorted demodulated carrier signal is received. In the subtraction unit 8, the constant voltage produced by the constant voltage source 9 and equal to the product of the demodulator slope and the carrier frequency is subtracted from this signal.

The output signal of subtraction unit 8 in subunit unit 10 is divided into a demodulated carrier signal from the output of demodulator 7.

 The signal coming from the output of the division unit 10 in multiplication unit 11 is multiplied by the signal from the output of demodulator 5. In subtraction unit 6, the output signal of multiplication unit 11, which is the compensation signal, is subtracted from the output signal of demodulator 5.

From the output of block 6 subtraction, an information signal is received that has no distortions ...

When using the device, the distortion of the information signal caused by instability of the speed of the carrier movement is eliminated.

The use of the device reduces the quality requirements of the tape transport mechanisms (MTL) due to the instability of the speed of movement of the magnetic carrier, and, as a result, simplifies the technical solutions in terms of the MTL kinematic scheme | provides the possibility of using small-sized MTL operating at low speeds of carrier movement; contributes to the creation of more technical equipment,

Claims (2)

1.Aksenov V, A, Vicz A „I. Exact magnetic recording of JM ,, Energie, 1973. 2. Davis P L. Application of accurate magnetic recording. M., Energie, 1967 (prototype) with