SU732984A1 - Adaptive correcting device for recording digital data on magnetic carrier - Google Patents

Description

The invention relates to devices for recording digital information using a multilevel code on a magnetic medium, and can be used in any field of radio engineering where digital magnetic recording devices _{5 are} used.

A device is known that uses the conversion of binary to multilevel [1]. The disadvantage of this device is that it does not use distortion correction. Yu

The closest in technical essence to the invention is an adaptive corrective device for recording digital information on a magnetic medium, containing a binary information source connected in series, a binary information converter ¹⁵ into a multilevel code, a frequency modulator, FM recording head [2].

The disadvantage of this device is the presence of distortion of a multi-level signal, leading to a decrease in the reliability of information transfer. This is due to the fact that transients arising in the recording-reproduction channel lead to the occurrence of intersymbol interference, which causes the presence of distortions in the multilevel signal.

The aim of the invention is to reduce the level of distortion and reducing the required frequency band of the recording / reproducing path.

The goal is achieved in that the device additionally includes a first low-pass filter, a differential amplifier, an adder, a gating circuit and a second low-pass filter, connected between the output of the binary information converter into a multi-level code and the input of the frequency modulator and connected in series, as well as a sampling-storage circuit , the input of which is connected to the output of the binary information converter into a multilevel code, the first output is connected to one of the inputs of the differential amplifier, and the second output to one ohm from the inputs of the adder.

In FIG. 1 shows a functional diagram of a device; in FIG. 2 - timing charts.

The device consists of a source of binary information, a converter 2 of binary information into a multi-level code, a first low-pass filter (LPF1) - an analog of a pass-through channel for recording and reproducing 3, a sampling circuit for storage 4, a differential amplifier 5, an adder 6, a reset circuit 7, a second filter low frequencies - LPF2 8, FM 9, recording heads 10, playback heads 11, frequency demodulator 12 and the converter 13 of the multi-level signal to binary code.

Formed from the input binary stream (Fig. 2, a) a multi-level signal (Fig. 26) is fed to the input of the low-pass filter 1 and to the input of the sampling-storage circuit, the inclusion of which allows you to compensate for the time delay introduced by the path. Since the low-pass filter is an analogue of the recording-playback channel, the signal at its output will be as if it had passed through the path (Fig. 2, c). This signal is fed to one of the inputs of the differential amplifier, and the signal from the output of the sampling-storage circuit is received at its other input (Fig. 2d). The selected error signal (Fig. 2/3), together with the signal from the sampling-storage circuit, is supplied to the adder. From the output of the adder, the signal (Fig. 2, g) is fed to the gating circuit, the output of which is a multilevel signal with predistortions (Fig. 2, g). The signal thus formed is fed to the input of the low-pass filter 2 and then to the FM channel for recording-reproduction. On (Fig. 2, h) presents the signal at the input of the Converter multilevel signal in binary code.

The degree of compensation of intersymbol distortions depends on how accurately the amplitude-frequency and phase-frequency characteristics (Ά4Χ and phase response) of the low-pass filter 1 correspond to the frequency response and phase response of the recording-playback path.

The device, on the one hand, compensates for signal distortion due to intersymbol interference and thereby improves the accuracy of the recording-playback process, and on the other hand, using narrow-band filters, reduces the required frequency band of the path and thereby increases the recording density with the same reliability.

Claims (2)

Noi information in a multilevel code, the first low-pass filter (LPF1) - analogue of the through-channel recording-playback 3, storage sampling circuit 4, differential amplifier 5, adder 6, dropping circuit 7, second low-pass filter - LPF2 8, FM 9, heads records 10, reproduction heads 11, frequency demodulator 12 and multilevel signal converter 13 to binary code. The multilevel signal formed from the input binary stream (Fig. 2, a) (Fig. 26) is fed to the input of LPF1 and to the input of the sample-storage scheme, the inclusion of which allows to compensate for the time delay introduced by the path. Since LPF1 is an analogue of the recording-playback channel, the signal at its output will be as if it passed through the path (Fig. 2, c). This signal goes to one of the inputs of the differential amplifier, and to the other its input comes a signal from the output of the sample-hold circuit (Fig. 2, d). The extracted error signal (Fig. 2/3) along with the signal from the sample-storage scheme is fed to the adder. From the output of the adder, a signal (Fig. 2) is fed to a gating circuit, at the output of which a multi-level signal with predistortion is obtained (Fig. 2, g). The signal thus generated is fed to the input of LPF2 and further to the FM recording-reproduction channel. In (Fig. 2, e) a signal is presented at the input of a multilevel signal to binary converter. The degree of compensation of intersymbol distortions depends on how accurately the amplitude-frequency and phase-frequency characteristics (frequency response and frequency response) of the low-pass filter 1 COOT corresponds to the frequency response and frequency response of the recording-reproduction path. On the one hand, the device compensates for signal distortion due to intersymbol interference and thereby increases the accuracy of the recording-reproduction process, and on the other hand, using narrow-band filters, reduces the required path bandwidth and thereby increases the recording density with the same accuracy. An adaptive correction device for recording digital information on magnetic media containing a binary source connected in series, a binary information converter into a multilevel code, a frequency modulator, a recording head, characterized in that in order to reduce distortion and reduce the required path bandwidth record-play, the device additionally introduces the first low-pass filter, a differential amplifier, an adder, a sampling circuit to the second phi The low frequencies connected between the output of the binary information converter to the multilevel code and the input of the Frequency Modulator and connected in series, as well as the sampling-storage circuit whose input is connected to the output of the binary information converter to the multilevel code, the first output is connected to one of the inputs of the differential amplifier, and the second output is to one of the inputs of the adder. Sources of information taken into account in the examination 1. US patent number 3754237, cl. H 04 to 13/24, published. 1976. 2. USSR Author's Certificate NO 610162, cl. C 11 V 5/09, 1976 (prototype). (rig. 1 a .. i i i. . . I. one . . I i. . .LI S ru D zhP P t / L / vy ig.2