SU974406A1 - Digital data magnetic recording method - Google Patents

Description

one

The invention relates to instrumentation, in particular, to recording and reproducing digital information on a movable magnetic carrier.

A modified, 1st recording method without returning to zero (BVNM) is known, according to which the recording of a digital information signal, represented as a successive binary code, is produced by forming a single-channel switching signal for each recording unit C1.

However, this method is characterized by a lack of density due to the fact that the minimum reproduction signal period carries 2 bits of the original information. In addition, there is no possibility of self-synchronization of the playback signal.

The purpose of the invention is to increase the recording density and ensure self-synchronization during playback.

The goal is achieved by the fact that, according to the method of magnetic recording of digital information represented by a serial zvoychikny code from the P-bit groups, which consists in forming a recording signal in the form of a switch sequence when recording units of information, recording a continuous sequence of units, starting from the second, produces two-time

by switching the recording signal in the information cycle, and after each n-bit group is recorded, an additional two-bit group is written from zero to the information units.

15

Claims (1)

To implement the proposed method, a known recording device having a serial code input, a trigger generating a recording signal, a recording signal amplifier with a recording head connected to its output head additionally input a sync pulse input, a delay element, a two-bit shift register, two circuits And and the OR circuit. At the same time, the input of the serial code is connected to the input of the shift register, and the input of the synchronization pulse pulses yy with the control register of this register, the input of one of the circuits AND the input element rzhki The first bit of the shift register is connected to the inputs of both AND circuits, the output of the second register bit is connected to the third input of the first circuit I. The output of the delay element is connected to the second input of the second circuit I. The outputs of the AND circuit are connected to the inputs of the OR circuit, the output of which is connected with a counting trigger input. FIG. 1 shows charts of recording and replaying signals; in fig. 2 is a functional diagram of the device that implements the method. FIG. 1 is indicated: a is the sequential code of the recorded information; b - recording signal; in - reproduced .signal; d - corrected: and formed two-pole signal; d - single signal; e - reproduced code. A device for implementing the proposed method (Fig. 2) contains the input of a sequential code of the recorded information 1, the input of clock pulses 2, a two-bit shift register, 3, an element of delay 4, circuit AND 5 and 6, circuit OR 7, trigger 8, amplifier captions 9, recording head 10. In digital magnetic recording, the upper cutoff frequency of the recording-reproduction channel is determined mainly by the path band, reproduction, including a carrier-head pair. When the recording signal is often switched beyond the upper limit of the reproduction path band, distortions arise, which are determined by the degree of overlap of the signals reproduced in each switch of the carrier magnetization. In the case when the switching frequency of the recording signal is several times higher than the upper limit of the reproduction path band, there is such a significant overlap of individual signals that the total reproduction signal remains practically unchanged, but transmits the phase of reversal of the first and after units. The frequency of remaking carriers when recording individual units surrounded by zeroes (a signal of the type ... 010 ...) is chosen equal to the frequency of the upper boundary of the reproduction path band. As a result. overlap AND the associated distortions in the reproduced signal are not observed (Fig. 1, diagrams a, b and c). At the same time, when recording a continuous sequence of units, the switching frequency of the carrier magnetization increases four times and a significant overlap of the reproduced signals occurs. In addition, when recording any continuous sequence of units, the number of switching of the carrier magnetization is always odd, i.e. The first and last switchings will be in antiphase (Fig. 1 diagrams a and b). Thus, the reproduced signal changes its polarity only when recording individual units surrounded by zeroes, and when recording the first and last units in their continuous sequence (Fig. 1, diagram c). After the necessary correction and shaping, the reproduced signal takes the form of a two-pole signal shown in diagram d (Fig. 1). From this signal, a monopolar signal is first formed and then the code sequence of the reproduced information is extracted (Fig. 1, diagrams e and f). To ensure self-synchronization, the SI1 of the playback in the sequential code of the recorded information periodically includes a two-bit combination of type 01 or 10. As a result, when writing long sequences of ones or zeros, they break with the change of the symbol, which leads to a change in the phase of the reproduced signal and allows you to maintain self-synchronization. The operation of the device that implements the proposed recording method occurs in the following sequence. The sequential code of the recorded information (FIG. 1, diagram a) with a bit following frequency of 2f is fed to the input 1 of the recorder. At the other input of the device 2, the synphonizing pulses are received, accompanying each bit of the received code. From the input of device 1, the serial code enters the two-phase shift register 3 and records there using clock pulses. The outputs of the shift register are connected to the inputs of two circuits, And 5 and 6, to the other inputs of which are also received 66 7 Delayed and non-5,974 delayed clock pulses. The delay of the sync pulses for half a period of their following is produced by the delay element 4. At the output of the circuit 5, a signal is generated at the end of each clock cycle in which it is transmitted with the code one. At the output of circuit 6, a signal is formed in the middle of a clock only in cases where the code one is transmitted in the current and previous clock, i.e. The signal at the output of circuit AND 6 is formed during the passage of a continuous sequence of units, starting with the second. The signals from the outputs of the AND 5 and 6 circuits are combined in the OR circuit 7 and from its output go to the counting input of the trigger 8. Records are formed at the trigger output (Fig. 1, diagram b), which, after the necessary amplification in the recording amplifier 9, goes to head & ku 10 entries. Thus, switching the recording signal while posting on the recording of single units; surrounded by a signal, occurs at a frequency not exceeding the frequency f, and when recording a continuous sequence of units, switching of the recording signal within the period of the passage of this sequence occurs at a frequency of 4f. As a result, the reproduced signal changes its polarity only when recording individual units, as well as at the end and beginning of a continuous sequence of units (Fig. 1, diagram c). After the necessary correction of the existing distortions and the formation of the reproduced signal, it takes the form of a two polar signal, shown in the diagram of the year (Fig. 1). From this signal, a unipolar signal is formed (Fig. 1, diagram e) and a code sequence of the reproduced information is made. Periodic inclusion of a two-bit O1 or Y code sequence in the recorded information provides, regularly or alternately, the signal when recording a sequence of 4 units, or the appearance of a pulse of one or another polarity when filled with zeroes, which maintains the synchronization mode . The proposed method allows to increase the recording density of digital information in comparison with the BNHM method twice due to the greater information capacity of the playback signal (4 bits of information for the minimum period of the playback signal in comparison with the 2 bits of the BNHM method). Periodic inclusion in the sequential code of the recorded anformation of the code group 01 or 1O ensures self-synchronization and maintains a rather high efficiency of the recording density. Thus, when recording a two-bit group, every six bits of the information being filled in, the effective recording density will be 3 bits for a minimum period, which is significantly more than in the BNM method. The formula of the invention of the method of magnetic recording of digital information represented by a serial binary code of n-bit groups, which consists in forming a recording signal in the form of a sequence of switchings when recording units of information, is different in order to increase the recording density and ensuring self-synchronization during playback, recording a continuous sequence of units, starting from the second, is performed by two times switching the recording signal in the information cycle, and after recording each An n-bit group is made to record an additional two-bit group of zero and information units. Sources of information are taken into account in the examination 1. V. Ryzhkov and others. External storage devices in a magical carrier. M., Energie, 1978, p. 98 (prototype). b D about D P R . P B P About 20 / X to TC 9 Tir 8 F 7G 7 G 6 zr A a a a