SU1113843A1 - Device for forming synchronizing pulses when reproducing multirack record - Google Patents

Abstract

DEVICE FORMING synchronization pulse when playing multi-track recording, comprising an input bus reproduced signal coupled to the input of the demodulator in the channel reproduction, the pulse generator and controlled by the counter, the output of which is connected to the output line synchronizing pulses and the first input unit generating an error signal, a second input which is connected to the output of the pulse generator, as well as the control unit of the presence of the reproduced signal, which differs. e so that, in order to reduce the error in the generation of synchronization pulses when the reproduced signals fall out, a channel selector with synchronization inputs and n control inputs connected respectively to the outputs of the error signal shaping and to the outputs of the monitoring unit of the presence of the reproduced signal of each channel, and the output connected to the input of the controlled counter, the output of the latter is connected to the S input of the monitoring unit Alice Sun (A produced signal, third input coupled to an output of the demodulator and the additional third input signal generating unit mismatch, wherein the additional paraphase pulse generator output is connected to an additional fourth input signal generating unit mismatch in each channel reproduction. CAD 00 4 00

Description

The invention relates to magnetic recording, in particular, to devices for generating synchronization pulses during reproduction of digital multi-track recording from magnetic media.

A device for generating synchronization pulses during reproduction from a magnetic recording medium is known, which comprises a phase detector which, with its output signals, converted into voltage, controls the frequency of the pulse generator l

The disadvantage of this device is low accuracy and reliability of operation, due to the low stability of the level of the regulating voltage at the outputs of the duration-to-amplitude converters and the dependence of this voltage on random factors (medium temperature, instability of the power source and)

It is also known to use a production device comprising a reproduced signal input bus which, through a demodulator and a deviation signal generating unit using a control element, acts on a controlled counter connected to a pulse generator 2

A disadvantage of this device is a significant error in the formation of synchronization pulses, due to the fact that in cases of lost reproducible signal, a pulse arrives at the input of the controlled divider, the instants of which are random, as determined by tra noises (the demodule threshold and limiting torus, and do not correspond to the true position of the reproduced signal.

The closest in technical sense to the present invention is a device for generating synchronization pulses during reproduction from a magnetic recording medium, containing an input reproducing bus of the signal connected to the input of the demodulator, a pulse generator, the output of the KOTopoio connected to the first input of the error signal generating unit and the input a controlled counter connected by an output to the output bus of synchronization pulses. The device also contains amplitude discriminators, the outputs of which are connected via an OR element to the first trigger and element inputs, and a digital signal installation unit connected in series and a switching unit, whose inputs are connected to the outputs of the error signal and trigger generating unit, and the outputs to controlled ones the counter, while the output of the demodulator is connected through the delay unit with the second input of the trigger

and with the second input element I, whose terminal is connected to a controllable counter connected to the output signal with the second input of the error signal generation unit 3.

In this device, the frequency of the synchronization pulses is equal to their frequency before the beginning of the fallout, however, the formation of synchronization pulses during the depositions is performed without taking into account changes in the speed of the carrier, which leads to a decrease in the fidelity of information reproduction. In addition, most digital magnetic recording devices use the multichannel recording principle.

The purpose of the invention is to reduce the error in the formation of synchronization pulses when a reproduced signal falls out,

The unallocated goal is achieved by the fact that in a synchronization pulse shaping device during playback of a multi-track recording, containing an input bus of the reproduced signal, connected to the input of the demodulator in the playback channel, a pulse generator, and a controlled counter, the output of KOTopoiO is connected to the output BUS of synchronization pulses and with the first input of the error signal generation unit, the second input of which is connected to the output of the pulse generator, as well as 6; J1k to the presence of the reproducing signal, in Each of the identical playback channels additionally introduces a channel selection block with I synchronization inputs and n control inputs connected respectively to the outputs of the error signal generation units and to the outputs of the control units for the presence of the reproduced signal of the channel and the output of the controlled counter connected to the input of the control unit for the presence of a playback signal, the auxiliary input of which is connected to the output of the demodulator and to the additional third input of the control unit beacon signal generating mismatch, the additional paraphase pulse generator output is connected to an additional input of a fourth signal generating unit mismatch in each channel reproduction,

Such a change in the structural scheme in the cases of the reproduction of the reproduced signal in the -th channel ensures that the phase ratio of the synchronization pulses and the reproduced signal that took place at the beginning of the fallout is preserved in this channel, and this ratio is preserved during the attack as well. at the same time, it does not remain postsc, but corresponds to all changes in the velocity of the carrier. This is due to the fact that the channel selection block determines the closest channel in which there is no fallout, and the use of the signals of the error block of this channel to control the operation of the ith counter. Since the changes in carrier speed are identical for all channels, the (th channel excludes synchronization error and, therefore, increases the noise immunity of the device as a whole. Figure 1 shows the block diagram of the device; Fig. 2 shows an example implementation of the channel selection block; 3 - time diagrams of operation. The device (Fig.) Contains h identical channels, in each of which between the input bus 1 of the reproduced signal and the output bus 2 of the synchronization pulses, the demodulator 3 is sequentially switched on, forming unit 4 the error signal, the channel selection block 5 and the controlled counter 6, the output of which is connected to the first input of block 4 and to one input of the control block 7 for the presence of a reproduced signal, the other input of which is connected to the output of demodulator 3. In addition, || The synchronization and i inputs of the control unit 5 are connected respectively to the outputs of blocks 4 and blocks 7 in 1 channels, and the synchronization inputs of blocks 4 of all channels are connected to the paraphase outputs of the generator 8 pulses. Channel selection block 5 (for three-channel version) contains (FIG three elements AND (for 2,3 and 4 inputs), two inverters and one OR element (for three inputs.). The device works as follows. Pulses from the output of the demodulator ( Fig. 3, plots b, e) and synchronization pulses from bus 2 arrive at the inputs of block 4, which, depending on the phase relationship of these pulses, generates control signals that allow or prohibit the passage of reference frequency signals from the paraphase outputs of the generator 8. Consider the operation of the device in moments of action The signal in the first channel (Fig. 3, plots a, c) from the time t ,, noi is affected) falls out, and the signal in the -th channel due to a static skew lags behind the recorded time i. i, where the clock interval. On epy1X1X g (Fig. 3) shows the impulses siihrs-, nizatsiya, i.e. the output signals of the counters 6, and the arrows in azano indicate the direction of the correction of the flux: synchronization pulses, which is carried out according to the signals of block 4 in each channel. The sync pulses of all channels are maintained in such a way that the beginning of the transition to the unit state of the last bit of counter 6 strictly corresponds to the middle of the symbol of the reproduced information. At time I, block 7 of the first channel generates a signal (Fig. 3, plot g), according to which the generator 8 pulses with correction of its channel block 4 stop transmitting to the input of the controlled counter 6 of this channel and the frequency pulses with correction of block 4 begin to arrive i -th channel. The selection of the -th channel is performed by block 5 of the first channel according to the algorithm given in the table (Fig. 2). The table contains a list of input signals to the control inputs of block 5 of the first channel, and the channel number from which synchronization signals from block 4 are selected for this combination of signals. The zero value of the output signal from block 7 corresponds to the case of dropout. For example, a combination of 011 (the first channel is affected, the second and third are serviceable) corresponds to the selection of synchronization signals arriving at the input of counter 6 of the first channel from block 4 of the second channel. As can be seen from the table, synchronization failure will occur only if all three channels are simultaneously affected, which is unlikely. According to FIG. 3, during the fallout, there will be four corrections (to the left) of the phases of the synchronization pulses at the output of the first channel counter 6 according to the signals of the 4th i channel, which in turn strictly correspond to changes in carrier speed. The amount of skew between the 1st and Ith channels is irrelevant, since it does not participate in the formation of correction signals. Thus, during time t, - 1, the synchronization pulses of the first channel, despite the fallout action, do not deviate from the middle of the reproduced signal, following all variations in carrier speed. Thus, the position error of the synchronization pulses relative to the edges of the reproduced signal is eliminated, which reduces the likelihood erroneous reproduction of information. S I lilllllil tf- - (paz.3 fig. 2 l ..,.,. F b .....,. Iffllll Unili i 1L

Claims (1)

> DEVICE FORMING SYNCHRONIZATION PULSES OF PLAYBACK PLAYLINE RECORDING, containing the input bus of the reproduced signal connected to the input of the demodulator in the playback channel, a pulse generator and a controlled counter, the output of which is connected to the output bus of the synchronization pulses and with the first input of the signal generating unit connected to the output of the pulse generator, as well as the control unit for the presence of the reproduced signal, characterized in that, in order to reduce errors in the generation of synchronization pulses during the occurrence of reproducible signals, a channel selection block with n synchronization inputs and η control inputs connected respectively to the outputs of the mismatch signal generating blocks and to the outputs of the control blocks for the presence of the reproduced signal of each channel is additionally introduced into each of η identical playback channels, and output connected to the input of the controlled counter ·, the output of the latter is connected to the input of the control unit for the presence of the reproduced signal the body input of which is connected to the output of the demodulator and to the additional third input of the mismatch signal generating unit, while the additional paraphase output of the pulse generator is connected to the additional fourth input of the mismatch signal generating unit in each playback channel