SU1049961A1 - Device for recording/reproducing digital data signals - Google Patents

Abstract

A DEVICE FOR RECORDING-PLAYING OF DIGITAL INFORMATION SIGNALS, containing serially connected digital code converter into a sinusoidal signal and a matching amplifier connected to the input of the tape recorder, as well as coding and decoding units, different in that, in order to increase the recording density, introduced into it, in order to improve the recording density, introduced into the tape recorder, characterized by the fact that, in order to increase the recording density, it was inserted into the tape recorder that it was inserted into the tape recorder to decode the decoding, in order to increase the recording density, introduced in order to increase the recording density. filter, multiplexer, binary to multilevel converter, clock and sync pulse generator, reference voltage source, isolating amplifier, detection extreme values, a multilevel code to binary converter, a demultiplexer, and a control voltage generating unit; the two inputs of the device are connected via corresponding filters to the multiplexer inputs, the output of which is connected via serially connected coding block and binary code to multilevel converter code into a sinusoidal signal, the first, second, third, fourth and fifth outputs of the clock generator and sync impulses The pulses are connected respectively to the additional control inputs of the matching amplifier, the digital code converter into a sinusoidal signal, the coding unit, to the first control input input of the binary to multilevel converter, (the second control input of which is connected to the output of the source of the reference voltage, and the output of the tape recorder is connected to the input of an isolating amplifier, the first output of which is connected to the input of the control voltage generating unit, the second through serially connected the extremal value detector, the multilevel code to binary converter, and the decoding unit with a demultiplexer input, whose outputs are connected to other inputs of the corresponding filters, and the first, second, third, and fourth outputs of the control voltage generator unit are connected respectively to the control inputs of the extreme values detector , a multilevel code to binary converter, a demultiplexer, and with an additional control input of a decoding unit.

Description

The invention relates to instrumentation, namely, devices for magnetic recording and reproducing information, and can be used in correlation measurements, as well as in noise compensation devices. It is known a multichannel recording device where in each channel information is recorded on a separate track. This device provides for the conversion of binary information into a sequence of pulses having three levels l. The drawbacks of the device are low recording density, as well as the need to use a special multi-channel tape recorder. Also known is a device that, using a multi-level code, allows to increase the recording density several times, and contains a source of digital information, a binary code converter to a multi-level frequency modulator, a recording head, a magnetic recording medium, a reproducing head, a frequency demodulator, a multilevel code-to-binary code converter, and a digital info receiver mation 2J. However, in this device, information loss is possible when converting a multilevel code to binary due to the effect on subsequent characters of the multilevel code of intersymbol distortion. The basic object is a device containing a source of digital information, a binary-to-multi-level converter, a multi-level code converter to a signal satisfying the selectivity condition, a frequency modulator, a recording head, a magnetic recording medium, a reproducing head, a frequency demodulator, a driver binary code and receiver of digital information. This device is implemented to minimize intersymbol distortion when converting multilevel code 3j. A disadvantage of multi-level code-recording recorders using frequency modulation is the inability to use household tape recorders with them, since household tape recorders do not satisfy the detonation requirements imposed on such devices, and the use of special tape recorders in these devices to their significant appreciation. Closest to the invention, the technical essence is a device for recording and reproducing information on a household tape recorder, containing a serially connected encoder, a converter of digital signals into sinusoidal and a matching amplifier, the output of which is connected to the input amplifier of a household tape recorder. In this case, a series-connected amplifier with an instantaneous automatic gain control and a sinusoidal-to-digital converter are connected between the output of the tape recorder and the input of the decoder. The drawback of the device is a low recording density, which is due to the fact that when recording a binary code, the amplitude differences of the code elements are not used, since the amplitudes of the zero and one bits of the code are the same, but they differ in the filling phase. Therefore, the recording density is determined only by the band of the recorded frequencies of the tape recorder, which sets the minimum length of the binary code element and cannot be high. The purpose of the invention is to increase the recording density. The goal is achieved by the fact that a matching amplifier connected to the input of the tape recorder, as well as encoding and decoding units, are entered into a device for recording and reproducing digital information signals containing a serially connected sine-wave converter. two filters, multiplexer, binary to multilevel converter, clock and sync pulse generator, reference voltage source, - separation an amplifier, an extremal value detector, a multilevel code to binary converter, a demultiplexer, and a control voltage generating unit, with two. device inputs are connected through the corresponding filters to the multiplexer inputs, the output of which is transformed through the serially connected coking unit and the binary to multi-level converter. The digital code bodies into a siiusoidal signal, the first, second, third, fourth and fifth outputs of the clock and sync generator are connected, respectively, to the additional control inputs of the matching amplifier, a digital code converter into a sinusoidal signal, a coding unit, to the first control input a binary-to-multi-level converter, the second control input of which is connected to the output of the reference voltage source, and the output of the tape recorder is connected to the input of the coupling amplifier, the first, the output of which is connected to the input of the control voltage shaping unit, secondly through the serially connected extreme value detector, the multi-level code to binary converter and the decoding unit with the input of the demultiplexer, whose outputs are connected to other inputs of the corresponding filters, and the first, second, the third and fourth outputs of the block (the control voltage shaping is connected to the control inputs of the extreme values detector of the multilevel code converter, respectively in binary, demultiplexer and with an additional control input to the decoding unit. FIG. 1 shows a block diagram of a device for recording-playing digital information signals; in fig. 2 - voltage plots at the outputs of the main units of the device during recording; in fig. 3 is the same when playing. The device contains, at the inputs, first and second filters -1 and 2, respectively, whose outputs are connected to the corresponding signal inputs of multiplexer 3. The output of multiplexer 3 is via serially connected coding unit 4, binary to multilevel converter 5, digital code to sinusoidal converter 6 and matching the amplifier 7 is connected to the input of the tape recorder 8. The output of the tape recorder 8 is connected to the care of a separate amplifier 9, the first output of which is connected to the input of the unit 10 to form the control The second output of amplifier 9 is connected to the input of a gated detector 11 of extreme values. The output of the detector 11 is connected to the signal input of the converter 12 multi-level code in binary. The output of the converter 12 is connected to the input of a decoding unit 13 connected to the information input of the demultiplexer 1, whose outputs are connected to the first inputs of the corresponding filters 1 and 2. The generator 15 of clock and clock pulses is connected to the control inputs of the multiplexer 3, coding unit k, converter 5 converter 6 and the matching amplifier:. The source 16 of the reference voltage is connected to the second control input of the converter 5. The block 10 is connected to the control inputs of the gated detector 11, the converter 12, the decoding unit 13 and. the demultiplexer 1 A. The second inputs of filters 1 and 2 are the inputs of the device, and the outputs are the outputs of the device. The number of possible levels in a multi-level code is determined by the signal-to-noise ratio of the pass-through recording-reproduction path. 3 of the considered device version, the binary code is converted into an eight-level one. The generator 15 is designed to form a clock pulse sequences P and Flj with a period T, shifted relative to each other (plot 1 and 2, Fig. 2) synchronizing voltage with a period T; j (plot 13, Fig. 2), synchronizing sequence of pulses Pz with a period. where n is the number of elements of the multilevel code (in diagrams 2 and 3, the period Id is equal to the duration of three elements of the binary code) and the sequence of rectangular pulses of the DD with a period of 1 "/ t, where, 2,3, .... k (in the diagram 10, Fig. 2). Source 16 is designed to form a constant reference voltage equal in a particular case to eight levels of a multilevel code. Block 10 is designed to form a pulse sequence P with a follow-up period ip and with a pulse duration of 2 "to (plot 3 of Fig. 3) from the synchronizing voltage (plot 2, fig. 3). The device can be implemented, for example, when using a household Tape-2 type tape recorder. The device works as follows. The analog signals of the first and second information channels are fed to the second inputs of filters 1 and 2, respectively. Filters 1 and 2 limit the spectrum of recorded frequencies. Multiplexer 3 at the time of arrival of the clock pulses of the sequence P from generator 15 (plot 1, Fig. 2) provides simultaneous separation of the sample and memorization of samples of analog signals coming from filters 1 and 2 (plots 3 and. Fig. 2). Then the pulp collector 3 compresses the two-channel signal: when the clock pulse arrives from the generator 15, the sequence fl / t (epor 1, fig multiplexer 3 generates a signal at the output that is proportional to the signal sampling from filter 1, and when received from the generator 15 clock pulse P (plot 2, fig. 2) multiplexer 3 generates a signal at the output proportional to the sampling of the signal from filter 2 The voltage at the output of multiplexer 3 is shown in figure 2 plot 5. On plot 6, the same voltage is presented in a different way. The belt scale for one period J of the sequence P. The coding block i, when each clock pulse of the sequences P4, P (plots 1 and 2, Fig. 2) arrives from generator 15, transforms the signal with a temporal compaction (plot 6, fig 2) to a binary digital code (plot 7, fig. 2). Convert 5 when the impulses of the sequence P are received from the generator 15 convert the binary digital code (plot 7, fig. 2) to the eight-level (plot E, Fig. 2) to expand the dynamic range during recording. In addition, each element of the eight-level code has a duration of about equal to the duration of the three elements of the binary code. The total number of elements of the eight-level Code P, | 2 (,. In this case, one element to-9 ka) is used for transmitting a constant reference voltage from a source 16 corresponding to eight code levels (shaded element on plot 8, FIG. 2), the remaining elements of the code level code are for transmission. chi information signal. In the specific case of T | 1000 µs, the duration of each element Co-TJ n 125 MKS, One element is assigned to create a reference level, and three elements - to transmit a multi-level code. For nine-bit binary code of a signal, when combining three bits, it is necessary to transmit each of the eight possible combinations to the corresponding levels of the eight-level code. Combinations 000 correspond to one level, 001 - two levels, ..., 111 eight levels. Then, for example, the binary number 101010111 is transmitted by six, three and eight levels, respectively. In this case, the higher bits of the binary code correspond to the higher bits of the eight-level code. A reference signal corresponding to eight levels is necessary to determine the number of levels in each information element of an eight-level code during playback. The shifted eight-level code (plot 9, fig. 2) from the output of converter 5 is fed to the signal input of converter 6. The control input of converter 6 of generator 15 receives a sequence of square pulses P4 with period 2 (j (plot 10, Fig. 2 The converter 6 generates an amplitude-phase-manipulated signal (plot 11, fig. 2) by multiplying the signals supplied to its signal and control inputs (plots 9 and 10, fig. 2). A low-pass filter (not shown) mounted on the output of a 6-form converter It emits a sinusoidal amplitude-phase-manipulated signal (plot 12, fig. 2), in which each bit of an eight-level digital code corresponds to a certain amplitude and phase of the sinusoidal voltage. At the same time, positive levels of the shifted multi-level code (plot 9, Fig. 2) are transmitted phase O filling, and negative

 . Such amplitude-phase (balanced) modulation allows approximately a twofold increase in the amplitude of the unit level compared with the usual amplitude modulation with voltage (plot 8, Fig. 2). unbiased multilevel code of the sequence of the front (plot 10,. ig. 2). Sinusoidal amplitude -. The azo-manipulated signal is supplied to the signal input of the matching amplifier 7. The control input of the matching amplifier 7 is supplied with the synchronization voltage from the generator 15 with a frequency (plot 13, Fig. 2). The matching amplifier 7 performs the summation of the voltages supplied to its signal and control inputs, ensures the matching of the parameters of the converter 6 and the recording amplifier of the tape recorder 8 (matching of signal levels, dynamic ranges, noise levels, etc.). The tape recorder 8 records on a single track of a universal magnetic tape divided by the band occupied frequencies of a sinusoidal amplitude-phase-manipulated signal (plot 12, fig. 2) and synchronization voltage (plot 13, fig. 2). From the linear output of the tape recorder 8, the sum signal is fed to the separation amplifier 9, which performs the separation of the information signal and the synchronization signal using filters. Block 10 of the synchronization signal (plot 2, Fig. 3) generates a pulse sequence: P4 (plot 3, Fig. 3) which provides for the demodulation of the information signal. The information signal, which is a sinusoidal amplitude-phase-manipulated si-nal (plot 1, fig. 3) from the second output of the coupling amplifier 9, is fed to the signal input of the extremum detector 11. With the help of a pulse sequence P4 of block 10 (plot, 3, fig. 3), it is detected by the extremum of a sinusoidal amplitude-phase-manipulated signal (plot i, fig. 3) at the end of each element of the eight-level code; (In this case, the transient from the previous (its code element ends. When each pulse of the P4 sequence arrives from the block

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10 (plot 3, fig. 3), detector 11 opens at the instants preceding the corresponding extremes of sinusoidal amplitude-phase 5 voltage of a nipulated voltage (ztora 1, fig o 3). The gated detector 11 forms a sequence of positive (plot k, Fig. 3) and negative (plot 5, Fig. 3) pulses.

10 Then these sequences are added, and the eight-level digital code is restored (plot 6 and 7 of Ig. 3). Transducer 12 uses a sync voltage from block 10 (plot 2, fig. 3) from the eight-level code (plot 6, fig. 3) to select the element with the reference signal. The amplitude of the reference signal, containing four

Level 20, stacked with a multilevel signal (plot 6, fig. 3), a signal is formed (epor 7, fig. 3) corresponding to the original multilevel signal

5 when recording (plot 8, fig. 2), then the converter 12 converts a multilevel (eight-ary-day) code into a binary by comparing the amplitudes of the information

30 code elements with the amplitude of the reference signal. As within each sequence of elements (in the case of a case) a multi-level code, demodulation of each information

35 of the element J; l ect with the help of its own reference signal, the level fluctuations in the process of recording-reproduction affect the same as the reference signal and the information

 items. This is equivalent to the action of instantaneous automatic gain control (MARA) with a constant time of the order of T, / 2, which allows maintaining high confidence

 reproduction of information. Direct use of MARU in multilevel code is impossible, since it will lead to alignment of amplitudes of multilevel code.

50 and, as a result, to errors in its g demodulation. The decoding unit 13, when a pulse sequence arrives at its control input from block 10, corresponding to zero-crossing synchronization steps (plot 2, Fig. 3), converts binary code combinations to an analog-discrete signal (plot 9, FIG 3), and the demultiplexer 1, using the same pulse sequence, extracts from the analog-discrete signal compacted in time (plot 9, fig. 3), voltages of the first and second channels (plots 10 and 11, fig. 3). Then the demultiplexer 1 reads these voltages at coincident times (plots 12 and 13, Fig. 3). The voltage of the first channel from the output of the demultiplexer 1 is fed to the input of filter 2, and the voltage of the second channel to the input of filter 1. The output of filter 2 is the output of the first channel of the device, and the output of filter 1 is the output of the second channel. Since the signal of the first information channel in the process of recording and reproduction passes through the filters 1 and 2, and the signal of the second information channel through the filters 2 and 1, the frequency distortions of the signals of the first and second information channels are identical. Since a household tape recorder has a predetermined recording frequency band and, consequently, a predetermined shortest recording element duration, the transition to the eight level code with a constant minimum recording element length makes it possible to reduce the binary element duration by 3 times. This provides an increase in the frequency band of the recorded signal by as many times, i.e. makes it possible to record information on a single track of a tape recorder from at least two channels. When playing, extremum detection at the end of each period of a sinusoidal amplitude-manipulated signal allows accurate amplitude counting even with fluctuations in front of it of the pulse front of the P4 sequence (plot 3, fig. 3) relative to the extremum of the sinusoidal signal (plot 1, fig. 3). Existence the fluctuations are due to changes in the phase characteristics of the through-channel recording / reproduction of the tape recorder 8. Using the reference signal when converting an eight-level code 3 d An equivalent, instantaneous automatic gain control action allows maintaining high accuracy of information reproduction with increased recording density. Thus, the proposed device by discretization and time multiplexing of a two-channel analog signal with subsequent sequential conversion into a binary digital code, into a multi-level digital code (using one code element as a reference signal) and into a sinusoidal amplitude-phase-manipulated signal provides recording of the reproduction of two information channels on a single track, which achieves a positive effect - an increase in the density of recording information. In this case, after reproducing, in the process of converting information, reading the values of a multilevel code along a sinusoidal amplitude-phase-manipulated signal occurs near the extremum at the end of each period of sinusoidal voltage, which allows eliminating intersymbol distortions due to the transient from the previous code element. In addition, the formation of a threshold for each multi-level code combination allows for accurate conversion of multi-level code to binary, even during short-term signal fading (the length of which NA exceeds T / 2). All this allows to ensure high reliability of reproduction of information. An additional advantage of the proposed device is that it ensures the identity of the end-to-end recording-reproducing characteristics of the two channels due to the cross-switching of the filters, which makes it possible to use it in correlation measurements. In addition, when this device is used in interference compensation devices, a high degree of interference compensation is provided. The proposed device is affordable and cheap compared to the base object, due to the implementation of recording and reproduction on a household tape recorder.

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Claims (1)

A DEVICE FOR RECORDING AND PLAYING DIGITAL INFORMATION SIGNALS, comprising a digitally-to-sinusoidal signal converter and a matching amplifier connected to the input of the tape recorder, as well as encoding and decoding units, characterized in that, in order to increase the recording density, two filters are introduced into it , multiplexer, binary code converter · multilevel, clock and clock pulse generator, reference voltage source, isolation amplifier, extra detector minimum values, a multilevel-to-binary code converter, a demultiplexer, and a control voltage generating unit, while two device inputs are connected through the corresponding filters to the multiplexer inputs, the output of which is connected through a coding unit and a binary-to-multi-level code converter to the information input of the digital code converter sine wave, first, second, third, fourth and fifth outputs of a clock and clock pulse generator respectively to the additional control inputs of a matching amplifier, a digital code to sinusoidal signal converter, coding unit, to the first control input of a binary to multi-level converter, the second control input of which is connected to the output of the reference voltage source, and the output of the tape recorder is connected to the input of the separation amplifier, the first the output of which is connected to the input of the control voltage generation unit, the second through the series-connected extreme value detector converter, a multilevel code to binary, and a decoding unit with a demultiplexer input, the outputs of which are connected to other inputs of the corresponding filters, and the first, second, third, and fourth outputs of the control voltage generation unit are connected respectively to the control inputs of the extreme value detector, the multilevel code to binary converter , demultiplexer and with an additional control input of the decoding unit. SU .... 1049961>