SU669385A1 - Device for reproducing digital information magnetic carrier - Google Patents

Description

I

The invention relates to instrument engineering and is intended to reproduce digital information from magnetic media, obtained, for example, from autonomous meters in oceanographic research.

Devices for reproducing digital information are known, comprising a circuit of serially connected magnetic heads, amplifiers, detectors and a shaper connected simultaneously to three electrical circuits parallel to each other, the first of which consists of an AND circuit, and the second - of serially connected delay circuits and a gating unit and a third is from the And scheme, the gating unit, the prohibition scheme and the driver, and also having two additional delay schemes, each of which is included between its And and b schemes lock gate 1 and 2.

However, these devices do not provide sufficient resistance to interference when recording and reproducing schuma.

The closest to the invention to the technical essence is a device for

playback of digital information signals from a magnetic carrier containing a circuit of serially connected magnetic heads, a linear amplifier, a detecting unit and a demodulator of the read signal 3.

The disadvantages of this device are the complexity and the lack of protection from interference in it, the source of which are sound recording and playback.

The purpose of the invention is to increase the resistance.

Claims (1)

This is achieved by the fact that in the device the detecting unit is made in the form of two parallel circuits, one of which consists of a series-connected threshold detector connected to the source, put a full reference voltage, an operational amplifier and a level converter on the transistor and a friend from a series-connected threshold detector connected to a negative reference voltage source, an operational amplifier, and a transient signal level converter torus, connected according to the scheme C common emitter, while the collector of each of the transistors is connected to its input of a demodulator containing two pulse shortening generators, two waiting multivibrator pulse extenders, two AND, RS-trigger schemes and an OR circuit, each of the two inputs of the demodulator are formed by a parallel-connected shaper and a waiting multivibrator, the output of the first shaper and the second waiting multivibrator are connected to the inputs of the second And circuit, the output of the second shaper and the first waiting multi the vibrator is connected to the inputs of the first circuit AND, and the outputs of the circuit AND are connected to the inputs of RS-flip-flop and the OR circuit connected in parallel. FIG. 1 given a block diagram of the device; in fig. 2 is a time chart illustrating the operation of the device. The device comprises a magnetic head 1, an operational linear amplifier 2, a detection unit and a demodulator. The detecting unit is made in the form of two pairs. Field circuits, one of which consists of series-connected threshold detector 3, connected to a positive reference voltage + Vo source of operational amplifier 4 and a signal level converter at transistor 5, and the other one of series-connected threshold a detector 6 connected to a negative reference voltage source -Vo, an operational amplifier 7, and a signal transducer on a transistor 8. The first circuit serves to isolate the positive and the second - negative half-periods of the incoming block signal with thresholds specified by the voltage -f Vo and -Vo, respectively. The reference voltages + Vo and -Vo are chosen so that, on the one hand, to exclude the ground, and on the other hand, to ensure reliable passage of the useful signal. The demodulator consists of two formers 9 and 10 for pulse shortening, two multivibrators 11 and 12 — pulse extenders, two AND, RS-flip-flop and OR circuits. In addition, each of the two inputs of the demodulator is formed by parallel included shaper and a waiting multivibrator. The inputs of the first driver 9 and the second standby multivibrator 12 are connected to the inputs of the second circuit AND 13, and the output of the second driver 10 and the first standby multivibrator 11 are connected to the first circuit AND 14. The outputs of the AND circuit are connected to the parallel-connected circuit OR 15 and the RS-trigger 16. The device works as follows. Digital information recorded on magnetic media using the three level recording method is read by magnetic head 1, and, as follows from the timing diagram, the positive half-period of the read signal (a) is negative if the digit "I" is read, while in the case of reading the figures “Oh, the negative half-period is positive. The signal is then inverted and amplified by operational amplifier 2 and fed to the input of the detecting unit (c). In the first circuit of the detector, positive half-periods are distinguished, and in the second, negative half-periods with thresholds specified by the voltage -l-Vo and -Vo. The selected positive and negative half cycles of the read signal are amplified again and inverted by operational amplifiers 4 and 7 (c, d), and then brought to the same level with the help of transducer level transducers 5 and 8, one of which is connected according to a common base circuit. to convert a signal with a negative polarity (f), and the other - according to a circuit with a common emitter to convert a signal of a positive polarity (e). As a result, as can be seen from the timing diagram, the value of the digits "1 and" O at the two outputs of the detection unit is determined by the temporal position of the e and f signals reduced to one level, with / leading f, if read "1, and f leading e reading the number “O. The decoding of digital values and the generation of digital information signals is carried out by a demodulator. The formers 9 and 10 shorten (h, q), and the waiting multivibrators 11 and 12 lengthen (k, i) pulses e and f. Using the And 13 and 14 circuits, the signals i are gated to the signals h, q (see Figs. 1 and 2), as a result of which a short pulse is generated at the output J, if the digit "1 is read, and at the output w, if it is read the figure "O. Using the OR 15 circuit, the clock frequency n is extracted, and the RS flip-flop 16 forms a digital sequence of ones and zeros. At the output of a device, digital information is obtained in a form suitable, for example, for its conversion from a serial form to a parallel one. The invention makes it possible to eliminate shumy, superimposed on the useful signal during the recording process, and shumy arising from reading digital information from magnetic media, as well as to simplify the design of the device due to the fact that it is equipped with a threshold detection unit and uses a simple read signal demodulation algorithm. The invention is a device for reproducing digital information from magnetic media, with