SU1277186A1 - Device for reproducing digital information from magnetic tape - Google Patents

Abstract

The invention relates to a magnetic recording and makes it possible to improve the accuracy of reproduction of information with a change in the level of the reproduced signal. The device contains a magnetic head 1 connected via serially connected playback amplifier 2, adder 3 and reproducing playback of low-pass filter 4 and 9 to the first input of subtractor 5 connected by a second input to the output of amplifier 2 playback and output through an amplitude comparator 6 with output bus 7 connected to one of the inputs of the adder 3, the detector 8 and the amplitude demodulator 10. If during the playback at the moment of time, the amplitude of the signal decreases, respectively and its response at the output of the filter 4. At the same time, the detected signal and the signal at the output of the filter 9 are proportionally reduced. Thus, the second input of the adder 3 receives pulses from the amplitude modulator 10, which is comparable to the playback signal. In this case, the baseline does not go beyond the playback signal, the device does not malfunction. 2 Il. (L Subtractor Amplitude Comparator

Description

This invention relates to magnetic recordings, namely, digital information display devices from magnetic tapes.

. The purpose of the invention is to increase the accuracy of information reproduction with a change in the level of the reproduced signal.

Figure 1 shows a block diagram of a device for reproducing digital information from a magnetic tape; 2, waveforms explaining the operation of the device.

A device for reproducing digital information from a magnetic tape contains a magnetic head 1 connected via serially connected playback amplifier 2, an adder 3 and a first low-pass filter 4 to the first input of a subtractor 5 connected by a second input to the output of a playback amplifier 2 and output through an amplitude comparator 6 - with an output bus 7 connected to one of the inputs of the adder 3. In addition, the device for reproducing digital information from a magnetic tape contains serially connected Tector 8, the second low-pass filter 9 and the amplitude modulator 10, the detector 8 is connected to the input of the output subtracter 5, and an amplitude modulator 10 is connected between vpsodnoy bus 7 and one of the inputs of the adder 3.

The device works as follows

The read head 1 and the amplified playback signal (Fig. 2, Iq) are fed to the first input of the subtractor 5. A signal from the baseline is received at its second input.

The baseline is formed as follows. The signal from the playback amplifier 2 is fed to the first input of the adder 3 and then to the input of the filter 4. The response of the playback signal at the output of the filter 4 has the form shown in FIG. 2, 16. The second input of the adder 3 receives a signal from the output of the modulator III, modulated in amplitude (Fig. 2, IV). The modulation law is determined by the reproduction signal envelope, in which the baseline is restored (Fig. 2, II). The envelope is extracted using detector 8 and filter 9,

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The operation of which is explained by the oscillograms in Figs. 2, IIIa and 2.111 is respectively. The response at the output of the filter 4 to the amplitude-modulated signal is shown in Fig. 2, 16. As a result, the sum of the two responses (Figs. 2, 15 and Figs. 2, IB) a base line is formed (FIG. 2, I g), relative to which a digital signal is generated using a comparator 6.

The points of intersection of the reproduced signal with the baseline correspond to the fronts of the digital signal.

If during the playback at time t, the amplitude of the signal decreases (Fig. 2, Ia), then its response at the output of filter 4 (Fig. 2, Ifi) will decrease accordingly. At the same time, the detected signal will be proportionally reduced (Fig. 2.111a.). And the signal at the output of the filter 9 (Fig. 2 III S). Thus, the second input of the adder 3 receives pulses from the amplitude modulator 10, which is commensurate with the playback signal. In this case, the baseline does not go beyond the reproduction signal (Fig. 2, It.), The device does not malfunction.

Claims (1)

Invention Formula A device for reproducing digital information from a magnetic tape, containing a magnetic head connected through serially connected playback amplifier, adder and first low pass filter to the first input of a subtractor connected by a second input to the output of the B1 output amplifier and output through an amplitude comparator - with an output bus connected to one from the inputs of the adder, characterized in that, in order to increase the accuracy of the reproduction of information when the level of the reproduced signal is changed, it is entered in series with the detector, the second low-pass filter and the amplitude modulator, the detector is connected to the output of the subtractor, and the amplitude modulator is connected between the output bus and one of the inputs of the adder.  five JffHr-TffVw. III Puz.Z