SU1429159A1 - Device for reproducing frequency-modulated signals from magnetic record carrier - Google Patents

Abstract

The invention relates to a magnetic recording technique, can be used in a precision magnetic recording apparatus for two-way. magnetic record carrier, allows to expand the dynamic range of the output signals due to the fact that the frequency-modulated information signal is squared before demodulation, which provides an expansion of the dynamic range of the signals at the input-demodulator and at the output-device. This is achieved by the fact that the device additionally contains a quad 5, two comparators 6 and 7, two sources of reference voltages 8 and 9, a single vibrator 11, two elements AND 10, 12, a generator of 13 pulses and element OR 14. 2 Il. c (O (L

Description

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I The invention relates to instrumentation, in particular, to a magnetic recording technique, and can be used in the equipment of accurate magnetic recording of frequency-modulated signals in information recording and processing means.

The purpose of the invention is to expand the di-nam range of the output signals.

Figure 1 shows the structural diagram of the proposed device; FIG. 2 shows timing diagrams of the signal I at the outputs of the corresponding elements.

The device contains a reproducing magnetic head 1, connected to the 2-channel separator, having the output 3 of the information signal; And the output 4 of the reference signal, the square of the HZ input connected to the output 3; information signal separator i 2 channels, a-output - with the first inputs of the first 6 and second 7 comparators, to the second inputs of which are connected the first 8 and second 9 sources of reference voltages, respectively.

The outputs of the first 6 and second 7 comparators are connected respectively to the first input of the first element I 10 and to the input of the one-vibrator 11,: the direct output of which is connected to the second input of the element 10 and the inverse output to the first input of the second element 12, To the second input of which is connected a generator of 13 pulses.

The outputs of the first and second elements AND 10 and 12 are combined by the OR element 14, the output connected to the information input of the shift register 15 To the output 4 of the reference signal of the 2-channel separator, connected in series are the phase detector 16, the low-pass filter 17, the generator 18, control voltage connected by a code to the control input of the shift register 15, as well as through the frequency divider 19 to the second input of the phase detector 16.

A shift offset register 15 is connected to a demodulator 20 connected by an output to an output unit 21, the output of which is the output of the device.

The device works as follows. ,

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After playing from the magnetic recording medium of the magnetic head 1 of the sum of the information frequency-modulated and reference signals, they are separated in the 2-channel separator. The information signal is squared in quad 5, with the result that at its output a frequency-modulated signal with a double carrier and with an extended dynamic range is formed. After amplification of the limiting level U (specified by the first 8 source of the reference voltage in the first comparator 6 and passing through the elements AND 10 and OR 14, the information signal is fed to the information input of the shift register 15, in which the temporal distortion of this signal is corrected by change the frequency controlling the transfer rate in the register. The control signal of the register 15 is generated by multiplying the frequency of the reference signal n times by a phase-locked circuit containing a phase detector 16, a filter 17 n Frequency, generator 18, control voltage, and frequency divider 19 on p. The value of n is chosen from the condition p / f, where f is the frequency of the carrier of the frequency-modulated signal, and f is the frequency of the reference signal recorded on the carrier. After demodulation in demodulator 20 and filtering in output block 21, an information signal is generated at the output of the device, free from temporal distortions and with an extended dynamic range.

The voltage and, generated by the first 8 source of the reference voltage, is chosen from the condition of providing the maximum dynamic range at the output of the demodulator 20. To reduce the effect of deep parasitic amplitude modulation on the dynamic range, the second comparator 7, the second source of 9 reference voltages, are used one-shot 11 with a restart, the second element AND 12. element OR 14 and the generator 13 pulses. When the level of the signal at the output of the quad 5 decreases to a value lower than the voltage TJ from the output of the second source 9 of the reference voltage, the one-vibrator 11 ceases to go.

five trigger pulses and, at its direct output, a zero potential is established that prohibits the passage of information pulses from the output of the first comparator 6 to the information input of the shift register 15. At the same time, at the inverse output of the single-vibrator 11 there will be a single potential allowing passage through the elements AND 12 and OR 14 to the control input of the register 15 of signals of a stable generator frequency 13 pulses equal to twice the carrier value, there is no signal at the output of the demodulator 20, and the noise level is determined only by the intrinsic noise of the demodulator 20 and the pulse generator 13.

Squaring the frequency-modulated information signal before demodulating it allows to expand the dynamic range and output signals at the output of the demodulator, the noise caused by variations in carrier speed is reduced by correcting the time distortion, as a result, the dynamic range of the output signals in the proposed device can be extended by 4-6 dB ..

Claims (1)

Invention Formula An apparatus for reproducing frequency modulated signals from a magnetic recording medium, comprising five a reproducing magnetic head connected to a channel splitter with information outputs to : the reference signal, and also connected to the output of the reference signal channel splitter and serially connected phase detector, low pass filter, voltage controlled oscillator associated with the control input of the shift register, demodulator and output unit, the second input of the phase detector connected via a frequency divider to the output of a generator controlled by a voltage, a tl, and that is because, in order to expand the dynamic range of the output signals, a quad is entered into it, the input connected to the output of of the channel’s splitter signal, and the output with the first inputs of the first and second comparators, to the second inputs of which the first .5 and second sources of reference voltages are connected, respectively; A ttor is connected to the input of the first element I, and the output of the second comparator is connected to the input of a single vibrator, the direct output of which is connected to another input of the first element I, and the inverse output to the input of the second element I, to another input of which the output of the pulse generator is connected , moreover, the outputs of the first and second elements AND are combined by the OR element, the output connected to the information input of the shift register. 0 five WY.Z, vsh.5 SP; 1; 1PPPPPPPPPPG 11 l yr hnnn fcrfinnriii 1sh. To Pppppo II LPPPPPPPPPL Fsh.g Editor A.Vorovich Compiled by A. Lukanin Tehred L. Serdyukova Proofreader M.Sharoshi Order 5132/48 Circulation 590 VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Subscription