KR900005920Y1 - Nrzi demodulating circuit of digital audio tape recorder - Google Patents

Abstract

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Description

With NRZI modulation of digital audio tape recorder

1 is a block diagram of an NRZI demodulation circuit diagram of a digital audio tape recorder of the present invention.

2 is an NRZI demodulation detail circuit diagram of a digital audio tape recorder of the present invention.

3 is a waveform diagram of each part of FIG.

* Explanation of symbols for main parts of the drawings

1: amplifier 2: full-wave rectifier circuit

3: level detection circuit 4: peak value detection circuit

5: Monomulti CH ₁ : Playhead

VR ₁ -VR ₂ : Variable resistor L ₁ : Coil

CP ₁ : Comparator R ₁ -R ₂ : Resistance

D ₁ -D ₅ : Diode

According to the present invention, a digital signal, a data signal, is non-returned to zero inverted (NRZI) modulation, that is, magnetized inversion only at a high potential among input data signals, recorded on a magnetic tape, and then the digital signal is reproduced with a modulated signal. The present invention relates to an NRZI demodulation circuit of a digital audio tape recorder capable of obtaining a data signal having the same waveform as the original digital signal with a simple circuit configuration.

In general, in recording a digital signal as a data signal on a magnetic tape of a digital audio tape recorder, it is modulated into a signal similar to the digital signal and recorded on a magnetic tape, and during reproduction, the modulated signal reproduced by the playback head is originally recorded. Since the circuit of converting the modulated signal to the original digital signal is very complicated, it is not only a cost increase factor but also its operation is not stabilized. There are various defects such as lack of reliability because the time base is changed and the accurate data storage is not achieved.

The present invention has been devised in view of the above-described conventional defects, and it is possible to obtain the same waveform as the original data signal with a simple circuit configuration, which will be described in more detail with reference to the accompanying drawings.

As shown in FIG. ₁ , an amplifier 1 for amplifying the signal reproduced by the reproduction head CH ₁ , a full-wave rectifying circuit 2 for full-wave rectifying the amplified signal, and the level of the full-wave rectified signal. A level detection circuit 3 for detecting a signal, a peak detection circuit 4 for maintaining a gap between peak detection and reproducing signals according to the detection level signal, and a mono signal for converting the detected signal into a data signal having a constant width. FIG. 2 is a detailed circuit diagram of FIG. 1, in which a reproduction head CH ₁ is formed of a transformer T ₁ and a diode D ₁ and D ₂ through an amplifier 1. (2) the transformer (T ₁₎ resistance to its output terminal (a) connected to the date side of the (R _1, R _2), the level detected by the variable resistor (VR ₁₎ and a diode (D _3, D ₄₎ The thrust terminal B of the level detection circuit 3 is connected to the input side of the circuit 3, and the resistors R ₃ -R ₅ , the coils L ₁ , the capacitors C ₁ , the diodes D ₅ , and Comparator (C P ₁ ) is connected to the input side of the peak value detection circuit (4), and its output terminal (C) is connected to the monolith (5) connected to the variable resistor (VR ₂ ) and the capacitor (C ₂ ) In the description of the drawings, reference numeral B ⁺ denotes a power supply terminal.

Referring to the effects of the present invention configured in this way in detail as follows.

First, when the modulated data signal as shown in Fig. 3A is NRZI modulated and the signal waveform as shown in Fig. 3B is recorded on magnetic tape, the playback head CH ₁ is used during playback. Reproduces the signal waveform as shown in (B) of FIG. 3 recorded on the magnetic tape on the magnetic tape, and outputs the amplified signal as shown in (C) of FIG. 3 through the amplifier 1, and The output amplified signal is input to the full-wave rectifying circuit 2 and outputs the full-wave rectified signal to its output terminal A as shown in (d) of FIG. 3, and the full-wave rectified signal is a level detecting circuit ( 3) a signal having a magnitude greater than or equal to the threshold voltage level, that is, a predetermined level or more, according to the change of the variable resistor VR ₁ to the output terminal B thereof, as shown in (e) of FIG. Signal is output and the detected signal is peak-to-peak A coil (L ₁₎ of claim soon as a signal is input as shown by the solid line in three degrees (F) in addition, its non-inverting input characters (+) - a comparator (CP _1), the inverting input terminal of the circuit 4 () And a dotted line in FIG. 3B as a signal delayed by a predetermined time (t ₁ ) by the coil (L ₁ ) and the capacitor (C ₁ ) because it is input through the capacitor (C ₁ ) and the resistor (R ₄ , R ₅ ). A signal as shown is input.

In this way, the inverting input terminal (−) of the comparator CP ₁ based on the difference between the magnitudes of the two input signals as shown in (bar) of FIG. 3 input to the comparator CP ₁ , that is, the intersection point CP of the two input signals. The low potential is output when the waveform of the solid line signal input to the signal is higher than the signal waveform of the dotted line applied to the non-inverting input terminal (+), and the high potential is the peak value detection circuit (4). The output terminal (C) of the comparator (CP ₁ ), which is the output side of the C), is output as shown in Fig. 3 (G) and is affected by disturbance such as precision of the mechanism, jitter, etc. In order to keep the constant constant, the output signal is input to the monomulti 5 and the constant signal waveform is output to the output side by the time constants of the variable resistor VR ₂ and the capacitor C ₂ . As shown in), the original data signal, i.e., Indicated is output is reproducing a digital signal as described.

As described above, the present invention is a circuit in which a digital signal is NRZI modulated to detect and reproduce a level and a peak value in a signal waveform recorded on a magnetic tape to obtain a waveform of the same signal as the original digital signal. In addition to the cost reduction effect, even in the case of high-density recording and reproduction, accurate intervals of the reproduction signals can be maintained, so that accurate digital signals can be reproduced, and operation of the circuit is stable, thereby providing reliability to the product. .

Claims (2)

In Sikkim reproducing a signal recorded a reproduction head (CH ₁₎ on a tape, the reproduction head (CH ₁₎ and the amplifier (1) for amplifying the reproduction signal, the full-wave rectification to full-wave rectification of the amplified signal circuit (2 ), And a level detecting circuit 3 comprising resistors R ₁ and R ₂ , variable resistors VR ₁ , and diodes D ₃ and D ₄ for detecting the threshold voltage level of the full-wave rectified signal. A digital audio tape comprising a peak detection circuit (4) for detecting peak values according to the detected level signal, and a monomulti (5) for maintaining a constant width of the detected peak waveform. NRZI demodulation circuit for record. The method of claim 1, wherein the peak detection circuit 4 has an inverting input terminal of the resistor (R ₅₎ and a comparator (CP ₁₎ via a resistor (R ₃₎ an output terminal (B) of the level detecting circuit 3 (-) junction box as well as connected to the coil (L ₁₎ and capacitor resistance through (C ₁₎ (R ₄₎ and the non-inverting input terminal (+) of the comparator (CP ₁₎ on, and the comparator (CP ₁₎ An NRZI demodulation circuit of a digital audio tape recorder, characterized in that the output terminal is connected to the cathode of the diode (D ₅ ) with the anode grounded and to the input side of the mono multi (5).