JPS58169339A - Processing circuit of reproduced signal - Google Patents

Abstract

PURPOSE:To enable the exact peak detection of a reproduced signal after differentiation thereof in the signal processing of a digital optical disc by using a window pulse that follows up the reproduced signal. CONSTITUTION:When the amplified waveform 2 of a reproduced signal is inputted to the + terminal of a differential amplifier 12 of a window forming circuit 16 and the waveform 11 following up the waveform 2 is inputted to the -terminal of the amplifier 12, such a window pulse 14 which eliminates the unstable region in the 0V position of a differential waveform 4 is obtained. If a pulse signal 6 is drawn out by passing the waveform 2 through a differentiator 3 and a zero cross detector 5 and the signal 6 and the pulse 14 are applied to an AND circuit, an exact peak pulse signal 15 is obtained in the output thereof. Since the unnecessary zero cross point after the differentiation is removed by the window, the peak desired to be drawn out is detected exactly.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of Application of the Invention The present invention relates to a reproduced signal processing circuit, which is suitable for # IIK signals of digital optical disks, and detects the peak of the reproduced signal to the differential signal obtained from the reproduced signal. The present invention relates to a signal processing circuit that performs zero cross point detection.

(2) Prior Art A conventional method for detecting the peak of a reproduced signal is shown in FIG. The reproduced signal read out from the optical head passes through an amplifier 1, a differentiator 5, and a zero cross detector 5 to obtain a zero cross signal 6. As a result, the reproduction signal of the digital optical disk contains a KDO acid component as shown in waveform 8 in FIG. Erroneous detection of the peak occurs due to noise riding on this ninth DC component. As a preventive measure, a window pulse 10 is created by slicing waveform 2 with DC pulses of waveform 8, and the severe pulse signal is obtained by ANDing this pulse and the zero ps signal 6, resulting in a %A circle. However, although this method can reduce the influence of noise on the DC component, it is not effective against the unstable region at the zero point of the waveform 4 after differentiation. (9) Since the reproduced signal fluctuates depending on the presence or absence of data in the data section, the frequency of the data pattern aK, the DOC level, and so on, it is unreasonable to slice it at a certain constant C level.

(5) Object of the Invention An object of the present invention is to provide a method for detecting peaks of a reproduced signal more reliably than conventional methods, and reducing the number of peaks detected due to noise or the like.

(4) Examples Hereinafter, examples of the present invention will be explained in detail with reference to FIG. 5 and 4wJ.

The reproduced signal, °, becomes a zero-cross signal 6 through an amplification 1111, a differentiator 3, and a zero-cross detector 5. However, I don't know what waveform 6 will look like after differentiation at the 0 ■ position.
Since this is an unstable region, a zero cross signal must not be detected in this region. The rising edge shown in waveform 6 is equivalent to the original bit. So for this part.

A technology to extract the waste is required.

Therefore, in the present invention, the amplified waveform 2 of the reproduced signal is input to the window creation circuit 16. Waveform 11 follows waveform 2 as shown in FIG. When the waveform 2 and the waveform 11 are input to the differential amplifier 12, a window pulse 14 is obtained which removes the unstable region of the Ov position of the differential waveform 4. 14.6
An accurate peak pulse signal can be obtained by ANDing.

According to the present invention, unnecessary zero-crossing points after differentiation are removed by the 1.11 window, so round peaks can be detected accurately.

In addition, countermeasures against noise riding on the DC component can be made by using the diode value of Fi16. If the value of the diode is selected to be large, the AND condition of the zero cross signal and the window pulse cannot be obtained in the case of high frequency noise, and there is no false detection of the peak.

As explained above, according to the present invention, the peak pulse signal can be accurately extracted from the reproduced signal.

Further, unlike conventional digital optical discs, there is no need to detect both peaks of the reproduced signal.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional circuit, Fig. 2 is a signal waveform of each part of the upper and distribution circuit, Fig. 5 is a block diagram showing an embodiment of the present invention, and Fig. 4 is a block diagram of each part of the circuit of the present invention. It is a signal waveform. 1...Amplifier 5...Differentiator 5...
Zero cross detector 9.12... Differential amplifier 11... Window pulse creation circuit □・- Toshi Susuda, my representative. 1st tense, 71 drawings 3 drawing Y Sai To drawing

Claims (1)

[Claims] 1. A reproduction signal processing circuit that uses a window pulse that follows the reproduction signal in order to reliably find the zero-crossing point after differentiation of the reproduction signal whose signal waveform has a DC component and an AC component.