JPS59203209A - Digital signal detector - Google Patents

Abstract

PURPOSE:To digitize the detection processing and make adjustment unnecessary and to enhance the degree of tolerance to noise by collating a digital pattern, to which the waveform of a reproduced signal is converted in an A/D converting circuit, with a standard pattern to detect the signal. CONSTITUTION:The waveform of the reproduced signal which is applied to the input of an analog-digital converting circuit 4 is converted differentially to a binary digital signal by a delay device 8 and a comparator 7. This digital signal is converted to parallel data by a series-parallel converter 9 to obtain a digital pattern P corresponding to the input signal. This digital pattern P is sent to a pattern collating circuit 5 and is compared and collated with standard patterns Qj. They are compared with each other in the collating circuit 5, and a code Mi corresponding to a standard pattern is outputted as the detection result. Differential conversion is used in the analog-digital converting circuit to enhance the degree of tolerance to noise having low frequency components, and standard patterns are selected to cope flexibly with the influence of peak shift and the variance of characteristics of a recording medium.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to digital tape recorders, digital
Conventional configurations of digital signals in magnetic and optical recording and reproducing systems for digital signals such as disks, and their problems In recent years, there has been remarkable development in digital audio, office automation, etc., but the recording and reproducing of these digital data is In the system, a digital signal detection device occupies an important position.

A conventional digital signal detection device will be explained below. FIG. 1 is a block diagram of a conventional digital signal detection device, in which 1 is an equalization circuit, 2 is a comparator, and 3 is a demodulation circuit.

The operation of the conventional digital signal detection device configured as described above will be explained below. First, consider the case where a reproduced signal waveform as shown in FIG. 2(a) is applied to the input of the equalization circuit 1. The reproduced signal waveform Id is equalized by the equalization circuit 1, and the influence of peak shift is removed. , is restored to a waveform similar to that at the time of recording, as shown in FIG. 2(b), and is applied to the comparator 2. This comparator 2 performs waveform shaping by comparing with the comparison voltage Vvef, and demodulates a signal as shown in FIG. 2(C), and the sign of the detection result appears in the output.

However, in the conventional configuration described above, the equalizer circuit 1 and the comparator 2 are configured with analog circuits, which requires delicate adjustment, which may cause deterioration of the signal-to-noise ratio and malfunction due to noise. However, it is difficult to fabricate a highly integrated IC, and it also has problems in that it is not adaptable to differences in the characteristics of recording media.

Purpose of the Invention The present invention solves the above-mentioned conventional problems. By configuring most of the device with digital circuits, there is no need for adjustment, the risk of malfunction due to noise is extremely small, and the I/O can be easily installed.
It is an object of the present invention to provide a digital signal detection device that can perform C conversion and also has flexible adaptability by introducing a pattern matching method.

Structure of the Invention The present invention includes an analog-to-digital conversion circuit that converts an input reproduction signal waveform into a digital pattern, a standard pattern storage circuit that stores a standard pattern based on the amount of modulation, and a digital pattern that converts an input reproduction signal waveform into a digital pattern. This is a digital signal detection device equipped with a pattern matching circuit that compares and matches the obtained digital pattern with a standard pattern and outputs the code corresponding to the standard pattern closest to the input pattern, and has stable and flexible operation. Description of Embodiment FIG. 3 shows the configuration of a digital signal detection device in an embodiment of the present invention, in which 4 is an analog-to-digital conversion circuit, 5 is a pattern matching circuit, and 6 is a standard It is a pattern memory circuit.

FIG. 4 shows an example of the configuration of the analog-to-digital conversion circuit 4, where γ is a comparator, 8 is a delay device with one sampling time,
9 is a serial/parallel converter.

The operation will be explained below.

First, the reproduced signal waveform applied to the input of the analog-to-digital conversion circuit 4 is differentially converted into a binary digital signal by the delay device 8 and the comparator 7. This operation is equivalent to the so-called delta modulation. This digital signal is converted into parallel data by a serial/parallel converter 9 to obtain a digital pattern P corresponding to the input signal. Next, this digital pattern P is sent to the pattern matching circuit 5 and compared and matched with a standard pattern matching.

This standard pattern, as shown in FIG. The standard pattern q+ corresponding to the code Mj is determined by averaging the digital patterns obtained, and is stored in the standard pattern storage circuit 6. The pattern matching circuit 5 generates a digital pattern P, ! corresponding to the input reproduced waveform.
Ji-tei pattern Q] is compared, and the distance D is calculated using the following formula.

Dj = lP - Q 12 Calculate this distance D for all standard patterns Qj, and find the code M1 corresponding to the standard pattern Qi that gives the minimum value D1. As a result, the code Mi is output.

In this way, according to this embodiment, by using differential conversion in the analog-to-digital conversion circuit, it is possible to increase the margin against noise with low frequency components, it is easy to integrate it into an IC, and it is also possible to select a standard pattern. This makes it possible to flexibly respond to the effects of peak shifts and changes in the characteristics of the recording medium.

In this embodiment, differential conversion is used in the analog-to-digital conversion circuit 4.
A D converter may be used, or a Walsh-Hadamard converter may be added. In this case, the scale of the device will be smaller, but the same detection ability can be obtained even if the number of focuses for each pattern is reduced. In addition, although Euclidean distance is used as a distance measure in the turn matching circuit 5, Manola Nobis distance or the like may also be used, and time axis normalization processing using the DP matching method may be added.
It is possible to significantly improve the margin against time axis fluctuations of the shift and reproduced signal waveforms.

Effects of the Invention The present invention detects signals by matching a standard pattern with a digital pattern converted from a reproduced signal waveform by an analog-to-digital conversion circuit, thereby significantly digitizing the detection process. There is no need for adjustment, and there is a high margin against noise.
It is possible to realize an excellent digital signal detection device that is adaptable to changes in recording media, etc., and can be easily integrated into an IC.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a conventional digital signal detection device;
Figures (2L) to (C) are waveform diagrams of the main parts of Figure 1, Figure 3 is a configuration diagram of a digital signal detection device in an embodiment of the present invention, and Figure 4 is an analog-to-digital conversion diagram in Figure 3. Detailed diagram of the circuit, Figure 5 is the standard pattern Q in Figure 3.
FIG. 2 is a configuration diagram showing a method for determining j. 1... Equalization circuit, 2... Comparator, 3...
demodulation circuit, 4...analog-digital conversion circuit,
5...Pattern matching circuit, 6...Standard pattern storage circuit, 7...Comparator, 8...Delay device, 9...Serial to parallel converter.

Claims (1)

[Claims] an analog-to-digital conversion circuit that receives a reproduced signal waveform as an input and outputs a digital pattern corresponding to the input; a standard pattern storage circuit that stores a standard pattern based on before modulation; It consists of a pattern matching circuit that matches the pattern, and a digital signal corresponding to the input playback signal waveform.
A digital signal detection device characterized by finding a standard pattern that is most similar to a pattern, and outputting a code word corresponding to the standard pattern as a detection signal.