JPS58128010A - Data separation circuit - Google Patents

Abstract

PURPOSE:To separate PCM data correctly even if distortion takes place in input data, by making a data separation level of an input data signal coincident with a reference potential level of a data separation circuit independently of the distortion of the input data signal. CONSTITUTION:A comparator 7' compares the input data 20 with the data separation reference potential 11' mentioned later and separates the PCM data. The PCM data of a processor 8 is led to an audio output terminal 13. A data error detection circuit 81 generates a pulse signal in response to the number of errors. A counter 9 counts an output pulse of the detection circuit 81. A processor 10 detects the count output of the counter 9, operates the data separation reference potential VT where the PCM data error is minimized and outputs corresponding digital signals. A converter 11 converts the digital signal into a reference potential V of a comparator 7'. A controller 12 varies the digital quantity of the processor 10. In the constitution like this, a voltage varying means 14 obtains the reference voltage VT where the PCM data error is minimized when the separation reference voltage V is changed from V1 to VN, and transmits the voltage to the comparator 7', allowing to separate the PCM data correctly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data separation circuit that separates PCM data from a video signal.

An example of this type of data separation circuit is the one shown in FIG.

That is, data inputted to the data input terminal 1 (a video signal formed by a PCM signal) is input to the t-amplifier 2. The data is input to one side of the level comparator 2 via the white beak removal circuit 4, and is applied to the rectifier circuit 3 consisting of a diode and a capacitor 32. The circuit performs envelope detection, and the output is The divided signal is divided by resistors 41 and 42 and applied as the other input of the level comparator, that is, the reference potential of level comparator 2 (C in Fig. 2).
), the level of human power is compared by a level comparator 2 and the PCM data is separated. 3 is a white beak detection circuit.However, the data separation level varies depending on the type of tape used and the recording condition.
For example, if distortion occurs in the human input data and its waveform changes as shown in FIG. 2 (5) to T shown in FIG. 2 (B), the reference potential C of the level comparator changes to the optimum separation level p of the data shown in
Therefore, there is a drawback that the data of part N in the second drawing cannot be separated correctly.

An object of the present invention is to eliminate the drawbacks of the prior art described above, and to manually control the data separation level (threshold threshold level) of the data signal and the reference potential level (threshold range pressure) of the theta circuit. The purpose is to easily match data signals regardless of distortion.

The present invention counts the amount of PCM data errors when changing the threshold voltage, calculates the threshold voltage that minimizes the amount of PCM data errors based on the relationship between the two, and calculates the threshold voltage that minimizes the amount of PCM data errors. The field voltage is used as the reference potential level of the data separation circuit.The present invention will be explained below with reference to the drawings.FIG. 5 is a block diagram showing an embodiment of the present invention.

In the figure, 7' is a comparator that separates PCM data by comparing input data 20 with a data separation reference potential (threshold voltage) 11/ to be described later, and 8&'L comparator 7' separates the PCM data. The detected PCM data is guided to the audio output terminal 15 in a well-known manner.
The data error detection circuit 81, which is equipped with a data error detection circuit 81, is composed of, for example, a logic circuit that generates a pulse signal according to the number of errors when a data error occurs, and since this is generally well known, a detailed explanation thereof will be omitted. . Reference numeral 9 indicates a counter for counting output pulses T of the data processing detection circuit 81, and reference numeral 10 indicates a data separation reference potential (threshold voltage VT) t-, which at the same time as detecting the count output of the counter 9, minimizes the PCM data error level i. arithmetic processing means, such as a microprocessor, which performs calculations and outputs a digital signal corresponding to the calculation result; 11, a loop converter which converts the digital signal into an analog signal, that is, a threshold voltage V of the comparator 7'; and 12; 1 shows a control device for varying the digital quantity of the processor 1o, which constitutes a threshold voltage pressure varying means 14rr:111. Here, as shown in FIGS. 4 and 5, the threshold wtvy voltage V
Count output the amount of PCM data film when changing from iV to vM, ko') Both t Y = A + B
Y + CV ” 0 If approximated by the quadratic formula, the threshold value that minimizes the PCM data error value is the pressure V.
T Cx, B・V=knee, given by c. Approximation of the quadratic equation can be easily obtained by using the method of least squares.

FIG. 6 is a diagram showing a 70-chart of the microprocessor 10.

As described above, the present invention accurately detects the threshold level of the human input signal and separates the data, so even if the human input signal is distorted, the PCM data can always be correctly separated. 0

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing a conventional example, and Figure 2 is an explanation thereof.
A waveform diagram of a human input signal, FIG. 3 is a block diagram showing an embodiment of the present invention, and FIGS. 4 and 5 are waveform diagrams of input signals, threshold voltage and number of PCM data errors for explanation. 6 is a principle diagram showing the data separation circuit 70 of the present invention.
-It is a chart. 20'...Human signal terminal, 7'...Comparator, 8.
...PCM processor, 81...PCM error detection circuit, 15-0. Output terminal, 9...Counter, 1
1...D/A converter, 10...Microprocessor, 1 patent attorney Susuki 1) Machibana 1 year old 1 Figure 7 2 Figure tA> (E5) 3 Figure

Claims (1)

[Claims] The circuit that separates PCM data from manual items has a threshold voltage variable means and a means for counting the amount of PCM data errors. The threshold voltage that minimizes the amount of data error is determined by arithmetic processing means,
A data separation circuit that correctly separates PCM data by comparing this voltage with the input signal.