JPH05160731A - Data identification device - Google Patents

Abstract

PURPOSE:To attain surer data identification by identifying data in response to gradient information of a waveform of samples before and after an identification point when the data are identified in the vicinity of a threshold voltage. CONSTITUTION:An analog signal 1a is outputted as a sampling clock 2b subject to synchronization recovery by a clock recovery means 2. Simultaneously the signal is A/D-converted in response to a sampling clock 2b by an A/D converter means 1. A differential means 3 takes a difference between sample points before and after a conversion data 1b sequentially and the polarity of the data is continuously outputted as polarity information 3b. A discrimination means 4 receives the polarity signal 3b at one input and the conversion data 1b as other input, discriminates the minimum/maximum value of the waveform data and outputs identification data 4b based on the information of the polarity signal at sample points before and after the identification point when the conversion data 1b are discriminated at the identification point and the level of the conversion data 1b enters a range of a threshold level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data discriminating apparatus for discriminating data from a demodulated analog data signal in digital data transmission.

[0002]

2. Description of the Related Art When a digitally modulated signal is demodulated and the analog signal is discriminated into digital data,
As a conventional data identification device, there is one as shown in FIG.

An example of a conventional data identification device will be described below with reference to the drawings. In the figure, 1a is a demodulated analog data signal, 2 is a demodulated analog data signal 1a
Sampling clock 2b synchronized with the input signal
Clock reproducing means 1 for reproducing the demodulated analog data signal 1a and A / D converting means for A / D converting the input signal according to the sampling clock 2b and outputting converted data 1b. A majority decision is made using the conversion data 1b at the points and the identification data 5b
Is a majority decision means for outputting.

Regarding the operation of the data discriminating apparatus configured as described above, the BP shown in FIG. 3 is shown here as a demodulated signal.
The SK demodulated data signal will be described below as an example.

First, the demodulated analog data signal 1a is input to the A / D conversion means 1. At the same time, the clock reproducing means 2 performs A / D conversion with the sampling clock 2b synchronized with the analog data signal 1a and outputs converted data 1b. In order to prevent the amplitude and the phase of the analog data signal 1a demodulated by the distortion in the transmission line from being affected and the occurrence of an identification error at the data identification point Ts, the majority decision deciding means 5 has sampling points before and after the identification point. By making a majority decision based on the converted data 1b, the occurrence of an identification error is prevented.

[0006]

However, the above-mentioned structure causes a problem when signals under the following conditions are input. When no distortion exists on the transmission line (shown by a broken line in FIG. 4), the original analog data signal 1a should be a signal whose amplitude is sufficiently smaller than the threshold voltage Vt at the identification point Tso. When an analog data signal 1a that is affected by distortion or the like on the transmission line and passes through the threshold voltage Vt after the identification point Tso is input as shown by the solid line in FIG. When a majority decision is made using the conversion data 1b00, 1b02 of the sampling points of, the amplitude of the analog data signal 1a at the discrimination point Tso is judged to be larger than the threshold voltage Vt, and in this example, it becomes an H level digital signal. Will be identified.

Similarly, when an analog data signal 1a as shown in FIG. 4B is input, if the majority decision is made using the conversion data 1b00, 1b02 of the sampling points before and after at the discrimination point Tso, the discrimination point The amplitude of the analog data signal 1a at Tso is judged to be smaller than the threshold voltage Vt, and in this example, it is discriminated as an L level digital signal. As described above, when the analog signal 1a that passes the threshold voltage Vt in the vicinity of the identification point Tso is input, there is a problem that incorrect identification may occur.

In view of the above problems, the present invention depends on the magnitude of the conventional signal amplitude even when the amplitude of the analog data signal demodulated due to distortion or the like on the transmission line is near the threshold voltage at the discrimination point. It is an object of the present invention to provide a data identification device capable of performing data identification more reliably than performing majority determination to identify data.

[0009]

In order to solve the above problems, a data discriminating apparatus of the present invention comprises a clock regenerating means for inputting a demodulated analog data signal and regenerating a sampling clock synchronized with this input signal. , A / D conversion means for A / D converting the analog data signal in accordance with the sampling clock which is the output of the clock reproduction means, the conversion data which is the output of the A / D conversion means, and the conversion data immediately before. And a difference means for outputting the polarity information of the result of the difference as a polarity signal, and a polarity signal which is an output signal of the difference means as one input and the conversion data as the other input. When the data is discriminated at the discrimination point, if the size of the converted data falls within a certain threshold range, the polarity signal of the polarity signal at the sample points before and after the discrimination point is Performs determination based on distribution are those having a structure of discriminating means for outputting identification data.

[0010]

As shown in FIG. 4, when the demodulated analog signal 1a is in the vicinity of the threshold voltage Vt, the difference is obtained by using the conversion data 1b00 and 1b02 of the sample points before and after the discrimination point Tso and the discrimination point Tso of the waveform. Detect the slope of the converted data in the neighborhood,
The polarity signal 3b is output. Data identification according to the slope of the waveform is performed by the polarity signal 3b.

That is, if the amplitude of the waveform in the vicinity of the threshold voltage Vt monotonously decreases, distortion or the like on the transmission line affects the phase and the amplitude, and originally the threshold voltage Vt.
Judge that the waveform should have an amplitude smaller than t. Similarly, if the amplitude of the waveform near the threshold voltage Vt monotonically increases, it is determined that the waveform should have a larger amplitude than the threshold voltage Vt.

As described above, the distortion or the like on the transmission line affects the phase and the amplitude, and even if the waveform amplitude of the demodulated analog signal 1a is near the threshold voltage Vt, the waveform passes the threshold voltage Vt. Since the data determination is performed according to the inclination at this time, more reliable data identification can be performed as compared with the conventional determination in which the majority determination based on the magnitude of the amplitude is performed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A data identification device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a data identification device according to an embodiment of the present invention. In the figure, 2 is a clock reproducing means for inputting a demodulated analog data signal 1a and outputting a synchronized sampling clock 2b, 1 is a sampling clock 2
A / D conversion means for A / D converting the analog data signal 1a and outputting the converted data 1b according to b, 3 sequentially takes the difference between the converted data 1b and the converted data 1b in the immediately preceding sample, and calculates the difference. The polarity information of the result of the polarity signal 3b
The difference means 4 for outputting the polarity data 3b as one input and the conversion data 1b as the other input, and when the conversion data 1b is discriminated at the discrimination point, the size of the conversion data 1b is a certain threshold value. When it is within the range, it is a discriminating means for discriminating between the minimum and maximum of the waveform data based on the information of the polarity signal at the sampling points before and after the discrimination point and outputting the discrimination data 4b. The operation of the data identification device configured as described above will be described below with reference to FIGS. 1, 4, and 5.

As the analog signal 1a, the sampling clock 2b which is synchronously reproduced by the clock reproducing means 2 is output. At the same time, the A / D conversion means 1 performs A / D conversion according to the sampling clock 2b. The difference means 3 sequentially takes the difference between the sample points before and after the converted data 1b and continuously outputs the polarity of the data as the polarity information 3b.

FIG. 5 is an example of a slightly detailed block diagram of the judging means 4. 41 shifts the polarity signal 3b and outputs the information of the polarity signal 3b before and after the identification point as the polarity holding data 41.
A shift register that outputs as b. If the polarity holding data 41b is (+, +), it is H level (-,-) If it is L level, the waveform judging circuit for judging the L level and outputting the judgment signal 42b. 43 is the conversion data 1b for data discrimination. It is detected whether or not it is near the threshold voltage Vt, and if it is near, a threshold value signal 43b is output. This is a threshold detection circuit that outputs an out-of-threshold value signal 43c (a signal that becomes the final identification data) if it is not in the vicinity. This threshold detection circuit can be composed of, for example, a digital comparator or the like. 44 is converted data 1 by the threshold signal 43b
If b is in the vicinity of the threshold voltage Vt, the judgment signals 42b of the preceding and succeeding samples are latched, and if it is outside the vicinity, the out-of-threshold signal 43c is latched by the clock obtained by dividing the sample clock 2b by the frequency dividing circuit 47 Then, the selection circuit outputs the final identification data 4b.

When a signal as shown in FIG. 4A is input as the demodulated analog data signal 1a (the broken line indicates that the transmission line is not distorted), the determination means 4 operates as follows. .. First, the conversion data 1b at the identification point Tso
Is considered to be in the vicinity of the threshold voltage Vt by the threshold detection circuit 43, and the within-threshold signal 43b is output. Therefore, as the output of the selection circuit 44, the determination signal 42b which is the output of the waveform determination circuit 42 is output as the identification data 4b. The determination signal 42b is determined according to the following from the polarity holding data 41b before and after the identification point Tso.

That is, the information indicating the slope of the waveform before and after the identification point Tso is the polarity holding data 41b as the shift register 41.
Held in. In this case, information (−, −) is held before and after the identification point Tso. Therefore, the demodulated analog data signal 1a monotonically decreases in the vicinity of the discrimination point Tso, and it is judged that the amplitude should be smaller than the threshold voltage Vt, and L level data is output as the judgment signal 42b. This signal becomes the identification data 4b which is the output of the selection circuit 44.

Similarly, when the demodulated analog data signal 1a as shown in FIG. 4 (b) is input, information (+, +) is held in the shift register 41 as the polarity holding data 41b before and after the identification point Tso. There is. Therefore, the demodulated analog signal data 1a monotonically increases in the vicinity of the discrimination point Tso, and if it is originally determined that the signal should have an amplitude smaller than the threshold voltage Vt, the H-level data is the determination signal 4.
2b and becomes the identification data 4b which is the output of the selection circuit 44.

[0019]

As described above, according to the present invention, the demodulated analog data signal is inputted and the clock reproducing means for reproducing the sampling clock synchronized with the input signal and the sampling clock which is the output of the clock reproducing means are provided. A / D for A / D converting the analog data signal
Conversion means and a difference means for sequentially taking the difference between the conversion data output from the A / D conversion means and the conversion data immediately before, and outputting the polarity information of the difference result as a polarity signal;
One input of the polarity signal, which is the output signal of this difference means,
When the converted data is used as the other input, and when the converted data is discriminated at the identification point, and the size of the converted data falls within a certain threshold range, the sample points before and after the identification point are detected. Distinguishing on the basis of the information of the polarity signal, and by providing a determining means for outputting identification data, distortion and the like on the transmission line affect the amplitude and phase of the demodulated analog data signal, and in the vicinity of the threshold voltage. Even when it is difficult to identify the data, it is possible to perform the data identification more reliably than the conventional data identification based on the majority decision based on the magnitude of the amplitude.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a data identification device according to the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional data identification device.

FIG. 3 is a block diagram showing a relationship between a demodulated analog signal and an identification point.

FIG. 4 is a diagram showing a relationship between a demodulated signal affected by distortion or the like on a transmission path and a threshold voltage.

FIG. 5 is a block diagram showing a slightly detailed configuration of the determination means in the embodiment of the present invention.

[Explanation of symbols]

 1 A / D conversion means 2 Clock reproduction means 3 Difference means 4 Judgment means 5 Majority decision judgment means 41 Shift register 42 Waveform judgment circuit 43 Threshold detection circuit 44 Selection circuit 47 Frequency divider circuit

Claims (1)

[Claims] 1. A clock reproduction means for inputting a demodulated analog data signal and reproducing a sampling clock synchronized with the input signal, and the analog data signal A according to the sampling clock output from the clock reproduction means. A / D conversion
A / D conversion means, a difference means for sequentially taking the difference between the conversion data output from the A / D conversion means and the previous conversion data, and outputting the polarity information of the result of the difference as a polarity signal. One input of the polarity signal, which is the output signal of the means,
When the converted data is used as the other input, and when the converted data is discriminated at the identification point, and the size of the converted data falls within a certain threshold range, the sample points before and after the identification point are detected. A data discriminating device comprising: a discriminating means for discriminating on the basis of information of a polarity signal and outputting discrimination data.