JP2000074968A - Signal detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a signal detector capable of removing noise pulses with a short pulse width having the same polarity as a signal pulse to be measured and the same pulse height. SOLUTION: The signal detecter is provided with a wave height analysis means 2 analyzing the pulse height value of input pulse, a pulse width analysis means 3 analyzing the pulse width of the input pulse and a gate means 4 shielding the output of the pulse-height analysis means 2 according to the analysis results of the pulse width. Here, it is desired to provide a pulse-height discriminator, a single channel pulse-height analyzer or a multichannel pulse-height analyzer as a crest height analyzer means 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal detection device which discriminates between a signal pulse and a noise pulse and detects only the signal pulse, for example, in counting a signal pulse of a radiation monitoring device.

[0002]

2. Description of the Related Art Conventionally, as this type of signal detecting device, for example, there has been one shown in FIG. In FIG. 9, 1 is an input terminal, 6 is a wave height discriminator connected to the input terminal 1, 7 is a monostable circuit connected to the output of the wave height discriminator 6, and 5 is connected to the output of the monostable circuit 7. Output terminal.

FIG. 10 shows the signal waveforms of the sections A to C in FIG. 9. In FIG. 10, b denotes the discrimination voltage of the pulse height discriminator 6, and c denotes the return voltage of the pulse height discriminator 6. When the pulse signal a is input to the input terminal 1, the wave height discriminator 6 has the same polarity as the signal pulse to be detected, and the output is inverted when the wave height crosses the discrimination voltage b at the fall of the pulse,
When the wave height returns to the return voltage c, the output is restored, and a pulse d is output during that time. Therefore, the noise pulse e having a small wave height can be removed. The monostable circuit 7 receives the output pulse d of the pulse height discriminator 6, is triggered by the falling edge of the pulse, and outputs a pulse f having a constant pulse width to the output terminal 5.

[0004]

Since the conventional signal detector is constructed as described above, in the example of FIG. 10, the pulse width having the same polarity and the same wave height as the signal pulse a to be detected is used. There is a problem that the noise pulse g having a short pulse width or the noise pulse h having a long pulse width cannot be removed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to obtain a signal detection device for reliably removing noise pulses.

[0006]

According to the present invention, there is provided a signal detecting apparatus comprising: a pulse height analyzing means for analyzing a peak value of an input pulse; a pulse width analyzing means for analyzing a pulse width of the input pulse; According to the analysis result of the pulse width,
A gate means for cutting off the output of the wave height analyzing means so as to take out only a signal pulse from an output terminal.

In the above configuration, a wave height discriminator is provided as wave height analyzing means.

Further, a single channel wave height analyzer is provided as wave height analyzing means.

In addition, a multi-channel wave height analyzer is provided as wave height analyzing means.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 shows Embodiment 1
1 is an input terminal, 2 is a pulse height analysis unit connected to the input terminal 1, 3 is a pulse width analysis unit connected to the input terminal 1 in parallel with the pulse height analysis unit 2, Reference numeral 4 denotes a gate circuit having a signal input terminal connected to the output of the pulse height analyzer 2 and a control input terminal connected to the output of the pulse width analyzer 3, and 5 denotes an output terminal connected to the gate circuit 4.

Next, the operation will be described. Now, when a pulse signal is input to the input terminal 1, the wave height analyzing unit 2 analyzes the wave height and outputs a wave height analysis result. On the other hand, the pulse width analyzer 3 analyzes the pulse width and outputs a one-shot pulse only when the set condition is satisfied. Gate circuit 4
Inputs the output pulse of the pulse width analyzer 3 to the control input, temporarily releases the gate, and takes in the analysis result of the pulse height analyzer 2 from the signal input and passes it. The result of the wave height analysis that has passed through the gate circuit 4 is output from the output terminal 5.

As described above, according to the first embodiment of the present invention, noting that the signal pulse has an inherent pulse width, the means for analyzing the pulse width and blocking the noise pulse is provided. Therefore, a pulse having a short pulse width and a pulse having a long pulse width other than the signal pulse to be measured can be excluded as noise pulses.

Embodiment 2 FIG. Embodiment 2 of the present invention will be described with reference to FIG. FIG. 2 is a block diagram showing a signal detection device according to the second embodiment.
Is a first pulse height discriminator connected to the input terminal 1, 22 is a first monostable circuit connected to the output of the first pulse height discriminator 21, and 31 is an input in parallel with the first pulse height discriminator 21. A second pulse height discriminator connected to terminal 1; 32, a second monostable circuit connected to the output of second pulse height discriminator 31;
, A delay circuit connected to the output of the second wave height discriminator 31 in parallel with the monostable circuit 32, a timer circuit 34 connected to the output of the delay circuit 33, and a delay circuit 35 connected to the output of the timer circuit 34. 3 is a monostable circuit, 36 is an AND circuit connected to the output of the second monostable circuit 32 and the output of the third monostable circuit 35, and 37 is a fourth monostable connected to the output of the AND circuit 36. The circuit 4 is a gate circuit to which the output of the first monostable circuit 22 is applied to its signal input terminal and the output of the fourth monostable circuit 37 to its control input terminal. Reference numeral 5 denotes an output terminal connected to the gate circuit 4.

FIG. 3 shows signal waveforms of the A to K portions in FIG. 2. In FIG. 3, b denotes the first wave height discriminator 2.
1 is a discrimination voltage, c is a return voltage of the first wave height discriminator 21 and the second wave height discriminator 31, and i is a second wave height discriminator 31.
Is the discrimination voltage.

Next, the operation will be described. When the pulse signal a is input to the input terminal 1, the first wave height discriminator 21 has the same polarity as the signal pulse to be detected, and the output is inverted when the wave height crosses the discrimination voltage b at the falling edge of the pulse. When the wave height returns to the reset voltage c, the output returns, and during that time, the pulse d
Is output. The first monostable circuit 22 receives the output pulse d of the first pulse height discriminator 21, is triggered by the falling edge of the pulse, and outputs a pulse f having a constant pulse width.

The discrimination voltage i of the second pulse height discriminator 31 is set so that the noise pulse height e and the discrimination voltage b of the first pulse height discriminator 21 have a relationship of e <i ≦ b. The polarity is the same as that of the signal pulse a to be tried, and when the wave height exceeds the discrimination voltage i, the output is inverted. When the wave height returns to the reset voltage c, the output is restored, and a pulse j is output during that time.
The second monostable circuit 32 receives the output pulse j of the second pulse height discriminator 31, is triggered by the falling edge of the pulse, and outputs a pulse k having a constant pulse width.

The delay circuit 33 receives the output pulse j of the second pulse height discriminator 31, delays the fall of the pulse j, and outputs a pulse m. The timer circuit 34 receives the output pulse m of the delay circuit 33, starts at the rising edge of the pulse m, inverts when the set time is reached, and outputs a pulse n reset at the falling edge of the pulse m. Third
The monostable circuit 35 receives the output pulse n of the timer circuit 34, is triggered by the rise of the pulse, and outputs a pulse p having a constant pulse width.

The AND circuit 36 is connected to the second monostable circuit 32
Output pulse k and output pulse p of the third monostable circuit 35
The pulse q is output under the AND condition of The fourth monostable circuit 37 receives the output pulse q of the AND circuit 36, is triggered by the rise of the pulse, and outputs a pulse r having a constant pulse width.

The gate circuit 4 inputs the output pulse r of the fourth monostable circuit 37 to the control input terminal, temporarily releases the gate cutoff, and outputs the output pulse f of the first monostable circuit 22 as a signal. Take it in from the input end and let it pass. The output pulse f that has passed through the gate circuit 4 is output from the output terminal 5. Note that the first pulse height discriminator 21 may be inverted at the rise instead of the fall of the signal pulse.

As described above, according to the second embodiment of the present invention, since the signal pulse and the noise pulse are distinguished by both the pulse height and the pulse width, they have the same polarity as the signal pulse to be detected. Noise pulses g, h with equivalent wave height
Can also be reliably removed.

Embodiment 3 Third Embodiment A third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a block diagram showing a signal detection device according to the third embodiment.
7 is the same as that of the second embodiment. In the third embodiment, the discrimination voltage b of the first pulse height discriminator 21 and the discrimination voltage i of the second pulse height discriminator 31 in the second embodiment are set to e <i.
= B, that is, in the case of a limited use in which a signal having a peak value higher than a normal noise level is discriminated as a signal, the second embodiment is omitted from the embodiments 21, 22, and 4 to provide a simple configuration. It was done. For the operation,
The operation is the same as the operation of 31 to 37 of the second embodiment.

Embodiment 4 Embodiment 4 of the present invention will be described with reference to FIG. FIG. 5 is a block diagram showing a signal detection device according to the fourth embodiment. In the figure, 23
Is a single channel wave height analyzer connected to the input terminal 1, and the other 1, 4, 5, 22, 31 to 37 are the same as those in the second embodiment.

FIG. 6 shows the signal waveforms of the portions A to C in FIG. 5. In FIG. 6, L is the discrimination voltage on the lower limit side of the window of the single channel peak height analyzer 23, and U is the upper limit side of the window. Discrimination voltage.

Next, the operation will be described. When the pulse signal a is input to the input terminal 1, the single-channel pulse height analyzer 23 has the same polarity as the signal pulse to be detected,
The pulse s is output only when the wave height is in the window between the discrimination voltages L and U. The peak value of the pulse is the upper limit level U
, A pulse x is generated in addition to the pulse d due to the level L and the reference voltage. A pulse y having a polarity opposite to that of the pulse x is generated, and the pulse d and the pulse y are ANDed. Pulse s is not generated. Other operations are the same as those of the second embodiment.

As described above, according to the fourth embodiment of the present invention, the signal pulse and the noise pulse can be discriminated from the single-channel pulse height analyzer to remove the noise pulse.

Embodiment 5 Embodiment 5 of the present invention will be described with reference to FIG. FIG. 7 is a block diagram showing a signal detection device according to the fifth embodiment. Reference numeral 24 denotes a multi-channel pulse height analyzer whose input side is connected to the input terminal 1 and whose output side is connected to the gate circuit 4.
Reference numerals 31 to 37 are the same as those in the second embodiment.

FIG. 8 shows signal waveforms of the portions A and B in FIG. Now, when the pulse signal a is input to the input terminal 1, the multi-channel peak analyzer 24 peak-holds the peak value V of the signal pulse a to be detected and discharges it (FIG. 8A). By counting the clock pulses at this time (FIG. 8A), the peak value is converted into the number of pulses and output. Other operations are the same as those of the second embodiment.

As described above, according to the fifth embodiment of the present invention, a signal pulse and a noise pulse can be distinguished and a noise pulse can be removed even by using a multi-channel pulse height analyzer.

[0029]

As described above, according to the present invention, only the signal pulse is detected from the input signal in which the signal pulse and the noise pulse are mixed, so that the signal pulse can be detected even in a noisy environment. There is an effect that detection and counting can be performed stably. As a result, the present invention is particularly effective when applied to, for example, a radiation monitoring device or a nuclear reactor instrumentation device, which requires highly reliable signal pulse counting.

Further, in a system using a composite sensor in which radiation sensors having different light emission decay times are combined, the present invention is also useful when discriminating a difference in pulse width and performing counting for each sensor.

Further, the present invention can also be used in a case where an index light source or the like is embedded in the radiation detector and online diagnosis is performed without affecting the measurement of the target radiation.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a signal detection device according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram showing a signal detection device according to Embodiment 2 of the present invention.

FIG. 3 is a diagram showing signal waveforms at various parts of a signal detection device according to a second embodiment.

FIG. 4 is a block diagram showing a signal detection device according to Embodiment 3 of the present invention.

FIG. 5 is a block diagram showing a signal detection device according to Embodiment 4 of the present invention.

FIG. 6 is a diagram illustrating signal waveforms at various parts of a signal detection device according to a fourth embodiment.

FIG. 7 is a block diagram showing a signal detection device according to Embodiment 5 of the present invention.

FIG. 8 is a diagram showing a signal waveform of each part of the signal detection device according to the fifth embodiment.

FIG. 9 is a block diagram showing a conventional signal detection device.

FIG. 10 is a diagram showing a signal waveform of each section of a signal detection device of a conventional example.

[Explanation of symbols]

1 input terminal, 2 pulse height analyzer, 3 pulse width analyzer,
4 gate circuit, 5 output terminals, 21 first pulse height discriminator, 22 first monostable circuit, 23 single channel pulse height analyzer, 24 multi-channel pulse height analyzer, 3
1 second pulse height discriminator, 32 second monostable circuit, 33
Delay circuit, 34 timer circuit, 35 third monostable circuit, 36 AND circuit, 37 fourth monostable circuit.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G035 AA08 AB09 AB11 AB13 AC05 AC12 AD23 AD27 AD49 AD50 AD61 2G088 EE06 EE21 EE25 FF09 GG01 GG09 GG21 KK01 KK02 KK28 LL06 LL11 5J039 BB04 BB14 KK02 KK10 KK13 KK13

Claims (4)

[Claims] 1. A pulse height analyzing means for analyzing a peak value of an input pulse, a pulse width analyzing means for analyzing a pulse width of the input pulse, and the pulse height analysis in accordance with a result of the pulse width analysis. And a gate means for cutting off the output of the means. 2. The signal detecting apparatus according to claim 1, further comprising a wave height discriminator as wave height analyzing means. 3. The signal detecting apparatus according to claim 1, further comprising a single-channel wave height analyzer as the wave height analyzing means. 4. The signal detecting device according to claim 1, further comprising a multi-channel wave height analyzer as wave height analyzing means.