JPS6026472B2 - Earthquake judgment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an earthquake determination method, and in particular to an earthquake determination method for identifying and extracting seismic waves from steady ground motion noise (crown noise) detected by an earthquake sensor. Regarding the method.

Problems to be Solved by the Subsidiary Technology and the Invention A conventional earthquake determination method will be explained with reference to FIG.

First, the digital input signal Si sent from the seismic telemeter is supplied to the obijo wave generator 3, which passes only the component to be observed and outputs the output signal Si' to the absolute value circuit 4. supply An absolute value circuit (rectifier circuit) 4 using a rectification function outputs an absolute value signal ISi'l of the signal Si'. This absolute value signal ISi'l is supplied to the short-time moving average circuit 6, and the moving average value Ss obtained by short-time sampling is supplied to the short-time moving average circuit 6.
(In this specification, the symbol - indicates an average value). Also, the absolute value signal ISi′l
is also supplied to the long-term moving average circuit 5 through the switching circuit 51, and the moving average value SI is determined by long-term samples. This moving average value SI based on long-time samples can be viewed as average ground motion noise. During the period when the comparator circuit 7 is outputting the output TG, that is, during the period when it is determined that there is an earthquake, the switching circuit 51' is open and a large sample input signal is not supplied to the long-term moving average circuit 5. The output of the long-term moving average circuit 5 is maintained at approximately the average ground motion noise level before the occurrence of the earthquake. A coefficient Q is added to the output signal SI of the long-term moving average circuit 5 in a multiplication circuit 71 to obtain an earthquake determination level signal TI. Here, the value of Q is determined by the threshold distribution of the instantaneous value of ground motion noise. In the comparison circuit 7, the earthquake determination level signal TI is compared with the short-time moving average value Ss, and when it is SsZTI, it is determined that it is an earthquake wave and a trigger output TG is issued. This trigger output TG is also used as a control signal to the switching circuit 51 as described above. An example of the signal waveform in the circuit of FIG. 3 is shown in FIG. If the above-mentioned process is performed by digital signal processing by a processor or the like, equivalent noise is generated mainly in the microwave processing in the microwave generator 3 due to calculation errors such as multiplication.

That is, as shown in FIG. 3, the width (dynamic range) of the input signal Si that can be handled varies from the encoder overload level Simax to the Toyoko noise level Nq.
However, for the input signal Si' after undergoing the furnace wave processing by the furnace wave generator 3, the width of the signal that can be handled is from Srmax to the noise level NI based on the calculation error in the furnace wave generator. Reduced. Here, Nq
The level difference between and Sjmax is 2obbuwani etc. gS band aX [dB
]. In this case, if the calculation is performed using the fixed-point method and the order of the wave generator is increased, NI becomes considerably larger than Nq.
The difference in q is calculated as the logarithm of the legs and reaches about 40 [dB].

Under the above conditions, if the ground motion noise level SI is lower than the calculation error noise level NI in the system shown in Figure 3, the seismic noise temperature SI will be masked by the calculation error noise level NI, making it difficult to accurately determine seismic waves. can't do it. However, in order to avoid the above-mentioned masking phenomenon by making the ground noise level SI higher than the calculation error noise level NI, it is possible to increase the range of seismic waves to be observed from Simax to Q・N.
1 (Q is a certain constant),
This is not a good idea as it will hinder the effective use of the handleable signal width secured in the observation system. Therefore, as a countermeasure for the above-mentioned inconvenience, it is possible to perform signal level conversion and subtract a certain coefficient A having a value of 1 or more to the input signal Si to make the ground motion noise level higher than the calculation error level. It is being done.

This method is shown in the level diagram of FIG. 5, with the level of Si on the left and the level of A multiplied by A on the right. It is expressed as a relationship between the Si levels. In addition, if the Si on the left side of the 3rd peak is greater than or equal to the cape X, the corresponding A on the right side will be smaller. Although the level of Si exceeds Sin x, in order to judge an earthquake, it is sufficient to judge whether the instantaneous value force level exceeds 1', and since n' is less than Simax in Fig. 5, it is necessary to judge the earthquake. It is possible. however,
In the conventional type shown in FIGS. 3 and 5, ground motion noise is not steady because it depends on weather conditions, etc.
The constant Q also depends on the distribution of the ground sardine noise level SI instantaneous value, so it may change during the course of operation.

Therefore, SI' becomes less than or equal to NI, or n' becomes S
There is a problem in that a situation in which I'max is exceeded makes it difficult to make accurate trigger determination. SUMMARY OF THE INVENTION An object of the present invention is to provide an earthquake determination method capable of appropriately determining a trigger even when ground motion noise is unsteady, in view of the problems of the conventional method described above.

Means for Solving the Problems In the present invention, an input signal from an earthquake detection section is input to a reactor wave circuit to extract a component to be observed, and an absolute value circuit receiving the output of the reactor wave circuit extracts the absolute value. ,
A long-term moving average value of the absolute value is determined in a long-term moving average value circuit that receives the output of the absolute value circuit via an opening/closing circuit, and a long-term moving average value of the absolute value is determined in a short-time moving average value that receives the output of the absolute value circuit. A short-time moving average value is obtained, and a comparison circuit that receives the signal on the output side of the chairman time moving average value circuit and the output signal of the short-time moving average circuit compares both signals to distinguish between ground noise and seismic waves. In the earthquake determination method, the input signal is amplified by a variable gain amplifier circuit and applied to a reactor wave circuit, and the gain of the variable gain amplifier circuit is adjusted based on the long-term moving average circuit output and the allowable noise level range. An earthquake determination method is provided which is characterized in that it is controlled by the output of a gain circuit control circuit based on comparison with a given predetermined reference value.

Embodiment A circuit diagram of a device used in an earthquake determination method as an embodiment of the present invention is shown in FIG.

In the circuit of FIG. 1, as in the case of FIG. 7 is provided. In the circuit shown in FIG. 4, a variable gain amplifier circuit 2 is further connected to the front stage of the furnace wave circuit 3, and the gain of the variable gain amplifier circuit is determined by comparing the output of the long-term moving average circuit 5 with a set value 81. It is controlled by the output signal of the gain control circuit 9 which is controlled by the result of . The gain of the variable gain amplifier circuit is A, and the long-time moving average circuit 5
Let the output of SI' be SI', and the set value by the set value circuit 81 be N
Let it be I+B. Here, 8 is a certain constant, and the set value is a reference value given by the allowable noise level range. Then, the gain of the variable gain amplifier circuit is controlled so that SI' becomes approximately equal to NI+3. The reason for this is that the amplitude of ground motion noise changes greatly depending on the atmospheric pressure, such as increasing as the atmospheric pressure decreases, so it may become difficult to distinguish between ground motion noise and seismic waves.To avoid this,
This is because it is necessary to suppress the long-term moving average value of ground motion noise to a certain value or less. The circuit in Figure 1 has SI′ and NI+
It operates to increase or decrease A so that the difference between 6 and 6 becomes zero.
In other words, when SI=NI13, A is not changed, but when SI>NI10P, A is decreased and SI<NI1
If it becomes +8, increase A. That is, as shown in FIG. 2, the gain A is controlled so that SI becomes a level NI18, which is slightly higher than NI, and accurate trigger determination processing is performed. Effects of the Invention According to the present invention, an earthquake determination method can be obtained that can perform appropriate trigger determination even when ground motion noise is unsteady.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a device used in an earthquake determination method as an embodiment of the present invention, Fig. 2 is an operation explanatory diagram explaining the operation of the circuit shown in Fig. 1, and Fig. 3 is a follower-type earthquake judgment method. A circuit diagram of the device used in the method, Fig. 4 is a waveform diagram showing the waveform of seismic waves, Fig. 5 is an operation explanatory diagram explaining the operation of the circuit shown in Fig. 1,
It is. 1: Signal input terminal, 2: Variable gain amplifier circuit, 3: Furnace wave circuit, 4: Absolute value circuit, 5: Long-term moving average circuit, 51:
Opening/closing circuit, 6: Short-time moving average circuit, 7: Comparison circuit, 7
1: Multiplication circuit, 8: Comparison circuit, 81: Setting value circuit, 9:
Gain control circuit. Figure 3 Figure 4 Sphere Figure 2 Figure 5

Claims (1)

[Claims] 1. Input the input signal from the earthquake detection unit into a filter circuit, extract the component to be observed, convert it into an absolute value in an absolute value circuit that receives the output of the filter circuit, and convert the output of the absolute value circuit into an open/close circuit. A long-term moving average value of the absolute value is determined in a long-term moving average value circuit that receives the output from the absolute value circuit, a short-term moving average value of the absolute value is determined in a short-term moving average value that receives the output of the absolute value circuit, and A comparator circuit that receives the signal on the output side of the time moving average value circuit and the output signal of the short time moving average circuit compares both signals, and makes an earthquake determination based on the discrimination between ground motion noise and seismic waves. In the determination method, the input signal is amplified by a variable gain amplifier circuit and applied to a filter circuit, and the gain of the variable gain amplifier circuit is set to a predetermined reference value given by the long-time moving average circuit output and the allowable noise level range. An earthquake determination method characterized by control based on the output of a gain circuit control circuit based on a comparison with