JPS592357B2 - seismograph system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a seismograph system whose characteristics can be arbitrarily converted.

Normally, the recorded waveform of a seismometer differs depending on the frequency characteristics and braking characteristics of the sensor.

That is, assuming a sensor with a resonant frequency ω and a damping coefficient, its characteristics will be a curve as shown in FIG. 1 a or b.

Here, figure a shows the response of the velocity vibrometer,
This is the case when the braking coefficient hIJ″−h>1.

In this case, if the resonance frequency ω is selected so that the frequency of the earthquake falls within region A of the characteristic curve, the relative motion between the pendulum and the ground surface will correspond to the vibration speed of the ground surface.

Also, Figure 1 shows the response of the acceleration vibrometer.
h<i, and the seismic frequency is in region B.
If the resonance frequency ω is selected so as to fall within the range C, a relative movement will be made corresponding to the displacement of the ground surface, and if it is selected to fall within region C, a relative motion will be made corresponding to the vibration acceleration of the ground surface.

Also, when converting this relative motion of the pendulum into an electrical signal,
There are two formats: one that outputs the data as is, and one that outputs the amount of change.

Therefore, even when observing the same earthquake, the waveforms output vary depending on the type of seismograph.

Since seismic data is useful only when data from multiple observation points are combined, it goes without saying that it is desirable that the seismographs at each observation point be of the same type.

Furthermore, if the resonance frequency ω and damping coefficient are incorrectly selected in the seismograph, the resulting output waveform will be significantly distorted, so it is necessary to strictly select them.

Therefore, a seismometer in which the above-mentioned resonance frequency ω and damping coefficient can be selected and changed to arbitrary values at any time is an ideal seismometer.

The present invention aims to provide the above-mentioned ideal seismograph system by introducing the concept of a virtual seismograph.

A detailed explanation will be given below based on examples.

FIG. 2 is a block diagram showing one embodiment of the present invention.
is a real seismograph, 2 is an n multiplier, 3 is a virtual seismograph, and 4 is an adder.

Here, the real seismometer 1 has a resonant frequency ω1 and a damping coefficient h1
An actual seismometer has frequency characteristics and damping characteristics, and if y is the true acceleration waveform of ground vibration, an output waveform is output as an electric signal according to the equation of motion shown in Equation 1.

In this case, the actual seismograph 1 outputs the vibration of the pendulum as it is converted into an electrical signal, where X is the relative displacement, Xl is the relative velocity, and the stone is the relative force [output corresponding to the velocity]. It is a waveform.

Here, m in Equation 1 is a constant determined by the type of seismograph.0 The output of this actual seismograph 1 can be various as described above, but the output of the first seismograph in this embodiment is Then, X□ for displacement
This example shows what outputs .

This signal X0 is multiplied by a constant n determined by the output format of the real seismograph 1 and the virtual seismograph 3 by the n-fold circuit 2 and is input to the virtual seismograph 3. Specifically, this constant n is It is expressed by the resonance frequencies ω□, ω2 of the position hands 1 and 3 and the damping coefficients he, h2, and Table 1 shows the constant n in each case.

The virtual seismograph 3 is a device that simulates a seismograph using, for example, a microcomputer, and its resonance frequency ω2 and damping coefficient ih2 can be determined extremely easily by simply inputting desired values as constants into the microcomputer, etc. Any value can be set.

In this virtual seismograph 3, the equation of motion shown by the following two formulas is solved based on the input nX1, and the displacement output x21 velocity output length2, acceleration output''
Output y:2.

Here, as a second example, if the actual seismograph 1 converts the change in the relative motion of a pendulum into an electrical signal, for example, the relative motion of the pendulum is converted into electricity and output. If electromagnetic induction is used, even if the relative motion of the pendulum is proportional to the displacement of the ground, the output will be proportional to the velocity of the ground.

Since the relative motion of the pendulum cannot be made to be proportional to the integral of the displacement of the ground, there are output formats that correspond to velocity and acceleration, but no output format that corresponds to displacement.

At this time, the virtual seismograph 3 is given nA1, which is the output slope of the real seismograph 1 multiplied by n by the n-times circuit 2, as an input, and solves the equation of motion shown in equation 3. Here, 3 The right side of the equation is isomorphic to the right side of equation 2, but since the input -i1 corresponds to the speed, the obtained
2 corresponds to velocity and X2 corresponds to acceleration.

Therefore, an output f x 2 d t corresponding to the displacement is also required.

Further, the constant n in the n-fold circuit 2 in this case has the values shown in Table 2.

Each output of the virtual seismograph 3 is sent to an adder 4, where a predetermined constant is calculated, added, and output as an output signal X.

The calculations performed in this adder 4 can be expressed as equations 4 or 5.

Equation 4 is an arithmetic expression used in the first example in which the real seismometer 1 converts the relative motion of the pendulum directly into an electrical signal, and Equation 5 is the equation used when the real seismometer 1 converts the relative motion of the pendulum into an electrical signal. This is an arithmetic expression used in the second example, which is a format in which a change is converted into an electrical signal.

Therefore, the resonant frequency ω of the actual seismometer 1 and the damping coefficient h□, which have been measured in advance, are input into the adder 4 in advance as constants necessary for its calculation.

Also, in the first example, the constant n in the n-fold circuit 2 is the first
The values shown in the table are used, and in the case of the second example, the values shown in Table 2 are used.

The output X of the adder 4 is the output waveform that will be output in response to the true acceleration waveform y of the ground vibration that is input to the system when the entire system shown in Fig. 2 is made into one seismograph system. be.

In other words, from the total of equation 1 H-"Tlf, --me4 child line 2 equations, substituting these equations (5 of 3), (5 of 4), and (5 of 5) into equation (5 of 2), we get 2 Considering the arithmetic expression 4 used in the first example in the case of expressions, (
5-6) Equation becomes.

Also, from equation 3, (6-2), (6-31). Substituting equation (6-4) into equation (6-2), considering equation 5 used in the second example in the case of equation 3, (
Equation 6-5) becomes.

As can be seen from Equation 6, the characteristics of this seismograph system are determined by the resonance frequency ω2 set in the virtual seismograph 3. Governed only by the damping coefficient h2, the resonant frequency ω□ of the real seismometer 1,
This is unrelated to the braking coefficient h0.

That is, in the seismograph system shown in FIG. 2, its characteristics can be arbitrarily selected.

As explained in detail above, according to the present invention, the output format of this seismograph system can be arbitrarily selected by appropriately selecting the constant n in accordance with the format of the actual seismograph being used. Furthermore, the resonant frequency and damping coefficient, which determine the characteristics of this seismograph system, can be easily set and changed as mentioned above, so by selecting the optimal value at any time, it can be adjusted according to the true frequency of ground vibration. It is no longer difficult to reduce the distortion of the output waveform to the utmost limit, and therefore it becomes possible to provide an ideal seismograph system.

Furthermore, in the embodiment shown in Fig. 2, the n-fold circuit, the virtual seismograph, and the adder are separated like a bird wafer, but the present invention is not particularly limited to this, and the output of the real seismograph is separated from the real seismograph. A function that multiplies a constant n determined in the form of the virtual seismograph function described later, a virtual seismograph function that simulates an seismograph using an arbitrarily selectable resonance frequency and damping coefficient, and various outputs from the virtual seismograph function. As long as it has the function of multiplying the vibration output by the resonant frequency of the actual seismometer and a constant derived from the damping coefficient and then adding these together, it may be integrated as a whole using a single microcomputer or the like.

Furthermore, it goes without saying that these can also be realized by analog circuits.

[Brief explanation of drawings]

Figure 1 is a characteristic curve to explain the type of seismograph, Figure 2
The figure is a block diagram showing one embodiment of the present invention. 1...Actual seismometer, 2...n-fold circuit, 3
...Virtual seismograph, 4...Addition i

Claims (1)

[Claims] 1. An actual seismometer that detects ground motion and converts it into an electrical signal waveform. The vibration waveform is input as an electrical signal, has arbitrarily settable frequency characteristics and dynamic characteristics, and a seismometer is simulated based on these. a virtual seismograph function, a function for multiplying the output of the real seismograph by a constant determined by the format and characteristics of the real seismograph and virtual seismograph functions, and inputting this into the virtual seismograph function; A seismometer system consisting of a device that has a function of multiplying various output signals outputted from the simulated results of the seismometer function by a constant derived from the frequency characteristics and damping characteristics of an actual seismometer, and adding these together.