JP4223984B2 - Dynamic characteristic simulation method, apparatus, and program - Google Patents

Description

  The present invention relates to a technique for simulating the dynamic characteristics of the indicated value of a measuring instrument, and in particular, electrically indicates the indicated value of a needle of a measuring instrument, such as a needle-type VU meter or a sound level meter, whose rising characteristics and time constants are defined. The present invention relates to a method, an apparatus, and a program for simulating.

Conventionally, there has been an integration circuit using L, C, and R as a method for electrically simulating the indicated value of the VU meter (see Non-Patent Document 1), but this simulator uses a single time constant for the VU meter. It was an approximation. There is also a method of simulating a VU meter using a computer (see Non-Patent Document 2), but this method considers an arithmetic mean value of sample data as an indication value of the VU meter, and the operation of the VU meter The characteristics were not accurately simulated.
None of the methods accurately simulates the characteristics of the needle of the needle-type VU meter, taking into account the mass of the needle itself and the influence of a braking device for preventing the needle from shaking too much.

Mitsuyuki Shibata, “Average loudness of program sound and volume level by VU meter”, NHK Technology Research, Vol. 22 No. 5 (Vol. 120), p. 433-439, 1970

Takashi Saito, “Analysis of VU meter indication value of program sound and volume feeling”, NHK 52nd Headquarters, Kanto Koshinetsu Regional Technical Report, p. 47-48, (September 2-3, 1999)

  With the spread of LEDs and computer graphics, not only needle-type VU meters and noise meters with mechanical mechanisms but also many types of meters that electrically display measured values on LEDs and CRTs. Yes. However, it has not been possible to accurately simulate the characteristics of the needle-type VU meter, noise meter, etc., taking into account the mass of the needle itself and the effect of the braking device to prevent the needle from shaking too much.

  The present invention has been made in view of such problems, and an object of the present invention is to prevent the mass of the needle itself of a measuring instrument such as a needle-type VU meter or a sound level meter, or excessive needle deflection. It is an object to provide a dynamic characteristic simulation method, apparatus, and program capable of accurately simulating characteristics in consideration of the influence of a braking device or the like.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.

(1) A method for simulating a dynamic characteristic of an indication value of a measuring instrument, an average value calculating step for calculating an average value of absolute values of an input signal that can be measured by the measuring instrument every fixed time ΔT, and the average value calculating step A simulation is performed using the output level Vo (n) corresponding to the nth input level Vi (n) calculated in step S3 and the n + 1th input level Vi (n + 1) calculated in the average value calculating step. A time constant setting step for setting a coefficient a corresponding to one of a plurality of time constants τ that approximates the time constant of the indicated value of the measuring device that is the target of the input level Vi (n + 1) ), The output level Vo (n), and the coefficient a set in the time constant setting step, the output level Vo (n + 1) corresponding to the input level Vi (n + 1) is obtained. A dynamic characteristic simulation having a calculation step Is the method.

(2) A dynamic characteristic simulation apparatus for simulating the dynamic characteristic of the indicated value of the measuring instrument, and an average value calculating unit that calculates an average value of absolute values of the input signal that can be measured by the measuring instrument every certain time ΔT; The output level Vo (n) corresponding to the nth input level Vi (n) calculated by the average value calculation unit, and the input level Vi (n + 1) calculated n + 1 by the average value calculation unit , And a time constant setting unit that sets a coefficient a corresponding to one of a plurality of time constants τ that approximates the time constant of the indicated value of the measuring instrument that is the object of simulation, and the input level The output level Vo (n) corresponding to the input level Vi (n + 1) using Vi (n + 1), the output level Vo (n), and the coefficient a set by the time constant setting unit. n + 1).

  (3) In the dynamic characteristic simulation apparatus according to (2) described above, the output level Vo (n) calculated by the calculation unit is updated and displayed every certain time ΔT.

(4) In the dynamic characteristic simulation apparatus according to (2) or (3) described above, the time constant setting unit calculates a coefficient a corresponding to the time constant τ by a = e ^{(−ΔT / τ)} .

  (5) In the dynamic characteristic simulation apparatus according to any one of (2) to (4), the calculation unit sets the output level Vo (n + 1) to Vo (n + 1) = a ×. Calculated as Vo (n) + (1-a) × Vi (n + 1).

  (6) In the dynamic characteristic simulation apparatus according to any one of (2) to (5) described above, the average value calculation unit varies a predetermined time ΔT for calculating an average value of absolute values of the input signal. I made it.

  (7) In the dynamic characteristic simulation apparatus according to any one of (2) to (6), the time constant setting unit sets the coefficient a to the output level Vo (n) and the input level. Vi (n + 1) is compared.

  (8) In the dynamic characteristic simulation apparatus according to any one of (2) to (6), the time constant setting unit sets the coefficient a to the output level Vo (n) and the input level. This is performed depending on the result of comparison with Vi (n + 1) and the output level Vo (n).

(9) A program for operating a computer as a dynamic characteristic simulation apparatus for simulating the dynamic characteristic of the indicated value of a measuring instrument, and calculating an average value of absolute values of input signals that can be measured by the measuring instrument every certain time ΔT An average value calculating step, an output level Vo (n) corresponding to the nth input level Vi (n) calculated in the average value calculating step, and an input level Vi (n + 1) calculated in the average value calculating step. n + 1) is used to calculate a coefficient a corresponding to one of a plurality of time constants τ approximating the time constant of the indicated value of the measuring device to be simulated, a = e ^Using the time constant setting step calculated by ^{(−ΔT / τ)} , the input level Vi (n + 1), the output level Vo (n), and the coefficient a set in the time constant setting step. The input Calculation step for calculating the output level Vo (n + 1) corresponding to the bell Vi (n + 1) by Vo (n + 1) = a.times.Vo (n) + (1-a) .times.Vi (n + 1). And a display step of updating and displaying the output level Vo (n) every the predetermined time ΔT.

(10) A program for operating a computer as a dynamic characteristic simulation apparatus for simulating the dynamic characteristic of an indication value of a measuring instrument, and calculating an average value of absolute values of input signals that can be measured by the measuring instrument every certain time ΔT An average value calculating step, an output level Vo (n) corresponding to the nth input level Vi (n) calculated in the average value calculating step, and an input level Vi (n + 1) calculated in the average value calculating step. n + 1) and a plurality of time constants τ that approximate the time constant of the indicated value of the measuring device to be simulated, depending on the output level Vo (n). Time constant setting step for calculating a coefficient a corresponding to one of the following: a = e ^{(−ΔT / τ)} , the input level Vi (n + 1), the output level Vo (n), and the time constant setting Before set in step Using the coefficient a, the output level Vo (n + 1) corresponding to the input level Vi (n + 1) is expressed as Vo (n + 1) = a * Vo (n) + (1-a) * Vi ( This is a program for causing a computer to execute a calculation step calculated in (n + 1) and a display step in which the output level Vo (n) is updated and displayed every certain time ΔT.

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.
According to the present invention, it is possible to accurately simulate the characteristics of the needle-type VU meter and the noise meter needle itself, taking into account the mass of the needle itself and the influence of the braking device for preventing the needle from shaking too much.
Further, according to the present invention, for example, the dynamic characteristics of an LED-displayed VU meter can be accurately matched to the dynamic characteristics of a needle-type VU meter, and the value indicated by the needle-type VU meter can be recorded as data, To be able to analyze.

First, an outline of an embodiment of the present invention will be described.
The indication value of a measuring instrument such as a needle-type VU meter or sound level meter does not depend only on the “input voice level” that is the input signal, but both the “current indication value” and the “new incoming voice level”. Depends on. Further, the time constants of the rising characteristics and the falling characteristics change dynamically depending on the “current instruction value” and the “new incoming voice level”.

  Therefore, in the embodiment of the present invention, the digital audio signal is divided into time intervals that are sufficiently shorter than the time constants of the rising characteristics and the falling characteristics, and an output signal corresponding to an instruction value such as a VU meter is provided at each time interval. So that First, the average value of the absolute values of the sample data in one section is obtained as the input audio level, and after changing the time constant dynamically from the “input audio level” and “output level at that time”, the time A coefficient corresponding to the constant is obtained, and a “new output level” is calculated from the “input audio level”, “the output level at that time”, and the coefficient corresponding to the time constant.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment of the invention, and the repetitive description thereof is omitted.

(Embodiment 1)
FIG. 1 is a diagram showing an example of the basic configuration of a dynamic characteristic simulation apparatus according to Embodiment 1 of the present invention. In the following description, a case where an audio signal (hereinafter referred to as an input audio signal) is input as an input signal of the dynamic characteristic simulation apparatus will be described. However, the input signal is not limited to the audio signal, and the measuring device Other signals that can be measured with may be used. The output signal is a signal that simulates an instruction value of a needle type VU meter or the like.

  As shown in FIG. 1, the dynamic characteristic simulation apparatus of the first embodiment calculates an absolute value of an A / D conversion unit 1 that converts an input audio signal into a digital signal and an input audio signal that is converted into a digital signal. The absolute value part 2, the short-time average value part 3 for calculating the arithmetic mean value of the output signal of the absolute value part 2 every fixed time ΔT, and the nth output signal Vo that is the output signal before the fixed time ΔT The time constant is determined from the delay unit 4 that outputs (n), the (n + 1) th input signal Vi (n + 1) and the nth output signal Vo (n) obtained from the input audio signal, and this time constant. Corresponds to the time constant setting unit 5 that outputs the coefficient corresponding to the time constant, the (n + 1) th input signal Vi (n + 1), the nth output signal Vo (n), and the time constant that is the output of the time constant setting unit 5. Based on the coefficient, the (n + 1) th output signal Vo (n + 1) corresponding to the (n + 1) th input signal Vi (n + 1) is calculated. And an arithmetic unit 6. The absolute value portion 2 and the short time average value portion 3 may be collectively referred to as an average value calculation portion.

  The dynamic characteristic simulation apparatus according to the first embodiment includes a DSP (digital signal processor) in which an absolute value unit 2, a short-time average value unit 3, a delay unit 4, a time constant setting unit 5, and a calculation unit 6 are partly or entirely. ) Or a program stored in a CPU and a storage device.

In the dynamic characteristic simulation apparatus according to the first embodiment, an A / D conversion unit 1 converts an input voice signal into, for example, a 48 kHz, 16-bit digital signal. In the absolute value part 2, the absolute value of each sample value is calculated. Next, the short-time average value unit 3 divides the sample data every fixed time ΔT, and calculates an arithmetic average value of absolute values for each section ΔT. The time ΔT of one section may be a sufficiently short time as compared with the rise and fall characteristics (about 300 ms) of the VU meter. For example, when the sampling frequency is 48 kHz, it is practically sufficient to take an average value every 1024 samples, that is, every 1024/48000 = 21.3 ms. Note that the shorter the averaging time, the more accurately the dynamic characteristics of the VU meter can be simulated. Here, the n-th output of the short-time average value unit 3 is described as Vi (n). When the average value is calculated every 21.3 ms, Vi (n) takes a new value every 21.3 ms. The time constant setting unit 5 corresponds to the time constant using the n + 1-th value Vi (n + 1) of the short-time average value part and the value Vo (n) one section before the output signal Vo (n + 1). The coefficient a is determined, and the determination method will be described later. The calculation unit 6 uses the value of the coefficient a determined for each section. Vo (n + 1) = a * Vo (n) + (1-a) * Vi (n + 1) (1)
And the (n + 1) th output Vo (n + 1) is output.

  FIG. 2 is a diagram for explaining the operation of a circuit having a time constant τ, and FIG. 3 is a diagram for explaining the relationship between an input signal and an output signal at the time of rising in the circuit having a time constant τ. 4 is a diagram for explaining the relationship between an input signal and an output signal at the time of falling in a circuit having a time constant τ.

  Based on FIGS. 2 to 4, the principle that an indication value of a needle type VU meter or the like can be simulated by the method of FIG. 1 will be described. When the input audio signal is a digital signal, the A / D converter 1 in FIG. 1 is not necessary.

  When a stationary audio signal without level fluctuation, for example, a sine wave, a triangular wave, white noise or the like is input, the needle shake of the needle-type VU meter is proportional to the average value of both wave rectification values of the input audio signal. Therefore, the absolute value portion 2 and the short-time average value portion 3 in FIG. 1 calculate a value corresponding to the shake of the needle type VU meter. The absolute value portion 2 corresponds to a double-wave rectifier circuit of a needle type VU meter.

In order to describe the dynamic characteristics with a time constant, the operation of the circuit 7 having the time constant τ shown in FIG. 2 will be considered here. As shown in FIG. 3 (1), the output signal when the input signal changes from V1 to V2 (V2 ≧ V1) at time t0 changes as shown in FIG. 3 (2). Expressed by the equation, Vo = (V2-V1) × (1-e ^{(-(t-t0) / τ)} ) + V1
= V1 * e ^{(-(t-t0) / τ)} + V2 * (1-e ^{(-(t-t0) / τ)} ) (2)
It is. However, it is set as the range of t> = t0. Further, as shown in FIG. 4 (1), the output signal when the input signal changes from V1 to V2 (V2 ≦ V1) at time t0 changes as shown in FIG. 4 (2). Expressed as an equation: Vo = (V1-V2) × e ^{(-(t-t0) / τ)} + V2
= V1 × e ^{(-(t-t0) / τ)} + V2 × (1-e ^{(-(t-t0) / τ)} ) (3)
It is. However, it is set as the range of t> = t0. Equations (2) and (3) are exactly the same, and it can be seen that the output signal can be calculated by equation (2) regardless of the magnitude of V1 and V2.

Consider the case where the input signal is discretely input at a time interval of ΔT in the circuit 7 of FIG. Assume that the nth input signal is Vi (n), the (n + 1) th input signal is Vi (n + 1), the nth output signal is Vo (n), and the (n + 1) th output signal is Vo (n + 1). When the output signal is Vo (n), the value Vo (n + 1) after ΔT time when the input signal changes from Vi (n) to Vi (n + 1) is obtained from the equation (2) as Vo (n +1) = Vo (n) * e ^{(-[Delta] T / [tau])} + Vi (n + 1) * (1-e ^{(-[Delta] T / [tau])} )
= A * Vo (n) + (1-a) * Vi (n + 1) (4)
Where a = e ^{(-ΔT / τ)}
Given in. That is, formula (1) is obtained.

  The time constant of the rise characteristic and the fall characteristic of the needle type VU meter are different due to the influence of the mass of the needle and the braking device for preventing the needle from being shaken excessively. As an example, consider a case where a needle type VU meter having a rising time constant τ of about 84 ms and a falling time constant τ of about 173 ms is simulated.

The time constant setting unit 5 in FIG. 1 determines the coefficient a corresponding to the time constant. When Vi (n + 1) ≧ Vo (n), the time constant of the rising characteristic is used, and Vi (n + 1) Since the time constant of the falling characteristic must be used in the case of <Vo (n), the coefficient a is a = e ^{(−ΔT / τ)} = e when Vi (n + 1) ≧ Vo (n). ^{(-21.3 / 84)} = 0.776
When Vi (n + 1) <Vo (n), a = e ^{(−ΔT / τ)} = e ^{(−21.3 / 173)} = 0.848
... (5)
It is. In addition, the value a in the equation (5) is a case where a short-time average value is obtained every 21.3 ms. In addition, when Vi (n + 1) = Vo (n), a (1) can be used to calculate Vo (n + 1) = Vo (n) = Vi (n) regardless of the value of a in equation (5). Therefore, it is included when Vi (n + 1) ≧ Vo (n).

  Such a time constant setting unit 5 includes, for example, a time constant storage unit (not shown) that stores time constants of rising characteristics and falling characteristics, and an (n + 1) th input signal Vi (n + 1) obtained from the current input signal. ) And the nth output signal Vo (n), a determination unit (not shown) that determines whether the output signal increases or decreases, a time constant corresponding to the determination result is read, and a coefficient corresponding to the time constant is calculated. And a coefficient unit (not shown) that is output to the calculation unit 6. Alternatively, the time constant setting unit 5 stores the time constant of the rising characteristic and the falling characteristic and the coefficient corresponding to each time constant as table data, and sets the coefficient corresponding to the time constant according to the determination result of the determination unit. A configuration may be used in which the read coefficient is output to the calculation unit 6.

  In the dynamic characteristic simulation apparatus according to the first embodiment, first, the time constant setting unit 5 compares the (n + 1) th input signal Vi (n + 1) with the nth output signal Vo (n), thereby obtaining an (n + 1) th output. Determine the increase or decrease of the signal (indicator value of the measuring instrument).

  Here, when the input signal Vi (n + 1) is larger, the time constant setting unit 5 sets the time constant of the rising characteristic as a coefficient for calculating the (n + 1) th output signal Vo (n + 1). By determining the corresponding coefficient and outputting the coefficient to the calculation unit 6, the calculation unit 6 calculates the output signal Vo (n + 1) according to the time constant of the rising characteristic.

  On the other hand, when the n + 1th input signal Vi (n + 1) and the nth output signal Vo (n) are compared, and the input signal Vi (n + 1) is smaller, the time constant setting unit 5 A coefficient corresponding to the time constant of the falling characteristic is determined as a coefficient for calculating the (n + 1) th output signal Vo (n + 1), and this coefficient is output to the calculating unit 6 so that the falling characteristic is obtained. The output signal Vo (n + 1) according to the constant is calculated.

  As described above, in the dynamic characteristic simulation apparatus according to the first embodiment, the coefficient a calculated from the time constant obtained by measuring the rising characteristic and the falling characteristic of the needle-type measuring instrument to be simulated, and the (n + 1) th Since the calculation means 6 calculates the (n + 1) th output signal Vo (n + 1) based on the input signal Vi (n + 1) and the nth output signal Vo (n), the needle type Therefore, it is possible to accurately simulate the characteristics of the VU meter and the sound level meter, taking into account the mass of the needle itself and the influence of the braking device for preventing the needle from shaking too much. At this time, by updating and displaying the output signal Vo (n + 1) every certain time ΔT, the needle type measuring instrument is accurately simulated in real time including the display unit (needle moving speed). be able to. For example, the VU value is calculated by calculating the voltage ratio between the output signal Vo (n + 1) updated every certain time ΔT and the voltage at 0 VU, and the LED or the like is calculated at every ΔT time based on this VU value. By updating the VU value obtained by electrically displaying the VU value on the CRT, an accurate real-time simulation can be performed. The output signal Vo (n + 1) is not limited to a configuration in which the output signal Vo (n + 1) is updated and displayed every certain time ΔT.

  As a result, the output signal Vo (n + 1) can be recorded as the indicated value data of the needle type VU meter, or the output signal Vo (n + 1) can be statistically analyzed. In this case, needless to say, the display update timing may be set to a timing different from the predetermined time ΔT.

  Note that the time constants of the rising characteristic and the falling characteristic in the dynamic characteristic simulation apparatus of the first embodiment are obtained by using the actually measured time constant of the needle type VU meter as an example, and are limited to the above-described values. It is not something. Since the indicated value of a measuring instrument such as a needle-type VU meter varies slightly depending on the measuring instrument, it is desirable to measure the time constant of the measuring instrument to be simulated and apply the calculation method according to the embodiment of the present invention.

  FIG. 6 shows an example of a flow chart of a program when the dynamic characteristic simulation apparatus according to the first embodiment is configured by a program stored in a CPU and a storage device.

First, the average value of the absolute value of the input signal is calculated every fixed time ΔT (step 61).
Next, the output level Vo (n) corresponding to the nth input level Vi (n) calculated in step 61 is compared with the n + 1th input level Vi (n + 1) calculated in step 61. Using the result, a coefficient a corresponding to one of a plurality of time constants τ that approximates the time constant of the indicated value of the measuring instrument to be simulated is calculated as a = e ^{(−ΔT / τ)} . (Step 62).

Next, using the input level Vi (n + 1), the output level Vo (n), and the coefficient a set in step 62, the output level Vo (n) corresponding to the input level Vi (n + 1). +1) is calculated by Vo (n + 1) = a * Vo (n) + (1-a) * Vi (n + 1) (step 63).
Next, the output level Vo (n) is updated and displayed every certain time ΔT (step 64).
When step 64 ends, the process returns to step 61.

(Embodiment 2)
The dynamic characteristic simulation apparatus according to the second embodiment of the present invention is different from the dynamic characteristic simulation apparatus according to the first embodiment except for the configuration of the time constant setting unit 5. Therefore, in the following description, the configuration and operation of the time constant setting unit 5 will be described in detail.

  If the center of gravity of the VU meter's needle is exactly at the center of rotation (rotation axis), the influence of the needle's own weight is considered negligible, but it is slightly on the pointer side and the influence of its own weight cannot be ignored. It is done.

Further, as shown in FIG. 7, the scale of the VU meter has a scale of −2 VU almost directly above. Accordingly, it is considered that the time constant changes as follows when the input audio signal rises and falls.
(1) In case of rising:
When the deflection of the needle 8 is small (for example, smaller than −2 VU), as shown in FIG. 8A, it is necessary to shake the needle largely against the gravity 9 of the needle 8, so the needle 8 is difficult to shake. . That is, the time constant is large. When the deflection of the needle 8 is large (for example, larger than −2 VU), the influence of the gravity 9 of the needle 8 on the torque (perpendicular to the needle) is small as shown in FIG. When the needle passes right above, it works in the same direction as the torque, so that the needle 8 is likely to swing. That is, the time constant becomes small.
(2) Falling:
When the deflection of the needle 8 is large (for example, when it is larger than −7 VU according to the actual measurement value), as shown in FIG. 8B, the influence of the gravity 9 of the needle 8 is small, and the indicated value passes directly above. If it is larger than -2 VU, it works in the direction opposite to the returning direction, so that the needle 8 is less likely to swing (not easily returned). That is, the time constant is large. When the deflection of the needle 8 is small (for example, smaller than −7 VU), as shown in FIG. 8A, the gravity 9 of the needle 8 is applied in the direction in which the needle 8 returns. Easier). That is, the time constant becomes small.

  Therefore, in order to more accurately simulate the dynamic characteristics of the VU meter, it is necessary to change the time constants of the rising characteristics and the falling characteristics in more detail. In the first embodiment, the needle-type VU meter is simulated with two types of rise and fall time constants. However, in the second embodiment, the rise and fall time constants further increase the n-th output signal Vo (n ) Will also be described as an example.

  The dynamic characteristic simulation apparatus according to the second embodiment prepares two time constants for each of the rising characteristic and the falling characteristic, and the time constants of the rising characteristic and the falling characteristic are indicated by the measuring instrument, that is, the nth output. By utilizing the dependence on the signal Vo (n), the dynamic characteristic of the VU meter is simulated more accurately.

  That is, the time constant setting unit 5 included in the dynamic characteristic simulation apparatus of the second embodiment includes, for example, a time constant storage unit (not shown) that stores two time constants for each rising characteristic and falling characteristic, and an input audio signal. The obtained n + 1-th input signal Vi (n + 1) and the n-th output signal Vo (n) are compared to determine the output signal increase / decrease, not shown, the determination result and the n-th output A time constant corresponding to the signal Vo (n) is read out, a coefficient corresponding to the time constant is calculated, and a coefficient part (not shown) is output to the calculation part 6.

  Therefore, the operation until the arithmetic average value of the absolute value is calculated from the input voice signal is the same as that of the dynamic characteristic simulation apparatus of the first embodiment. However, in the dynamic characteristic simulation apparatus according to the second embodiment, the time constant setting unit 5 sets the n + 1-th value Vi (n + 1) of the short-time average value unit and the value of the previous section of the output signal Vo (n + 1). Vo (n) is compared to determine the increase / decrease of the output signal, the coefficient a is determined using the determination result and the nth output signal Vo (n), and the arithmetic unit 6 uses the coefficient a. Since the (n + 1) -th output Vo (n + 1) is calculated by the equation (1), a more accurate simulation can be performed even when the time constants of the rising characteristics and the falling characteristics depend on the indicated values of the measuring instrument. It becomes possible.

  The time constant stored in the time constant setting unit 5 of the second embodiment is about 84 ms when the time constant of the rising characteristic of the needle type VU meter is −2 VU or less (the voltage ratio is 0.79 or less of 0 VU), and is −2 VU. When the time constant is larger, the time constant is about 42 ms. When the time constant of the falling characteristic is −7 VU or more (0.45 of 0 VU in voltage ratio), it is about 173 ms, and when it is smaller than −7 VU, the time constant is about Consider the case of 101 ms as an example.

  When quantization is performed with 16 bits and −18 dBFS (Full Scale) is set to 0 VU, a sine wave having an amplitude of 4095 is 0 VU. Therefore, the average absolute value of the 0 VU sine wave is 2 × 4095 / π = 2607.0. That is, the value of −2 VU is 2607.0 × 0.79 = 2059.5, and the value of −7 VU is 2607.0 × 0.45 = 1173.2.

  The value of a when the input signal is obtained every 21.3 ms is determined by the time constant setting unit 5 as follows.

In the case of Vi (n + 1) ≧ Vo (n) and Vo (n) ≦ 2059.5, a = e ^{(−21.3 / 84)} = 0.766
When Vi (n + 1) ≧ Vo (n) and Vo (n)> 2059.5, a = e ^{(−21.3 / 42)} = 0.602
When Vi (n + 1) <Vo (n) and Vo (n) <1173.2, a = e ^{(-21.3 / 101)} = 0.810
When Vi (n + 1) <Vo (n) and Vo (n) ≧ 1173.2, a = e ^{(−21.3 / 173)} = 0.848
... (6)
In the case of a needle-type VU meter, as shown by the curves 10 and 11 in FIG. It is possible to simulate the actual measurement value indicated by (2) almost accurately. FIG. 5 shows the relationship between the elapsed time after the 0 VU input signal is input to the needle-type VU meter and the indicated value (curve 10) and the input signal is 0 at time 0 ms after the 0 VU input signal is applied for a long time. It is a figure which shows the relationship (curve 11) of the elapsed time at the time of becoming and an instruction | indication value. The vertical axis is the indication value of the needle type VU meter (the voltage ratio between the output signal Vo (n) and the voltage at 0 VU), and the horizontal axis is the elapsed time. X is an actual measurement value, and curves 10 and 11 are simulation results. Curves 10 and 11 use different time constants before and after 150 ms.

In order to further improve the accuracy, the number of levels for switching the time constant may be further increased. Further, the dynamic characteristics of the needle type VU meter vary somewhat depending on the product, so it is preferable to determine the value a by actually measuring the time constant of the VU meter to be simulated. The time constant of the needle type VU meter given as an example is one of measurement examples.
In addition, (triangle | delta) shown in FIG. 5 is a case where it simulated using one time constant for every rising characteristic and falling characteristic like (5) Formula of Embodiment 1. FIG.

An example of a program flow diagram when the dynamic characteristic simulation apparatus of the second embodiment is configured by a program stored in a CPU and a storage device is the same as that in FIG. However, in the time constant setting step (step 62), the output level Vo (n) corresponding to the nth calculated input level Vi (n) and the n + 1th calculated input level Vi (n + 1) The coefficient corresponding to one of a plurality of time constants τ that approximates the time constant of the indicated value of the measuring instrument that is the object of simulation, depending on the result of comparing the output level Vo (n) The difference from the first embodiment is that a is calculated by a = e ^{(−ΔT / τ)} .

  The invention made by the present inventor has been specifically described based on the embodiment of the invention, but the invention is not limited to the embodiment of the invention and does not depart from the gist of the invention. Of course, various changes can be made.

It is a figure which shows the example of a fundamental structure of the dynamic characteristic simulation apparatus of Embodiment 1 of this invention. It is a figure for demonstrating the circuit with time constant (tau). It is a figure for demonstrating the relationship (in the case of V2> = V1) of the input signal and output signal in a circuit with time constant (tau). It is a figure for demonstrating the relationship (in the case of V2 <= V1) of the input signal and output signal in a circuit with time constant (tau). The relationship between the elapsed time after the 0VU input signal is input to the needle-type VU meter and the indicated value (curve 10), and the input signal becomes 0 at time 0ms after the 0VU input signal is applied for a long time It is a figure which shows the relationship (curve 11) of elapsed time of this, and instruction value. 3 is an example of a flowchart of a program when the dynamic characteristic simulation apparatus of the first embodiment is configured by a program stored in a CPU and a storage device. FIG. It is a figure for demonstrating the scale of a VU meter. It is a figure for demonstrating the relationship between the instruction value and the time constant in the dynamic characteristic simulation apparatus of Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... A / D conversion part 2 ... Absolute value part 3 ... Short time average value part 4 ... Delay part 5 ... Time constant setting part 6 ... Calculation part 7 ... Circuit with time constant (tau) 8 ... Arrow which shows a needle 9 ... Needle An arrow Vo (n) indicating the gravity applied to the nth output signal Vo (n + 1) ... an n + 1th output signal Vi (n + 1) ... an n + 1th input signal Vo ... an output signal Vi ... an input signal t0 ... Time V1, V2 ... Input signal level τ ... Time constant

Claims (10)

A method of simulating the dynamic characteristics of the indicated value of a measuring instrument,
An average value calculating step for calculating an average value of the absolute values of the input signal that can be measured by the measuring device every certain time ΔT;
An output level Vo (n) corresponding to the nth input level Vi (n) calculated in the average value calculating step, and an input level Vi (n + 1) calculated n + 1 in the average value calculating step. A time constant setting step for setting a coefficient a corresponding to one of a plurality of time constants τ that approximates the time constant of the indicated value of the measuring device to be simulated using
The output corresponding to the input level Vi (n + 1) using the input level Vi (n + 1), the output level Vo (n), and the coefficient a set in the time constant setting step. A calculation step for calculating the level Vo (n + 1);
A dynamic characteristic simulation method comprising: A dynamic characteristic simulation apparatus for simulating the dynamic characteristic of the indicated value of a measuring instrument,
An average value calculating unit that calculates an average value of absolute values of the input signal that can be measured by the measuring device every certain time ΔT;
The output level Vo (n) corresponding to the nth input level Vi (n) calculated by the average value calculation unit, and the input level Vi (n + 1) calculated n + 1 by the average value calculation unit , And a time constant setting unit that sets a coefficient a corresponding to one of a plurality of time constants τ that approximates the time constant of the indicated value of the measuring device to be simulated,
An output corresponding to the input level Vi (n + 1) using the input level Vi (n + 1), the output level Vo (n), and the coefficient a set by the time constant setting unit. A calculation unit for calculating the level Vo (n + 1);
A dynamic characteristic simulation apparatus. The dynamic characteristic simulation apparatus according to claim 2,
A dynamic characteristic simulation apparatus that updates and displays the output level Vo (n) calculated by the arithmetic unit every certain time ΔT. In the dynamic characteristic simulation apparatus according to claim 2 or 3,
The time constant setting unit is a dynamic characteristic simulation apparatus that calculates a coefficient a corresponding to the time constant τ by a = e ^{(−ΔT / τ)} . In the dynamic characteristic simulation apparatus according to any one of claims 2 to 4,
The operation unit is a dynamic characteristic simulation apparatus that calculates the output level Vo (n + 1) by Vo (n + 1) = a * Vo (n) + (1-a) * Vi (n + 1). In the dynamic characteristic simulation apparatus according to any one of claims 2 to 5,
The average value calculation unit is a dynamic characteristic simulation apparatus in which a predetermined time ΔT for calculating an average value of absolute values of the input signals is variable. In the dynamic characteristic simulation apparatus according to any one of claims 2 to 6,
The time constant setting unit is a dynamic characteristic simulation device that sets the coefficient a by comparing the output level Vo (n) and the input level Vi (n + 1). In the dynamic characteristic simulation apparatus according to any one of claims 2 to 6,
The time constant setting unit sets the coefficient a depending on the result of comparing the output level Vo (n) and the input level Vi (n + 1) and the output level Vo (n). Dynamic characteristic simulation device. A program for operating a computer as a dynamic characteristic simulation apparatus for simulating the dynamic characteristic of an indicated value of a measuring instrument,
An average value calculating step for calculating an average value of the absolute values of the input signal that can be measured by the measuring device every certain time ΔT;
An output level Vo (n) corresponding to the nth input level Vi (n) calculated in the average value calculating step, and an input level Vi (n + 1) calculated n + 1 in the average value calculating step. The coefficient a corresponding to one of a plurality of time constants τ approximating the time constant of the indicated value of the measuring device to be simulated is calculated as a = e ^{(−ΔT /} time constant setting step calculated by ( ^τ) ,
The output corresponding to the input level Vi (n + 1) using the input level Vi (n + 1), the output level Vo (n), and the coefficient a set in the time constant setting step. An operation step for calculating the level Vo (n + 1) by Vo (n + 1) = a * Vo (n) + (1-a) * Vi (n + 1);
A display step of updating and displaying the output level Vo (n) for each predetermined time ΔT;
A program that causes a computer to execute. A program for operating a computer as a dynamic characteristic simulation apparatus for simulating the dynamic characteristic of an indicated value of a measuring instrument,
An average value calculating step for calculating an average value of the absolute values of the input signal that can be measured by the measuring device every certain time ΔT;
An output level Vo (n) corresponding to the nth input level Vi (n) calculated in the average value calculating step, and an input level Vi (n + 1) calculated n + 1 in the average value calculating step. Corresponding to one of a plurality of time constants τ approximating the time constant of the indicated value of the measuring device to be simulated, depending on the result of comparing the output level Vo (n) Time constant setting step for calculating the calculated coefficient a with a = e ^{(−ΔT / τ)} ,
The output corresponding to the input level Vi (n + 1) using the input level Vi (n + 1), the output level Vo (n), and the coefficient a set in the time constant setting step. An operation step for calculating the level Vo (n + 1) by Vo (n + 1) = a * Vo (n) + (1-a) * Vi (n + 1);
A display step of updating and displaying the output level Vo (n) for each predetermined time ΔT;
A program that causes a computer to execute.

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