JP7318211B2 - SOUND PROPAGATION SIMULATION SYSTEM AND SOUND PROPAGATION SIMULATION METHOD - Google Patents

Description

The present invention relates to a sound wave propagation simulation system and sound wave propagation simulation method for simulating characteristics of sound wave propagation in a sound field.

Impulse is one of the sound wave propagation simulation methods for knowing the characteristics of sound wave propagation, i.e., how sound waves emitted from a sound source are received at a receiving position in a certain sound field (acoustic space). A technique for obtaining a response is known (see Patent Document 1, for example).

Using a computer, this method uses information such as the position of the boundary surrounding the sound field, the position of the sound source, and the receiving position (the position of the sound receiving point). The virtual image method) predicts the propagation path, which is the path of the sound wave emitted from the sound source when it reaches the receiving position as a direct wave or a reflected wave. Next, the electronic computer obtains the response when the impulse signal emitted at the sound source position reaches the reception position via each sound wave propagation path, and further summarizes the responses for each propagation path to obtain the impulse response are getting

Furthermore, the acquired impulse response is used for convolution calculation of the transmission signal transmitted from the sound source, and as a result of the calculation, data simulating the reception signal received at the reception position is obtained.

JP-A-2002-159097

In the conventional sound wave propagation simulation method, when obtaining data on the reception signal received at the reception position by convolution calculation of the impulse response and the transmission signal transmitted from the sound source, for one transmission signal, A convolution calculation using one impulse response is performed on the entire transmitted signal.

By the way, a transmission signal transmitted from a sound source is a sound wave having a certain length along the time axis.

Conventional sound wave propagation simulation methods work under conditions where the environment of the sound wave propagation path from the sound source to the reception position in the sound field does not change during the period from when the sound source starts transmitting the transmission signal until it finishes transmitting. If so, it is possible to obtain data that well simulates the received signal received at the receiving position.

Therefore, in the conventional sound wave propagation simulation method, the position of the sound source and the receiving position do not change even when the length of the transmitted signal elapses, and the boundary condition of the boundary of the sound field does not change. The simulation results are good if there is no change in the flow of the sound-transmitting medium at .

However, in an actual sound field, the environment of the sound wave propagation path often changes over time.

For example, if at least one of the transmitting station, which is the sound source, and the receiving station, which is the receiving position, is mounted on a moving object, the relative positions of the transmitting station and the receiving station may change over time. be. Such a change in the relative positions of the transmitting station and the receiving station leads to a change in the distance of the propagation path in terms of the environment of the sound wave propagation path. is also affected by the Doppler effect.

In the case of underwater acoustic communication, the water surface is the boundary of the sound field that reflects sound waves. , the reflection position of the sound wave in the sound wave propagation path is displaced over time. In this case, regarding the environment of the sound wave propagation path, changes occur in the reflectance and the amount of phase fluctuation due to reflection as boundary conditions on the water surface, which is the boundary of the sound field.

However, in the conventional sound wave propagation simulation method, even if the environment of the sound wave propagation path changes over time in the sound field, it is impossible to simulate the received signal affected by the change. The reality is that it is not done.

Therefore, according to the present invention, it is possible to perform a process of obtaining data simulating a received signal by convolution of an impulse response and a transmitted signal with the influence of temporal changes in the environment of the sound wave propagation path in the sound field. A sound wave propagation simulation system and a sound wave propagation simulation method capable of obtaining data simulating a received signal in a sound field under conditions affected by temporal changes in the environment of the sound wave propagation path. is intended to provide

In order to solve the above-mentioned problems, the present invention provides an input device, a signal division device that divides a transmission signal to generate a plurality of small signals with sequentially different transmission times, a propagation path environment calculation device, and a small signal. A computing device that performs signal length correction calculation, an impulse response computing device, a computing device that performs convolution calculation, a processing device that integrates convolution data, a time division device, and a computing device that performs weighted smoothing calculation. , in a state where parameters of fluctuation conditions that change with the passage of time are set for calculation conditions required for performing a sound wave propagation simulation, the impulse response calculation device calculates the transmission of the small signal. The computing device that performs the convolution calculation has a function of obtaining the impulse response at the wave time, and performs convolution calculation of the small signal and the impulse response at the wave time of the small signal to obtain the convolution data. The processing device has a function of generating full convolution data by combining all of the convolution data, and the time division device processes the full convolution data according to a unit time corresponding to a set sampling frequency. The computing device for performing the weighted smoothing calculation is provided with a function of equally spaced division in the time axis direction, and performs the weighted smoothing calculation. A function of determining a representative point so that the total energy of a received signal of a small signal is equal; calculating a waveform passing through the representative point in the time domain; A sound wave propagation simulation system having a configuration having a function of obtaining data simulating a received signal when the signal is received by a wave receiver.

In addition, with respect to the calculation conditions required for performing the sound wave propagation simulation, the parameters of the fluctuation conditions that change with the passage of time are set by an electronic computer. a step of generating a plurality of small signals that differ in sequence; a step of obtaining an impulse response at the transmission time of the small signal; and performing a convolution calculation of the small signal and the impulse response at the transmission time of the small signal. a step of obtaining convolution data; a step of generating full convolution data combining all the convolution data; performing interval division; and determining, for each of a plurality of time domains generated by the equal interval division in the time axis direction, a representative point so that the total energy of the received small signals existing in the time domain is equal. Then, a waveform passing through the representative points in the time domain is calculated, and the calculation result of the waveform is used as data simulating the reception signal when the transmission signal transmitted from the transmitter is received by the receiver A sound wave propagation simulation method for carrying out a step of obtaining.

According to the sound wave propagation simulation system and the sound wave propagation simulation method of the present invention, the process of obtaining data simulating the received signal by convolution of the impulse response and the transmitted signal includes the temporal change of the environment of the sound wave propagation path in the sound field. In the sound field, it is possible to obtain data simulating received signals under conditions affected by temporal changes in the environment of the sound wave propagation path. .

1 is a schematic diagram illustrating an embodiment of a sound wave propagation simulation system; FIG. 1 is a schematic diagram showing an example of a sound field; FIG. FIG. 4 is a diagram illustrating a process of dividing a transmission signal to generate small signals; FIG. 10 is a diagram showing a convolution calculation process of a small signal and an impulse response at the transmission time of the small signal; FIG. 10 is a diagram showing a process of convolution calculation of another small signal and an impulse response at the transmission time of the another small signal; FIG. 10 is a diagram showing a process of generating data simulating a received signal based on convolution data for all small signals; FIG. 2 is a flowchart showing a sound wave propagation simulation method performed using the sound wave propagation simulation system of FIG. 1;

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments for implementing a sound wave propagation simulation system and a sound wave propagation simulation method of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing an embodiment of a sound wave propagation simulation system. FIG. 2 is a schematic diagram showing an example of a sound field to be simulated. FIG. 3 shows a process of dividing a transmission signal to generate small signals. FIG. 3(a) is a diagram showing an example of a transmission signal, and FIG. FIG. 10 is a diagram showing an example of a small signal to be processed; FIG. 4 shows a process of convolution calculation of a small signal and an impulse response at the transmission time of the small signal. FIG. 4(b) is a diagram showing the convolution data obtained by the convolution calculation of the small signal and the impulse response of FIG. 4(a). FIG. 5 shows the process of convolution calculation of another small signal and the impulse response at the transmission time of the another small signal. FIG. FIG. 5(b) shows the convolution data obtained by convolving another small signal with the impulse response of FIG. 5(a). FIG. 6 shows processing for generating data simulating a received signal based on convolution data for all small signals. FIG. FIG. 6(b) is a diagram showing a state in which a unit time corresponding to the sampling frequency is set for all convolution data, and FIG. 6(c) is a received signal obtained as a result of weighted smoothing calculation. FIG. 4 is a diagram showing simulated data;

FIG. 7 is a flowchart showing a sound wave propagation simulation method implemented using the sound wave propagation simulation system of FIG.

The acoustic wave propagation simulation system of this embodiment is indicated by reference numeral 1 in FIG. A calculation device 5, a small signal length recording device 6, an impulse response calculation device 7, a calculation device 8 that performs convolution calculation, a convolution calculation result recording device 9, a determination device 10, and a convolution data recording device. It is configured to include a processing device 11 that performs integration processing, a time division device 12, a calculation device 13 that performs weighted smoothing calculation, and an output device 14. FIG.

The input device 2 is a device for an operator (not shown) to set calculation conditions required for sound wave propagation simulation.

Calculation conditions set by the input device 2 are, as shown in FIG. It includes parameters of fixed conditions such as the frequency, amplitude and signal length of transmission signal A to be transmitted (see FIG. 3(a)), directivity characteristics and frequency characteristics of transmitter 17 and receiver 18, sampling frequency, and the like.

In this embodiment, the shape of the sound field 15 is, for example, a rectangular parallelepiped as shown in FIG. Therefore, the boundaries 16a, 16b, 16c, 16d, 16e, and 16f of the sound field 15 are the four side surfaces, the upper surface, and the lower surface surrounding the rectangular parallelepiped. By setting the positions of the boundaries 16a, 16b, 16c, 16d, 16e, and 16f, the shape of the sound field 15 and the size of the sound field 15 are determined.

Note that the shape of the sound field 15 is generally set to a shape other than a rectangular parallelepiped as long as it is a shape to which processing for obtaining an impulse response by the mirror image method or the sound ray method can be applied. It is of course possible to

Further, in the input device 2, as another calculation condition, as will be described later, the transmission signal A is divided and processed to generate a plurality of small signals Bn (n=1, 2, 3, . . . ) as a reference time Δt (see FIG. 3(b)) is set. The smaller the set value of this time Δt, the more detailed simulation can be performed, but the amount of calculation increases. Therefore, it is preferable to set the time Δt to be equal to or longer than the unit time corresponding to the sampling frequency set as the fixed condition. Also, the time Δt should be set so that the change of the parameter of the fluctuation condition described later with the passage of time for each time Δt leads to the change of the propagation path environment required for the calculation of the impulse response.

Furthermore, in the input device 2, as other calculation conditions, boundary conditions at each boundary 16a, 16b, 16c, 16d, 16e, and 16f of the sound field 15, which are calculation conditions that change with the passage of time, The direction and velocity of the medium that transmits the sound wave, the velocity of sound in the medium, the position and velocity of the transmitter 17, the position and velocity of the receiver 18, etc. are set as parameters of the fluctuation conditions.

The boundary conditions of the boundaries 16a, 16b, 16c, 16d, 16e, and 16f of the sound field 15 are the reflectance of the sound wave and the amount of phase variation occurring in the sound waves reflected at the boundaries 16a, 16b, 16c, 16d, 16e, and 16f. and including.

When the sound field 15 is assumed to be a room, a hall, or an interior space of a building, the boundary conditions of the four walls, the ceiling, and the floor are set for the boundaries 16a, 16b, 16c, 16d, 16e, and 16f. do it.

On the other hand, for example, when the propagation of sound waves in the sound field 15 is assumed to be the propagation of acoustic signals for acoustic communication in the open ocean, the upper boundary 16e of the sound field 15 includes sea surface is set, and the boundary condition of the bottom of the sea is set for the lower boundary 16f of the sound field 15. FIG. At this time, on the sea surface, a phase shift may occur in the reflected sound waves due to the Doppler effect as the sea surface fluctuates up and down due to the influence of waves and the like. Therefore, as the boundary condition of the sea surface, for example, changes in the reflectance and the amount of phase fluctuation on the sea surface with the passage of time may be obtained by a statistical method, and the results may be used.

Further, the boundaries 16a, 16b, 16c, and 16d corresponding to the four sides of the sound field 15 may be set to have zero reflectance under boundary conditions. Furthermore, in a harbor or the like, if there is an object that reflects sound waves, such as a quay wall or a breakwater, on the side of the transmitter 17, each boundary 16a, 16b, 16c, 16d corresponding to the four sides of the sound field 15 has , set a boundary condition with the reflectance of the object that reflects the sound wave.

Each parameter of the fluctuation condition is set as a function with the time t0 at which the transmission of the transmission signal A by the transmitter 17 is started as a reference, and the elapsed time t from the time t0 as a variable.

Note that the variable condition, which is a calculation condition that changes with the passage of time, may be set to at least one of the parameters described above as the variable condition. In this case, the remaining parameters that are not set as variable conditions may be set in the input device 2 as fixed conditions using constants.

Further, in the input device 2, it is of course possible to set fixed conditions and variable conditions other than those exemplified as long as the parameters affect the propagation of sound waves in the sound field 15 to be simulated.

The input device 2 has a function of sending the set transmission signal A and information on the time Δt to the signal dividing device 3 . The input device 2 also has a function of sending to the computing device 4 a function representing the parameters of the set fluctuation conditions. Furthermore, the input device 2 has a function of sending the set fixed conditions to the calculation device 4 as well.

When the signal dividing device 3 receives the information of the transmission signal A and the time Δt from the input device 2, the transmission signal A as shown in FIG. It has a function of dividing each signal and generating a plurality of divided signals (hereinafter referred to as small signals Bn (n=1, 2, 3, . . . )) as shown in FIG. 3(b). . 3A and 3B are schematic diagrams.

As a result, the small signal Bn (n=1, 2, 3, . . . ) is transmitted when the elapsed time t from time t0 is (n−1)·Δt. Also, the signal length of each small signal Bn (hereinafter referred to as the small signal length) is equal to the time Δt.

FIG. 3B shows, as an example, the signal dividing device 3 dividing the transmission signal A shown in FIG. is generated. In FIG. 3B, for convenience of illustration, each of the small signals B1, B2, B3, B4, and B5 are indicated by figures ◯, Δ, □, ◇, and x, respectively.

Each of the small signals B1, B2, B3, B4, and B5 is assigned one amplitude (waveform) for each corresponding period in the transmission signal A. FIG.

As a specific example, for example, when the signal length of the transmission signal A is 10 seconds and the time Δt is set to 1 second, the signal division device 3 divides 10 small signals B1, B2, B3, . Generate. In this case, each of the small signals B1, B2, B3, . The length is 1 second.

The signal splitting device 3 has a function of sending information C about the transmission time and amplitude of the small signal Bn generated by splitting the transmission signal A to the computing device 4 and the computing device 8 .

The propagation path environment calculator 4 has a function of obtaining a propagation path environment required for calculating the impulse response at the transmission time of the small signal Bn.

Therefore, the calculation device 4 has a function of receiving parameters of fixed conditions and variable conditions from the input device 2 .

Further, when the transmission time of the small signal Bn is given as the value of the elapsed time t from the transmission start time t0 of the transmission signal A (t=(n−1)·Δt), the calculation device 4 calculates the fluctuation condition It has a function of calculating the variation condition at the transmission time of the small signal Bn by performing a calculation process of substituting the elapsed time t into the function representing each parameter of . As a result, each parameter of the fluctuation condition has a value at the transmission time of the small signal Bn.

Further, the calculation device 4 generates the sound field 15 as shown in FIG. has a function of obtaining a direct wave propagation path 19 and reflection wave propagation paths 20a, 20b, and 20c reflected at boundaries as propagation paths of sound waves reaching the wave receiver 18 from the transmitter 17. . Techniques for obtaining the propagation paths 19, 20a, 20b, and 20c of the direct wave and the reflected waves are conventionally used for acquisition of sound wave propagation paths when measuring the impulse response, such as the mirror image method, the sound ray method, and others. Alternatively, a conventionally proposed method may be adopted. Although there are usually more than three propagation paths for reflected waves, only three propagation paths 20a, 20b, and 20c for reflected waves are shown in FIG. 2 as representatives for convenience of illustration.

Further, when the propagation paths 19, 20a, 20b, and 20c are determined as described above, the calculation device 4 uses the parameters of the fixed conditions and the variable conditions to generate the transmitter 17 at the transmission time of the small signal Bn. The arrival time and amplitude response when the impulse signal emitted at the position reaches the position of the wave receiver 18 via the respective propagation paths 19, 20a, 20b, 20c is defined as , 20d individually.

As a result, the calculation device 4 can obtain the information D of the propagation paths 19, 20a, 20b, and 20c and the result E of the response obtained for each of the propagation paths 19, 20a, 20b, and 20c as the propagation path environment. can.

Calculation device 4 has a function of sending information D of obtained propagation paths 19, 20a, 20b, 20c to calculation device 5, and a function of sending response result E obtained for each of propagation paths 19, 20a, 20b, 20c to calculation device 4. It has a function to send to 7.

The calculation device 5 has a function of correcting the length of the small signal Bn (n=1, 2, 3, . . . ) based on the Doppler calculation.

For example, if the distances of the propagation paths 19, 20a, 20b, and 20c from the transmitter 17 to the receiver 18 decrease with the passage of time, the wavelength will decrease due to the Doppler effect. The small signal length of the small signal Bn when it reaches 18 is shorter than the time Δt used to divide the original transmission signal A.

On the other hand, if the distances of the propagation paths 19, 20a, 20b, and 20c from the transmitter 17 to the receiver 18 increase over time, the wavelength increases due to the Doppler effect. The small signal length of the small signal Bn when it reaches the wave generator 18 is longer than the time Δt.

Therefore, the calculation device 5 selects, among the parameters of the fluctuation conditions set by the input device 2, parameters relating to changes in the distance between the transmitter 17 and the receiver 18 over time, for example, the transmitter It has a function of receiving information on the position and speed of the wave generator 17 and the position and speed of the wave receiver 18 .

Furthermore, based on the information D of each of the propagation paths 19, 20a, 20b, and 20c received from the calculation apparatus 4, the calculation device 5 calculates the transmission time of the small signal Bn for each of the propagation paths 19, 20a, 20b, and 20c. , the change in the distance that occurs until the time Δt, which is the small signal length at the time of transmission of the small signal Bn, is obtained, and based on the amount of change in the distance per time Δt, the small signal length of the small signal Bn is calculated. It has the ability to perform correction calculations.

The computing device 5 has a function of sending the correction result F of the obtained small signal length of the small signal Bn to the recording device 6 .

The recording device 6 has a function of recording the correction result F of the small signal length of the small signal Bn received from the computing device 5 .

The impulse response calculation device 7 calculates the small signal Bn as shown in FIGS. It has a function to obtain the impulse response at the transmission time of . FIG. 4(a) shows an example of the impulse response at the transmission time of the small signal B1 (see FIGS. 3(a) and 3(b)) that coincides with the transmission time of the transmission signal A. FIG. (a) shows an example of the impulse response at the transmission time of the small signal B2 (see FIGS. 3A and 3B), which is Δt after the transmission time of the small signal B1.

The computing device 7 has a function of sending to the computing device 8 the impulse response information G at the transmission time of the obtained small signal Bn.

Calculation device 8 has a function of receiving transmission time and amplitude information C of small signal Bn from signal division device 3, a function of reading correction result F of the small signal length of small signal Bn from recording device 6, and a calculation device 7. and a function of receiving impulse response information G at the transmission time of the small signal Bn.

Further, the computing device 8 performs a convolution calculation of the small signal Bn and the impulse response at the transmission time of the small signal Bn, and reflects the correction result of the small signal length of the small signal Bn in the calculation result. It has a function of generating convolution data for the small signal Bn.

For example, for the small signal B1 (see FIG. 3(b)), the convolution data shown in FIG. 4(b) is generated by performing the convolution calculation using the impulse response shown in FIG. 4(a). be. This convoluted data is a hypothetical received signal BX1 received by the wave receiver 18 assuming that only the small signal B1 is transmitted from the wave transmitter 17 as a transmission signal at time t0. Become.

Similarly, for the small signal B2 (see FIG. 3(b)), the convolution data shown in FIG. 5(b) is generated by performing the convolution calculation using the impulse response shown in FIG. 5(a). be done. Assuming that only the small signal B2 is transmitted from the wave transmitter 17 as a transmission signal at a time (t=.DELTA.t) after the time t0 has elapsed from the time t0, the convoluted data is received. A virtual received signal BX2 received by the receiver 18 is obtained.

The calculation device 8 has a function of sending the obtained convolution data H to a convolution calculation result recording device 9 .

The recording device 9 has a function of recording the convolution data H received from the computing device 8 .

When the calculation device 8 finishes processing a certain small signal Bn (n=1, 2, 3, . It has a function of adding the time Δt to the elapsed time t from the start time t0 and updating the elapsed time t from the time t0 (t=t+Δt).

The determination device 10 then has a function of determining whether or not the updated elapsed time t is less than the signal length of the transmission signal A.

If the determination device 10 determines that the elapsed time t after updating is less than the signal length of the transmission signal A, the determination device 10 sends the determination result I together with the information on the elapsed time t after updating to the computing device 4 and the computing device. Send to 5.

When receiving the determination result I from the determination device 10, the calculation device 4 targets the small signal Bn whose transmission time is the updated elapsed time t from the time t0 when the transmission of the transmission signal A starts. It has a function of resuming the process of determining the propagation path environment required to calculate the impulse response at the transmission time of the signal Bn. Further, when the calculation device 5 receives the determination result I from the determination device 10, the small signal Bn (n=1, 2, 3 . . . ) has a function to restart the correction calculation of the small signal length.

On the other hand, when it is determined that the elapsed time t after updating is not less than the signal length of the transmission signal A, the determination device 10 has a function of sending the determination result J to the processing device 11 .

Thus, when it is determined that the elapsed time t after updating is not less than the signal length of the transmission signal A, the elapsed time from the time t0 has reached the signal length of the transmission signal A. Therefore, in this case, all the small signals Bn generated by the division processing of the transmission signal A are subjected to convolution calculation using the impulse response at the transmission time of each small signal Bn, and the generated convolution data H is recorded. It is recorded in the device 9.

Therefore, when the processing device 11 receives the determination result J from the determination device 10, the processing device 11 reads out the convolution data H regarding all the small signals Bn recorded in the recording device 9 as convolution data integration processing, and ), it has a function of generating all the convolution data K by combining all the convolution data H. Note that FIG. 6(a) shows only hypothetical received signals BX1, BX2 and BX3 corresponding to the small signals B1, B2 and B3 in order to avoid complication of the drawing.

The processing device 11 has a function of sending the generated full convolution data K to the time division device.

When the time division device 12 receives the full convolution data K from the processing device 11, the unit time ( It has a function to perform equal interval division in the time axis direction according to the sampling period). A plurality of regions generated by the division processing in the direction of the time axis by the time division device 12 will be referred to as time regions L hereinafter.

Calculation device 13 that performs weighted smoothing calculation calculates received signal BXn (n=1, 2, 3, . As shown in FIG. 6(c), it has a function of calculating one representative point indicated by the figure ● in each time domain L so that the total energy is equal.

Although the received signal BXn (n=1, 2, 3, . . . ) of the small signal Bn is shown graphically in FIG. It has the small signal length corresponding to Δt or the small signal length of the small signal Bn corrected and calculated by the computing device 5 . Therefore, many of the received signals of the small signal Bn extend over adjacent time domains L. FIG.

Therefore, the calculation device 13 reads out the correction result of the small signal length of the small signal Bn recorded in the recording device 6, and then, regarding the received signal of the small signal Bn spanning the adjacent time regions L, the calculation device 13 has a function of weighting the ratio of the length of time included in each time region L and distributing energy to each time region L. FIG.

Further, when one representative point in each time domain L is determined as described above, the calculating device 13 calculates a waveform passing through each representative point, and outputs the waveform calculation result to the transmitter 17 (Fig. 2) is obtained as data M simulating the received signal when the transmitted signal A is received by the wave receiver 18 (see FIG. 2).

The computing device 13 further has the function of sending data M simulating the received signal to the output device 14 .

The output device 14 outputs the data M simulating the received signal received from the computing device 13 to a demand part of the data M, such as a display device (not shown) or another computing device using the data M simulating the received signal. It has functionality.

Input device 2, signal division device 3, calculation device 4, calculation device 5, recording device 6, calculation device 7, calculation device 8, recording device 9, determination device 10, processing device 11, time division device 12, calculation device 13. All of the output devices 14 may be implemented as a function in one computer, or may be distributed and implemented in a plurality of computers in any number and in any combination. .

The sound wave propagation simulation system 1 of the present embodiment configured as described above is used for carrying out the sound wave propagation simulation method according to the processing procedure shown in FIG. In the following description, the sound wave propagation simulation system 1 of this embodiment is simply referred to as the simulation system 1 of this embodiment.

When starting the sound wave propagation simulation method, an operator (not shown) uses the input device 2 to set calculation conditions required for sound wave propagation simulation (step SA1). The calculation conditions to be set are the parameters of fixed conditions, the time Δt as a reference when dividing the transmission signal A to generate a plurality of small signals Bn (n=1, 2, 3, . . . ), and the variation Contains condition parameters.

In this way, when the calculation conditions are set using the input device 2, in the simulation system 1 of the present embodiment, first, the signal dividing device 3 divides the transmission signal based on the calculation conditions set in step SA1. A is divided every time Δt to generate a small signal Bn (step SA2).

Next, in the simulation system 1 of the present embodiment, as an initial state at the start of processing, first, the elapsed time t from the time t0 when transmission of the transmission signal A is started is set to 0 seconds (t=0) (step SA3).

In this state, in the simulation system 1 of the present embodiment, the computing device 4 performs processing for determining the propagation path environment required for computing the impulse response at the transmission time of the small signal Bn (step SA4).

Next, the calculation device 5 performs correction calculation processing for the small signal length of the small signal Bn (step SA5). The correction result F of the small signal length of the small signal Bn is recorded in the recording device 6 .

Thus, when the small signal Bn, the propagation path environment, and the correction result F of the small signal length of the small signal Bn are obtained, the simulation system 1 of the present embodiment causes the calculation device 7 to calculate the transmission time of the small signal Bn. is performed to obtain the impulse response (step SA6).

Next, the calculation device 8 performs convolution calculation of the small signal Bn obtained in step SA2 and the impulse response at the transmission time of the small signal Bn obtained in step SA6 to obtain convolution data H. (Step SA7). This convolution data H is recorded in the recording device 9 .

In the simulation system 1 of the present embodiment, when step SA7 is completed, the determination device 10 determines that the time Δt is added to update the elapsed time t from time t0 (t=t+Δt) (step SA8).

Next, the determination device 10 performs a process of determining whether or not the updated elapsed time t is less than the signal length of the transmission signal A (step SA9).

If it is determined in the determination process of step SA9 that the elapsed time t after updating is less than the signal length of the transmission signal A, the determination device 10 sends the determination result I to the calculation device 4 and the calculation device 5. , in the simulation system 1 of the present embodiment, the processing from step SA4 is restarted based on the updated elapsed time t.

Therefore, the simulation system 1 of the present embodiment continues the processing loop from step SA4 to step SA9 until it is determined that the elapsed time t after updating is not less than the signal length of the transmission signal A in the determination processing of step SA9. is repeated. As a result, in step SA2, the simulation system 1 of the present embodiment performs step SA4 to step SA7 according to the order of the wave transmission times for all the small signals Bn generated with the wave transmission times shifted by time Δt. can be performed sequentially. As a result, in the simulation system 1 of the present embodiment, the convolution data H can be obtained by convolving the small signal Bn and the impulse response at the transmission time of the small signal Bn for all the small signals Bn.

On the other hand, if it is determined in the determination process of step SA9 that the elapsed time t after updating is not less than the signal length of the transmission signal A, the determination device 10 sends the determination result J to the processing device 11 .

When the processing device 11 receives the determination result J, the processing device 11 combines the convolution data H regarding all the small signals Bn to perform convolution data integration processing to generate the full convolution data K (step SA10).

When the full convolution data K is generated in step SA10, in the simulation system 1 of the present embodiment, the time division device 12 processes the full convolution data K in a unit time corresponding to the sampling frequency set by the input device 2. At the same time, division is performed at equal intervals in the direction of the time axis (step SA11).

Next, in the simulation system 1 of the present embodiment, the computing device 13, based on the information of the received signal BXn (n=1, 2, 3, . . . ) of the small signal Bn present in each divided time domain L, A representative point is determined one by one in each time domain L, and a weighted smoothing calculation is performed to calculate a waveform passing through each representative point, and the transmission signal A transmitted from the transmitter 17 is received by the receiver 18. Data M simulating the received signal when the signal is received is obtained (step SA12).

After that, in the simulation system 1 of the present embodiment, the output device 14 performs processing for outputting the data M simulating the received signal obtained in step SA12 to the demand section (step SA13).

Thus, according to the simulation system 1 of the present embodiment, the sound wave propagation simulation method including steps SA1 to SA13 can be implemented.

As a result, the simulation system 1 of the present embodiment uses the environment of the sound wave propagation paths 19, 20a, 20b, and 20c in the sound field 15 for the process of obtaining the data simulating the received signal by convolving the impulse response and the transmitted signal. Reception in a situation where it is possible to perform processing that is affected by temporal changes, and in the sound field 15, it is affected by temporal changes in the environment of the sound wave propagation paths 19, 20a, 20b, and 20c. Data M simulating the signal can be obtained.

Therefore, according to the simulation system 1 of the present embodiment and the sound wave propagation simulation method performed using the same, for example, when acoustic communication is performed between a mobile body in water and a fixed station, or between mobile bodies in water, transmission of waves Influence of phase fluctuation of sound wave due to Doppler effect caused by relative position of device 17 and wave receiver 18 changing over time Based on the influence of the phase fluctuation of the reflected wave due to the Doppler effect that occurs in the Simulated data M can be obtained.

Therefore, in the simulation system 1 of the present embodiment and the sound wave propagation simulation method performed using the system, the calculation conditions required for sound wave propagation simulation include parameters of variable conditions that change over time. When obtaining the data M simulating the received signal as a result of the sound wave propagation simulation targeting the sound field 15, an effect of improving the accuracy of the obtained data M can be expected.

Note that the sound wave propagation simulation system and sound wave propagation simulation method of the present disclosure are not limited to the above embodiments.

In the embodiment, an example is shown in which the input device 2 sets the time Δt as a reference when dividing the transmission signal A to generate a plurality of small signals Bn (n=1, 2, 3, . . . ). However, the input device 2 may set the number of divisions when the transmission signal A is divided to generate the small signals Bn. In this case, in the sound wave propagation simulation system and sound wave propagation simulation method of the present disclosure, the value of time Δt may be obtained by dividing the signal length of transmission signal A by the set number of divisions.

The sound wave propagation simulation system of the present disclosure may be applied to any technical field as long as it is a technical field in which signals and information are transmitted and transmitted by propagating sound waves and ultrasonic waves in the air or water.

It goes without saying that various modifications can be made without departing from the gist of the present invention.

2 input device 3 signal division device 4 calculation device 5 calculation device 7 calculation device 8 calculation device 11 processing device 12 time division device 13 calculation device A transmission signal B1, B2, B3, B4, B5, Bn small signal, H convolution data, K full convolution data L time domain, M data

Claims (2)

an input device;
a signal splitting device for splitting a transmission signal to generate a plurality of small signals having different transmission times;
a propagation path environment calculation device;
a computing device for performing a correction calculation of the small signal length;
an impulse response calculator;
a computing device that performs convolution computation;
a processing device that integrates convolutional data;
a time division device;
a computing device that performs weighted smoothing computation;
An input device for setting parameters of fluctuation conditions that change over time with respect to calculation conditions required to perform sound wave propagation simulation ;
A function of determining the propagation paths of the direct wave and the reflected wave using the parameters, and obtaining the response of the impulse signal for each propagation path,
The impulse response calculation device has a function of obtaining an impulse response at the transmission time of the small signal based on the response of the propagation path ,
The computing device that performs the convolution calculation has a function of obtaining the convolution data by performing convolution calculation of the small signal and the impulse response at the transmission time of the small signal,
The processing device has a function of generating full convolution data combining all the convolution data,
The time division device has a function of dividing the entire convolution data at equal intervals in the time axis direction according to the unit time corresponding to the set sampling frequency,
The calculation device for performing the weighted smoothing calculation calculates representative points for each of a plurality of time domains generated by the equally spaced division in the time axis direction so that the total energy of the received small signals existing in the time domain is equal. and calculating a waveform passing through the representative points in the time domain, and using the waveform calculation result to simulate the reception signal when the transmission signal transmitted from the transmitter is received by the receiver A sound wave propagation simulation system characterized in that it has a function to obtain as data that has been processed. by electronic computer
A step of setting parameters of fluctuation conditions that change with the passage of time for calculation conditions required to perform sound wave propagation simulation;
determining the propagation paths of the direct wave and the reflected wave using the parameters, and determining the response of the impulse signal for each propagation path;
a step of dividing a transmission signal to generate a plurality of small signals having different transmission times;
obtaining an impulse response at a transmission time of the small signal based on the response of the propagation path ;
performing a convolution calculation of the small signal and the impulse response at the transmission time of the small signal to obtain convolution data;
generating full convolution data combining all the convolution data;
A step of dividing the entire convolution data at equal intervals in the time axis direction according to the unit time corresponding to the set sampling frequency;
a step of determining a representative point for each of a plurality of time domains generated by equally spaced division in the time axis direction so that the total energy of the received small signals present in the time domain is equal;
A step of calculating a waveform passing through the representative points in the time domain, and obtaining the calculation result of the waveform as data simulating the reception signal when the transmission signal transmitted from the transmitter is received by the receiver. and a method for simulating sound wave propagation.

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