Signal generating device, signal generating program, and signal generating method

Abstract

To reduce the time required for calculations performed for signal generation.SOLUTION: A radar simulator 1 is configured so as to extract, from a frequency waveform represented by a function of frequency, a section corresponding to a frequency that satisfies an extraction condition set in advance and indicating that the amplitude of the frequency waveform is high, as an extracted waveform. The radar simulator 1 is configured so as to convert the extracted waveform extracted by the extraction unit into a time waveform that is represented by a function of time, and to generate the converted time waveform as a signal.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a signal generating device, a signal generating program, and a signal generating method. [Background technology]

[0002] Patent Document 1 describes a signal generating device that generates a signal using an inverse Fourier transform. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-205557 A Summary of the Invention [Problem to be solved by the invention]

[0004] When generating a time waveform expressed as a function of time, a method of adding together multiple time waveforms with different frequencies is usually used. In this method, the calculation time increases in proportion to both the number of sample points in one time waveform and the number of time waveforms, and the time required for signal generation becomes long.

[0005] Furthermore, even when a signal is generated by performing a calculation using an inverse Fourier transform to convert a frequency waveform expressed as a function of frequency into a time waveform, the calculation time increases in proportion to both the number of sample points in the frequency waveform and the number of frequency waveforms, and the processing time for the inverse Fourier transform is added, further lengthening the time required to generate the signal.

[0006] An object of the present disclosure is to reduce the time required for calculations performed to generate a signal. [Means for solving the problem]

[0007] One aspect of the present disclosure is a signal generating device (1) including an extraction unit (S10 to S140) and a conversion unit (S150). The extraction unit is configured to extract, as an extracted waveform, a portion corresponding to a frequency that satisfies a preset extraction condition indicating that the amplitude of the frequency waveform is large in a frequency waveform that is a waveform expressed as a function of frequency.

[0008] The conversion unit is configured to convert the waveform extracted by the extraction unit into a time waveform, which is a waveform expressed as a function of time, and generate the converted time waveform as a signal. The signal generating device of the present disclosure thus configured extracts a portion of a frequency waveform with a large amplitude and converts the extracted waveform into a time waveform, thereby shortening the time required for the calculation to convert the frequency waveform into a time waveform. Note that the signal generating device of the present disclosure extracts a portion of a frequency waveform with a large amplitude and converts it into a time waveform, so that a signal can be generated so that the difference from the time waveform generated by converting the entire frequency waveform is small.

[0009] Another aspect of the present disclosure is a signal generation program (24) for causing a computer to function as an extractor and a converter. A computer controlled by the signal generating program of the present disclosure can constitute part of the signal generating device of the present disclosure, and can obtain the same effects as the signal generating device of the present disclosure.

[0010] Yet another aspect of the present disclosure is a signal generation method for extracting, as an extracted waveform, a portion corresponding to a frequency that satisfies a preset extraction condition indicating that the amplitude of the frequency waveform is large from a frequency waveform that is a waveform expressed as a function of frequency. The signal generation method of the present disclosure further converts the extracted waveform into a time waveform that is a waveform expressed as a function of time, and generates the converted time waveform as a signal.

[0011] The signal generation method of the present disclosure configured in this manner is a method executed by the signal generation device of the present disclosure, and by executing this method, it is possible to obtain the same effects as the signal generation device of the present disclosure. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a block diagram showing a configuration of a radar simulator. [Diagram 2] 13 is a flowchart showing a received wave generating process. [Diagram 3] FIG. 1 is a diagram showing a specific example of a two-dimensional Fourier spectrum. [Figure 4] 1A and 1B are diagrams illustrating an extracted spectral array and a received wave generated based on the extracted spectral array; [Diagram 5] 11 is a graph showing the relationship between the calculation time required to generate a received wave and the wave number. [Figure 6] 1A to 1C are diagrams showing a procedure for generating a received wave by adding together a plurality of time waveforms. [Figure 7] FIG. 13 is a diagram showing an extracted rectangle and an extracted figure. [Figure 8] FIG. 13 is a diagram illustrating a method for generating a time waveform from a one-dimensional Fourier spectrum. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The radar simulator 1 of this embodiment includes a display unit 11, an operation input unit 12, a data storage unit 13, a data input / output unit 14, and a control unit 15, as shown in FIG.

[0014] The display unit 11 includes a display device (not shown) and displays various images on the display screen of the display device. The operation input unit 12 outputs input operation information for identifying an input operation performed by a user via a keyboard and a mouse (not shown).

[0015] The data storage unit 13 is a storage device for storing various data. The data input / output unit 14 inputs and outputs data to and from an external device connected via a wire or wirelessly.

[0016] The control unit 15 is mainly composed of a microcomputer including a CPU 21, a ROM 22, a RAM 23, etc. Various functions of the microcomputer are realized by the CPU 21 executing a program stored in a non-transitive substantial recording medium. In this example, the ROM 22 corresponds to the non-transitive substantial recording medium storing the program. Furthermore, the execution of this program executes a method corresponding to the program. Note that some or all of the functions executed by the CPU 21 may be configured in hardware using one or more ICs, etc. Also, the number of microcomputers constituting the control unit 15 may be one or more.

[0017] A simulation program 24 is stored in the ROM 22. The simulation program 24 may be pre-installed in the radar simulator 1, or may be installed from a recording medium or via a network. Examples of the recording medium include an optical disk, a magnetic disk, and a semiconductor memory.

[0018] The simulation program 24 is configured to reproduce the three-dimensional shape of a road and the three-dimensional shape of the area around the road in a virtual space using highly accurate three-dimensional map data, and to run a vehicle on the road reproduced in the virtual space. Furthermore, the simulation program 24 is configured to simulate the transmission and reception of radar waves by a radar device mounted on a vehicle running in the virtual space.

[0019] By starting the simulation program 24 stored in the ROM 22, a radar simulation is executed which simulates the running of a vehicle and the transmission and reception of radar waves by the radar device.

[0020] Next, a procedure for a received wave generating process for generating radar waves (hereinafter, received waves) received by a radar device in a radar simulation will be described. The received wave generation process is started after the end of the transmission wave generation process each time the transmission wave generation process for generating radar waves (hereinafter, transmission waves) to be transmitted by the radar device is executed in the radar simulation. The transmission wave generation process is executed each time a preset radar wave transmission period elapses in the virtual space formed by the radar simulation.

[0021] When the received wave generation process is executed, the CPU 21 of the control unit 15 first sets the number of transmitted waves p stored in the RAM 23 in S10 as shown in Fig. 2. Specifically, the CPU 21 stores a value indicating the number of transmitted waves generated in the most recent transmitted wave generation process in the number of transmitted waves p.

[0022] Next, the CPU 21 stores 0 in the transmission wave identification number q provided in the RAM 23 in S20. Furthermore, in S30, the CPU 21 selects the q-th transmission wave from among one or more transmission waves generated in the most recent transmission wave generation process.

[0023] Then, in S40, the CPU 21 calculates the X-axis direction index range (idx_min to idx_max) for the two-dimensional Fourier spectrum of the radar wave received by the radar device as a result of the q-th transmission wave being reflected by an object (hereinafter, the q-th received wave).

[0024] Here, the process at S40 will be specifically described. In this embodiment, the two-dimensional Fourier spectrum of one received wave is defined by equation (1).

[0025] In formula (1), F is a component of the two-dimensional Fourier spectrum, A is the maximum amplitude of the q-th received wave, φ is the phase of the q-th received wave, and f is the frequency of the q-th received wave. In addition, idx is an integer between 0 and 255, and idy is an integer between 0 and 1023. In addition, W=256 and H=1024.

[0026]

number

[0027] The two-dimensional Fourier spectrum FS1 shown in Figure 3 is a specific example of the two-dimensional Fourier spectrum of one received wave. The X-axis of the two-dimensional Fourier spectrum FS1 indicates the frequency corresponding to the speed of the object that reflected the radar wave. The Y-axis of the two-dimensional Fourier spectrum FS1 indicates the frequency corresponding to the distance of the object that reflected the radar wave.

[0028] First, the CPU 21 determines the maximum amplitude A, phase φ, and frequency f of the two-dimensional Fourier spectrum of the q-th received wave based on the result of the radar simulation. The maximum amplitude A, phase φ, and frequency f of the received wave are determined based on the type and position of the object that reflected the q-th transmitted wave.

[0029] Furthermore, in equation (1) into which the determined maximum amplitude A, phase φ, and frequency f are substituted, the CPU 21 calculates as an X-axis index minimum value idx_min the minimum value of the X-axis position where the amplitude of the two-dimensional Fourier spectrum is equal to or greater than a preset extraction judgment value, as shown in the two-dimensional Fourier spectrum FS1 in Fig. 3. Furthermore, the CPU 21 calculates as an X-axis index maximum value idx_max the maximum value of the X-axis position where the amplitude of the two-dimensional Fourier spectrum is equal to or greater than a preset extraction judgment value. Note that in the two-dimensional Fourier spectrum FS1, the amplitude of the two-dimensional Fourier spectrum is equal to or greater than the extraction judgment value in the region inside the extraction figure Fex.

[0030] When the process of S40 ends, the CPU 21 stores the value of the X-axis direction index minimum value idx_min calculated in S40 in the X-axis direction position idx provided in the RAM 23 in S50, as shown in FIG.

[0031] Next, in S60, CPU 21 calculates the Y-axis direction index range (idy_min to idy_max) at X-axis direction position idx. That is, CPU 21 calculates the Y-axis direction index minimum value idy_min and the Y-axis direction index maximum value idy_max. Specifically, as shown in Fig. 3, CPU 21 calculates the minimum value of the Y-axis direction position at which the amplitude of the two-dimensional Fourier spectrum is equal to or greater than the extraction determination value at X-axis direction position idx as Y-axis direction index minimum value idy_min. Furthermore, CPU 21 calculates the maximum value of the Y-axis direction position at which the amplitude of the two-dimensional Fourier spectrum is equal to or greater than the extraction determination value at X-axis direction position idx as Y-axis direction index maximum value idy_max.

[0032] When the process of S60 ends, the CPU 21 stores the Y-axis direction index minimum value idy_min calculated in S60 in the Y-axis direction position idy provided in the RAM 23 in S70, as shown in FIG.

[0033] Then, in S80, the CPU 21 calculates the value of the two-dimensional Fourier spectrum at (idx, idy) based on the formula (1), and adds the calculated value at the point (idx, idy) in the extracted spectrum array.

[0034] The extracted spectrum array, as shown in extracted spectrum array SA1 in FIG. 4, shows the values ​​of the two-dimensional Fourier spectrum expressed by equation (1), with the frequency corresponding to the speed of the object that reflected the radar wave on the X-axis and the frequency corresponding to the distance of the object that reflected the radar wave on the Y-axis.

[0035] In the initial state, the extracted spectrum array has all (idx, idy) values ​​set to 0. Then, in S80, each time a value is added at a point (idx, idy), the value at the point (idx, idy) is increased by the added value.

[0036] An extracted Fourier spectrum ES1 in the extracted spectrum array SA1 in FIG. 4 is a two-dimensional Fourier spectrum of one received wave whose amplitude is equal to or greater than the extraction determination value.

[0037] When the process of S80 ends, the CPU 21 determines in S90 whether or not the value stored in the Y-axis direction position idy is equal to or greater than the Y-axis direction maximum index value idy_max calculated in S60, as shown in Fig. 2. If the value stored in the Y-axis direction position idy is less than the Y-axis direction maximum index value idy_max, the CPU 21 increments the Y-axis direction position idy in S100 and proceeds to S80. That is, the CPU 21 adds 1 to the value stored in the Y-axis direction position idy and stores the value in the Y-axis direction position idy.

[0038] On the other hand, if the value stored in the Y-axis direction position idy is equal to or greater than the Y-axis direction maximum index value idy_max, the CPU 21 determines in S110 whether the value stored in the X-axis direction position idx is equal to or greater than the X-axis direction maximum index value idx_max calculated in S40. If the value stored in the X-axis direction position idx is less than the X-axis direction maximum index value idx_max, the CPU 21 increments the X-axis direction position idx in S120 and proceeds to S60. That is, the CPU 21 adds 1 to the value stored in the X-axis direction position idx and stores the value in the X-axis direction position idx.

[0039] On the other hand, if the value stored in the X-axis direction position idx is equal to or greater than the X-axis direction index maximum value idx_max, then in S130, CPU 21 increments the transmission wave identification number q. That is, CPU 21 adds 1 to the value stored in the transmission wave identification number q. Furthermore, in S140, CPU 21 determines whether the value stored in the transmission wave identification number q is equal to or greater than the value stored in the transmission wave number p.

[0040] Here, if the value stored in the transmission wave identification number q is less than the value stored in the transmission wave number p, the CPU 21 proceeds to S30. On the other hand, if the value stored in the transmission wave identification number q is equal to or greater than the value stored in the transmission wave number p, the CPU 21 performs inverse fast Fourier transform on the extracted spectrum array created by adding values ​​in the process of S80 in S150 to generate a received wave, and ends the received wave generation process.

[0041] The extracted spectrum array SA2 in FIG. 4 is an example of the result of extracting two-dimensional Fourier spectra located inside the extraction circle for all received waves from 0th to (p-1). Graph G1 in Fig. 4 is an example of a time change of a received wave generated by performing a fast Fourier inverse transform on an extracted spectrum array. A time waveform WF1 in graph G1 shows a time change of a real part of the generated received wave. A time waveform WF2 in graph G1 shows a time change of an imaginary part of the generated received wave.

[0042] The radar simulator 1 configured in this way extracts, as an extracted spectrum array, a portion corresponding to a frequency that satisfies a preset extraction condition indicating that the amplitude of the two-dimensional Fourier spectrum is large in the two-dimensional Fourier spectrum, which is a waveform expressed as a function of frequency. The extraction condition in this embodiment is that the amplitude of the two-dimensional Fourier spectrum is equal to or greater than an extraction threshold value.

[0043] The radar simulator 1 then converts the extracted spectrum sequence into a time waveform represented as a function of time, and generates the converted time waveform as a signal. Such a radar simulator 1 extracts a portion with a large amplitude in a two-dimensional Fourier spectrum and performs a calculation to convert the extracted spectrum array into a time waveform, thereby shortening the time required for the calculation to convert a frequency waveform into a time waveform. Note that, since the radar simulator 1 extracts a portion with a large amplitude in a frequency waveform and converts it into a time waveform, it is possible to generate a signal so that the difference with the time waveform generated by converting the entire frequency waveform is small.

[0044] FIG. 5 is a diagram comparing the calculation time required to generate a received wave in this embodiment with the calculation time required to generate a received wave by adding up multiple time waveforms as shown in FIG. 6, while changing the number of transmitted waves (i.e., the number of waves).

[0045] FIG. 6 shows that a waveform WF14 of a received wave is generated by adding together three time waveforms WF11, WF12, and WF13 having different frequencies. 5, when the wave number is 1, there is almost no difference in the calculation time between this embodiment and the case where a received wave is generated by adding together multiple time waveforms. However, when the wave number is 10, 100, 1000, or 10000, the calculation time in this embodiment is about 10 to 100 times shorter than the calculation time when a received wave is generated by adding together multiple time waveforms.

[0046] In the above-described embodiment, the radar simulator 1 corresponds to a signal generating device, the simulation program 24 corresponds to a signal generating program, S10 to S140 correspond to the processing of an extracting unit, and S150 corresponds to the processing of a converting unit.

[0047] Moreover, the two-dimensional Fourier spectrum corresponds to a frequency waveform, the extracted spectrum array corresponds to an extracted waveform, and the amplitude of the two-dimensional Fourier spectrum corresponds to an extracted parameter. Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment and can be implemented in various modified forms.

[0048] [Variation 1] For example, in the above embodiment, the extraction condition is that the amplitude of the two-dimensional Fourier spectrum is equal to or greater than the extraction judgment value. However, as shown in the two-dimensional Fourier spectrum FS2 in FIG. 7, the extraction condition may be a frequency included in an extraction figure that is preset to include a frequency at which the amplitude of the two-dimensional Fourier spectrum is a peak (hereinafter, referred to as a peak frequency). The extraction figure in the two-dimensional Fourier spectrum FS2 is an extraction rectangle Rex. Moreover, the extraction figure that is preset to include the peak frequency is not limited to a rectangle, and may be a circle, for example, as shown in the extraction circle Cex in the two-dimensional Fourier spectrum FS3.

[0049] [Variation 2] In the above embodiment, a part corresponding to a frequency that satisfies a preset extraction condition is extracted from a two-dimensional Fourier spectrum. However, the frequency waveform is not limited to a two-dimensional spectrum, and for example, as shown in Fig. 8, a part corresponding to a frequency that satisfies an extraction condition may be extracted from a one-dimensional spectrum, or may be extracted from a three- or more-dimensional spectrum.

[0050] [Variation 3] In the above embodiment, the extraction condition is that the amplitude of the two-dimensional Fourier spectrum is equal to or greater than the extraction judgment value. However, as shown in Fig. 8, for example, the extraction condition may be that the power is equal to or greater than a predetermined subtraction extraction judgment value Jex in a one-dimensional Fourier spectrum FS4 in which the horizontal axis is frequency and the vertical axis is power. The subtraction extraction judgment value Jex is a value obtained by subtracting a predetermined subtraction value SV from the peak power PWpeak. The peak power PWpeak is the power at the frequency that is a peak in the one-dimensional Fourier spectrum FS4.

[0051] FIG. 8 shows that in a one-dimensional Fourier spectrum FS4, extracted waveforms Wex1, Wex2, and Wex3 are extracted, and a waveform WF21 of a received wave is generated by performing an inverse fast Fourier transform on the extracted waveforms Wex1, Wex2, and Wex3.

[0052] It should be noted that the power corresponds to the extraction parameter, and the peak power PWpeak corresponds to the peak parameter. [Variation 4] In the above embodiment, the amplitude of the two-dimensional Fourier spectrum is used as the extraction parameter, but the extraction parameter is not limited to the amplitude, and may be any parameter that has a positive correlation with the magnitude of the amplitude. For example, the power may be used as the extraction parameter, as shown in the one-dimensional Fourier spectrum FS4 in FIG.

[0053] [Variation 5] In the above embodiment, a form in which a signal is generated using an inverse Fourier transform has been shown, but any transform method capable of transforming a frequency waveform into a time waveform may be used, for example, wavelet transform.

[0054] [Variation 6] In the above embodiment, a radar wave is generated as a signal, but the signal is not limited to a radar wave. For example, an audio signal may be generated.

[0055] The control unit 15 and the method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit 15 and the method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit 15 and the method described in the present disclosure may be realized by one or more dedicated computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by a computer. The method for realizing the functions of each unit included in the control unit 15 does not necessarily need to include software, and all of the functions may be realized using one or more hardware.

[0056] In the above embodiments, multiple functions of one component may be realized by multiple components, or one function of one component may be realized by multiple components. Also, multiple functions of multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Also, part of the configuration of the above embodiments may be omitted. Also, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

[0057] In addition to the above-described radar simulator 1, the present disclosure can also be realized in various forms, such as a system including the radar simulator 1 as a component, a program for causing a computer to function as the radar simulator 1, a non-transient physical recording medium such as a semiconductor memory on which the program is recorded, and a signal generation method. [Explanation of symbols]

[0058] 1... radar simulator, 15... control unit, 24... simulation program

Claims

1. A signal generating device (1) for generating a signal corresponding to a received wave received by a radar device in a radar simulation simulating the transmission and reception of radar waves by the radar device, comprising: an extraction unit (S10 to S140) configured to calculate a frequency waveform, which is a waveform expressed as a function of frequency, within a frequency range that satisfies a preset extraction condition indicating that the amplitude of the received wave is large, based on one or more preset received wave functions indicating a relationship between the amplitude of one or more received waves for the one or more transmitted waves transmitted by the radar device in the radar simulation and the frequency of the received waves; a conversion unit (S150) configured to convert the frequency waveform calculated by the extraction unit into a time waveform, which is the waveform expressed as a function of time, and generate the converted time waveform as a signal of the received wave; A signal generating device (1) comprising:

2. 2. A signal generating device according to claim 1, The extraction condition is that an extraction parameter having a positive correlation with the magnitude of the amplitude of the frequency waveform is equal to or greater than a preset extraction determination value.

3. 2. A signal generating device according to claim 1, an extracted parameter at a frequency where an extracted parameter having a positive correlation with the magnitude of the amplitude of the frequency waveform reaches a peak is defined as a peak parameter; A value obtained by subtracting a preset subtraction value from the peak parameter is set as a subtraction extraction judgment value, A signal generating device, wherein the extraction condition is that the extraction parameter of the frequency waveform is equal to or greater than a predetermined subtraction extraction judgment value.

4. 2. A signal generating device according to claim 1, The frequency at which an extracted parameter having a positive correlation with the magnitude of the amplitude of the frequency waveform peaks is defined as a peak frequency, A signal generating device, wherein the extraction condition is that the frequency in the frequency waveform is included inside an extraction pattern that is preset to include the peak frequency.

5. In a radar simulation simulating the transmission and reception of radar waves by a radar device, a signal generating device (1) computer that generates a signal corresponding to a received wave received by the radar device in the radar simulation, an extraction unit (S10 to S140) configured to calculate a frequency waveform, which is a waveform expressed as a function of frequency, within a frequency range that satisfies a preset extraction condition indicating that the amplitude of the received wave is large, based on one or more preset received wave functions indicating a relationship between the amplitude of one or more received waves for the one or more transmitted waves transmitted by the radar device in the radar simulation and the frequency of the received waves; and A conversion unit (S150) configured to convert the frequency waveform calculated by the extraction unit into a time waveform, which is the waveform expressed as a function of time, and generate the converted time waveform as a signal of the received wave. A signal generating program (24) for functioning as

6. A signal generation method executed by a signal generation device (1) in a radar simulation simulating transmission and reception of radar waves by a radar device, the signal generation method generating a signal corresponding to a received wave received by the radar device in the radar simulation, comprising: For each of one or more transmission waves transmitted by the radar device in the radar simulation, a frequency waveform is calculated that is a waveform expressed as a function of frequency within a frequency range that satisfies a preset extraction condition indicating that the amplitude of the reception wave is large, based on one or more preset reception wave functions that indicate a relationship between the amplitude of one or more reception waves for the one or more transmission waves and the frequency of the reception waves; A signal generating method for converting the calculated frequency waveform into a time waveform, which is a waveform expressed as a function of time, and generating the converted time waveform as a signal of the received wave.

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