Radar simulator and program

Abstract

A clustering unit (S120) clusters rays using ray information and basic information, which is information used to calculate the ray information. A phase addition unit (S150) calculates, for each ray, a phase rotation amount at a reception point calculated from the path length of a propagation path, and calculates a complex propagation loss, which is a propagation loss represented by a complex value with the phase rotation amount taken into account. A cluster information generation unit (S140, S160 to S170) sums the complex propagation losses of rays belonging to the same cluster for each cluster generated by the clustering unit, and sets the summed result as the total propagation loss and phase of an integrated ray obtained by integrating all rays belonging to the cluster.

Description

Radar simulator, program Cross-reference of related applications

[0001] This international application claims the interests of Japanese Patent Application No. 2024-232727, filed with the Japan Patent Office on 27 December 2024, the entire disclosure thereof incorporated herein by reference.

[0002] This disclosure relates to a technique for calculating radar waveforms through simulation.

[0003] A technique for simulating in-vehicle radar using ray tracing is known. In ray tracing, the intensity and transmission angle of rays (i.e., light or electromagnetic waves) transmitted from a transmission point, as well as the refraction and reflection of rays by objects in the path from the transmission point to the reception point, are simulated by a computer to calculate the intensity and reception angle of the rays received at the reception point. Achieving the resolution required for vehicle control requires tracking a large number of rays, which necessitates a massive amount of computation. Patent Document 1 below proposes a technique for clustering rays to reduce the amount of computation required.

[0004] German Patent Application Publication No. 102021210464

[0005] However, after detailed examination by the inventors, it was found that in the prior art, the average value of the information of each ray belonging to the cluster is used as the information of the clustered rays, and a problem was found in that the intensity of the rays at the receiving point cannot be accurately determined. In other words, as one of the pieces of information of a ray, propagation loss according to the propagation path is determined for each ray, and the intensity of the ray at the receiving point (i.e., the amplitude or power of the received signal) is determined from the propagation loss. However, the amount of phase rotation of a ray at the receiving point differs for each ray depending on the propagation path length, and even if the amplitude is the same, the received level will also be different if the amount of phase rotation is different. In other words, if the intensity of the rays calculated from the propagation loss is simply averaged as the information of the cluster, the received level at the receiving point cannot be determined accurately, and as a result the signal waveform finally calculated together with other rays will be inaccurate.

[0006] One aspect of this disclosure is the provision of a technique to suppress signal degradation due to ray clustering.

[0007] One aspect of the present disclosure is a radar simulator comprising a ray tracing unit, a clustering unit, a phase addition unit, and a cluster information generation unit. The ray tracing unit uses ray tracing to set up a plurality of rays that indicate the transmission point and reception point of a radar wave, and the propagation path of the radar wave from the transmission point to the reception point, and calculates ray information for each ray, which includes at least the path length of the propagation path and the propagation loss along the propagation path. The clustering unit clusters the rays using the ray information and basic information which is information used to calculate the ray information. The phase addition unit calculates the amount of phase rotation at the reception point calculated from the path length of the propagation path for each ray, and calculates a complex propagation loss which is the propagation loss expressed as a complex value that takes the amount of phase rotation into account. The cluster information generation unit sums up the complex propagation losses of each ray belonging to the same cluster for each cluster generated by the clustering unit, and uses the summed result as the total propagation loss and phase of the integrated ray which integrates all rays belonging to the cluster.

[0008] This configuration makes it possible to suppress signal degradation due to ray clustering.

[0009] One aspect of this disclosure is a program that causes a computer to function as a ray tracing unit, a clustering unit, a phase addition unit, and a cluster information generation unit. The ray tracing unit uses ray tracing to set up a plurality of rays that indicate the transmission and reception points of radar waves, and the propagation path of radar waves from the transmission point to the reception point, and calculates ray information for each ray, which includes at least the path length of the propagation path and the propagation loss along the propagation path. The clustering unit clusters the rays using the ray information and basic information which is information used to calculate the ray information. The phase addition unit calculates the amount of phase rotation at the reception point calculated from the path length of the propagation path for each ray, and calculates a complex propagation loss which is the propagation loss expressed as a complex value that takes this phase rotation amount into account. The cluster information generation unit sums up the complex propagation losses of each ray belonging to the same cluster for each cluster generated by the clustering unit, and takes the summed result as the total propagation loss and phase of the integrated ray which integrates all rays belonging to the cluster.

[0010] By running such a program, signal degradation due to ray clustering can be suppressed.

[0011] This is a block diagram showing the configuration of the radar simulator. This is an explanatory diagram illustrating the overview of the radar simulation model. This is a flowchart of the clustering process. This is a table showing the clustering conditions and how to calculate each piece of information regarding the integrated ray. This is an explanatory diagram showing how to determine the transmission path length of the integrated ray. This is an explanatory diagram showing a numerical example for determining the transmission path length of the integrated ray.

[0012] Embodiments of this disclosure will be described below with reference to the drawings.

[0013] [1. Configuration] The radar simulator 1 calculates information acquired by the vehicle-mounted radar through simulation.

[0014] In the radar simulator 1, as shown in Figure 2, a transmission model 100 that simulates the transmission section of an in-vehicle radar and a reception model 200 that simulates the reception section of an in-vehicle radar are used. The radar simulator 1 calculates the propagation characteristics between the transmission point and the reception point by ray tracing. Furthermore, the radar simulator 1 calculates the waveform of the beat signal based on the calculated propagation characteristics, the directivity of the antenna, and the modulation scheme used in the in-vehicle radar.

[0015] Transmitting model 100 includes, for example, a signal generator 101, a phase shifter 102, a transmitting amplifier 103, and a transmitting antenna 104. The signal generator 101 generates a modulated transmit signal. The phase shifter 102 changes the phase of the transmit signal generated by the signal generator 101. The transmitting amplifier 103 amplifies the transmit signal output from the phase shifter 102. The transmitting antenna 104 emits radio waves according to the transmit signal amplified by the transmitting amplifier 103. Receiving model 200 includes, for example, a receiving antenna 201, a mixer 202, a receiving amplifier 203, a filter 204, and an AD converter 205. The receiving antenna 201 receives radio waves and outputs a received signal. The mixer 202 generates a beat signal by mixing the received signal from the receiving antenna 201 with the transmit signal. The receiving amplifier 203 amplifies the beat signal generated by the mixer 202. The filter 204 removes unwanted components from the beat signal amplified by the receiving amplifier 203. The AD converter 205 converts the beat signal output from the filter 204 into a digital value.

[0016] Ray tracing assumes an omnidirectional transmitting antenna 104 and a receiving antenna 201. Rays that reach the receiving antenna 201 (i.e., the receiving point) are extracted from the many rays radiated from the transmitting antenna 104 (i.e., the transmitting point). Ray tracing also generates ray information for each of the extracted rays. Details of the ray information will be described later.

[0017] The radar simulator 1 may be provided in a vehicle equipped with an on-board radar, or in a cloud-based server capable of communicating with a vehicle equipped with an on-board radar, or in both the vehicle and the server.

[0018] As shown in Figure 1, the radar simulator 1 comprises a storage unit 2 and a calculation unit 3.

[0019] The memory unit 2 stores at least scenario information 21, asset information 22, ray tracing setting information 23, directional information 24, and modulation information 25.

[0020] Scenario information 21 is time-based positional information for a vehicle equipped with a vehicle-mounted radar (hereinafter referred to as "the vehicle") and for targets, structures, etc., present around the vehicle.

[0021] Asset information 22 is information that shows the three-dimensional shape, material, etc. of the player's vehicle, target, and structures that appear in scenario information 21.

[0022] The ray tracing settings information 23 is various information necessary for ray tracing calculations, in addition to the scenario information 21 and asset information 22. The ray tracing settings information 23 may include, for example, the maximum number of reflections and the radar wave frequency setting value.

[0023] The directional information 24 is information that shows the relationship between the direction as seen from the transmitting point (i.e., transmitting antenna 104) or the receiving point (i.e., receiving antenna 201), the gain, and the phase.

[0024] The modulation information 25 is information related to the modulation of the radar wave, that is, information that determines the waveform of the transmission signal generated by the signal generator 101, and includes information related to the center frequency, bandwidth, and chirp shape of the radar wave.

[0025] The arithmetic unit 3 is primarily composed of a microcomputer equipped with a CPU 31, ROM 32, RAM 33, etc. The various functions of the microcomputer are realized by the CPU 31 executing a program stored in a non-transitional physical recording medium. In this example, ROM 32 corresponds to the non-transitional physical recording medium that stores 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 31 may be configured in hardware using one or more ICs, etc. Also, the number of microcomputers constituting the arithmetic unit 3 may be one or more.

[0026] The ROM 32 stores the simulation program. The simulation program may be pre-installed on the radar simulator 1, or it may be installed via a recording medium or network. Examples of recording media include optical discs, magnetic discs, and semiconductor memory.

[0027] The calculation unit 3 includes a ray tracing unit (hereinafter referred to as the ray tracing unit) 41, a ray integration unit 42, and a waveform calculation unit 43 as functional blocks that represent the functions realized by executing the simulation program.

[0028] The ray tracing unit 41 sets up multiple rays with slightly different radiation directions, simulating radar waves emitted from the transmission point. Based on the scenario information 21, asset information 22, and ray tracing setting information 23, the ray tracing unit 41 calculates the propagation path of the rays and extracts rays from the transmission point to the reception point. For each of the extracted rays, the ray tracing unit 41 calculates ray information that reflects the propagation characteristics of the propagation path.

[0029] Ray information may include the transmission direction of the ray at the transmission point and the reception direction of the ray at the reception point. The transmission and reception directions of the ray may be represented by (α, β) using a horizontal angle α and a vertical angle β, or by a three-dimensional vector (x, y, z). In the following explanation, the transmission and reception directions will be represented using (α, β).

[0030] Ray information includes the signal wavelength λ, the ray propagation path length r from the transmission point to the reception point, and the propagation loss L along the propagation path. Ｐ , Number of reflections N within the propagation path ｒｅｆ The signal may also include Doppler information, etc. The frequency f may be used instead of the wavelength λ. Propagation loss L Ｐ L may be expressed as the amplitude of the signal received at the receiving point when a signal with a unit intensity amplitude is transmitted from the transmitting point. In the following, propagation loss L Ｐ As such, the amplitude of the signal received at the receiving point is used, and the amplitude L ＰIt is denoted as such. As the Doppler information, the relative velocity Vr between the host vehicle and the reflecting object in the propagation path may be used, or the Doppler shift amount ΔD calculated from the relative velocity Vr and the wavelength λ may be used. In the following description, the Doppler shift amount ΔD is used as the Doppler information and is denoted as the Doppler information ΔD.

[0031] The ray integration unit 42 acquires the ray information, which is the calculation result, from the ray tracer unit 41, and performs clustering to integrate similar rays using the ray information. Hereinafter, the cluster generated by the clustering is also referred to as an integrated ray. The ray integration unit 42 generates integrated ray information for each cluster (that is, integrated ray). The integrated ray information is information having the same items as the ray information.

[0032] The waveform calculation unit 43 calculates the signal waveform of the beat signal based on the integrated ray information acquired from the ray integration unit 42, the directivity information 24 and the modulation information 25 acquired from the storage unit 2. Specifically, the signal waveform of the beat signal is calculated by mixing, through calculation, the transmission signal calculated by the modulation information 25 and the reception signal calculated from the transmission signal, the integrated ray information, and the directivity information 24.

[0033] [2. Processing] Next, the clustering process executed by the arithmetic unit 3 to realize the function as the ray integration unit 42 will be described using the flowchart of FIG. 3.

[0034] The clustering process is repeatedly executed every time the ray information is generated by the ray tracer unit 41.

[0035] When the clustering process is started, in S110, the arithmetic unit 3 acquires the ray information, which is the calculation result, from the ray tracer unit 41. Let the number of ray information to be acquired be N Ｒ pieces.

[0036] In S120, the arithmetic unit 3 executes clustering using the ray information. In the clustering, as shown in FIG. 4, the transmission direction (α ｔ , β ｔ ), the reception direction (α ｒ , β ｒ ), the number of reflection times N ｒｅｆRays with similar Doppler information ΔD and propagation path length r are merged into the same cluster.

[0037] Note that the transmission direction (α ｔ , β ｔ When using ), the horizontal angle α in the transmission direction of the two rays of interest. ｔ The difference, and the vertical angle β ｔ One of the conditions for including the same cluster (hereinafter referred to as the clustering condition) is that the differences between the two values ​​are all within an acceptable range. Reception direction (α ｒ , β ｒ When using ), the horizontal angle α in the receiving direction of the two rays of interest. ｒ The difference, and the vertical angle β ｒ One of the clustering conditions is that the differences between the two values ​​are all within an acceptable range. Number of reflections N ｒｅｆ When using, the number of reflections N ｒｅｆ One of the clustering conditions is that the two rays are identical. When using Doppler information ΔD, one of the clustering conditions is that the difference in Doppler information ΔD between the two rays of interest is within an acceptable range. When using propagation path length r, one of the clustering conditions is that the difference in propagation path length r between the two rays of interest is within an acceptable range.

[0038] Then, the length from the lower limit to the upper limit of the expected propagation path length r is divided into multiple unit intervals of a fixed length, and clustering is performed for each divided unit interval. Specifically, clusters are generated by merging rays that have a propagation path length r belonging to the unit interval of interest and that satisfy all of the clustering conditions described above.

[0039] The length of the unit interval may be set to, for example, 0.1 m. The size of the unit interval and the size of the tolerance range used in the clustering conditions are set, for example, to obtain the information resolution required in subsequent processing. Below, the number of clusters, i.e., integrated rays, generated by clustering is N. ＣＲ It is represented as follows. However, N ＣＲ ≤N Ｒ That is the case.

[0040] In steps S130 to S180, the calculation unit 3 calculates the N generated in S120. ＣＲ For each of the individual clusters, the process of calculating integrated ray information is repeated. In other words, the calculation unit 3 calculates C = 1 to N ＣＲ For each cluster C identified by [the specified method], the integrated ray information is calculated for each cluster C by repeating the processes S140 to S170 in order.

[0041] In S140, the arithmetic unit 3 calculates the transmission direction (α) based on the ray information of the rays belonging to cluster C, which is the integrated ray information of cluster C. ＣＰｔ , β ＣＰｔ ), receiving direction (α ＣＰｒ , β ＣＰｒ ), and calculate the Doppler information ΔD. Below, cluster C is N Ｓ Each ray belongs to a specific group, and k is used as an identifier to distinguish each ray.

[0042] As shown in Figure 4, the transmission direction (α ＣＰｔ , β ＣＰｔ ) is the transmission direction (α) of each ray belonging to cluster C. ｔ (k), β ｔ (k) is the power value L of the propagation loss. Ｐ (k) ２ The weighted average value is used. This notation is for the power value L Ｐ (k) ２ However, amplitude L Ｐ This means it is proportional to the square of (k).

[0043] Receiving direction (α ＣＰｒ , β ＣＰｒ ) is the receiving direction (α) of each ray belonging to cluster C. ｒ (k), β ｒ (k) is the power value L of the propagation loss. Ｐ (k) ２ Use the weighted average value.

[0044] Doppler shift amount ΔD ＣＰ This represents the Doppler shift amount ΔD(k) of each ray belonging to cluster C, and the power value L of the propagation loss. Ｐ (k) ２ Use the weighted average value.

[0045] Each cluster belonging to cluster C has the same number of reflections N. ｒｅｆ Therefore, the number of reflections in cluster C is N ｒｅｆ Use it as is.

[0046] In S150, the calculation unit 3 calculates the phase rotation amount θ of each ray belonging to cluster C. Ｐ (k) is calculated using equation (1) or equation (2). c is the speed of light.

[0047] The first term on the right-hand side of equation (1) represents the amount of phase rotation corresponding to the propagation path length r(k), and the second term on the right-hand side indicates that the phase reverses each time the ray is reflected. Equation (2) is a modified version of equation (1) using the relationship λ = c / f.

[0048] In S160, the calculation unit 3 calculates the propagation loss L, which is the integrated ray information of cluster C. ＣＰ and phase θ ＣＰ This is calculated using equation (3).

[0049] (3) The right-hand side of equation (3) represents the amplitude L, which is the propagation loss of each ray belonging to cluster C. Ｐ (k) is the phase rotation amount θ calculated in S150. Ｐ By taking (k) into account, the propagation loss expressed as a complex value can be expressed as N Ｓ This means summing up all the individual rays. Also, the phase θ ＣＰ 0 ≤ θ ＣＰ It is set to <2π. Since the integrated ray information does not represent the average value of multiple rays belonging to a cluster, but rather information that integrates multiple rays, the summation value is used for propagation loss.

[0050] In S170, the calculation unit 3 calculates the phase θ of cluster C calculated in S160. ＣＰ And from the propagation path length r(k) of each ray belonging to cluster C, the propagation path length r of the integrated ray information of cluster C is obtained. ＣＰ This is determined by first determining the propagation path length r(k) of each ray belonging to cluster C, and the amplitude L of the propagation loss. Ｐ The weighted average value by (k) is taken as the provisional path length tr. Then, as shown in Figure 5, within the unit interval associated with cluster C, the phase is θＣＰ Multiple candidate distances are set. Of the set candidate distances, the candidate distance closest to the provisional path length tr is set to the propagation path length r of cluster C. ＣＰ We have decided on this.

[0051] In S180, the arithmetic unit 3 determines whether the calculation of integrated ray information has been completed for all clusters C. If the calculation is not completed, it specifies another cluster and repeats the process from S140 to S170. If the calculation is completed, it terminates the process.

[0052] [3. Example of Operation] For example, as shown in Figure 6, Ray 1 and Ray 2 form the same cluster, and the propagation path lengths of Ray 1 and Ray 2 are r(1) = 10 [m] and r(2) = 10.0911 [m], and the amplitude is L Ｐ (1) = 1, L Ｐ (2) = 9, phase is θ Ｐ (1) = 0 [rad], θ Ｐ (2) Let = π / 2 [rad]. In this case, the amplitude of the integrated ray is L ＣＰ =√82, phase is θ ＣＰ This becomes = 0.46π [rad]. Also, the provisional path length is tr = 10.0820 [m].

[0053] Within the unit interval, θ ＣＰ If there are two candidate distances r1 and r2 such that = 0.46π [rad], then candidate distance r2, which is closer to the hypothetical path length tr, will be the cluster propagation path length r ＣＰ It was adopted as, r ＣＰ This equals 10.0832m.

[0054] In summary, the integrated ray information is the propagation path length r. ＣＰ =10.0832 [m], amplitude L ＣＰ =√82, phase θ ＣＰ The value adopted is = 0.46π [rad].

[0055] [4. Correspondence of Terms] Transmission direction in this embodiment (α ｔ , β ｔ ), receiving direction (α ｒ , β ｒ ), Number of reflections N ｒｅｆ, the Doppler information ΔD and the propagation path length r correspond to the basic information of the present disclosure. The phase rotation amount θ in this embodiment Ｐ is taken into account and the amplitude L represented by a complex value Ｐ corresponds to the complex propagation loss of the present disclosure. The amplitude L of the integrated ray in this embodiment ＣＰ corresponds to the total propagation loss of the present disclosure. S120 in this embodiment corresponds to the clustering unit of the present disclosure, S150 corresponds to the phase load unit of the present disclosure, and S140, S160 to S170 correspond to the cluster information generation unit of the present disclosure.

[0056] [5. Effects] According to the embodiments described in detail above, the following effects can be obtained.

[0057] (5a) In the radar simulator 1, the amplitude L of the integrated ray calculated for each cluster C ＣＰ is calculated in consideration of the phase rotation amount θ Ｐ that occurs in the propagation path of each ray belonging to the cluster C. Therefore, compared with the conventional technology that does not consider the phase rotation amount θ ＣＰ in the calculation of the amplitude L of the integrated ray Ｐ , the amplitude L of the integrated ray ＣＰ can be calculated with high accuracy. As a result, it is possible to suppress a large change in the signal waveform calculated using the integrated ray information, which is the result of clustering, compared with the signal waveform calculated without performing clustering. That is, according to the radar simulator 1, it is possible to suppress the deterioration of the signal waveform while suppressing the calculation amount.

[0058] (5b) In the radar simulator 1, the amplitude L Ｐ represented by a complex value with the phase rotation amount θ Ｐ taken into account is summed up, and together with the amplitude L ＣＰ of the integrated ray, the phase θ ＣＰ of the integrated ray is calculated, and the propagation path length r ＣＰ of the integrated ray is determined so as to match the calculated phase θ ＣＰ . As a result, since the information calculated for the integrated ray is consistent, it is possible to improve the accuracy of the calculation using the integrated ray information.

[0059] [6. Other Embodiments] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be implemented in various modifications.

[0060] (6a) In the above embodiment, for a part of the integrated ray information, when calculating the integrated ray information from the ray information, the weighted average of the power L Ｐ ２ is used, but the weighted average of the amplitude L Ｐ may also be used.

[0061] (6b) In the above embodiment, rays in which all of the transmission direction (α ｔ , β ｔ ), reception direction (α ｒ , β ｒ ), number of reflections N ｒｅｆ , Doppler information ΔD, and propagation path length r are similar are included in the same cluster. For example, rays in which a part of the transmission direction (α ｔ , β ｔ ), reception direction (α ｒ , β ｒ ), number of reflections N ｒｅｆ , Doppler information ΔD, and propagation path length r are similar may be included in the same cluster.

[0062] (6c) The arithmetic unit 3 and its method described herein may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the arithmetic unit 3 and its method described herein may be implemented by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, the arithmetic unit 3 and its method described herein may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium. The method for implementing the functions of each part included in the arithmetic unit 3 does not necessarily have to include software, and all of its functions may be implemented using one or more hardware components.

[0063] (6d) Multiple functions of one component in the above embodiment 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. Furthermore, some of the configurations of the above embodiment may be omitted. Furthermore, at least some of the configurations of the above embodiment may be added to or replaced with the configurations of other above embodiments.

[0064] (6e) In addition to the radar simulator 1 described above, the present disclosure can also be realized in various forms, such as a system comprising the radar simulator 1, a program for causing a computer to function as the radar simulator 1, a non-transitional physical recording medium such as a semiconductor memory on which the program is recorded, and a radar simulation method.

[0065] [7. Technical Concept Disclosed in This Specification] [Item 1] A radar simulator comprising: a ray tracing unit that uses ray tracing to set up a plurality of rays indicating a transmission point and a reception point of a radar wave, and the propagation path of the radar wave from the transmission point to the reception point, and calculates ray information for each ray that includes at least the path length of the propagation path and the propagation loss in the propagation path; a clustering unit that clusters the rays using the ray information and basic information which is information used to calculate the ray information; a phase addition unit that calculates a phase rotation amount at the reception point calculated from the path length of the propagation path for each ray, and calculates a complex propagation loss which is the propagation loss expressed as a complex value with the phase rotation amount taken into account; and a cluster information generation unit that, for each cluster generated by the clustering unit, sums up the complex propagation losses of each ray belonging to the same cluster, and uses the summation result as the total propagation loss and phase of an integrated ray which integrates all rays belonging to the cluster.

[0066] [Item 2] A radar simulator according to Item 1, wherein the basic information used for clustering in the clustering unit includes at least one of the following, calculated for each ray in the ray tracing unit: the transmission direction at the transmission point, the reception direction at the reception point, the number of reflections in the propagation path, the path length of the propagation path, and the amount of Doppler shift caused by reflection.

[0067] [Item 3] A radar simulator according to Item 1 or Item 2, wherein the phase addition unit is configured to use the number of reflections in the propagation path for calculating the amount of phase rotation.

[0068] [Item 4] A radar simulator according to any one of items 1 to 3, wherein the cluster information generation unit determines the propagation path length of the integrated ray using the phase of the integrated ray.

[0069] [Item 5] A radar simulator according to any one of Items 1 to 3, wherein the cluster information generation unit determines the propagation path length of the integrated ray within a range of distances that can be considered to be the same cluster as the cluster to which the integrated ray belongs.

[0070] [Item 6] A radar simulator according to any one of Items 1 to 3, wherein the cluster information generation unit calculates a provisional path length by weighting the propagation path length of each ray belonging to the integrated ray by the propagation loss of each ray, and determines the candidate distance that is closest to the provisional path length among a plurality of candidate distances that coincide with the phase of the integrated ray, within the range of propagation path lengths that can be considered to be the same cluster as the cluster to which the integrated ray belongs, as the propagation path length of the integrated ray.

[0071] [Item 7] A program to cause a computer to function as: a ray tracing unit that uses ray tracing to set up a plurality of rays indicating the transmission point and reception point of a radar wave, and the propagation path of the radar wave from the transmission point to the reception point, and calculates ray information for each ray that includes at least the path length of the propagation path and the propagation loss along the propagation path; a clustering unit that clusters the rays using the ray information and basic information which is information used to calculate the ray information; a phase addition unit that calculates the amount of phase rotation at the reception point calculated from the path length of the propagation path for each ray, and calculates a complex propagation loss which is the propagation loss expressed as a complex value that takes the amount of phase rotation into account; and a cluster information generation unit that, for each cluster generated by the clustering unit, sums up the complex propagation losses of each ray belonging to the same cluster, and uses the summed result as the total propagation loss and phase of an integrated ray which integrates all rays belonging to the cluster.

Claims

1. A radar simulator comprising: a ray tracing unit (41) that uses ray tracing to set up a plurality of rays indicating the transmission point and reception point of a radar wave, and the propagation path of the radar wave from the transmission point to the reception point, and calculates ray information for each ray that includes at least the path length of the propagation path and the propagation loss along the propagation path; a clustering unit (42: S120) that clusters the rays using the ray information and basic information which is information used to calculate the ray information; and a phase addition unit (42: S150) that calculates the amount of phase rotation at the reception point calculated from the path length of the propagation path for each ray, and calculates a complex propagation loss which is the propagation loss expressed as a complex value that takes the amount of phase rotation into account. A radar simulator comprising: a cluster information generation unit (42: S140, S160-S170) that, for each cluster generated by the clustering unit, sums up the complex propagation losses of each ray belonging to the same cluster, and uses the summed result as the total propagation loss and phase of the integrated ray which integrates all rays belonging to the cluster; and 2. A radar simulator according to claim 1, wherein the basic information used for clustering in the clustering unit includes at least one of the following, calculated for each ray in the ray tracing unit: the transmission direction at the transmission point, the reception direction at the reception point, the number of reflections in the propagation path, the path length of the propagation path, and the amount of Doppler shift caused by reflection.

3. A radar simulator according to claim 1, wherein the phase addition unit is configured to use the number of reflections in the propagation path for calculating the amount of phase rotation.

4. A radar simulator according to claim 1, wherein the cluster information generation unit determines the propagation path length of the integrated ray using the phase of the integrated ray.

5. A radar simulator according to claim 1, wherein the cluster information generation unit determines the propagation path length of the integrated ray within a range of distances that can be considered to be the same cluster as the cluster to which the integrated ray belongs.

6. A radar simulator according to claim 1, wherein the cluster information generation unit calculates a provisional path length by weighting the propagation path length of each ray belonging to the integrated ray by the propagation loss of each ray, and determines the candidate distance that is closest to the provisional path length from among a plurality of candidate distances that coincide with the phase of the integrated ray, within the range of propagation path lengths that can be considered to be the same cluster as the cluster to which the integrated ray belongs, as the propagation path length of the integrated ray.

7. A program to cause a computer to function as: a ray tracing unit that uses ray tracing to set up a plurality of rays indicating the transmission and reception points of radar waves, and the propagation path of radar waves from the transmission point to the reception point, and calculates ray information for each ray that includes at least the path length of the propagation path and the propagation loss along the propagation path; a clustering unit that clusters the rays using the ray information and basic information which is information used to calculate the ray information; a phase addition unit that calculates the amount of phase rotation at the reception point calculated from the path length of the propagation path for each ray, and calculates a complex propagation loss which is the propagation loss expressed as a complex value that takes the amount of phase rotation into account; and a cluster information generation unit that, for each cluster generated by the clustering unit, sums up the complex propagation losses of each ray belonging to the same cluster, and uses the summed result as the total propagation loss and phase of an integrated ray which integrates all rays belonging to the cluster.

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