Radar device

Abstract

To provide a radar device to be easily mounted and capable of correctly obtaining information on an object even when a plurality of objects is present.SOLUTION: In a radar device 1, when a code obtained by encoding an appearance pattern of a peak on a Doppler frequency axis expected while an object is at a standstill is defined as an assigned code, a processing section 6 sets a correspondence with respective transmission antennas 3a so as to generate the peak associated with each one of transmission signals in a bin corresponding to "1" of the assigned code. A modulation section 22 performs phase shift modulation following a linear block code as the assigned code.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a radar device that detects an object by transmitting radio waves from multiple antennas. [Background technology]

[0002] As a method for improving the resolution of a radar device, there is a MIMO (Multi-Input Multi-Output) technology that transmits radio waves from multiple transmitting antennas. In this MIMO technology, since it is necessary to separate the transmission signals from each transmitting antenna in order to detect an object, for example, by Doppler division multiplexing, phase shift keying is performed using a different phase shift amount for each transmitting antenna, and each transmission signal is separated as a different signal component on the Doppler frequency axis. For example, Patent Document 1 proposes improving the accuracy of identifying multiple transmission signals from a received signal by reducing the number of transmitting antennas compared to the number of phases used for modulation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6881177 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as shown in Patent Document 1, for example, depending on the speed of an object, the position of the peak may shift in the Doppler frequency, which is called aliasing. If the aliased peak overlaps with the peak of another object, the transmitted signal cannot be separated, and there is a risk that accurate information about the object cannot be obtained, such as the speed of the object cannot be accurately estimated or the accuracy of angle measurement is deteriorated.

[0005] In this case, it is possible to reduce overlaps when multiple objects are present to one by making the intervals between pairs of peaks corresponding to each transmitted signal on the Doppler frequency into a different Golomb ruler. However, since a large number of phases are required to perform phase shift keying so as to obtain a Golomb ruler, it is difficult to implement in practice.

[0006] The present disclosure has been made in consideration of the above-mentioned circumstances, and an object of the present disclosure is to provide a radar device that is easy to implement and can accurately obtain information about objects even when multiple objects are present. [Means for solving the problem]

[0007] A radar device (1) according to one embodiment of the present disclosure includes a transmitting antenna unit (3) having a plurality of transmitting antennas (3a), an oscillator unit (21) that generates a continuous wave common signal, a modulator unit (22) that performs phase shift keying on a plurality of branch signals obtained by branching the common signal into the same number as the transmitting antennas, by rotating the phase of each of the branch signals by a different amount of phase rotation, and generates a plurality of transmission signals to be input to the plurality of transmitting antennas, a receiving antenna unit (4) having one or more receiving antennas (4a), a receiver unit (5) that generates a reception code that encodes an appearance pattern of a peak on a Doppler frequency axis for each of the one or more reception signals received by the receiving antenna unit, and a processor (6) that generates information about an object that has reflected a radiation wave from the transmitting antenna unit based on the reception code generated by the receiving unit, and when an assignment code is an encoding of an appearance pattern of a peak on the Doppler frequency axis expected when the object is stationary, the modulator unit performs phase shift keying according to a linear block code as the assignment code. This makes it easy to implement, and makes it possible to obtain accurate object information even when multiple objects exist. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating a configuration example of a radar device according to a first embodiment; [Diagram 2] FIG. 1 shows an example of an antenna arrangement and an example of an assigned code and a received code. [Diagram 3] FIG. 1 is a diagram showing an example of the generation of assigned codes in a Doppler bin; [Figure 4] A diagram explaining the flow of object detection processing [Diagram 5] FIG. 13 is a diagram for explaining the configuration of a processing unit and a calculation flow according to a third embodiment. [Figure 6] FIG. 13 is a diagram for explaining the configuration of a processing unit and a calculation flow according to a fourth embodiment. [Figure 7] FIG. 13 is a diagram for explaining the configuration of a processing unit and a calculation flow according to the fifth embodiment. [Figure 8] FIG. 13 is a diagram for explaining the configuration of a processing unit and a calculation flow according to the sixth embodiment. [Figure 9] FIG. 13 is a diagram for explaining the configuration of a processing unit and a calculation flow according to the seventh embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a number of embodiments will be described with reference to the drawings. Note that the same reference numerals will be used to denote substantially common parts in the respective embodiments.

[0010] (First embodiment) A first embodiment will be described below. The radar device 1 shown in Fig. 1 is assumed to be mounted on a vehicle and used to obtain information on various objects present around the vehicle. The radar device 1 includes a transmitter 2, a transmitting antenna unit 3, a receiving antenna unit, a receiving unit 5, and a processing unit 6. The transmitting antenna unit 3 has M transmitting antennas 3a1 to 3aM, as shown in Fig. 2 as an example of an antenna arrangement, where M is an integer of 2 or more. The transmitting antennas 3a are arranged in a row at preset intervals along a preset arrangement direction.

[0011] As shown as an example of a transmitting side arrangement, the receiving antenna unit 4 has N receiving antennas 4a1 to 4aN, where N is an integer equal to or greater than 1. When multiple receiving antennas 4a are provided, they are arranged at intervals different from the transmitting antennas 3a and in the same direction as the arrangement direction of the transmitting antennas 3a.

[0012] Now, for example, assume that an object to be detected is present in a direction tilted by θ with respect to the front direction of the transmitting antenna unit 3 and the receiving antenna unit 4. In this case, as is well known, the receiving antenna 4a1 receives the signals transmitted from the transmitting antennas 3a1, 3a2, and 3aM. Similarly, the other receiving antennas 4a also receive the signals transmitted from their respective transmitting antennas 3a.

[0013] This forms a virtual array of M×N receiving antennas 4a in total, which are arranged at different distances from a single reference receiving antenna 4a. As a result, it is possible to obtain the same angular resolution as when one transmitting antenna and M×N receiving antennas are provided.

[0014] 1, the transmission unit 2 includes an oscillation unit 21 and a modulation unit 22. The oscillation unit 21 generates a continuous wave common signal, and outputs the generated common signal to the modulation unit 22.

[0015] The modulation unit 22 branches the common signal generated by the oscillation unit 21 to generate M branch signals, the same number as the number of transmitting antennas 3a. Specifically, the modulation unit 22 sets a different amount of phase rotation for each of the M branch signals, and generates M transmission signals by performing phase shift keying to rotate the phase of the branch signal by the set amount of phase rotation.

[0016] For example, if the number of phases used in phase shift keying is P, where P is an integer greater than M and p=0, 1, 2,...P-1, then modulation unit 22 performs phase shift keying using P phase rotation amounts expressed as phase rotation amount (Δφ)=p×360° / P. However, since P>M, not all of the P phase rotation amounts are used when phase shift keying is performed, but only some of them are used.

[0017] The modulation unit 22 performs phase shift keying so that the assigned code becomes a linear cyclic block code, as will be described later in detail. Here, the assigned code is an encoded version of the expected pattern of peaks on the Doppler frequency axis when an object present within the measurement range is stationary. The pattern of peaks is determined by the phase assignment to each transmission signal. For example, when the number of phases is P and the number of transmitting antennas 3a is M, the assigned code is expressed as a code with a code length of P bits, M bits of which are "1", and the remaining PM bits are "0". For example, when the number of transmitting antennas 3a is 2 and the number of phases is 5, a 5-bit code of, for example, "11000" can be set as the assigned code.

[0018] The receiving unit 5 generates a receiving code by encoding the appearance pattern of the peak on the Doppler frequency axis for each of the N received signals output from each receiving antenna 4a of the receiving antenna unit 4, and outputs the generated code to the processing unit 6. Here, the receiving code is an encoding of the appearance pattern obtained from the peak detection result on the Doppler frequency axis of the actual received signal. For example, when the number of phases is P and the number of transmitting antennas 3a is M, the receiving code is expressed as a code in which M bits out of P bits of a code length equal to the number of phases used in phase shift keying are "1", and the remaining PM bits are "0".

[0019] For example, as shown in the code example in Figure 2, when "11000" is set as the assigned code and phase shift keying is performed, peaks are detected at M points out of the P points into which the Doppler observation range is divided in a distance-velocity map in which the vertical axis is distance and the horizontal axis is velocity that can be uniquely determined based on the Doppler frequency. Therefore, for example, the received code received when no object is present will have a peak detected at the position of the black circle. Then, by associating the peak position with "1" and the position where no peak exists with "0", a 5-bit code of "11000" is obtained as the received code.

[0020] The processing unit 6 is configured with a microcomputer having a CPU 61 and a memory 62 such as a RAM or ROM. The processing unit 6 controls the entire radar device 1 by executing a program 63 stored in the memory 62 by the CPU 61. In addition, the processing unit 6, which will be described in detail later, performs phase shift keying in which the assigned code becomes a linear cyclic block code in the modulation unit 22, and generates object information based on the cross-correlation between the assigned code and the received code. At this time, various data used for the calculation of the phase number, the assigned code, or the cross-correlation are stored in the memory 62 as a database 64.

[0021] The processing unit 6 may be configured with one microcomputer or multiple microcomputers. The method of realizing the functions of the processing unit 6 is not limited to software, and some or all of the functions may be realized using one or multiple pieces of hardware.

[0022] Next, the operation and effects of the above-mentioned configuration will be described. As described above, in the radar device 1 using the MIMO technology, it is necessary to separate the transmission signals from each transmitting antenna 3a in order to detect an object. Note that separating the transmission signals means identifying which transmitting antenna 3a the received signal is a reflection of the radiation wave from. In this case, for example, by making the number of transmitting antennas smaller than the number of phases used for modulation, the accuracy of identifying multiple transmission signals from the received signal may be improved.

[0023] However, depending on the speed of an object present within the measurement range, the position of the peak in the Doppler frequency may shift, i.e., aliasing may occur, and as a result, the aliased peak may overlap with the peaks of other objects, making it impossible to separate the transmitted signals. If it becomes impossible to separate the transmitted signals, it may become impossible to accurately estimate the speed of the object, the accuracy of the angle measurement may deteriorate, and it may become impossible to obtain accurate information about the object.

[0024] In this case, it is possible to reduce overlaps in the presence of multiple objects to one by making the intervals between pairs of peaks corresponding to each transmission signal on the Doppler frequency into a different Golomb ruler. However, the Golomb ruler has the problem that the number of phases required increases as the number of transmission signals to be multiplexed increases. For example, when multiplexing 12 transmission signals, the length of the Golomb ruler is 85, so the number of phases required is at least double that, 170. However, it is currently difficult to implement such a number of phases.

[0025] Therefore, the radar device 1 is easy to implement and can accurately obtain object information even when multiple objects are present, as described below. In other words, the radar device 1 performs phase shift keying in the modulation unit 22 based on an assigned code that is easy to implement and can accurately obtain object information even when multiple objects are present.

[0026] First, the conditions required for the assigned code will be explained. For example, suppose there are two objects within the measurement range, one of which does not undergo aliasing while the other does, and the result is obtained as a range-velocity map. In this case, if radar measurement is performed by performing phase shift keying based on a certain assigned code, the actually obtained range-velocity map will be the result of a logical OR operation between the assigned code without aliasing and the assigned code that has been cyclically shifted once. Hereinafter, the logical OR operation will be referred to as an OR operation. In this case, in order to make it possible to separate each transmission signal, it is considered desirable that the assigned code be a code that satisfies the following condition.

[0027] 1. There should be few correspondences between "1" and "1" between cyclically shifted codes. In other words, the original code and the cyclically shifted code should have as many combinations of "1" and "0" as possible in the same bit position. The points where "1" and "1" correspond to each other correspond to overlapping peaks. 2. The result of the OR operation must be unique. In other words, the code must have a small number of combinations that produce the same result as the OR operation.

[0028] Here, we consider linear cyclic block codes as a code that may satisfy the above conditions. For example, if the code length is 8 bits, linear cyclic block codes use only specific codes from a set of 256 codes that have a large Hamming distance from each other. The selected codes become codewords.

[0029] A linear cyclic block code has a characteristic of cyclicity, in which the cyclic shift of a code word also becomes a code word. A large Hamming distance means that there are few correspondences between "1" and "1" and "0" and "0", which means that there is less overlap between peaks on the Doppler frequency axis. Therefore, as in the case of selecting a so-called error correcting code, it is expected that the number of overlaps of peaks on the Doppler frequency axis can be reduced by selecting a linear cyclic block code with a large Hamming distance as an assigned code. Therefore, the radar device 1 performs phase shift keying using a linear cyclic block code having cyclicity as an assigned code.

[0030] In this case, the assigned code is a code in which M bits are "1" and PM bits are "0" when the number of transmitting antennas 3a is M as described above. As an example, when the number of transmitting antennas 3a1 is M=4, the number of phases P=8 can be selected to obtain a linear cyclic block code having 4 bits of "1". This number of phases may be appropriately selected within a range in which phase shift keying can be performed by the modulation unit 22.

[0031] Now, when the number of phases is selected to be P=8, for example, "10001011" can be set as the assigned code that is a linear cyclic block code. Note that "10001011" indicates that in an 8-bit binary number, the most significant bit is "1", followed by "0", and the least significant bit is "1".

[0032] Then, the radar device 1 performs phase shift keying so that a peak associated with each transmission signal occurs in a bin corresponding to the assigned code "1" when the Doppler bins of the Doppler bin number (Nd=256) are viewed for each Nd / P as shown in Fig. 3. Note that in Fig. 3, the black bins correspond to the assigned code "1" and the shaded blocks correspond to the assigned code "0".

[0033] Specifically, the processing unit 6 of the radar device 1 repeatedly executes the object detection process shown in Fig. 4. First, the processing unit 6 acquires an assigned code (S1). In the case of this embodiment, the assigned code is preset and stored in the database 64. Therefore, the processing unit 6 reads out the assigned code from the database 64 in step S1.

[0034] Next, the processing unit 6 sets the correspondence with each transmitting antenna 3a so that a peak associated with each transmitting signal occurs in a bin corresponding to "1" of the assigned code (S2). For example, the processing unit 6 sets the phase rotation amount for each transmitting signal when performing phase shift keying so that the transmitting antenna 3a1 corresponds to the bin "0", the transmitting antenna 3a2 corresponds to the bin "128", the transmitting antenna 3a3 corresponds to the bin "192", and the transmitting antenna 3a4 corresponds to the bin "255". Note that the correspondence with each transmitting antenna 3a may also be set in advance and stored as the database 64.

[0035] Then, the processing unit 6 judges whether the predetermined measurement start timing has arrived (S3), and if it judges that the measurement start timing has not arrived (S3: NO), it waits. On the other hand, if the processing unit 6 judges that the measurement start timing has arrived (S3: YES), it performs radar measurement (S4). In this step S4, the processing unit 6 operates the transmitting unit 2 for a predetermined measurement period according to the set conditions, outputs radiated waves from each transmitting antenna 3a, and receives reflected waves from the object at the receiving unit 5.

[0036] In this case, if the assigned code is "10001011", the cyclically shifted code obtained by folding back becomes "11000101", and the minimum Hamming distance between them is 3. That is, in this embodiment, the modulation unit 22 performs phase shift keying such that the minimum Hamming distance between the assigned code and a code group consisting of cyclic shifts of the assigned code is 3 or more. The code group consisting of cyclic shifts corresponds to a set of expected values ​​of actual received codes.

[0037] Next, the processing unit 6 analyzes the correlation between the assigned code and the received code (S5). This received code can be obtained by, for example, performing a two-dimensional Fourier transform (2D Fourier transform) (2D Fourier transform (2D Fourier transform)) on the actually received signal and peak detection (CFAR). In other words, the processing unit 6 estimates the circumstances under which the received code was obtained from the relationship between the known assigned code and the received code, which is the actually obtained measurement result, and verifies the accuracy of the estimation, that is, the reliability of separation.

[0038] For example, if the assigned code is "10001011" and the received code is "11001111", the received code coincides with the result of an OR operation between the assigned code and a code obtained by cyclically shifting the assigned code. Therefore, the receiver 5 can infer that there are two objects and aliasing occurs at one of the objects. The processor 6 can verify the accuracy of the inference by analyzing whether the same received code can be obtained by other combinations. That is, the processor 6 can separate each transmission signal when multiple objects are present.

[0039] Then, the processing unit 6 generates information such as the distance and speed of the object based on the analysis result (S6). The generated information is output to an electronic control device for display control or speed control mounted on the vehicle, and is used for notifying the driver and controlling the vehicle speed. The calculation of the cross-correlation in step S5 and the generation of information in step S6 will be described in detail in another embodiment described later. In this way, the radar device 1 performs phase shift keying in accordance with a linear cyclic block code as the assigned code in the modulation unit 22.

[0040] According to the radar device 1 described above, the following effects can be obtained. The radar device 1 includes a transmitting antenna unit 3 having multiple transmitting antennas 3a, an oscillator unit 21 that generates a continuous wave common signal, a modulator unit 22 that performs phase shift keying on multiple branch signals obtained by branching the common signal into the same number as the transmitting antennas 3a, rotating the phase of each of the branch signals by a different amount of phase rotation, and generates multiple transmission signals to be input to the multiple transmitting antennas 3a, a receiving antenna unit 4 having one or more receiving antennas 4a, a receiving unit 5 that generates a receiving code that encodes the appearance pattern of peaks on the Doppler frequency axis for each of the one or more receiving signals received by the receiving antenna unit 4, and a processing unit 6 that generates information about an object that has reflected the radiation wave from the transmitting antenna unit 3, based on the receiving code generated by the receiving unit 5.

[0041] The radar device 1 assigns an assigned code that is an encoded version of the pattern of peaks on the Doppler frequency axis that are expected when an object is stationary. The processing unit 6 then sets a correspondence with each transmitting antenna 3 a so that a peak associated with each transmission signal occurs in a bin corresponding to the assigned code "1". The modulation unit 22 then performs phase shift keying modulation in accordance with a linear cyclic block code as the assigned code.

[0042] Linear cyclic block codes have the property that a cyclic shift of a codeword also becomes a codeword, which is called cyclicity. Therefore, by choosing a codeword with a large Hamming distance, it is possible to reduce the overlap of peaks on the Doppler frequency axis. In other words, it is easier to separate each transmitted signal.

[0043] This allows the speed of each object to be accurately estimated if the transmitted signals can be separated. Also, by using assigned codes with a large Hamming distance between codes, the number of overlapping peaks can be kept low, reducing angle measurement errors. In other words, object information can be obtained accurately. Also, the required code length of the assigned codes, that is, the number of phases (P) when performing phase shift keying, can be roughly twice the number (M) of transmitting antennas 3a. Therefore, it is easy to implement, and even when there are a plurality of objects, information of the objects can be accurately obtained.

[0044] In the modulation unit 22 of the radar device 1, phase shift modulation is performed such that the minimum Hamming distance between the assigned code and a code group composed of a cyclic shift of the assigned code is 2 or more. As a result, overlapping of peaks can be further reduced, separation of each transmission signal becomes easy, and the reliability of the separated result can be improved.

[0045] Also, in the modulation unit 22, the phase shift modulation can be configured such that the minimum Hamming distance between the assigned code and the code group composed of the cyclic shift is 3 or more. Even with such a configuration, overlapping of peaks can be further reduced, separation of each transmission signal can be easily performed, and the reliability of the separated result can be improved.

[0046] (Second Embodiment) Hereinafter, the second embodiment will be described. In the second embodiment, another method for setting or selecting an assigned code will be described. Also, the second embodiment can be combined with one or more other embodiments if there is no conflict.

[0047] The radar device 1 can be configured such that in the modulation unit 22, phase shift modulation is performed such that the code polynomial of the assigned code is divisible by a polynomial having a period equal to or longer than the code length of the code polynomial.

[0048] Also, the radar device 1 can be configured such that in the modulation unit 22, for a code group obtained by cyclically shifting the assigned code, phase shift modulation is performed such that C < D when the maximum number of overlapping bits is C and the minimum Hamming distance is D.

[0049] Furthermore, the radar device 1 can be configured in the modulation unit 22 to perform phase shift keying in which, as the assigned code, where K is the number of overlapping objects and Q is an integer equal to or greater than K, an OR operation is performed on any Q codes in a code group formed of the assigned code and cyclic shifts of the assigned code, and each result is a different code.

[0050] Examples of the assigned code that can perform such phase shift keying include the Hamming code, CRC code, BCH code, Reed-Solomon code, cyclic Golay code, and M-sequence code described in the first embodiment. Below, a method for determining the assigned code for each code will be described, but since each code is well known, the following will illustrate a method for determining the code using a code polynomial of the variable x. In the following equations, "^" indicates a power and "=" indicates that the code polynomial of the assigned code can be divided by a polynomial having a period equal to or greater than the code length of the code polynomial.

[0051] a) Example of Hamming code When the assigned code is "01011001" Sign polynomial:x^5+x^3+x^2=x^2×(x^3+X+1) A 7-bit code word, for example "0101100", is found from the above code polynomial, and then bit extension is performed by adding "1" to the end of the found code word to find the assigned code = "01011001". In this case, bit extension can be achieved by adding one bit, "1" or "0", to the end or beginning of the code word, or by inserting it between bits.

[0052] However, as is the case with other methods, bit extension is not essential and is intended to facilitate calculations in the processing unit 6. For example, it can be obtained as follows. If the assigned code is "10001011", Sign polynomial:x^6+x^2+1=x^3×(x^3+x+1) For example, a code word "1000101" is found using the above code polynomial, and a bit extension is performed by adding "1" to the end of the found code word to find the assigned code "10001011".

[0053] b) Example of CRC code Sign polynomial:x^15+x^12+x^7+x^6+x^5+x^4+x+1=(x^7+x^2)×(x^8++x^7+x^6+x^4+x^2+X+1) The assigned code = "1001000010111011" is obtained from the code word obtained by the above code polynomial.

[0054] c) Example of BCH code Sign polynomial:x^14+x^13+x^12+x^7+x^6+x^5+x^2+X=(x^4++x^3+x^2)×(x^10++x^8+x^5+x^4+x^2+X+1) For example, a code word "111000010100110" is found using the above code polynomial, and a bit extension is performed by adding "1" to the end of the found code word to find the assigned code "1110000101001101".

[0055] d) Example of Reed-Solomon code Sign polynomial:x^3+x+1 For example, a code word "000010000011010001001" is found using the above code polynomial, and a bit extension is performed by adding "1" to the end of the found code word to find the assigned code "0000100000110100010011".

[0056] e) Examples of cyclic Golay codes Sign polynomial:x^11+x^10+x^6+x^5+x^4+x^2+1 For example, a code word "011101110101011111111010" is found using the above code polynomial, and a bit extension is performed by adding "1" to the end of the found code word to find the assigned code "011101110101011111110101".

[0057] f) Example of M-sequence code Sign polynomial:x^3+x+1 For example, a code word "1110100" is found using the above code polynomial, and a bit extension is performed by adding "1" to the end of the found code word to find the assigned code "11101001".

[0058] By setting an assigned code from such a codeword and performing phase shift keying in modulation section 22 using the assigned code, similar to the first embodiment, implementation is easy and object information can be obtained accurately even when multiple objects are present.

[0059] Third embodiment The third embodiment will be described below. In the third embodiment, a specific method for analyzing the cross-correlation between the assigned code and the received code in step S5 of FIG. 4 described in the first embodiment will be described. Note that the same reference numerals are used for parts common to those described in the other embodiments, and detailed description will be omitted. Also, the contents described in the third embodiment can be combined with one or more other embodiments if there is no conflict.

[0060] As shown in Fig. 5 as an example of a calculation block configuration, the processing unit 6 of the radar device 1 of this embodiment includes a metric calculation unit 601 that calculates a cross-correlation function between an assigned code and a received code. In this embodiment, the metric calculation unit 601 calculates a correlation value between an assigned code and a received code as a relationship with a time delay (τ) indicating how many bits the assigned code has been shifted, as shown in an example of a calculation result. Note that, for the sake of explanation, Fig. 5 shows a mode in which the assigned code used for phase shift keying in the modulation unit 22 is input to the processing unit 6, but the assigned code is a parameter set in the modulation unit 22 by the processing unit 6 and is therefore known to the processing unit 6.

[0061] At this time, the metric calculation unit 601 calculates the cross-correlation function between the assigned code and the received code based on the Hamming distance. For example, if the calculation result of the OR operation of the assigned code and the code obtained by shifting the assigned code by 1 bit is called the calculation code for convenience, the metric calculation unit 601 determines that the correlation value is high if the Hamming distance between the received code and the calculation code is small, and calculates that the correlation value is low if the Hamming distance between the received code and the calculation code is large. In the case of Fig. 5, it is shown that the correlation value between the assigned code and the received code is high when τ=8, i.e., shifted by 8 bits, and when τ=10, i.e., shifted by 10 bits.

[0062] The calculation result of the metric calculation unit 601 is output to the estimation unit 602. The estimation unit 602 then extracts peaks with high correlation values ​​by threshold processing that uses a threshold to extract those with high cross-correlation. This makes it possible to obtain the delay time for the received code, that is, the shift amount of the assigned code corresponding to the actual received code, and as a result, each transmitted signal can be separated.

[0063] Then, if it is possible to separate each transmission signal, then it is possible to estimate the speed of an object such as target object 100 in speed estimation unit 603, and to estimate the angle of each object in angle estimation unit 604, and therefore it is possible to generate information such as the distance, speed or angle of each object in information generation unit 605.

[0064] As described above, the radar device 1 of this embodiment includes a metric calculation unit 601 that calculates the cross-correlation between the assigned code and the received code. This makes it possible to separate the transmitted signals based on the cross-correlation when multiple peaks overlap. Therefore, it is easy to implement, and even when multiple objects exist, it is possible to accurately obtain information about the objects, and it is possible to obtain the same effects as the first embodiment and other embodiments.

[0065] (Fourth embodiment) The fourth embodiment will be described below. In the fourth embodiment, a specific method for analyzing the cross-correlation between the assigned code and the received code in step S5 of FIG. 4 described in the first embodiment will be described. Note that the same reference numerals are used for parts common to those described in the other embodiments, and detailed description will be omitted. Also, the contents described in the fourth embodiment can be combined with one or more other embodiments if there is no conflict.

[0066] 6 as an example of a calculation block configuration, the processing unit 6 of the radar device 1 of this embodiment includes a metric calculation unit 611 that calculates the cross-correlation between the assigned code and the received code. The metric calculation unit 611 compares the received code with overlap pattern data 613 that stores in advance all or part of expected values ​​of the received code assumed when multiple objects exist, and calculates the difference therebetween as the Hamming distance.

[0067] The overlap pattern data 613 is, for example, a list of all or part of the expected received codes when the number of phases is P and the number of overlapping objects is assumed to be two, which is stored in the database 64 in advance. The overlap pattern data 613 is referred to when the metric calculation unit 611 calculates the cross-correlation between the assigned code and the received code. Note that the overlap pattern data 613 shown in FIG. 6 is an example. Other overlap pattern data 613 having a different expected number of overlapping objects can also be stored. In other words, the overlap pattern data 613 is data in which all or part of the expected received codes are listed in advance for the overlapping situation of all or part of the objects assumed.

[0068] As described above, since the assigned codes are preset, it is possible to know in advance the expected value of the actually obtained received codes by assuming the number of overlapping objects. In other words, the overlap pattern data 613 correlates with the assigned codes. Therefore, if the expected values ​​of the received codes are listed and stored as the overlap pattern data 613, it is possible to obtain the cross-correlation between the received codes obtained during actual measurement and the assigned codes by referring to the overlap pattern data 613.

[0069] For example, suppose that the Hamming distance between overlap pattern No. 1 and the received code is 3, the Hamming distance between overlap pattern No. 2 and the received code is 4, the Hamming distance between overlap pattern No. 3 and the received code is 0, and the Hamming distance between overlap pattern No. U and the received code is 3. In this case, the cross-correlation between the received code and the assigned code will have the highest peak for overlap pattern No. 3, the correlation value between overlap patterns No. 1 and No. U is relatively low, and the correlation value of overlap pattern No. 2 is relatively the lowest. Note that the Hamming distance calculation result shown in Figure 6 is an example.

[0070] The calculation result by the metric calculation unit 611 is output to the estimation unit 612. The estimation unit 612 detects a peak in the cross-correlation between the expected value of the received code and the received code by performing threshold processing for extracting high cross-correlation by using a threshold value on the calculation result, or by performing processing for obtaining a maximum or minimum value on the calculation result. Note that although the minimum value of the Hamming distance is obtained in this embodiment, it is also possible to configure the system to obtain, for example, the maximum value of the Hamming distance depending on how the duplication pattern data 613 is generated. Furthermore, the threshold processing and the processing for obtaining a minimum or maximum value can be combined.

[0071] Then, the estimation unit 612 estimates the overlap pattern corresponding to the received signal in the overlap pattern data 613 based on the peak in the detected cross-correlation. For example, in the case of FIG. 6, when overlap pattern No. 3 is detected as a peak, the estimation unit 612 identifies overlap pattern No. 3 as the overlap pattern corresponding to the received signal. Since the overlap pattern is a code obtained by assuming the presence of an object in advance, once the overlap pattern is known, it is possible to estimate the object corresponding to that pattern. In other words, it is possible to reproduce a situation in which each transmitted signal is substantially separated.

[0072] If it is possible to separate each transmission signal, then, for example, the speed of each object can be estimated in the speed estimation unit 603, and the angle of each object can be estimated in the angle estimation unit 604, and therefore, information such as the distance, speed, or angle of each object can be generated in the information generation unit 605.

[0073] As described above, the radar device 1 of this embodiment includes a metric calculation unit 611 that calculates the expected value of a received code and the cross-correlation of the received code. The metric calculation unit 611 calculates the Hamming distance as the difference between the received code and overlap pattern data 613 that stores in advance all or part of the expected values ​​of the received code assumed when multiple objects exist. This makes it possible to first estimate an overlap pattern that has a high cross-correlation with the received code.

[0074] Since the overlap pattern data 613 is an expected value of the reception signal assumed according to the state of the object, if an overlap pattern with high cross-correlation can be estimated, the state of the object can be estimated from the overlap pattern. In other words, the expected state of the object can be estimated from the actual reception signal. This makes it possible to obtain the cross-correlation between the assigned code and the reception code, and to reproduce a state in which each transmission signal is substantially separated.

[0075] Therefore, it is easy to implement, and it is possible to obtain the same effects as the first embodiment and other embodiments, such as being able to accurately obtain object information even when multiple objects exist. In this case, for received signals that are not included in the overlap pattern data 613, it is possible to obtain an overlap pattern by calculating cross-correlation in combination with, for example, the third embodiment.

[0076] Fifth embodiment The fifth embodiment will be described below. In the fifth embodiment, a specific method for analyzing the cross-correlation between the assigned code and the received code in step S5 of FIG. 4 described in the first embodiment will be described. Note that the same reference numerals are used for parts common to those described in the other embodiments, and detailed description will be omitted. Also, the content described in the fifth embodiment can be combined with one or more other embodiments if there is no conflict.

[0077] 7 as an example of a calculation block configuration, the processing unit 6 of the radar device 1 of this embodiment includes a metric calculation unit 621 that calculates the cross-correlation between an assigned code and a received code. As shown in detail as a calculation block, the metric calculation unit 621 includes a correlation calculation block 621a that calculates the cross-correlation between an assigned code and a received code, and a difference calculation block 621b that refers to correlation calculation result data 623 and calculates the difference from the calculation result of the correlation calculation block 621a.

[0078] The correlation calculation block 621a is a calculation block for obtaining the cross-correlation between the assigned code and the received code as, for example, the relationship between the correlation value and the delay time shown as the calculation result in Fig. 5, similarly to the metric calculation unit 601 in the first embodiment. The difference calculation block 621b is a calculation block for calculating the difference between the calculation result of the correlation calculation block 621a and correlation calculation result data 623 stored in advance in the database 64, for example.

[0079] The correlation calculation result data 623 is data that is obtained by calculating in advance all or part of the calculation results of the cross-correlation between the expected value of the received code and the assigned code, which is assumed when multiple objects exist. That is, the correlation calculation result data 623 stores data indicating the cross-correlation, such as the relationship between the correlation value and the delay time shown in the calculation result of FIG. 5, in association with the number of assumed objects, etc. Also, the correlation calculation result data 623 is stored as data that can be compared with the calculation result of the correlation calculation block 621a. That is, the correlation calculation result data 623 is data that is obtained by calculating in advance all or part of the calculation results of the cross-correlation between the expected value of the received code and the assigned code, for the overlapping state of all or part of the assumed objects.

[0080] In the case of such a configuration, when radar measurement is performed, first, the correlation calculation block 621a calculates a cross-correlation function between the assigned code and the received code, and the calculation result is output to the difference calculation block 621b. Next, the difference calculation block 621b compares the calculation result of the correlation calculation block 621a with the correlation calculation result data, and calculates the difference between them.

[0081] The calculation result of the difference calculation block 621b is output to the estimation unit 622, and the estimation unit 622 detects a peak in the cross-correlation between the assigned code and the received code by performing threshold processing on the difference using a threshold value to extract those with high cross-correlation, or by performing processing to find the maximum or minimum value of the difference.

[0082] Since the correlation calculation result data 623 indicates the cross-correlation between the expected value of the received signal and the assigned signal in a certain situation, it is possible to estimate the situation of the object corresponding to the actual received signal by detecting the peak in the cross-correlation. In other words, it is possible to reproduce the situation in which each transmission signal is substantially separated based on the correlation calculation result data 623.

[0083] If it is possible to separate each transmission signal, then, for example, the speed of each object can be estimated in the speed estimation unit 603, and the angle of each object can be estimated in the angle estimation unit 604, and therefore, information such as the distance, speed, or angle of each object can be generated in the information generation unit 605.

[0084] As described above, the radar device 1 of this embodiment includes a metric calculation unit 621 that calculates the cross-correlation between the assigned code and the received code. The metric calculation unit 621 compares the calculation result of the cross-correlation between the assigned code and the received code with correlation calculation result data 623 that stores in advance all or part of the calculation results of the cross-correlation between the received code assumed when multiple objects exist and the assigned code from which the received signal is obtained, and calculates the difference. This makes it possible to estimate the state of the object corresponding to the received code, and to reproduce the state in which each transmission signal is substantially separated.

[0085] Therefore, it is easy to implement, and it is possible to obtain the same effects as the first embodiment and other embodiments, such as being able to accurately obtain object information even when multiple objects exist. In this case, for received signals not included in the correlation calculation result data 623, it is possible to estimate an overlapping pattern by calculating cross-correlation in combination with the third embodiment, or to perform estimation based on the overlapping pattern data 613 in combination with the fourth embodiment.

[0086] Sixth embodiment The sixth embodiment will be described below. In the sixth embodiment, a specific method for analyzing the cross-correlation between the assigned code and the received code in step S5 of FIG. 4 described in the first embodiment will be described. Note that the same reference numerals are used for parts common to those described in the other embodiments, and detailed description will be omitted. Also, the content described in the sixth embodiment can be combined with one or more other embodiments if there is no conflict.

[0087] As shown in FIG. 8 as an example of a calculation block configuration, the processing unit 6 of the radar device 1 of this embodiment includes a metric calculation unit 631 that calculates a cross-correlation function between an assigned code and a received code, and an estimation unit 632 that detects a peak in the cross-correlation function between the assigned code and the received code.

[0088] The metric calculator 631 is a calculation block for determining the cross-correlation function between the assigned code and the received code as the relationship between the correlation value and delay time shown as the calculation result in FIG. 5, for example, like the metric calculator 601 in the first embodiment.

[0089] As shown in detail in the calculation block, the estimation unit 632 includes the following calculation blocks: a calculation peak detection block 632a which detects peaks in the calculation results of the metric calculation unit 631; a correlation peak detection block 632b which compares the received code with the correlation calculation result data 623 to detect peaks in the cross-correlation; and an overlap pattern estimation block 632c which estimates the overlap state of peaks based on the outputs of these calculation blocks.

[0090] The calculation peak detection block 632a detects peaks in the cross-correlation between the assigned code and the received code by performing threshold processing on the calculation results of the metric calculation unit 631 using a threshold to extract those with high cross-correlation, or by performing processing to find the maximum and minimum values ​​of the calculation results.

[0091] The correlation peak detection block 632b compares the received code with the correlation calculation result data 623 and executes threshold processing for extracting those with high cross-correlation using a threshold, or processing for obtaining a maximum or minimum value for the calculation result, thereby estimating the peak in the cross-correlation between the received code and the correlation calculation result data 623, that is, data with a high correlation value with the received signal among the data included in the correlation calculation result data 623. However, since information on the received code is included in the cross-correlation calculation result as the output of the metric calculation unit 632a, when using this information, it is not essential to input the received code to the correlation peak detection block 632b.

[0092] The overlap pattern estimation block 632c estimates the overlap state of the peaks corresponding to the actual overlap state of the objects by comparing the peaks detected by the calculation peak detection block 632a with the peaks detected by the correlation peak detection block 632b. At this time, the overlap pattern estimation block 632c, for example, calculates the difference between the two peaks as a Hamming distance, and if the Hamming distance is small, it determines that the peak detection results of each block are valid and estimates the overlap state of the objects corresponding to the peaks. This makes it possible to estimate the state of the objects corresponding to the received codes, and to reproduce the state in which each transmission signal is substantially separated.

[0093] Then, from the estimation results of the estimation unit 632, for example, the speed of each object can be estimated in the speed estimation unit 603, and the angle of each object can be estimated in the angle estimation unit 604, so that information such as the distance, speed, or angle of each object can be generated in the information generation unit 605.

[0094] As described above, the radar device 1 of this embodiment includes the metric calculation unit 621 that finds the cross-correlation between the assigned code and the received code, and the estimation unit 632 that detects a peak in the cross-correlation between the assigned code and the received code.

[0095] Then, the estimation unit 632 estimates the overlapping state of objects by performing threshold processing for extracting peaks using a threshold on the calculation result of the metric calculation unit 631, or by comparing the peak detected by performing processing for obtaining a maximum value, minimum value, or extreme value on the calculation result of the metric calculation unit with a peak obtained by comparing the received signal with the correlation calculation result data 623. This makes it possible to reproduce a state in which each transmission signal is substantially separated.

[0096] Therefore, it is easy to implement, and it is possible to obtain the same effects as the first embodiment and other embodiments, such as being able to accurately obtain object information even when multiple objects exist. In this case, for received signals not included in the correlation calculation result data 623, it is possible to estimate an overlapping pattern by calculating cross-correlation in combination with the third embodiment, or to perform estimation based on the overlapping pattern data 613 in combination with the fourth embodiment.

[0097] Seventh embodiment The seventh embodiment will be described below. In the seventh embodiment, a specific method for analyzing the cross-correlation between the assigned code and the received code in step S5 of FIG. 4 described in the first embodiment will be described. Note that the same reference numerals are used for parts common to those described in the other embodiments, and detailed description will be omitted. Also, the contents described in the seventh embodiment can be combined with one or more other embodiments if there is no conflict.

[0098] As shown in FIG. 9 as an example of a calculation block configuration, the processing unit 6 of the radar device 1 of this embodiment includes a metric calculation unit 641 that calculates the cross-correlation between the assigned code and the received code, and an estimation unit 642 that detects a peak in the cross-correlation between the assigned code and the received code.

[0099] The metric calculator 641 is a calculation block for determining the cross-correlation function between the assigned code and the received code as the relationship between the correlation value and delay time shown as the calculation result in FIG. 5, for example, like the metric calculator 601 in the first embodiment.

[0100] As shown in detail in the calculation blocks, the estimation unit 642 includes a calculation peak detection block 642a which detects peaks in the calculation results of the metric calculation unit 641, an overlap pattern estimation block 642b which compares the calculation results of the metric calculation unit 641 with overlap pattern data 613 to estimate the overlap state of peaks, and a calculation block of a selector 642c which selects, from the detection result of the calculation peak detection block 642a and the estimation result of the overlap pattern estimation block 642b, the one which has a higher reliability of correlation value with the received signal.

[0101] The calculation peak detection block 642a detects peaks in the cross-correlation between the assigned code and the received code by performing threshold processing on the calculation results of the metric calculation unit 641 using a threshold to extract those with high cross-correlation, or by performing processing to find the maximum and minimum values ​​of the calculation results.

[0102] The overlapping pattern estimation block 642b compares the calculation result of the metric calculation unit 641 with the correlation calculation result data 623, and estimates the peak in the cross-correlation between them, that is, the data contained in the correlation calculation result data 623 that has a high correlation value with the calculation result.

[0103] Then, the selector 642c selects, from the detection result of the calculation peak detection block 642a and the estimation result of the overlapping pattern estimation block 642b, the one that has a higher cross-correlation with the received signal, for example, a relatively smaller Hamming distance. If the two results match, then either one can be selected, and if the certainty of both is determined to be low, then a configuration can be used in which peaks are detected based on other methods described in other embodiments.

[0104] That is, in this embodiment, a peak corresponding to the overlapping state of objects is detected by a plurality of methods, and the more reliable one is selected. Since the overlapping pattern data 613 is an expected value of the reception signal assumed according to the state of the object, if an overlapping pattern with high cross-correlation can be estimated, the state of the object can be estimated from the overlapping pattern. In other words, the assumed state of the object can be estimated from the actual reception signal. This makes it possible to obtain the cross-correlation between the assigned code and the reception code, and to reproduce the state in which each transmission signal is substantially separated.

[0105] As described above, the radar device 1 of this embodiment includes a metric calculation unit 621 that calculates the cross-correlation between the assigned code and the received code, and an estimation unit 642 that detects a peak in the cross-correlation between the assigned code and the received code. The estimation unit 642 compares a peak calculated from the calculation result of the metric calculation unit 641 with a peak obtained by comparing the calculation result with the overlap pattern data 613, thereby estimating the overlap state of objects.

[0106] This makes it possible to reproduce a situation in which each transmission signal is substantially separated. Therefore, it is easy to implement, and it is possible to obtain the same effects as the first embodiment and other embodiments, such as being able to accurately obtain object information even when multiple objects exist. In this case, for received signals that are not included in the overlap pattern data 613, it is possible to estimate an overlap pattern by calculating cross-correlation in combination with the third embodiment, or to estimate based on the correlation calculation result data 623 in combination with the fifth embodiment.

[0107] The control unit and the method described in the present disclosure may be realized by a special-purpose 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 and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be realized by one or more special-purpose 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. Also, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by a computer.

[0108] In addition to the inventions described in the claims, this case includes the following inventions: [1] a transmitting antenna unit having a plurality of transmitting antennas; an oscillator for generating a continuous wave common signal; a modulation unit that performs phase shift keying on each of a plurality of branch signals obtained by branching the common signal into the same number as the transmission antennas, in such a manner that each branch signal rotates a phase by a different amount of phase rotation, thereby generating a plurality of transmission signals to be input to the plurality of transmission antennas; a receiving antenna section having one or more receiving antennas; a receiving unit that generates a receiving code by encoding a peak appearance pattern on a Doppler frequency axis for each of one or more receiving signals received by the receiving antenna unit; a processing unit that generates information about an object that has reflected a radiation wave from the transmitting antenna unit based on the reception code generated by the receiving unit, If the assigned code is an encoding of the expected peak appearance pattern on the Doppler frequency axis when the object is stationary, then A radar device that performs phase shift keying according to a linear cyclic block code as the assigned code in the modulation unit. [2] The radar device according to [1], wherein in the modulation unit, phase shift keying is performed such that the minimum Hamming distance between the assigned code and a code group composed of a cyclic shift of the assigned code is 2 or more. [3] The radar device according to [1] or [2], wherein in the modulation unit, phase shift keying is performed such that the minimum Hamming distance between the assigned code and a code group composed of a cyclic shift of the assigned code is 3 or more. [4] The radar device according to any one of [1] to [3], wherein in the modulation unit, phase shift keying is performed such that the code polynomial of the assigned code is divisible by a polynomial having a period equal to or longer than the code length of the code polynomial. [5] The radar device according to any one of [1] to [4], wherein in the modulation unit, phase shift keying is performed such that for a code group obtained by cyclically shifting the assigned code, when the maximum number of overlapping bits is C and the minimum Hamming distance is D, C < D. [6] The radar device according to any one of [1] to [5], wherein in the modulation unit, phase shift keying is performed such that the assigned code is any one of a Hamming code, a CRC code, a BCH code, a Reed-Solomon code, a cyclic Golay code, and an M-sequence code. The described radar device. [7] The radar device according to any one of [1] to [6], wherein the assigned code is subjected to bit extension by adding 1 or 0 for 1 bit so that the code length is a power of 2. [8] The radar device according to any one of [1] to [7], wherein in the modulation unit, as the assigned code, when the number of overlapping objects is K and an integer equal to or greater than K is Q, phase shift keying is performed such that the results of OR operations on any Q codes of a code group composed of the assigned code and a cyclic shift of the assigned code are different codes. [9] 9. The radar device according to any one of [1] to [8], further comprising a metric calculation unit for calculating a cross-correlation between the assigned code and the received code.

[10] The radar device according to claim 1, further comprising a metric calculation unit that compares the received code with overlap pattern data in which all or part of expected values ​​of the received code assumed when multiple objects are present are stored in advance, and calculates the difference.

[11] The radar device according to [9] or

[10] , wherein the metric calculation unit compares the calculation result of the cross-correlation between the assigned code and the received code with correlation calculation result data in which the calculation result of all or part of the cross-correlation between the received code assumed when a plurality of objects are present and the assigned code from which the received signal is obtained is stored in advance, and calculates the difference therebetween.

[12] The radar device according to claim 10 or 11, wherein the metric calculation unit calculates the difference using a Hamming distance.

[13] an estimation unit that detects a peak in a result of a cross-correlation calculation between the assigned code and the received code; the estimation unit detects a peak by performing threshold processing for extracting a peak using a threshold value on the calculation result of the metric calculation unit, or by performing processing for obtaining a maximum value, a minimum value, or an extreme value on the calculation result of the metric calculation unit, and compares the peak with correlation calculation result data in which the calculation result of all or a part of the cross-correlation between the reception code assumed when the reception signal and a plurality of objects exist and the assignment code from which the reception signal is obtained is stored in advance; The radar device according to any one of [9] to

[12] , which estimates an overlapping state of objects by comparing the above.

[14] an estimation unit that detects a peak in a calculation result of a cross-correlation between the assigned code and the received code, The radar device according to any one of [9] to

[13] , wherein the estimation unit estimates the overlapping state of objects by comparing a peak calculated from the calculation result of the metric calculation unit with a peak obtained by comparing the calculation result of the metric calculation unit with overlapping pattern data in which all or part of the expected values ​​of the received codes assumed when multiple objects are present are stored in advance. [Explanation of symbols]

[0109] In the drawing, 1 indicates a radar device, 2 indicates a transmitting unit, 3 indicates a transmitting antenna unit, 3a indicates a transmitting antenna, 4 indicates a receiving antenna unit, 4a indicates a receiving antenna, 5 indicates a receiving unit, 6 indicates a processing unit, 21 indicates an oscillator unit, 22 indicates a modulator unit, 601, 611, 621, 631, 641 indicate metric calculation units, 602, 612, 622, 632, 642 indicate estimation units, 613 indicates overlapping pattern data, and 623 indicates correlation calculation result data.

Claims

1. A transmitting antenna section (3) having a plurality of transmitting antennas (3a); An oscillator (21) for generating a continuous wave common signal; a modulation unit (22) for performing phase shift keying on each of a plurality of branch signals obtained by branching the common signal into the same number as the transmission antennas, in which the phase of each of the branch signals is rotated by a different phase rotation amount, to generate a plurality of transmission signals to be input to the plurality of transmission antennas; a receiving antenna section (4) having one or more receiving antennas (4a); a receiving unit (5) for generating a receiving code by encoding a peak appearance pattern on a Doppler frequency axis for each of one or more receiving signals received by the receiving antenna unit; a processing unit (6) that generates information about an object that has reflected the radiation wave from the transmitting antenna unit based on the reception code generated by the receiving unit, If the assigned code is an encoding of the expected peak appearance pattern on the Doppler frequency axis when the object is stationary, then The radar device, wherein the modulation section performs phase shift keying according to a linear block code as the assigned code.

2. 2. The radar device according to claim 1, wherein said modulation section performs phase shift keying such that a minimum Hamming distance between said assigned code and a code group formed by cyclic shifts of said assigned code is 2 or more.

3. 2. The radar device according to claim 1, wherein the modulation section performs phase shift keying such that a minimum Hamming distance between the assigned code and a code group formed by cyclic shifts of the assigned code is 3 or more.

4. 2. The radar device according to claim 1, wherein the modulation section performs phase shift keying so that a code polynomial of the assigned code is a polynomial that can be divided by a polynomial having a period equal to or greater than the code length of the code polynomial.

5. 2. The radar device according to claim 1, wherein the modulation section performs phase shift keying for the code group obtained by cyclically shifting the assigned code such that, when a maximum number of overlapping bits is C and a minimum Hamming distance is D, C<D.

6. 2. The radar device according to claim 1, wherein said modulation section performs phase shift keying so that said assigned code is any one of a Hamming code, a CRC code, a BCH code, a Reed-Solomon code, a cyclic Golay code and an M-sequence code.

7. 2. The radar device according to claim 1, wherein the assigned code is bit-extended by adding one bit of 1 or 0 so that the code length becomes a power of two.

8. 2. The radar device according to claim 1, wherein the modulation section performs phase shift keying as the assigned code in such a manner that, when a number of overlapping objects is K and Q is an integer equal to or greater than K, a result of ORing the assigned code and any Q codes of a code group formed by cyclic shifts of the assigned code is a different code.

9. 2. The radar device according to claim 1, further comprising a metric calculation unit (601, 611, 621, 631, 641) for calculating a cross-correlation function between the assigned code and the received code.

10. 2. The radar device according to claim 1, further comprising a metric calculation unit that compares the received code with overlap pattern data in which all or part of expected values ​​of the received code assumed when a plurality of objects are present are stored in advance, and calculates the difference therebetween.

11. 10. The radar device according to claim 9, wherein the metric calculation unit compares a calculation result of the cross-correlation between the assigned code and the received code with correlation calculation result data in which a calculation result of all or a part of a cross-correlation between the received code assumed when a plurality of objects are present and the assigned code from which the corresponding received signal is obtained is stored in advance, and calculates a difference therebetween.

12. 12. The radar device according to claim 10, wherein the metric calculation unit calculates the difference using a Hamming distance.

13. An estimation unit (602, 612, 622, 632, 642) for detecting a peak in a calculation result of a cross-correlation between the assigned code and the received code, 10. The radar device according to claim 9, wherein the estimation unit estimates an overlapping state of objects by performing threshold processing on the calculation result of the metric calculation unit to extract a peak using a threshold, or by comparing a peak detected by performing processing to find a maximum value, a minimum value or an extreme value on the calculation result of the metric calculation unit with a peak obtained by comparing the peak with correlation calculation result data in which a calculation result of all or a part of a cross-correlation between an expected value of the received code assumed when the received signal and a plurality of objects are present and the assigned code from which the received signal is obtained is stored in advance.

14. An estimation unit (602, 612, 622, 632, 642) that detects a peak in a calculation result of a cross-correlation between the assigned code and the received code, 10. The radar device according to claim 9, wherein the estimation unit (642) estimates an overlapping state of objects by comparing a peak calculated from the calculation result of the metric calculation unit with a peak obtained by comparing the calculation result of the metric calculation unit with overlapping pattern data in which all or part of expected values ​​of the received codes assumed when a plurality of objects are present are stored in advance.

Images