Radar device, radar operating method, and computer-readable recording medium

Abstract

The radar device (10) comprises: a signal generating unit (100) which generates a signal as a source signal; a pseudo-random number generating unit (102) which generates a pseudo-random number sequence composed of pseudo-random numbers; a true random number generating unit (101) which generates a true random number sequence composed of true random numbers; a modulation code synthesizing unit (103) which synthesizes the pseudo-random number sequence and the true random number sequence to generate a modulation code sequence for modulating the phase of the signal; and a phase modulating unit (104) which modulates the phase of the source signal using the modulation code sequence to generate a transmission signal.

Description

Technical Field

[0001] The present invention relates to a radar device, a radar operating method, and a computer-readable recording medium. Background Art

[0002] Radar is a device that irradiates an object with radio waves and measures the reflected waves from the object, thereby measuring the relative distance between the radar and the object or the object's relative speed. The FMCW (Frequency Modulated Continuous Wave) method is a radar method that is low-cost and has excellent distance and speed measurement capabilities. In particular, the fast FMCW method has higher resolution than the existing slow FMCW method. The fast FMCW method uses a relatively short linear frequency modulation signal sweep time of several microseconds.

[0003] Radars that use the MIMO (Multiple Input Multiple Output) method can measure angles and improve angular resolution. The MIMO method uses multiple transmitting antennas and multiple receiving antennas.

[0004] In order to prevent interference between transmission waves from multiple transmitting antennas, there is a method of modulating the phase. Conventionally, there is a known technique of modulating the phase by assigning 0 or π to each element of a pseudo-random number sequence with high autocorrelation, such as an M sequence or a Gold sequence.

[0005] Spoofing is a threat in radar operations. Spoofing involves inserting radio waves loaded with reflected waves into the radar from outside, thereby erroneously measuring the value. As a countermeasure to spoofing, Non-Patent Document 1 discloses a method for modulating the chirp of a slow FMCW radar using a relatively simple pseudo-random number and detecting the attack using the frequency and amplitude of the beat signal. Slow FMCW radars use the slow FMCW method.

[0006] Prior art literature

[0007] Non-patent literature

[0008] Non-Patent Document 1: Suzuki, Nashimoto et al., “Randomization of Chirp Signals in FMCW Radar,” SCIS 2018 Symposium on Cryptography and Information Security, Niigata, Japan, January 23-26, 2018, The Institute of Electronics, Information and Communication Engineers. Summary of the Invention

[0009] Problems to be solved by the invention

[0010] In order to determine whether there is deception, the slow FMCW radar needs to change (modulate) the slope of the FMCW signal to UP or DOWN.

[0011] Fast FMCW radars require the centralized processing of multiple waveforms to measure the position or velocity of an object. Fast FMCW radars utilize the fast FMCW method. The frequency of the beat signal varies depending on the slope of the FMCW signal. Therefore, when fast FMCW radars use the same spoofing method as slow FMCW radars, this can negatively impact the position and velocity of the object being measured.

[0012] Furthermore, it is known that the pseudo-random number sequences such as the M sequence and the Gold sequence used in MIMO radar for phase modulation do not change much, so when observing halfway, the next value can be estimated. MIMO radar is a radar that uses the MIMO method.

[0013] Therefore, relatively simple interference countermeasures are not a countermeasure against spoofing attacks that estimate the sequence used to modulate the phase.

[0014] The present invention aims to provide a radar device that can reduce the risk of a sequence being estimated for phase modulation and implement a countermeasure that does not adversely affect the position or velocity of a measurement object. Typically, the radar device of the present invention employs a fast FMCW method.

[0015] Means for solving problems

[0016] The radar device of the present invention comprises: a signal generating unit that generates a signal as a source signal; at least one pseudo-random number generating unit that generates a pseudo-random number sequence composed of pseudo-random numbers of one bit or more; a true random number generating unit that generates a true random number sequence composed of true random numbers of one bit or more; at least one modulation code synthesizing unit that synthesizes the pseudo-random number sequence and the true random number sequence to generate a modulation code sequence for modulating the phase of a signal and containing a component derived from the true random number sequence; and at least one phase modulating unit that modulates the phase of the source signal using the modulation code sequence to generate a transmission signal, the modulation code sequence being a modulation code sequence obtained by synthesizing two modulation code sequences so that the component derived from the true random number sequence disappears.

[0017] Effects of the Invention

[0018] According to the radar apparatus of the present invention, it is possible to provide a radar apparatus capable of reducing the risk of a sequence for phase modulation being estimated and achieving a countermeasure that does not adversely affect the position, velocity, etc. of a measurement object. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a configuration example of the radar device 10 according to the first embodiment.

[0020] Figure 2 This is an example of the hardware configuration of the signal processing device 110 according to the first embodiment.

[0021] Figure 3 This is a sequence diagram showing the operation of the radar device 10 according to the first embodiment.

[0022] Figure 4 This is a diagram illustrating the flow of generating the transmission signal S105 according to the first embodiment.

[0023] Figure 5 This is a diagram for explaining the operation of the demodulation unit 121 according to the first embodiment.

[0024] Figure 6 This is a configuration example of a radar device 10 according to a modification of the first embodiment.

[0025] Figure 7 This is a configuration example of the signal processing device 110 according to a modification of the first embodiment.

[0026] Figure 8 This is a sequence diagram showing the operation of the radar device 10 according to the modified example of the first embodiment.

[0027] Figure 9 This is a configuration example of a radar device 20 according to a modification of the first embodiment.

[0028] Figure 10 This is a hardware configuration example of a computer 200 according to a modification of the first embodiment.

[0029] Figure 11 This is a diagram illustrating an example of a process of generating random numbers by the true random number generator 225 according to the modification of the first embodiment.

[0030] Figure 12 This is a flowchart showing the operation of the true random number generator 225 according to the modification of the first embodiment.

[0031] Figure 13 This is a configuration example of the signal processing device 110 according to a modification of the first embodiment.

[0032] Figure 14 This is a configuration example of the radar device 30 according to the second embodiment.

[0033] Figure 15 This is a sequence diagram showing the operation of the radar device 30 according to the second embodiment.

[0034] Figure 16 This is a configuration example of a radar device 40 according to a modified example of the second embodiment.

[0035] Figure 17 This is a hardware configuration example of the reception control computer 410 according to a variation of the second embodiment.

[0036] Figure 18 This is a hardware configuration example of the transmission control computer 400 according to a modified example of the second embodiment. DETAILED DESCRIPTION

[0037] Implementation Method 1

[0038] Hereinafter, this embodiment will be described in detail with reference to the accompanying drawings.

[0039] ***Description of the structure***

[0040] Typically, the radar device 10 of this embodiment adopts a fast FMCW (Frequency Modulated Continuous Wave) method and a MIMO (Multiple Input Multiple Output) method. The MIMO method uses multiple transmitting antennas and multiple receiving antennas.

[0041] Figure 1 The following shows an example configuration of the radar device 10 according to this embodiment. Black dots in this figure indicate that multiple lines connected to the black dots are connected to each other. If no black dots are drawn at the intersection of multiple lines, the multiple lines are not connected to each other.

[0042] As shown in this figure, the radar device 10 includes a transmitting unit 15 and a receiving unit 16 .

[0043] The transmitter 15 includes a signal generator 100, a true random number generator 101, multiple pseudo-random number generators 102, multiple modulation code synthesizers 103, multiple phase modulators 104, and multiple transmitting antennas 105. In this figure, the transmitting antennas 105 are designated "105-1" and "105-2" to identify each other. The same applies to the various other elements included in each radar apparatus described in this specification.

[0044] The number of pseudo-random number generating units 102 , the number of modulation code synthesizing units 103 , and the number of phase modulating units 104 are consistent with the number of transmitting antennas 105 .

[0045] Typically, the signal generator 100, true random number generator 101, pseudo-random number generator 102, modulation code synthesizer 103, and phase modulator 104 are each comprised of circuits. A single circuit may implement multiple components of the radar device 10. Furthermore, multiple circuits may implement a single component of the radar device 10. Each component described as a circuit may also be comprised of a computer. Each computer described in this specification may also be comprised of multiple computers. A computer can appropriately convert digital signals into analog signals, and vice versa.

[0046] The signal generating unit 100 generates a signal as a source signal S101 .

[0047] The true random number generator 101 generates a true random number sequence S102 consisting of true random numbers of 1 bit or more.

[0048] The true random number generator 101 may also convert the extreme value of the beat signal S110 into a binary number to generate a 1-bit true random number. Alternatively, the true random number generator 101 may use the beat signal S110 corresponding to each of the plurality of LPF units 108 to generate random number bits corresponding to each of the plurality of LPF units 108, and perform an exclusive-OR operation or an exclusive-NOR operation on the generated random number bits to generate a 1-bit true random number.

[0049] The pseudo-random number generator 102 generates a pseudo-random number sequence S103 consisting of pseudo-random numbers of 1 bit or more.

[0050] The modulation code synthesis unit 103 synthesizes the pseudo-random number sequence S103 and the true random number sequence S102 to generate a modulation code sequence S104, which modulates the phase of the signal and includes components derived from the true random number sequence S102. The components derived from the true random number sequence S102 are the effects of the true random number sequence S102 contained in the elements. The modulation code sequence S104 is synthesized from the two modulation code sequences S104, eliminating the components derived from the true random number sequence S102. The two modulation code sequences S104 can be identical or different.

[0051] In addition, the method of synthesizing the pseudo-random number sequence S103 and the true random number sequence S102 and the method of synthesizing the two modulation code sequences S104 may be different.

[0052] The modulation code synthesis unit 103 may generate a modulation code sequence by performing an exclusive-OR operation or an exclusive-NOR operation.

[0053] The elements of a sequence are the smallest units that make up the sequence. As a specific example, a sequence is made up of permutations. In this example, the elements of a sequence are the elements of the permutation.

[0054] The phase modulation unit 104 modulates the phase of the source signal S101 using a modulation code sequence S104 to thereby generate a transmission signal S105 .

[0055] The transmission antenna 105 converts the transmission signal S105 into a transmission wave S106 and transmits the transmission wave S106.

[0056] The receiving unit 16 includes multiple receiving antennas 106, multiple mixing units 107, multiple LPF (Low Pass Filter) units 108, multiple ADC (Analog-to-Digital Converter) units 109, and a signal processing device 110. The LPF unit is also called a low-pass filter unit.

[0057] The number of mixers 107 , the number of LPFs 108 , and the number of ADCs 109 are equal to the number of receiving antennas 106 .

[0058] Typically, the frequency mixer 107 , the LPF 108 , and the ADC 109 are each configured by a circuit.

[0059] The receiving antenna 106 receives a reception wave S107 corresponding to the transmission wave S106 and converts the reception wave S107 into a reception signal S108 .

[0060] The mixer 107 generates a mixed output signal S109 by mixing the source signal S101 and the reception signal S108.

[0061] The LPF section 108 extracts the low-frequency component of the mixing output signal S109 to thereby generate a beat signal S110 .

[0062] Source signal S101 is a signal generated by signal generator 100. True random number sequence S102 is a sequence composed of signals generated by true random number generator 101. Pseudo random number sequence S103 is a sequence composed of signals generated by pseudo random number generator 102. Modulation code sequence S104 is a sequence composed of signals generated by modulation code synthesizer 103 by synthesizing true random number sequence S102 and pseudo random number sequence S103. Transmitted signal S105 is a signal obtained by phase modulator 104 modulating source signal S101 using modulation code sequence S104.

[0063] In addition, regarding the bits constituting the true random number sequence S102, it is assumed that neither the number of bits having a value of 0 nor the number of bits having a value of 1 is significantly greater than the other.

[0064] The transmission wave S106 is a signal transmitted by the transmission antenna 105. The reception wave S107 is the transmission wave S106 reflected by the object 11 and is a signal that reaches the reception antenna 106.

[0065] The number of transmission waves S106 is the same as the number of transmission antennas 105. The maximum number of reception waves S107 is the same as the number obtained by multiplying the number of transmission antennas 105 and the number of reception antennas 106. Figure 1 As shown, when the radar device 10 has two transmitting antennas 105 and four receiving antennas 106, there are a maximum of eight received waves S107. The transmitting antenna 105 and the receiving antenna 106 may be formed by a single antenna.

[0066] Received signal S108 is generated by receiving antenna 106 using received wave S107. Received signal S108 corresponds to transmitted signal S105. Mixed output signal S109 is the signal generated by mixing mixer 107 using source signal S101 and received signal S108. Beat signal S110 is the signal filtered by LPF 108. Digital signal S111 is the signal digitized by ADC 109.

[0067] Figure 2 The following shows an example of the hardware configuration of the signal processing device 110. The signal processing device 110 is a general computer.

[0068] As shown in this figure, the signal processing device 110 includes, as hardware, a processor 111, a digital signal interface 112, and a memory 113. Each piece of hardware included in the signal processing device 110 is connected by a signal line.

[0069] As shown in this figure, the signal processing device 110 includes a demodulation unit 121 and an object measurement unit 122 as functional elements.

[0070] The processor 111 is an IC (Integrated Circuit) that performs arithmetic processing and controls the hardware included in the signal processing device 110. Specific examples of the processor 111 include a CPU (Central Processing Unit), a DSP (Digital Signal Processor), or a GPU (Graphics Processing Unit).

[0071] As a specific example, digital signal interface 112 is a serial communication interface. Specific examples of the serial communication interface include SPI (Serial Peripheral Interface), UART (Universal Asynchronous Receiver Transmitter), or I2C (Inter-Integrated Circuit). Digital signal interface 112 is used to connect signal processing device 110 to external hardware. The external hardware includes modulation code synthesis unit 103 and ADC unit 109.

[0072] The memory 113 is composed of at least one of a volatile storage device and a non-volatile storage device. Specifically, the volatile storage device is a RAM (Random Access Memory). Specifically, the non-volatile storage device is a ROM (Read Only Memory), an HDD (Hard Disk Drive), or a flash memory.

[0073] The cache memory and the like included in the processor 111 may also be included in the memory 113 .

[0074] The demodulation unit 121 demodulates the beat signal S110 using the modulation code sequence S104 .

[0075] The functions of the demodulation unit 121 and the object measurement unit 122 are realized by a program. The program is stored in the memory 113 and executed by the processor 111.

[0076] Each program described in this specification may be recorded in a computer-readable form on a non-volatile recording medium. As a specific example, the non-volatile recording medium is an optical disc or a flash memory.

[0077] The radar operation program is a general term for the program used when operating each radar device described in this manual. The radar operation program can also be provided as a program product.

[0078] ***Description of the action***

[0079] The operation procedure of the radar device 10 corresponds to the radar operation method. In addition, the program for realizing the operation of the radar device 10 corresponds to the radar operation program.

[0080] Figure 3 1 is a sequence diagram showing an example of the operation of the radar device 10. The operation of the radar device 10 will be described with reference to this diagram.

[0081] The true random number generator 101 generates a true random number sequence S102 and sends it to the modulation code synthesizer 103. The true random number sequence S102 is a sequence of true random numbers. True random numbers may also include complex pseudo-random numbers. Complex pseudo-random numbers are pseudo-random numbers whose random value is difficult to estimate. Specifically, complex pseudo-random numbers are generated using the Mersenne Twister algorithm or a permuted congruential generator (PCG).

[0082] The true random number generator 101 is, for example, a ring oscillator formed by connecting an odd number of oscillators in a rosary shape. The true random number sequence S102 is, for example, a sequence of “1, 1, 1, 0, 0, . . . ”

[0083] The pseudo-random number generator 102 generates a pseudo-random number sequence S103 and sends the pseudo-random number sequence S103 to the modulation code synthesizer 103. The pseudo-random number sequence S103 is a sequence composed of pseudo-random numbers.

[0084] The pseudo-random number generator 102 is, for example, an M-sequence or a Gold-sequence generator. The pseudo-random number sequence S103 is, for example, a sequence consisting of bits such as "1, 0, 1, 0, 1, . . . ".

[0085] Modulation code synthesis unit 103 uses true random number sequence S102 and pseudo random number sequence S103 to generate modulation code sequence S104, and transmits modulation code sequence S104 to phase modulation unit 104 and demodulation unit 121. True random number sequence S102, pseudo random number sequence S103, and modulation code sequence S104 all have the same sequence length. Sequence length refers to the number of elements in a sequence. Modulation code sequence S104, for example, consists of one-bit elements such as "0, 1, 0, 0, 1, ...." Below, each element of modulation code sequence S104 is assumed to be a one-bit element.

[0086] As a specific example, the modulation code synthesis unit 103 synthesizes the true random number sequence S102 and the pseudo random number sequence S103 using an XOR operation or an XNOR operation. The XOR operation is also called an exclusive OR operation. The XNOR operation is also called an exclusive NOT OR operation.

[0087] As a specific example, Figure 1 As shown, consider the case where there are two pseudo-random number generators 102. Let the true random number sequence S102 be r. Let the pseudo-random number sequence S103 generated by the pseudo-random number generator 102-1 be m1. Let the pseudo-random number sequence S103 generated by the pseudo-random number generator 102-2 be m2.

[0088] When modulation code synthesis unit 103 uses an XOR operation to synthesize r and m1 and r and m2, modulation code sequence S104 is expressed as XOR(r, m1) and XOR(r, m2), respectively. In this case, each element of modulation code sequence S104 is affected by true random number sequence S102. In other words, modulation code sequence S104 includes components derived from true random number sequence S102.

[0089] Equation 1 shows how the two are combined by performing an XOR operation. In the final term of Equation 1, r disappears. That is, XOR(r, m1) and XOR(r, m2) are the two modulation code sequences S104 combined, eliminating the component derived from the true random number sequence S102. Furthermore, Equation 1 corresponds to the case where demodulation is performed using a modulation code sequence S104 different from the modulation code sequence S104 used for modulation.

[0090] XOR(XOR(r,m1),XOR(r,m2))=XOR(XOR(m1,m2),XOR(r,r))=XOR(m1,m2) (Formula 1)

[0091] The signal generating section 100 sends the source signal S101 to the phase modulating section 104 and the frequency mixing section 107 .

[0092] The phase modulation unit 104 performs phase modulation on the source signal S101 using the modulation code sequence S104 to generate a transmission signal S105 , and transmits the transmission signal S105 to the transmission antenna 105 .

[0093] As a specific example, phase modulation unit 104 converts modulation code sequence S104 into a phase by setting the phase modulation amount to 0 when the bit is 0 and to π when the bit is 1. The following description assumes that phase modulation unit 104 converts modulation code sequence S104 into a phase as shown in this example.

[0094] Figure 4 An example of a flow of generating the transmission signal S105 is shown.

[0095] The modulation code synthesis unit 103 synthesizes the true random number sequence S102 and the pseudo random number sequence S103 using an exclusive OR operation to generate a modulation code sequence S104.

[0096] Phase modulator 104 phase-modulates source signal S101 using modulation code sequence S104, thereby generating transmission signal S105. Phase modulator 104 sets the phase modulation amount to 0 when a bit of modulation code sequence S104 is 0, and sets the phase modulation amount to π when a bit of modulation code sequence S104 is 1.

[0097] The transmission antenna 105 transmits a transmission wave S106 to the outside world. The transmission wave S106 is reflected by the object 11.

[0098] The reception antenna 106 receives the reception wave S107 , converts the reception wave S107 into a reception signal S108 , and transmits the reception signal S108 to the frequency mixing unit 107 .

[0099] The mixer 107 mixes the received signal S108 and the source signal S101 to generate a mixed output signal S109, and sends the mixed output signal S109 to the LPF 108. Mixing means multiplying signals. Mixing is expressed as (Equation 2).

[0100] cosf s t·cosf r t=[cos{(f s -f r )t}+cos{(f s +f r )t}] / 2 (Formula 2)

[0101] f s represents the frequency of the source signal S101. r represents the frequency of the received signal S108. cos represents the cosine function. t represents time. Typically, f s and f r Indicates the frequency of time change. As a specific example, f s and f r is the frequency corresponding to the linear frequency modulation signal. s and f r is the frequency corresponding to the linear frequency modulation signal.

[0102] The LPF section 108 extracts the low frequency component of the mixed output signal S109. s -f r ) is considered as a low-frequency component, and at a frequency of (f s +f r ) is not considered as a low-frequency component.

[0103] The beat signal S110 is a signal extracted by the LPF section 108. According to (Equation 2), the beat signal S110 is expressed as cos{(f s -f r )t} / 2. That is, the beat signal S110 is a signal having frequency difference information between the source signal S101 and the received signal S108. The LPF unit 108 transmits the beat signal S110 to the ADC unit 109.

[0104] The ADC unit 109 converts the beat signal S110 , which is an analog signal, into a digital signal to thereby generate a digital signal S111 , and transmits the digital signal S111 to the demodulation unit 121 .

[0105] The demodulator 121 demodulates the digital signal S111 using the modulation code sequence S104 to generate a demodulated signal, which is then sent to the object measurement unit 122 .

[0106] Digital signal S111 contains information about multiple transmission waves S106 transmitted by multiple transmission antennas 105. Demodulation unit 121 extracts transmission wave S106 from a single transmission antenna 105 from digital signal S111, thereby demodulating digital signal S111. Considering the phase shift due to phase modulation included in beat signal S110, digital signal S111 is expressed as in (Equation 3). Each term in (Equation 3) corresponds to a unit of linear frequency modulation signal.

[0107]

[0108] represents the amount of phase modulation performed by the phase modulation unit 104-i. bi represents the frequency of the beat signal S110 corresponding to the transmitting antenna 105 - i , and N represents the total number of transmitting antennas 105 .

[0109] For example, Figure 1 As shown in FIG, there are two transmitting antennas 105. In this case, when demodulation unit 121 performs demodulation using modulation code sequence S104-1, the demodulated signal is expressed as in (Equation 4).

[0110]

[0111] here, therefore, thus,

[0112] Modulation and demodulation are equivalent to rotating the phase. When the phase is rotated by 2π, the phase rotates by 1 turn. In other words, rotating the phase by 2π is the same as not rotating the phase. In the case of , demodulation is equivalent to performing an XOR operation on the bit string. Therefore, it can be considered that (Equation 4) in The component corresponds to the result of performing an XOR operation on one element of the modulation code sequence S104-1 and one element of the modulation code sequence S104-2. and are generated based on the true random number sequence S102. However, when the demodulation unit 121 demodulates the digital signal S111, the components of the true random number sequence S102 contained in the digital signal S111 are lower than each other. and are generated based on the pseudo-random number sequence S103. That is, when the pseudo-random number generator 102 generates a sequence with high autocorrelation as the pseudo-random number sequence S103, the demodulator 121 appropriately integrates the signal within the range of one cycle unit (called one scanning unit in FMCW radar) of the pseudo-random number sequence S103, and the result is cos{f b1 t} components reinforce each other, As a specific example, a sequence with high autocorrelation is an M sequence or a Gold sequence.

[0113] By using cos{f b1 t} components reinforce each other, the demodulation unit 121 can extract cos{f b1 t} ingredient.

[0114] Figure 5 121 is a diagram for explaining an example of the operation of the demodulation unit 121 .

[0115] Consider the sum of the signals demodulated by the demodulation unit 121 in units of one cycle of the pseudo random number sequence S103. b1 The t} component corresponds to a signal demodulated using the correct modulation code sequence. The correct modulation code sequence is the modulation code sequence S104 used by the phase modulation unit 104 when generating the transmission signal S105 corresponding to the digital signal S111. The components correspond to signals demodulated using an incorrect modulation code sequence. When demodulation unit 121 uses an incorrect modulation code sequence for demodulation, the phases of the signals often become inconsistent. Therefore, demodulation unit 121 cannot obtain a cumulative signal result, and instead obtains a signal attenuation result.

[0116] The object measuring unit 122 calculates the distance from the radar device 10 to the object 11 , the speed of the object 11 , and the angle between the radar device 10 and the object 11 based on the demodulated signal.

[0117] As described above, the true random number sequence S102 is canceled out in the demodulated signal. Therefore, the modulation using the true random number sequence S102 does not affect the distance, speed, and angle measured by the object measurement unit 122.

[0118] ***Description of the Effects of Implementation Method 1***

[0119] As described above, the radar device 10 of the present embodiment adopts the MIMO method and the FMCW method and develops a signal sequence for modulation, thereby achieving the following effects.

[0120] The modulation code synthesis unit 103 generates a modulation code sequence S104 based on the true random number sequence S102 and the pseudo-random number sequence S103. The phase modulation unit 104 uses the modulation code sequence S104 to modulate the phase of the source signal S101, thereby generating a transmission signal S105. The pseudo-random number sequence S103 used by each phase modulation unit 104 is generated by a different pseudo-random number generation unit 102. Therefore, each phase modulation unit 104 always generates a different transmission signal S105. As a result, the transmission waves S106 transmitted by each transmitting antenna 105 always differ from each other. Consequently, the radar device 10 can always prevent the multiple transmission waves S106 from interfering with each other.

[0121] The demodulation unit 121 performs demodulation using the modulation code sequence S104. At this time, the components based on the true random number sequence S102 are canceled out. Therefore, the modulation using the true random number sequence S102 does not affect the position and speed of the object 11 measured by the object measurement unit 122.

[0122] Even if an attacker obtains pseudo-random number sequence S103 by observing transmission wave S106, the attacker cannot estimate true random number sequence S102. Therefore, the attacker cannot estimate modulation code sequence S104. Thus, the radar device 10 of this embodiment can reduce the risk of spoofing attacks.

[0123] ***Other structures***

[0124] <Variation 1>

[0125] In radar device 10, at least one of transmitting antenna 105 and receiving antenna 106 may be only one. If there is only one transmitting antenna 105, the number of pseudo-random number generators 102, the number of modulation code synthesizers 103, and the number of phase modulators 104 may each be one. If there is only one receiving antenna 106, the number of mixers 107, the number of LPFs 108, and the number of ADCs 109 may each be one.

[0126] That is, in the radar device 10 , each element described in this embodiment as having a plurality of elements may be included in at least one element.

[0127] <Variation 2>

[0128] Hereinafter, differences from the above-described embodiment will be described with reference to the drawings.

[0129] Figure 6The following describes a configuration example of the radar device 10 according to this modification.

[0130] Furthermore, the frequency mixers 107 may correspond to the respective phase modulators 104 . That is, the number of frequency mixers 107 may be a value obtained by multiplying the number of phase modulators 104 by the number of receiving antennas 106 .

[0131] Figure 7 A configuration example of the signal processing device 110 according to this modification is shown. The signal processing device 110 does not include the demodulation unit 121 .

[0132] Figure 8 1 is a sequence diagram showing an example of the operation of the radar device 10 according to this modification. The difference between the operation of the radar device 10 according to this embodiment and the operation of the radar device 10 according to this modification will be described with reference to this diagram.

[0133] The signal generating section 100 does not send the source signal S101 to the mixing section 107 .

[0134] The modulation code synthesis unit 103 does not send the modulation code sequence S104 to the signal processing device 110 .

[0135] The phase modulation unit 104 also transmits the transmission signal S105 to the mixing unit 107 .

[0136] The mixer 107 receives the transmission signal S105 instead of the source signal S101 and mixes the transmission signal S105 with the reception signal S108 to generate a mixed output signal S109. The mixed output signal S109 is a demodulated signal of the reception signal S108.

[0137] When the mixer 107 receives multiple transmission signals S105, it mixes each transmission signal S105 with the received signal S108. In this case, the number of mixed output signals S109 generated by the mixer 107 matches the number of transmission signals S105 received by the mixer 107. The LPF 108 then generates a beat signal S110 corresponding to each mixed output signal S109, and the ADC 109 generates a digital signal S111 corresponding to each beat signal S110.

[0138] In this case, the radar device 10 may include one mixer 107 for each receiving antenna 106, or may include multiple mixers 107 for each receiving antenna 106. When the radar device 10 includes one mixer 107 for each receiving antenna 106, as a specific example, the mixer 107 switches the transmission signal S105 used for mixing at regular intervals. When the radar device 10 includes multiple mixers 107 for each receiving antenna 106, as a specific example, the number of transmission signals S105 and the number of mixers 107 are the same, and each mixer 107 corresponds to a different transmission signal S105.

[0139] The signal processing device 110 does not receive the modulation code sequence S104.

[0140] The object measuring unit 122 uses the digital signal S111 instead of the demodulated signal.

[0141] As described above, according to this variation, mixing unit 107 performs demodulation using transmitted signal S105. Therefore, mixing unit 107 simultaneously performs demodulation. Consequently, signal processing device 110 does not need to include demodulation unit 121. Consequently, radar device 10 does not need to store modulation code sequence S104. Furthermore, signal processing device 110 according to this variation can also be used in conventional radar devices.

[0142] <Variation 3>

[0143] Figure 9 The following shows a configuration example of a radar device 20. The radar device 20 has a configuration different from that of the radar device 10, and implements a portion of the functions of the radar device 10 using a computer.

[0144] The radar device 20 is composed of a transmitter 25 and a receiver 26. The transmitter 25 and the receiver 26 share a computer 200.

[0145] The transmitting unit 25 is composed of a signal generating unit 201 , a plurality of phase modulating units 202 , and a plurality of transmitting antennas 203 .

[0146] The signal generating section 201 is the same as the signal generating section 100 . The phase modulating section 202 is the same as the phase modulating section 104 . The transmitting antenna 203 is the same as the transmitting antenna 105 .

[0147] The number of phase modulation units 202 matches the number of transmission antennas 203 .

[0148] The receiving unit 26 includes a plurality of receiving antennas 204 , a plurality of frequency mixing units 205 , a plurality of LPF units 206 , and a plurality of ADC units 207 .

[0149] The receiving antenna 204 is the same as the receiving antenna 106. The mixing unit 205 is the same as the mixing unit 107. The LPF unit 206 is the same as the LPF unit 108. The ADC unit 207 is the same as the ADC unit 109.

[0150] The number of the mixing units 205 , the number of the LPF units 206 , and the number of the ADC units 207 are the same as the number of the receiving antennas 204 .

[0151] Source signal S201 is the same as source signal S101. Modulation code sequence S204 is a sequence of signals generated by computer 200. Modulation code sequence S204 may also be a sequence of analog signals. Transmission signal S205 is the same as transmission signal S105.

[0152] The transmission wave S206 is the same as the transmission wave S106, and the reception wave S207 is the same as the reception wave S107.

[0153] The received signal S208 is the same as the received signal S108. The mixed output signal S209 is the same as the mixed output signal S109. The beat signal S210 is the same as the beat signal S110. The digital signal S211 is the same as the digital signal S111.

[0154] Figure 10 1 shows an example of the hardware configuration of a computer 200. The computer 200 is a general computer.

[0155] The computer 200 includes a processor 211 , a digital signal interface 212 , and a memory 213 as hardware.

[0156] The computer 200 includes, as functional elements, a demodulator 221 , an object measuring unit 222 , a pseudo-random number generator 223 , a modulation code generator 224 , and a true random number generator 225 .

[0157] The processor 211 is the same as the processor 111. The digital signal interface 212 is the same as the digital signal interface 112. The digital signal interface 212 is used to connect the phase modulation unit 202 and the ADC unit 207 to the computer 200. The memory 213 is the same as the memory 113.

[0158] The demodulator 221 , the object measuring unit 222 , the pseudo-random number generator 223 , the modulation code generator 224 , and the true random number generator 225 are implemented by programs. The programs are stored in the memory 213 and executed by the processor 211 .

[0159] The operation of the radar device 20 will be described.

[0160] The operation of the radar device 20 is the same as that of the radar device 10. Figure 3In the sequence diagram, the same actions are obtained by rewriting the true random number generator 101 into a true random number generator 225, the pseudo random number generator 102 into a pseudo random number generator 223, the modulation code synthesis unit 103 into a modulation code generator 224, the signal generator 100 into a signal generator 201, the phase modulator 104 into a phase modulator 202, the transmitting antenna 105 into a transmitting antenna 203, the mixer 107 into a mixer 205, the receiving antenna 106 into a receiving antenna 204, the object 11 into an object 21, the LPF unit 108 into an LPF unit 206, the ADC unit 109 into an ADC unit 207, the demodulator 121 into a demodulator 221, and the object measurement unit 122 into an object measurement unit 222.

[0161] The true random number generator 225 may also generate a true random number sequence using the digital signal S211 of the ADC unit 207 .

[0162] Figure 11 This figure illustrates an example of the process of generating a true random number sequence based on the digital signal S211 by the true random number generator 225. The digital signal S211 shown in the middle section of this figure is a sine wave signal (hereinafter referred to as a sine wave signal) obtained by digitizing the beat signal S210.

[0163] As a specific example, it is considered that the true random number generator 225 uses the peak value of the sine wave signal as a random number, thereby generating a random number from the digital signal S211.

[0164] exist Figure 11 In the graph of the digital signal S211, the peak value of the sine wave is indicated by a mark ▽. When the peak values ​​of the sine waves corresponding to one scan are collected to generate a histogram, as shown in FIG. Figure 11 As shown in the lower section of . In this histogram, it can be observed that the values ​​are well dispersed and no significant deviation of the values ​​is observed. Therefore, the true random number generator 225 can make use of the peak value of the sine wave such as this example when generating random numbers.

[0165] Figure 12 This is a flowchart showing an example of a procedure in which the true random number generator 225 generates a 1-bit random number based on the digital signal S211 .

[0166] (Step S11: Peak Detection Processing)

[0167] The true random number generator 225 detects a peak value from the digital signal S211 .

[0168] As a specific example, the true random number generator 225 is as follows Figure 11When multiple peaks are observed in the digital signal S211, the maximum value, minimum value, average value, or median value of the multiple peaks is defined as the peak value. The term "extreme value" is a general term for the maximum value, minimum value, maximum value, and minimum value of the digital signal S211.

[0169] (Step S12: Sequence Generation Process)

[0170] The true random number generator 225 generates a 1-bit sequence using the value of the detected peak value. A 1-bit sequence is a sequence consisting of a 1-bit signal.

[0171] As a specific example, the true random number generation unit 225 uses a method of assigning 0 or 1 depending on whether the peak is an even number, a method of generating a 1-bit random number using the peak value as a seed of a pseudo-random function, or a method of using a hash function to generate a hash value corresponding to the peak value and adopting the value of a certain bit of the generated hash value.

[0172] (Step S13: Data Confirmation Process)

[0173] When the true random number generator 225 has processed all the digital signals S211 corresponding to all the receiving antennas 204, the true random number generator 225 returns to step S11. Otherwise, the true random number generator 225 proceeds to step S14.

[0174] (Step S14: Random Number Selection Process)

[0175] The true random number generator 225 selects a 1-bit random number from the 1-bit sequence generated in step S12 .

[0176] As a specific example, the true random number generator 225 uses a method of cyclically referring to i=1, 2, 3, . . . , 1, 2, . . . and the digital signal S211 - i or a method of using a result obtained by performing an XOR operation on all random numbers.

[0177] As described above, the true random number generator 225 can generate a 1-bit random number from a single chirped signal.

[0178] The effects of the radar device 20 are the same as those of the radar device 10 .

[0179] <Variation 4>

[0180] In this embodiment, the case where each functional component of the signal processing device 110 is implemented by software has been described. However, as a modification, each functional component may be implemented by hardware.

[0181] Figure 13 A hardware configuration example of the signal processing device 110 according to this modification is shown.

[0182] When each functional component is implemented by hardware, as shown in this figure, signal processing device 110 includes electronic circuit 114 instead of processor 111. Alternatively, although not shown, signal processing device 110 includes electronic circuit 114 instead of processor 111 and memory 113. Electronic circuit 114 is a dedicated electronic circuit that implements the functions of each functional component (and memory 113). Electronic circuits are sometimes referred to as processing circuits.

[0183] As the electronic circuit 114 , a single circuit, a complex circuit, a programmed processor, a parallel programmed processor, a logic IC, a GA (Gate Array), an ASIC (Application Specific Integrated Circuit), or an FPGA (Field-Programmable Gate Array) is assumed.

[0184] Each functional component may be implemented by a single electronic circuit 114 or distributed across multiple electronic circuits 114. Alternatively, some functional components may be implemented by hardware, while others may be implemented by software.

[0185] The processor 111, memory 113, and electronic circuit 114 are collectively referred to as a “processing circuit.” That is, the functions of the various functional components of the signal processing device 110 are implemented by the processing circuit.

[0186] Similar to the signal processing device 110 , the computer 200 may include an electronic circuit instead of the processor 211 or instead of the processor 211 and the memory 213 .

[0187] Implementation Method 2

[0188] Hereinafter, differences from the above-described embodiment will be described with reference to the drawings.

[0189] The radar device 30 of this embodiment is a radar device that adopts the fast FMCW method and the MIMO method. The radar device 30 includes hardware that has a function of transmitting signals and hardware that has a function of receiving signals. The two hardware are different hardware.

[0190] ***Description of the structure***

[0191] Figure 14 A configuration example of the radar device 30 is shown.

[0192] As shown in this figure, the radar device 30 includes a transmitting module 31 and a receiving module 32 .

[0193] The transmission module 31 includes a signal generation unit 300 , an encryption processing unit 301 , a plurality of pseudo-random number generation units 302 , a plurality of modulation code synthesis units 303 , a plurality of phase modulation units 304 , and a plurality of transmission antennas 305 .

[0194] Signal generation unit 300 is identical to signal generation unit 100. Encryption processing unit 301 is typically comprised of a circuit. Pseudo-random number generation unit 302 is identical to pseudo-random number generation unit 102. Modulation code synthesis unit 303 is identical to modulation code synthesis unit 103. Phase modulation unit 304 is identical to phase modulation unit 104. Transmitting antenna 305 is identical to transmitting antenna 105.

[0195] The number of pseudo-random number generating units 302 , the number of modulation code synthesizing units 303 , and the number of phase modulating units 304 are consistent with the number of transmitting antennas 305 .

[0196] The signal generating unit 300 is also referred to as a transmitting-side signal generating unit. The source signal S301 is also referred to as a transmitting-side source signal. The signal generating unit 300 generates a signal as the source signal S301.

[0197] The signal generation unit 300 synchronizes the source signal S301 with the source signal S312 using the synchronization signal S313. As a specific example, the signal generation unit 300 makes the source signal S301 and the source signal S312 identical at a certain point in time.

[0198] The encryption processing unit 301 is also referred to as the sending-side encryption processing unit. The encryption sequence S303 is also referred to as the sending-side encryption sequence. The encryption processing unit 301 receives the true random number sequence S316 and uses it to generate the encryption sequence S303, which is a sequence of encryption-related signals. The true random number sequence S316 consists of true random numbers of one bit or more. Sequences related to encryption are sequences associated with encryption algorithms. Sequences related to encryption can also be sequences obtained by encrypting plaintext.

[0199] The pseudo-random number generator 302 is also referred to as a sending-side pseudo-random number generator. The pseudo-random number sequence S302 is also referred to as a sending-side pseudo-random number sequence. The pseudo-random number generator 302 generates a pseudo-random number sequence S302 consisting of pseudo-random numbers of one bit or more.

[0200] Modulation code synthesis unit 303 is also referred to as the transmitting-side modulation code synthesis unit. Modulation code sequence S304 is also referred to as the transmitting-side modulation code sequence. Modulation code synthesis unit 303 synthesizes pseudorandom number sequence S302 and encryption sequence S303 to generate modulation code sequence S304. Modulation code sequence S304 is identical to modulation code sequence S104. However, modulation code sequence S304 includes components derived from encryption sequence S303 instead of components derived from true random number sequence S102.

[0201] The phase modulation unit 304 modulates the phase of the source signal S301 using a modulation code sequence S304 to generate a transmission signal S305 .

[0202] The signal generation unit 300 and the encryption processing unit 301 each include a communication IF (Interface) for communicating with the reception module 32. As a specific example, the communication IF is a Wi-Fi (registered trademark) module or an Ethernet (registered trademark) module.

[0203] The receiving module 32 has multiple receiving antennas 306, multiple mixing units 307, multiple LPF units 308, multiple ADC units 309, a signal processing device 310, a signal generating unit 311, a synchronization signal generating unit 312, an encryption processing unit 313, multiple modulation code synthesis units 314, multiple pseudo-random number generating units 315 and a true random number generating unit 316.

[0204] Receiving antenna 306 is identical to receiving antenna 106. Mixing unit 307 is identical to mixing unit 107. LPF unit 308 is identical to LPF unit 108. ADC unit 309 is identical to ADC unit 109. Signal processing device 310 is identical to signal processing device 110. Signal generating unit 311 is identical to signal generating unit 100. Typically, synchronization signal generating unit 312 is comprised of a circuit. Encryption processing unit 313 is identical to encryption processing unit 301. Modulation code synthesis unit 314 is identical to modulation code synthesis unit 103. Pseudo-random number generating unit 315 is identical to pseudo-random number generating unit 102. True random number generating unit 316 is identical to true random number generating unit 101.

[0205] The number of mixers 307 , LPFs 308 , and ADCs 309 matches the number of receiving antennas 306 .

[0206] The number of modulation code synthesis units 314 and the number of pseudo-random number generation units 315 are consistent with the number of transmission antennas 305 .

[0207] The mixer 307 receives the signal as a reception signal S308 and generates a mixing output signal S309 by mixing the source signal S312 and the reception signal S308.

[0208] The LPF section 308 extracts the low-frequency component of the mixing output signal S309 to thereby generate a beat signal S310 .

[0209] The signal generation unit 311 is also referred to as a receiving-side signal generation unit. The source signal S312 is also referred to as a receiving-side source signal. The signal generation unit 311 generates a signal corresponding to the source signal S301 as the source signal S312.

[0210] The signal generating unit 311 synchronizes the source signal S312 with the source signal S301 using the synchronization signal S313 .

[0211] The synchronization signal generation unit 312 generates a synchronization signal S313 for synchronizing signals, and transmits the synchronization signal S313 to the transmission module 31 .

[0212] The encryption processing unit 313 is also called the receiving-side encryption processing unit. The encryption sequence S317 is also called the receiving-side encryption sequence. The encryption processing unit 313 receives the true random number sequence S316 and uses the true random number sequence S316 to generate the encryption sequence S317, which is a sequence of signals related to encryption.

[0213] Modulation code synthesis unit 314 is also referred to as the receiving-side modulation code synthesis unit. Modulation code sequence S315 is also referred to as the receiving-side modulation code sequence. Modulation code synthesis unit 314 synthesizes pseudorandom number sequence S314 and encryption sequence S317 to generate modulation code sequence S315. Modulation code sequence S315 is the same as modulation code sequence S304.

[0214] The pseudo-random number generator 315 is also referred to as a receiving-side pseudo-random number generator. The pseudo-random number sequence S314 is also referred to as a receiving-side pseudo-random number sequence.

[0215] The true random number generation unit 316 generates a true random number sequence S316 and sends the true random number sequence S316 to the sending module 31 .

[0216] The synchronization signal generation unit 312 and the true random number generation unit 316 each have a communication IF for communicating with the transmission module 31 .

[0217] Source signal S301 is identical to source signal S101. Pseudo-random number sequence S302 is identical to pseudo-random number sequence S103. Encryption sequence S303 is a sequence consisting of signals generated by encryption processing unit 301. Modulation code sequence S304 is a sequence consisting of signals generated by modulation code synthesis unit 303. Transmission signal S305 is a sequence consisting of signals generated by phase modulation unit 304. Transmission wave S306 is identical to transmission wave S106.

[0218] Received wave S307 is identical to received wave S107. Received signal S308 is identical to received signal S108. Mixed output signal S309 is identical to mixed output signal S109. Beat signal S310 is identical to beat signal S110. Digital signal S311 is identical to digital signal S111. Source signal S312 is generated by signal generator 311. Synchronization signal S313 is generated by synchronization signal generator 312. Synchronization signal S313 is used to synchronize transmitting module 31 and receiving module 32. Pseudo-random number sequence S314 is a sequence of signals generated by pseudo-random number generator 315. Modulation code sequence S315 is a sequence of signals generated by modulation code synthesizer 314. True random number sequence S316 is a sequence of signals generated by true random number generator 316. Encryption sequence S317 is a sequence of signals generated by encryption processor 313.

[0219] Radar device 10 differs from radar device 30 in that transmitting module 31 and receiving module 32 are separate hardware components. Therefore, each of transmitting module 31 and receiving module 32 includes components corresponding to signal generator 100, pseudo-random number generator 102, and modulation code synthesizer 103. Furthermore, transmitting module 31 and receiving module 32 share a true random number sequence S316.

[0220] The synchronization signal generating unit 312 drives the signal generating unit 300 and the signal generating unit 311 to align the signal transmission timings, thereby achieving synchronization between the transmitting module 31 and the receiving module 32 .

[0221] The transmission module 31 may include at least one of the true random number generator 316 and the synchronization signal generator 312 instead of the reception module 32 .

[0222] The internal structure of the signal processing device 310 is the same as the internal structure of the signal processing device 110. Therefore, the description of the signal processing device 310 is omitted.

[0223] The radar device 30 may be a single radar device including the transmission module 31 and the reception module 32. Furthermore, the radar device 30 may be composed of a plurality of radar devices located in different regions, such as a bistatic radar or a multistatic radar.

[0224] ***Description of the action***

[0225] Figure 15 1 is a sequence diagram showing an example of the operation of the radar device 30. The operation of the radar device 30 will be described with reference to this diagram.

[0226] The true random number generator 316 generates a true random number sequence S316 and sends the true random number sequence S316 to the encryption processing unit 301 and the encryption processing unit 313. As a result, the encryption processing unit 301 and the encryption processing unit 313 can share the true random number sequence S316.

[0227] The true random number generator 316 may execute the operations described in this paragraph only once when the radar device 30 is activated, or may repeatedly execute the operations described in this paragraph at a predetermined time interval, such as each scan. Alternatively, the true random number generator 316 may execute the operations described in this paragraph upon a demodulation failure by the demodulation unit 121.

[0228] Encryption processing unit 301 encrypts plaintext M using true random number sequence S316, generating encrypted sequence S303, and sends encrypted sequence S303 to modulation code synthesis unit 303. Encryption processing unit 313 encrypts plaintext M using true random number sequence S316, generating encrypted sequence S317, and sends encrypted sequence S317 to modulation code synthesis unit 314. Plaintext M can be any plaintext or arbitrarily generated. Plaintext is unencrypted data. Encrypted sequence S303 and encrypted sequence S317 are the same. Encryption processing unit 301 and encryption processing unit 313 share plaintext M.

[0229] When initially generating the encryption sequence S303 and the encryption sequence S317, as a specific example, the encryption processing unit 301 and the encryption processing unit 313 use a pre-shared initial value. The encryption processing unit 301 and the encryption processing unit 313 may also use the true random number sequence S316 as a secret key.

[0230] The encryption processing unit 301 and the encryption processing unit 313 generate a sequence of signals that is difficult for an attacker to estimate.

[0231] As a specific example, encryption processing unit 301 and encryption processing unit 313 each use a block cipher or a stream cipher as an encryption algorithm. As a specific example, the block cipher is AES (Advanced Encryption Standard) or Camellia (registered trademark). As a specific example, the stream cipher is KCipher (registered trademark)-2.

[0232] As another specific example, encryption processing unit 301 generates encrypted sequence S303 using the aforementioned method, performs an XOR operation on generated encrypted sequence S303 and true random number sequence S316, executes a hash function using the result of the XOR operation, and sets the hash function result as encrypted sequence S303. In this example, encryption processing unit 313 performs the same process as encryption processing unit 301 used to generate encrypted sequence S303, thereby generating encrypted sequence S317. In this example, encryption processing unit 301 and encryption processing unit 313 share a hash function.

[0233] The pseudo-random number generation unit 302 generates a pseudo-random number sequence S302 and transmits the pseudo-random number sequence S302 to the modulation code synthesis unit 303 .

[0234] The pseudo-random number generation unit 315 generates a pseudo-random number sequence S314 and transmits the pseudo-random number sequence S314 to the modulation code synthesis unit 314 .

[0235] The modulation code synthesis unit 303 generates a modulation code sequence S304 using the encryption sequence S303 and the pseudo-random number sequence S302 , and transmits the modulation code sequence S304 to the phase modulation unit 304 .

[0236] The modulation code synthesis unit 314 generates a modulation code sequence S315 using the encryption sequence S317 and the pseudo-random number sequence S314 , and transmits the modulation code sequence S315 to the demodulation unit 121 .

[0237] Similar to the modulation code synthesis unit 103 , the modulation code synthesis unit 303 and the modulation code synthesis unit 314 synthesize signal sequences.

[0238] Synchronization signal generator 312 transmits synchronization signal S313 to each of signal generator 300 and signal generator 311. Synchronization signal generator 312 transmits synchronization signal S313 to correct any synchronization offset between signal generator 300 and signal generator 311, which operate using different oscillators. Typically, signal generator 300 and signal generator 311 generate the same signal.

[0239] The timing at which the synchronization signal generating unit 312 transmits the synchronization signal S313 may be arbitrary. As a specific example, the synchronization signal generating unit 312 transmits the synchronization signal S313 every chirp or every scan.

[0240] The signal generating section 300 generates a source signal S301 and transmits the source signal S301 to the phase modulating section 304. Similarly, the signal generating section 311 generates a source signal S312 and transmits the source signal S312 to the frequency mixing section 307.

[0241] The phase modulation unit 304 performs phase modulation on the source signal S301 using a modulation code sequence S304 to generate a transmission signal S305 , and transmits the transmission signal S305 to the transmission antenna 305 .

[0242] The phase modulation unit 304 performs phase modulation on the source signal S301 in the same manner as the phase modulation unit 104 .

[0243] The transmission antenna 305 transmits a transmission wave S306 to the outside world. The transmission wave S306 is reflected by the object 33.

[0244] The reception antenna 306 receives the reception wave S307 , converts the reception wave S307 into a reception signal S308 , and transmits the reception signal S308 to the frequency mixing unit 307 .

[0245] The mixing unit 307 generates a mixing output signal S309 by mixing the reception signal S308 and the source signal S312 , and transmits the mixing output signal S309 to the LPF unit 308 .

[0246] The LPF section 308 extracts a low-frequency component of the mixing output signal S309 to thereby generate a beat signal S310 , and transmits the beat signal S310 to the ADC section 309 .

[0247] The ADC unit 309 converts the beat signal S310 , which is an analog signal, into a digital signal to thereby generate a digital signal S311 , and transmits the digital signal S311 to the demodulation unit 121 .

[0248] The demodulation unit 121 demodulates the digital signal S311 using the modulation code sequence S315 to generate a demodulated signal, which is then sent to the object measurement unit 122 .

[0249] The demodulator 121 of the radar device 30 demodulates the digital signal S311 in the same manner as the demodulator 121 of the radar device 10 .

[0250] ***Description of the Effects of Implementation Method 2***

[0251] The radar device 30 of this embodiment has the following effects in addition to the same effects as the radar device 10 of the first embodiment.

[0252] The transmitting module 31 includes an encryption processing unit 301, and the receiving module 32 includes an encryption processing unit 313. Furthermore, the encryption processing unit 301 and the encryption processing unit 313 each generate an encrypted signal sequence. This allows the radar device 30 to reduce the number of communications required to share the true random number sequence S316.

[0253] In the fast FMCW method, the sweep time for one chirp is short. According to this embodiment, the transmitting module 31 and the receiving module 32 can perform separate processing. Therefore, the risk of processing delays due to the time required for communication to share the true random number sequence S316 is relatively low. Therefore, this embodiment is particularly effective in radar devices that employ the fast FMCW method.

[0254] ***Other structures***

[0255] <Variation 5>

[0256] When initially generating the encryption sequence S303 and the encryption sequence S317, the encryption processing unit 301 and the encryption processing unit 313 do not need to use the pre-shared initial value.

[0257] In this variation, as a specific example, encryption processing unit 301 and encryption processing unit 313 share a random number generation algorithm and use true random number sequence S316 as a random number seed to generate a random number sequence. Encryption processing unit 301 sets the random number sequence as encryption sequence S303. Encryption processing unit 313 sets the random number sequence as encryption sequence S317.

[0258] <Variation 6>

[0259] The true random number generation unit 316 may also encrypt the true random number sequence S316.

[0260] In this variation, as a specific example, encryption processing unit 301 and encryption processing unit 313 share a decryption key for decrypting true random number generator 316, and use the decryption key to decrypt the encrypted true random number sequence S316. In this example, modulation code synthesis unit 303 uses true random number sequence S316 instead of encryption sequence S303, and modulation code synthesis unit 314 uses true random number sequence S316 instead of encryption sequence S317. That is, encryption sequence S303 and encryption sequence S317 may each include true random number sequence S316.

[0261] <Variation 7>

[0262] Figure 16 The following shows a configuration example of a radar device 40. The radar device 40 has a configuration different from that of the radar device 30.

[0263] The relationship between the radar device 40 and the radar device 30 is the same as the relationship between the radar device 20 and the radar device 10. That is, the radar device 40 is a device that realizes a part of the functions of the radar device 30 by using a computer.

[0264] As shown in this figure, the radar device 40 includes a transmitting module 41 and a receiving module 42 as hardware.

[0265] The transmission module 41 includes a transmission control computer 400, a signal generating unit 401, a plurality of phase modulation units 404, and a plurality of transmission antennas 405. The number of the phase modulation units 404 matches the number of the transmission antennas 405.

[0266] The signal generating section 401 is the same as the signal generating section 100 . The phase modulating section 404 is the same as the phase modulating section 104 . The transmitting antenna 405 is the same as the transmitting antenna 105 .

[0267] The receiving module 42 includes a signal generating unit 402 , a plurality of receiving antennas 406 , a plurality of frequency mixing units 407 , a plurality of LPF units 408 , a plurality of ADC units 409 , and a receiving control computer 410 .

[0268] The signal generating unit 402 is the same as the signal generating unit 100. The receiving antenna 406 is the same as the receiving antenna 106. The mixing unit 407 is the same as the mixing unit 107. The LPF unit 408 is the same as the LPF unit 108. The ADC unit 409 is the same as the ADC unit 109.

[0269] Source signal S401 is identical to source signal S301. Modulation code sequence S404 is a sequence of modulation codes generated by transmission control computer 400. Transmission signal S405 is identical to transmission signal S305. Transmission wave S406 is identical to transmission wave S306. The number of transmission waves S406 matches the number of transmission antennas 405.

[0270] Received wave S407 is identical to received wave S307. The maximum number of received waves S407 is equal to the number obtained by multiplying the number of transmitting antennas 405 by the number of receiving antennas 406. Received signal S408 is identical to received signal S308. Mixer output signal S409 is identical to mixer output signal S309. Beat signal S410 is identical to beat signal S310. Digital signal S411 is identical to digital signal S311. Source signal S412 is identical to source signal S312. Synchronization signal S413 is a signal generated by reception control computer 410. True random number sequence S416 is a sequence of signals generated by reception control computer 410.

[0271] Figure 17 The following shows an example of the hardware configuration of the reception control computer 410. The reception control computer 410 is a general computer.

[0272] As shown in this figure, the reception control computer 410 includes a processor 411 , a digital signal interface 412 , an analog signal interface 413 , and a memory 414 as hardware.

[0273] In addition, as functional elements, the receiving control computer 410 has a demodulation unit 421, an object measurement unit 422, a pseudo-random number generation unit 423, a modulation code generation unit 424, an encryption processing unit 425, a synchronization signal generation unit 426 and a true random number generation unit 427.

[0274] The processor 411 is the same as the processor 111. The memory 414 is the same as the memory 113.

[0275] The digital signal interface 412 is the same as the digital signal interface 112 . The digital signal interface 412 is used to connect the ADC unit 409 and the reception control computer 410 .

[0276] Analog signal interface 413 is, for example, a Digital-to-Analog Converter (DAC). Analog signal interface 413 is used to connect reception control computer 410 and external hardware. Assume that synchronization signal S413 is input to signal generator 401 and signal generator 402. Therefore, external hardware includes signal generator 401 and signal generator 402. Specifically, synchronization signal S413 is a reset signal, an enable signal, or a trigger signal.

[0277] Similar to the signal processing device 110 , the reception control computer 410 may include an electronic circuit instead of the processor 411 or instead of the processor 411 and the memory 414 .

[0278] The demodulator 421 , the object measuring unit 422 , the pseudo-random number generator 423 , the modulation code generator 424 , the encryption processor 425 , the synchronization signal generator 426 , and the true random number generator 427 are implemented by programs. The programs are stored in the memory 414 and executed by the processor 411 .

[0279] Figure 18 The following shows an example of the hardware configuration of the transmission control computer 400. The transmission control computer 400 is a general computer.

[0280] As shown in this figure, the transmission control computer 400 includes a processor 431 , a digital signal interface 432 , and a memory 433 as hardware.

[0281] Furthermore, the transmission control computer 400 includes a pseudo-random number generation unit 441 , a modulation code generation unit 442 , and an encryption processing unit 443 as functional elements.

[0282] The processor 431 is the same as the processor 111. The memory 433 is the same as the memory 113.

[0283] The digital signal interface 432 is the same as the digital signal interface 112 . The digital signal interface 432 is used to connect the transmission control computer 400 and the phase modulation unit 404 .

[0284] Similar to the signal processing device 110 , the transmission control computer 400 may include an electronic circuit instead of the processor 431 or instead of the processor 431 and the memory 433 .

[0285] The pseudo-random number generator 441 , the modulation code generator 442 , and the encryption processor 443 are implemented by programs. The programs are stored in the memory 433 and executed by the processor 431 .

[0286] The operation of the radar device 40 will be described. The operation of the radar device 40 is the same as that of the radar device 30. Figure 15 In the sequence diagram, the true random number generator 316 is rewritten as a true random number generator 427, the encryption processing unit 301 is rewritten as an encryption processing unit 443, the encryption processing unit 313 is rewritten as an encryption processing unit 425, the pseudo-random number generator 302 is rewritten as a pseudo-random number generator 441, the pseudo-random number generator 315 is rewritten as a pseudo-random number generator 423, the modulation code synthesis unit 303 is rewritten as a modulation code generator 442, the modulation code synthesis unit 314 is rewritten as a modulation code generator 424, the synchronization signal generator 312 is rewritten as a synchronization signal generator 426, and the signal generator 300 is rewritten as a signal generator 427. The same actions are achieved by rewriting the signal generating unit 401 into the signal generating unit 402, rewriting the phase modulating unit 304 into the phase modulating unit 404, rewriting the transmitting antenna 305 into the transmitting antenna 405, rewriting the object 33 into the object 43, rewriting the receiving antenna 306 into the receiving antenna 406, rewriting the mixing unit 307 into the mixing unit 407, rewriting the LPF unit 308 into the LPF unit 408, rewriting the ADC unit 309 into the ADC unit 409, rewriting the demodulating unit 121 into the demodulating unit 421, and rewriting the object measuring unit 122 into the object measuring unit 422.

[0287] The true random number generator 427 may also perform the same processing as that of the true random number generator 225 , thereby generating a true random number sequence S416 using the digital signal S411 .

[0288] ***Other Implementations***

[0289] The above-described embodiments can be freely combined, arbitrary components of the embodiments can be modified, or arbitrary components of the embodiments can be omitted.

[0290] The above embodiments are merely preferred examples in nature and are not intended to limit the scope of the invention, its applications, and uses.

[0291] In addition, the embodiment is not limited to the contents shown in Embodiments 1 and 2, and various changes can be made as needed.

[0292] Label Description

[0293] 10, 20, 30, 40: Radar device; 11, 21, 33, 43: Object; 31, 41: Transmitter module; 32, 42: Receiver module; 15, 25: Transmitter; 16, 26: Receiver; 100, 201, 300, 311, 401, 402: Signal generator; 101, 316: True random number generator; 102, 302, 315: Pseudorandom number generator; 103, 303, 314: Modulation code synthesizer; 104, 202, 304, 404: Phase modulator; 105, 203, 305, 405: Transmitter antenna; 106, 204, 306, 406 : Receiving antenna; 107, 205, 307, 407: Mixing unit; 108, 206, 308, 408: LPF unit; 109, 207, 309, 409: ADC unit; 110, 310: Signal processing device; 200: Computer; 301, 313: Encryption processing unit; 312: Synchronization signal generation unit; 400: Transmission control computer; 410: Reception control computer; 111, 211, 411, 431: Processor; 112, 212, 412, 432: Digital signal interface; 113, 213, 414, 433: Memory; 114: Electronic circuit; 413: Module Pseudo-signal interface; 121, 221, 421: Demodulation unit; 122, 222, 422: Object measurement unit; 223, 423, 441: Pseudo-random number generation unit; 224, 424, 442: Modulation code generation unit; 225, 427: True random number generation unit; 425, 443: Encryption processing unit; 426: Synchronization signal generation unit; S101, S201, S301, S312, S401, S412: Source signal; S102, S316, S416: True random number sequence; S103, S302, S314: Pseudo-random number sequence; S104, S204, S304, S31 5. S404: modulation code sequence; S105, S205, S305, S405: transmitting signal; S106, S206, S306, S406: transmitting wave; S107, S207, S307, S407: receiving wave; S108, S208, S308, S408: receiving signal; S109, S209, S309, S409: mixing output signal; S110, S210, S310, S410: beat signal; S111, S211, S311, S411: digital signal; S303, S317: encryption sequence; S313, S413: synchronization signal.

Claims

1. A radar device, comprising: a signal generating unit that generates a signal as a source signal; at least one pseudo-random number generator that generates a pseudo-random number sequence consisting of pseudo-random numbers of one bit or more; a true random number generator that generates a true random number sequence consisting of true random numbers of 1 bit or more; at least one modulation code synthesis unit that synthesizes the pseudo-random number sequence and the true random number sequence to generate a modulation code sequence for modulating the phase of a signal and including a component derived from the true random number sequence; and at least one phase modulation unit that modulates the phase of the source signal using the modulation code sequence to generate a transmission signal, The modulation code sequence is a modulation code sequence obtained by synthesizing two modulation code sequences so that the components derived from the true random number sequence disappear, thereby when the modulation code sequence is used for demodulation, the components derived from the true random number sequence in the demodulated signal are offset, wherein the two pseudo-random number sequences used to respectively generate the two modulation code sequences are generated by different pseudo-random number generation units, and the modulation code sequence used by each phase modulation unit is generated by synthesizing the pseudo-random number sequences generated by different pseudo-random number generation units and the true random number sequence, thereby generating mutually different transmission signals when the phase of the source signal is modulated using the modulation code sequence.

2. The radar device according to claim 1, wherein The modulation code synthesis unit generates the modulation code sequence by performing an exclusive-OR operation or an exclusive-NOR operation.

3. The radar device according to claim 1, wherein The radar device comprises: at least one transmitting antenna that converts the transmission signal into a transmission wave and transmits the transmission wave; at least one receiving antenna that receives a reception wave corresponding to the transmission wave and converts the reception wave into a reception signal; at least one mixing unit configured to generate a mixed output signal by mixing the source signal and the received signal; at least one low-pass filter section that extracts a low-frequency component of the mixing output signal to generate a beat signal; and a demodulation unit that demodulates the beat signal using the modulation code sequence, The number of the at least one pseudo-random number generator, the number of the at least one modulation code synthesizer, and the number of the at least one phase modulator are respectively consistent with the number of the at least one transmitting antenna. The number of the at least one mixing unit and the number of the at least one low-pass filter unit are respectively consistent with the number of the at least one receiving antenna.

4. The radar device according to claim 2, wherein: The radar device comprises: at least one transmitting antenna that converts the transmission signal into a transmission wave and transmits the transmission wave; at least one receiving antenna that receives a reception wave corresponding to the transmission wave and converts the reception wave into a reception signal; at least one mixing unit configured to generate a mixed output signal by mixing the source signal and the received signal; at least one low-pass filter section that extracts a low-frequency component of the mixing output signal to generate a beat signal; and a demodulation unit that demodulates the beat signal using the modulation code sequence, The number of the at least one pseudo-random number generator, the number of the at least one modulation code synthesizer, and the number of the at least one phase modulator are respectively consistent with the number of the at least one transmitting antenna. The number of the at least one mixing unit and the number of the at least one low-pass filter unit are respectively consistent with the number of the at least one receiving antenna.

5. The radar device according to claim 1, wherein The radar device comprises: at least one transmitting antenna that converts the transmission signal into a transmission wave and transmits the transmission wave; at least one receiving antenna that receives a reception wave corresponding to the transmission wave and converts the reception wave into a reception signal; at least one mixing unit configured to generate a mixed output signal by mixing the transmission signal and the reception signal; as well as at least one low-pass filter section that extracts a low-frequency component of the mixing output signal to generate a beat signal, The number of the at least one pseudo-random number generator, the number of the at least one modulation code synthesizer, and the number of the at least one phase modulator are respectively consistent with the number of the at least one transmitting antenna. The number of the at least one mixing unit and the number of the at least one low-pass filter unit are respectively consistent with the number of the at least one receiving antenna.

6. The radar device according to claim 2, wherein: The radar device comprises: at least one transmitting antenna that converts the transmission signal into a transmission wave and transmits the transmission wave; at least one receiving antenna that receives a reception wave corresponding to the transmission wave and converts the reception wave into a reception signal; at least one mixing unit configured to generate a mixed output signal by mixing the transmission signal and the reception signal; as well as at least one low-pass filter section that extracts a low-frequency component of the mixing output signal to generate a beat signal, The number of the at least one pseudo-random number generator, the number of the at least one modulation code synthesizer, and the number of the at least one phase modulator are respectively consistent with the number of the at least one transmitting antenna. The number of the at least one mixing unit and the number of the at least one low-pass filter unit are respectively consistent with the number of the at least one receiving antenna.

7. The radar device according to any one of claims 3 to 6, wherein: The true random number generator converts the extreme value of the beat signal into a binary number to generate a 1-bit true random number.

8. The radar device according to any one of claims 3 to 6, wherein: The radar device includes a plurality of low-pass filter units. The true random number generation unit generates random number bits corresponding to the plurality of low-pass filter parts respectively using beat signals corresponding to the plurality of low-pass filter parts possessed by the radar device, and performs an exclusive-OR operation or an exclusive-NOR operation using the generated random number bits, thereby generating a 1-bit true random number.

9. A radar device, wherein: The radar device has a transmitting module and a receiving module. The sending module has: a sending-side signal generating unit, which generates a signal as a sending-side source signal; at least one sending-side pseudo-random number generator that generates a sending-side pseudo-random number sequence consisting of pseudo-random numbers of one bit or more; a transmission-side encryption processing unit that receives a true random number sequence consisting of true random numbers of one bit or more and uses the true random number sequence to generate a transmission-side encryption sequence that is a sequence of signals related to encryption; at least one transmitting-side modulation code synthesizing unit that synthesizes the transmitting-side pseudo-random number sequence and the transmitting-side encryption sequence to generate a transmitting-side modulation code sequence for modulating the phase of a signal and containing a component derived from the transmitting-side encryption sequence; and at least one phase modulation unit that modulates the phase of the transmission-side source signal using the transmission-side modulation code sequence to generate a transmission signal, The receiving module has: a receiving-side signal generating unit, which generates a signal corresponding to the sending-side source signal as a receiving-side source signal; at least one receiving-side pseudo-random number generator that generates a receiving-side pseudo-random number sequence consisting of pseudo-random numbers of one bit or more; a receiving-side encryption processing unit that receives the true random number sequence and generates a receiving-side encryption sequence that is a sequence of encryption-related signals using the true random number sequence; at least one receiving-side modulation code synthesis unit configured to synthesize the receiving-side pseudo-random number sequence and the receiving-side encryption sequence to generate a receiving-side modulation code sequence for modulating the phase of a signal and including a component derived from the receiving-side encryption sequence; at least one mixing unit that receives a signal as a reception signal and generates a mixed output signal by mixing the reception-side source signal and the reception signal; at least one low-pass filter section that extracts a low-frequency component of the mixing output signal to generate a beat signal; and a demodulation unit that demodulates the beat signal using the receiving-side modulation code sequence, The two transmitting-side modulation code sequences are synthesized to eliminate components derived from the transmitting-side encryption sequence. The two receiving-side modulation code sequences are obtained by synthesizing two receiving-side modulation code sequences so that the components derived from the receiving-side encryption sequence disappear. The number of the at least one transmitting-side pseudo-random number generator, the number of the at least one receiving-side pseudo-random number generator, the number of the at least one transmitting-side modulation code synthesizer, the number of the at least one receiving-side modulation code synthesizer, and the number of the at least one phase modulator are respectively consistent with the number of the at least one transmitting antenna. The number of the at least one mixing unit and the number of the at least one low-pass filter unit are respectively consistent with the number of the at least one receiving antenna.

10. The radar device according to claim 9, wherein The receiving module includes a synchronization signal generating unit that generates a synchronization signal for synchronizing signals and transmits the synchronization signal to the transmitting module. The transmission side signal generating unit synchronizes the transmission side source signal with the reception side source signal using the synchronization signal. The reception-side signal generating section synchronizes the reception-side source signal with the transmission-side source signal using the synchronization signal.

11. The radar device according to claim 9, wherein The transmitting side modulation code synthesis unit performs an exclusive OR operation or an exclusive NOR operation to generate the transmitting side modulation code sequence. The receiving-side modulation code synthesis unit performs an exclusive-OR operation or an exclusive-NOR operation to generate the receiving-side modulation code sequence.

12. The radar device according to claim 10, wherein The transmitting side modulation code synthesis unit performs an exclusive OR operation or an exclusive NOR operation to generate the transmitting side modulation code sequence. The receiving-side modulation code synthesis unit performs an exclusive-OR operation or an exclusive-NOR operation to generate the receiving-side modulation code sequence.

13. The radar device according to any one of claims 9 to 12, wherein: The receiving module includes a true random number generating unit that generates the true random number sequence and sends the true random number sequence to the sending module.

14. The radar apparatus according to claim 13, wherein: The true random number generator converts the extreme value of the beat signal into a binary number to generate a 1-bit true random number.

15. The radar apparatus according to claim 13, wherein The radar device includes a plurality of low-pass filter units. The true random number generation unit generates random number bits corresponding to the plurality of low-pass filter parts respectively using beat signals corresponding to the plurality of low-pass filter parts possessed by the radar device, and performs an exclusive-OR operation or an exclusive-NOR operation using the generated random number bits, thereby generating a 1-bit true random number.

16. A radar operation method, wherein: The signal generating unit generates a signal as a source signal, At least one pseudo-random number generator generates a pseudo-random number sequence consisting of pseudo-random numbers of 1 bit or more. The true random number generator generates a true random number sequence consisting of true random numbers of 1 bit or more. At least one modulation code synthesis unit synthesizes the pseudo-random number sequence and the true random number sequence to generate a modulation code sequence for modulating the phase of a signal and including a component derived from the true random number sequence. At least one phase modulator modulates the phase of the source signal using the modulation code sequence to generate a transmission signal. The modulation code sequence is a modulation code sequence obtained by synthesizing two modulation code sequences so that the components derived from the true random number sequence disappear, thereby when the modulation code sequence is used for demodulation, the components derived from the true random number sequence in the demodulated signal are offset, wherein the two pseudo-random number sequences used to respectively generate the two modulation code sequences are generated by different pseudo-random number generation units, and the modulation code sequence used by each phase modulation unit is generated by synthesizing the pseudo-random number sequences generated by different pseudo-random number generation units and the true random number sequence, thereby generating mutually different transmission signals when the phase of the source signal is modulated using the modulation code sequence.

17. A computer-readable recording medium having a radar operating program recorded thereon, wherein: The radar application program causes a computer-generated signal to serve as a source signal. causing the computer to generate a pseudo-random number sequence consisting of pseudo-random numbers of 1 bit or more, causing the computer to generate a true random number sequence consisting of true random numbers of 1 bit or more, causing the computer to synthesize the pseudo-random number sequence and the true random number sequence to generate a modulation code sequence for modulating the phase of a signal and containing a component derived from the true random number sequence, causing the computer to modulate the phase of the source signal using the modulation code sequence to generate a transmission signal, The modulation code sequence is a modulation code sequence obtained by synthesizing two modulation code sequences so that the components derived from the true random number sequence disappear, thereby when the modulation code sequence is used for demodulation, the components derived from the true random number sequence in the demodulated signal are offset, wherein the two pseudo-random number sequences used to respectively generate the two modulation code sequences are generated by different pseudo-random number generating units, and each modulation code sequence used by the computer is generated by synthesizing the pseudo-random number sequences generated by different pseudo-random number generating units and the true random number sequence, thereby generating mutually different transmission signals when the phase of the source signal is modulated using the modulation code sequence.

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