Radar system and timing adjustment method

Abstract

To accurately correct a timing difference of signals between antenna devices without performing high-speed sampling processing even when there is an individual difference in signal characteristics of each antenna device.SOLUTION: A radar system 100 has a plurality of antenna devices and a calibration signal generator 13 for distributing calibration signals to the plurality of antenna devices. Each of the plurality of antenna devices includes a transmission signal generator 10 which outputs a transmission signal that is a frequency continuous modulated wave signal in response to a transmission trigger signal, a reception unit 11 which generates a reception digital signal by executing reception processing in response to the reception trigger signal, and a correction control unit 12 which calculates the phase of the reception digital signal, corrects the output timing of the reception trigger signal and the transmission trigger signal based on the slope of the phase difference of the signals between the plurality of antenna devices with respect to time, and then outputs the signal.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a radar system and a method for adjusting timing. [Background technology]

[0002] In a radar system that detects a target by transmitting an FMCW (Frequency Modulated Continuous Wave) signal via multiple antennas and receiving an echo signal reflected from the target, it is necessary to match the amplitude, phase, and timing of the signal between multiple antenna devices and combine the received echo signals. For example, Patent Document 1 discloses a technique for correcting the timing difference of the signal transmitted from each antenna element by estimating the response of the impulse signal output from each antenna element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 191957 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology described in Patent Document 1, when there are individual differences in signal characteristics between antenna devices, such as variations in the rising characteristics of received echo signals, it is difficult to accurately measure the signals received by each antenna device in order to correct the timing difference between the signals between the antenna devices. In order to accurately measure the signals received by each antenna device, a measuring device with high time resolution and high-speed sampling processing is required.

[0005] The present disclosure has been made to solve the problems described above, and aims to accurately correct the signal timing difference between antenna devices without performing high-speed sampling processing, even when there are individual differences in the signal characteristics of each antenna device. [Means for solving the problem]

[0006] In order to achieve the above object, a radar system according to the present disclosure includes a plurality of antenna devices that transmit a transmission signal and receive an echo signal reflected from a target, and a calibration signal generator that outputs a calibration signal to the plurality of antenna devices. Each of the plurality of antenna devices includes a transmission signal generator, a receiving unit, and a correction control unit. The transmission signal generator outputs a transmission signal that is a continuous frequency modulated wave signal in response to a transmission trigger signal. The receiving unit performs reception processing on the transmission signal or the calibration signal in response to a reception trigger signal to generate a reception digital signal. The correction control unit corrects the output timing of the transmission trigger signal and the reception trigger signal before outputting them. The correction control unit calculates the phase of the reception digital signal generated by performing reception processing on the calibration signal, corrects the output timing of the reception trigger signal based on the slope of the phase difference of the reception digital signal with respect to time between the antenna devices, calculates the phase of the reception digital signal generated by performing reception processing on the transmission signal, and corrects the output timing of the transmission trigger signal based on the slope of the phase difference of the reception digital signal with respect to time between the plurality of antenna devices.

[0007] A radar system according to the present disclosure includes a plurality of antenna devices that receive echo signals reflected from a target, and a calibration signal generator that outputs a calibration signal to the plurality of antenna devices. Each of the plurality of antenna devices includes a receiver and a correction controller. In response to a reception trigger signal, the receiver performs reception processing on the calibration signal to generate a reception digital signal. The correction controller corrects the output timing of the reception trigger signal before outputting it. The correction controller calculates the phase of the reception digital signal generated by performing reception processing on the calibration signal, and corrects the output timing of the reception trigger signal based on the slope of the phase difference of the reception digital signals between the plurality of antenna devices with respect to time.

[0008] In addition, the timing adjustment method according to the present disclosure is a timing adjustment method performed by a radar system having a plurality of antenna devices that receive echo signals reflected from a target and a calibration signal generator that outputs a calibration signal to the plurality of antenna devices, in which the radar system calculates the phase of a received digital signal generated by performing reception processing on the calibration signal, and corrects the timing of receiving the echo signal based on the slope with respect to time of the phase difference of the received digital signals between the plurality of antenna devices. Effect of the Invention

[0009] According to the present disclosure, by calculating the phase of a received digital signal generated by receiving and processing a frequency continuous modulated wave signal, and correcting the timing of outputting a trigger signal based on the slope over time of the phase difference of the received digital signals between the antenna devices, it is possible to accurately correct the timing difference of signals between each antenna device without performing high-speed sampling processing, even if there are individual differences in the signal characteristics of each antenna device. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing a configuration example of a radar system according to a first embodiment; [Diagram 2]FIG. 1 is a conceptual diagram showing temporal changes in amplitude, frequency, phase, and phase difference of two systems of signals in the antenna device according to the first embodiment. [Diagram 3] Flowchart showing a receiving system timing correction process according to the first embodiment [Figure 4] Flowchart showing a transmission system timing correction process according to the first embodiment [Diagram 5] 1 is a flowchart showing radar transmission and reception processing according to the first embodiment. [Figure 6] FIG. 13 is a diagram showing wiring when correcting timing of a receiving system of a radar system according to a second embodiment. [Figure 7] FIG. 13 is a diagram showing wiring when correcting the timing of a transmission system of a radar system according to a second embodiment. [Figure 8] Flowchart showing a receiving system timing correction process according to the second embodiment [Figure 9] Flowchart showing a transmission system timing correction process according to the second embodiment [Figure 10] FIG. 13 is a diagram showing a configuration example of a radar system according to a third embodiment. [Figure 11] Flowchart showing a receiving system timing correction process according to the third embodiment [Figure 12] Flowchart showing a transmission system timing correction process according to the third embodiment DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a radar system according to the present embodiment will be described in detail with reference to the drawings. Note that in the drawings, the same or corresponding parts are designated by the same reference characters, and their description will not be repeated in principle.

[0012] (Embodiment 1) Fig. 1 shows a configuration example of a radar system 100 according to the first embodiment. In the figure, a solid arrow indicates an analog signal, and a dashed arrow indicates a digital signal. The radar system 100 includes antenna devices #1 to #n that transmit a frequency-continuously modulated wave signal as a transmission signal and receive an echo signal of the transmission signal reflected from a target, a calibration signal generator 13 that outputs an FMCW signal as a calibration signal for timing correction, and a signal distributor 14 that distributes the calibration signal to the antenna devices #1 to #n. The frequency-continuously modulated wave transmitted as the transmission signal is preferably a frequency-continuously modulated wave pulse signal that is a pulse signal.

[0013] Antenna device #1 includes an antenna 1 that emits a transmission signal and receives an echo signal that is the transmission signal reflected from a target, a circulator 3 that switches between transmission and reception of antenna device #1, a signal switch 2 that switches between blocking and passing signals between the circulator 3 and antenna 1, and a signal switch 5 that switches between a calibration signal direction and a transmission return direction. The calibration signal direction and the transmission return direction will be described later.

[0014] The antenna device #1 also includes a transmission signal generator 10 that outputs a transmission signal when it receives a transmission trigger signal output from the correction control unit 12, a power amplifier 8 that amplifies the transmission signal output from the transmission signal generator 10, a directional coupler 6 that extracts a part of the transmission signal amplified by the power amplifier 8 and inputs it to the signal switcher 5, a low-noise amplifier 9 that amplifies the input signal, and a directional coupler 7 that inputs the calibration signal to the low-noise amplifier 9 when the signal switcher 5 switches to the calibration signal direction and inputs the transmission signal to the low-noise amplifier 9 when the signal switcher 5 switches to the transmission return direction. In other words, the calibration signal direction is the direction in which the calibration signal is input to the low-noise amplifier 9, and the transmission return direction is the direction in which the transmission signal is input to the low-noise amplifier 9. Here, the directional coupler 6 is an example of a transmission-side directional coupler, and the directional coupler 7 is an example of a reception-side directional coupler.

[0015] Furthermore, antenna device #1 includes a signal switch 4 that switches between blocking and passing a signal from the circulator 3 to the low-noise amplifier 9, a receiver 11 that performs reception processing by AD converting the signal output from the low-noise amplifier 9 into a digital signal upon receiving a reception trigger signal output from a correction control unit 12, and a correction control unit 12 that corrects the transmission timing and reception timing based on the digital signal obtained by performing reception processing by the receiver 11. Hereinafter, the digital signal output by the receiver 11 after performing reception processing is referred to as a received digital signal.

[0016] The antenna devices #2 to #n have the same configuration as the antenna device #1. The correction control units 12 of the antenna devices #2 to #n send the received digital signal of the calibration signal to the correction control units 12 of the antenna devices #1 to #n-1, respectively. The correction control unit 12 of the antenna device #n-1 adjusts the receiving timing to that of the antenna device #n based on the received digital signal of the calibration signal received from the antenna device #n and the received digital signal of the calibration signal received from its own receiving unit 11. The correction control unit 12 of the antenna device #n-2 adjusts the receiving timing to that of the antenna device #n-1 based on the received digital signal of the calibration signal received from the antenna device #n-1 and the received digital signal of the calibration signal received from its own receiving unit 11. By repeating this process and the correction control unit 12 of the antenna device #1 adjusts the receiving timing to that of the antenna device #2 based on the received digital signal of the calibration signal received from the antenna device #2 and the received digital signal of the calibration signal received from its own receiving unit 11, the receiving timing of all the antenna devices can be adjusted.

[0017] Similarly, the correction control units 12 of the antenna devices #2 to #n send the reception digital signal of the transmission signal to the correction control units 12 of the antenna devices #1 to #n-1, respectively. The correction control unit 12 of the antenna device #n-1 adjusts the transmission timing to the antenna device #n based on the reception digital signal of the transmission signal received from the antenna device #n and the reception digital signal of the transmission signal received from its own receiving unit 11. The correction control unit 12 of the antenna device #n-2 adjusts the transmission timing to the antenna device #n-1 based on the reception digital signal of the transmission signal received from the antenna device #n-1 and the reception digital signal of the transmission signal received from its own receiving unit 11. By repeating this, the correction control unit 12 of the antenna device #1 adjusts the transmission timing to the antenna device #2 based on the reception digital signal of the transmission signal received from the antenna device #2 and the reception digital signal of the transmission signal received from its own receiving unit 11, and the transmission timing of all the antenna devices can be adjusted. Hereinafter, the system from the antenna 1 to the receiving unit 11 is referred to as the reception system, and the system from the transmission signal generator 10 to the antenna 1 is referred to as the transmission system. Also, if the antenna device is considered as a signal path, it is counted as system 1, system 2, etc.

[0018] First, the timing correction of the receiving system will be described. In the radar system 100, for all antenna devices, the signal switch 2 is controlled to switch to the terminal direction so that the calibration signal for timing correction is not input to the antenna 1, and the signal between the circulator 3 and the antenna 1 is blocked. Also, the signal switch 4 is controlled to switch to the terminal direction so that the transmission signal does not leak from the circulator 3 to the low-noise amplifier 9, and the signal between the circulator 3 and the low-noise amplifier 9 is blocked.

[0019] Upon receiving a trigger signal output from correction control unit 12 of antenna device #1, calibration signal generator 13 outputs a calibration signal which is an FMCW signal. The calibration signal output from calibration signal generator 13 is distributed to antenna devices #1 to #n by signal distributor 14 and then input to signal switch 5 of each antenna device. The electrical length from signal distributor 14 to signal switch 5 of each antenna device is the same.

[0020] Antenna devices #1 to #n control signal switch 5 to switch to the calibration signal direction, and input the calibration signal to low-noise amplifier 9 via directional coupler 7. When receiver 11 receives a reception trigger signal output from correction control unit 12 at the same timing by all antenna devices, receiver 11 performs reception processing on the calibration signal. Receiver 11 outputs a received digital signal of the calibration signal to correction control unit 12.

[0021] The correction control units 12 of the antenna devices #1 to #n-1 each receive the digital signal of the calibration signal output from the correction control units 12 of the antenna devices #2 to #n. The correction control units 12 of the antenna devices #1 to #n-1 each calculate the phase of the digital signal of the calibration signal input from the receiving unit 11 and the digital signal of the received calibration signal, and calculate the phase difference between the two systems of the received digital signal, that is, the correction control unit 12 itself and the antenna device that received the digital signal of the calibration signal. Hereinafter, the phase of the received digital signal is referred to as the reception phase. The correction control unit 12 calculates a timing difference, which is the delay difference of the reception systems between the two systems, based on the slope of the phase difference between the two systems with respect to time. The correction control unit 12 corrects the timing of the reception systems between the two systems by adjusting the timing of the reception trigger signal to be output to the receiving unit 11 based on the calculated delay difference of the reception systems between the two systems. In the antenna device in which the timing of the reception systems has been corrected, the receiving unit 11 thereafter performs reception processing in response to the corrected reception trigger signal. By sequentially correcting the timing of the two reception systems from antenna device #n-1 and antenna device #n to antenna device #2 and antenna device #1, it is possible to synchronize the reception timing of all the antenna devices.

[0022] The radar system 100 corrects the timing of the transmission system after the timing of the reception system is corrected. When the transmission signal generator 10 of the antenna devices #1 to #n receives a transmission trigger signal output from the correction control unit 12 at the same timing for all the antenna devices, the transmission signal generator 10 outputs a transmission signal that is an FMCW signal. The transmission signal output from the transmission signal generator 10 is amplified by the power amplifier 8, a part of which is extracted by the directional coupler 6, and input to the signal switcher 5. The antenna devices #1 to #n control the signal switcher 5 to the transmission return direction, and input the transmission signal to the low noise amplifier 9 via the directional coupler 7. When the reception unit 11 receives a reception trigger signal output from the correction control unit 12 at a timing where the delay difference of the reception system is corrected, the reception unit 11 performs reception processing on the transmission signal. The reception unit 11 outputs a reception digital signal of the transmission signal to the correction control unit 12.

[0023] The correction control units 12 of the antenna devices #1 to #n-1 each receive the digital reception signal of the transmission signal output from the correction control units 12 of the antenna devices #2 to #n. Based on the digital reception signal of the transmission signal input from the receiving unit 11 and the digital reception signal of the received transmission signal, the correction control units 12 of the antenna devices #1 to #n-1 each calculate the reception phase of two systems, that is, the antenna device itself and the antenna device that has received the digital reception signal of the transmission signal, and calculate the phase difference between the two systems. The correction control unit 12 calculates the delay difference of the transmission system between the two systems based on the slope of the phase difference between the two systems with respect to time. The correction control unit 12 corrects the timing of the transmission system between the two systems by adjusting the timing of the transmission trigger signal to be output to the transmission signal generator 10 based on the calculated delay difference of the transmission system between the two systems. In the antenna device in which the timing of the transmission system has been corrected, the transmission signal generator 10 thereafter outputs a transmission signal in response to the corrected transmission trigger signal. By sequentially correcting the timing of the two transmission systems from antenna device #n-1 and antenna device #n to antenna device #2 and antenna device #1, it is possible to synchronize the transmission timing of all the antenna devices.

[0024] The radar system 100 starts operating as a radar after correcting the timing of the receiving system and the transmitting system. The antenna devices #1 to #n control the signal switch 2 to switch to the passing direction so that the antenna 1 can radiate the transmitting signal. The signal switch 4 is controlled to switch to the passing direction so that the antenna 1 can receive the received echo signal. The signal switch 5 is controlled to switch to the terminal direction so that the transmitting signal is not input to the low noise amplifier 9 via the directional coupler 6 and the directional coupler 7. In all the antenna devices, the transmitting signal output from the transmitting signal generator 10 in response to the corrected transmitting trigger signal output from the correction control unit 12 is amplified by the power amplifier 8 and then radiated from the antenna 1. This makes it possible to transmit a transmitting signal with the delay difference of the transmitting system corrected.

[0025] In all antenna devices, when an antenna 1 receives an echo signal, the echo signal is amplified by a low-noise amplifier 9 and then input to a receiving unit 11. A received digital signal of the echo signal that has been subjected to reception processing by the receiving unit 11 in response to a corrected reception trigger signal output from a correction control unit 12 is input to the correction control unit 12. The correction control unit 12 sends a received digital signal that is the echo signal to a signal processing unit. The signal processing unit combines the received digital signals of the echo signals of all the antenna devices. This makes it possible to receive an echo signal in which the delay difference in the receiving system has been corrected.

[0026] Here, the timing correction of the receiving system and the transmitting system will be specifically described with reference to FIG. 2. FIGS. 2(a) to 2(d) are conceptual diagrams showing the temporal changes in amplitude, frequency, phase, and phase difference of two systems of received digital signals of an antenna device. In FIGS. 2(a) to 2(d), the graph of the first system of the two systems is shown by a solid line, and the graph of the second system is shown by a dashed line. As shown in FIG. 2(a), when the amplitude rise characteristics are different between the two systems, as shown in FIG. 2(b), the frequency chirps from the point when the amplitude rises to its full potential, resulting in a difference in the receiving phase between the two systems as shown in FIG. 2(c). When the receiving phase is different, the phase difference between the two systems has a slope with respect to time as shown in FIG. 2(d).

[0027] fi is the chirp start frequency [unit: Hz], α is the frequency chirp slope [unit: Hz / s], τ n is the chirp start time of n systems [unit: s], f n (t) is the receiving frequency of n systems [unit: Hz], θ n If (t) is the receiving phase of n systems [unit: rad], f n (t) is expressed by Equation 1. Here, the chirp start time is the origin of the time when there is no delay in the rise characteristic of the amplitude with respect to time. n (τ n )=0, then θ n (t) is expressed by Equation 2. The phase difference θ 1 (t)-θ 2 (t) is expressed by the formula 3.

[0028]

number

[0029]

number

[0030]

number

[0031] As can be seen from Equation 3, the phase difference between the two systems is a linear function of the time variable t. By adjusting the timing of the transmission trigger signal and the reception trigger signal output from the correction control unit 12, respectively, so that the gradient of the phase difference 2πα(τ2-τ1) becomes 0, it is possible to synchronize the transmission timing and the reception timing between the two systems.

[0032] The correction control unit 12 measures the phases of two points in a stable time period in the calibration signal and the FMCW signal, which is a transmission signal, and calculates the slope of the phase difference between the two systems with respect to time. The correction control unit 12 calculates the delay difference between the reception system and the transmission system between the two systems based on the slope of the phase difference between the two systems with respect to time. The correction control unit 12 corrects the timing of the reception system and the transmission system between the two systems by adjusting the timing of the reception trigger signal output to the reception unit 11 and the transmission trigger signal output to the transmission signal generator 10 based on the calculated delay difference between the reception system and the transmission system between the two systems. As shown in FIG. 2(a), when the amplitude rise characteristics differ between the two systems, it is difficult to accurately measure the timing difference between the two systems from the rise time of the amplitude. The correction control unit 12 does not measure the unstable time period at the rise of the FMCW signal, but calculates an accurate timing difference by measuring the phase of a time period in which the amplitude of the FMCW signal is constant and stable. When the frequencies of the FMCW signals between the two systems are both changing, the correction control unit 12 determines that the time period is a time period in which the amplitude of the FMCW signal is constant and stable. Generally, in order to measure the exact timing difference from the rising edge of the amplitude and the chirp start time of the frequency, high-speed sampling processing with high time resolution is required. However, according to the first embodiment, the correction control unit 12 can calculate the exact timing difference simply by measuring the phase of two points in the FMCW signal during a stable time period and calculating the gradient of the phase difference between the two systems, and therefore does not require high-speed sampling processing.

[0033] The flow of the reception system timing correction process executed by the radar system 100 will be described with reference to FIG. 3. The reception system timing correction process starts, for example, when the radar system 100 is started up or when a timing correction instruction is input to the radar system 100. The antenna devices #1 to #n control the signal switch 2 to switch to the terminal direction (step S11). The signal switch 4 is controlled to switch to the terminal direction (step S12). The signal switch 5 is controlled to switch to the calibration signal direction (step S13). The calibration signal generator 13 outputs a calibration signal in response to a trigger signal output from the correction control unit 12 (step S14). The calibration signal output from the calibration signal generator 13 is distributed to each antenna device by the signal distributor 14, and then input to the signal switch 5 of each antenna device. The electrical length from the signal distributor 14 to each signal switch 5 is the same.

[0034] The calibration signal output from the signal switch 5 is input to the low-noise amplifier 9 via the directional coupler 7 and amplified. In response to a reception trigger signal output from the correction control unit 12 at the same timing to all the antenna devices, the receiving unit 11 performs reception processing on the calibration signal output from the low-noise amplifier 9 (step S15). The receiving unit 11 outputs a received digital signal of the calibration signal to the correction control unit 12.

[0035] Correction control unit 12 receives the received digital signal of the calibration signal from correction control unit 12 of the corresponding other antenna device. Correction control unit 12 calculates the reception phases of two systems, that is, itself and the antenna device that received the received digital signal of the calibration signal, based on the received digital signal of the calibration signal output from receiving unit 11 and the received digital signal of the calibration signal received from the corresponding other antenna device (step S16), and calculates the phase difference between the two systems (step S17).

[0036] The correction control unit 12 calculates the delay difference between the two reception systems based on the gradient of the phase difference between the two systems with respect to time (step S18). The correction control unit 12 adjusts the timing of the reception trigger signal output to the reception unit 11 based on the calculated delay difference between the reception systems between the two systems, thereby correcting the timing of the reception systems between the two systems (step S19). If there is an antenna device whose reception system timing has not been corrected (step S20; NO), the process returns to step S15, and steps S15 to S19 are repeated. In step S15 from the second time onwards, the reception unit 11 of the antenna device whose reception system timing has been corrected performs reception processing on the calibration signal output from the low-noise amplifier 9 in response to the corrected reception trigger signal. If the reception system timing of all the antenna devices has been corrected (step S20; YES), the process ends. By repeatedly executing steps S15 to S19 and correcting the reception system timing between the two systems in order, the reception timing between all the antenna devices can be matched.

[0037] Next, the flow of the transmission system timing correction process executed by the radar system 100 will be described with reference to FIG. 4. The transmission system timing correction process starts when the reception system timing correction process is completed. The antenna devices #1 to #n switch the signal switch 5 to the transmission return direction (step S21). The transmission signal generators 10 of the antenna devices #1 to #n output transmission signals, which are FMCW signals, in response to a transmission trigger signal output from the correction control unit 12 at the same timing for all the antenna devices (step S22). The transmission signal output from the transmission signal generator 10 is amplified by the power amplifier 8, and a part of it is extracted by the directional coupler 6 and input to the signal switch 5.

[0038] The transmission signal input to the signal switch 5 is input to the low-noise amplifier 9 via the directional coupler 7 and amplified. In response to a reception trigger signal output from the correction control unit 12 at a timing when the delay difference in the reception system has been corrected, the receiving unit 11 performs reception processing on the transmission signal output from the low-noise amplifier 9 (step S23). The receiving unit 11 outputs a received digital signal of the transmission signal to the correction control unit 12.

[0039] The correction control unit 12 receives a received digital signal of the transmission signal from the correction control unit 12 of the corresponding other antenna device. Based on the received digital signal of the transmission signal output from the receiving unit 11 and the received digital signal of the transmission signal received from the corresponding other antenna device, the correction control unit 12 calculates the reception phases of two systems, that is, its own system and the antenna device that has received the received digital signal of the transmission signal (step S24), and calculates the phase difference between the two systems (step S25).

[0040] The correction control unit 12 calculates the delay difference between the two transmission systems based on the gradient of the phase difference between the two systems with respect to time (step S26). The correction control unit 12 adjusts the timing of the transmission trigger signal output to the transmission signal generator 10 based on the calculated delay difference between the transmission systems between the two systems, thereby correcting the timing of the transmission systems between the two systems (step S27). If there is an antenna device whose timing of the transmission system has not been corrected (step S28; NO), the process returns to step S22, and steps S22 to S27 are repeated. In step S22 from the second time onwards, the transmission signal generator 10 of the antenna device whose transmission timing has been corrected outputs a transmission signal that is an FMCW signal in response to the corrected transmission trigger signal. If the timing of the transmission systems of all the antenna devices has been corrected (step S28; YES), the process ends. By repeatedly executing steps S22 to S27 and correcting the timing of the transmission systems between the two systems in order, the transmission timing between all the antenna devices can be matched.

[0041] Next, the flow of radar transmission and reception processing executed by the radar system 100 will be described with reference to FIG. 5. When the radar system 100 completes the reception system timing correction processing shown in FIG. 3 and the transmission system timing correction processing shown in FIG. 4, the radar system 100 starts operation as a radar and starts radar transmission and reception processing. The antenna devices #1 to #n control the signal switch 2 to switch to the signal passing direction (step S31). The signal switch 4 is controlled to switch to the passing direction (step S32). The signal switch 5 is controlled to switch to the termination direction (step S33). In all the antenna devices, the transmission signal generator 10 outputs a transmission signal in response to the corrected transmission trigger signal output from the correction control unit 12 (step S34). The output transmission signal is amplified by the power amplifier 8, and then the transmission signal is radiated from the antenna 1 (step S35).

[0042] In all antenna devices, when the antenna 1 receives an echo signal (step S36), the echo signal is input to the low-noise amplifier 9 and amplified. In response to the corrected reception trigger signal output from the correction control unit 12, the receiving unit 11 performs reception processing on the echo signal output from the low-noise amplifier 9 (step S37). The receiving unit 11 inputs the received digital signal of the echo signal to the correction control unit 12. The correction control unit 12 sends the received digital signal of the echo signal to the signal processing unit. The signal processing unit combines the received digital signals of the echo signals of all antenna devices (step S38) and ends the processing.

[0043] In the examples of Figures 3 to 5, the receiving system timing correction process and the transmitting system timing correction process are performed before the radar system 100 starts operating as a radar, but this is not limited to the above, and the receiving system timing correction process and the transmitting system timing correction process may be performed during operation as a radar.

[0044] As described above, according to the first embodiment, by calculating the reception phase of the continuous frequency modulated wave signal and calculating the timing difference based on the gradient of the phase difference between the antenna devices with respect to time, it is possible to accurately correct the timing difference without performing high-speed sampling processing even when there are individual differences in the signal characteristics of each antenna device. Furthermore, according to the first embodiment, even when the radar system 100 is in operation as a radar, there is no need to change the wiring connections, and it is possible to repeatedly correct the timing of the reception system and the transmission system every time there is a fluctuation in the delay difference between each system.

[0045] (Embodiment 2) In the first embodiment, the timing can be adjusted even during operation as a radar by incorporating a calibration signal generator 13 and a signal distributor 14 into the system. In contrast, in the second embodiment, one transmission signal generator 10 of the antenna device is used as a calibration signal generator, so that the calibration signal generator 13 is not required.

[0046] Timing correction of the receiving system of the radar system 200 according to the second embodiment will be described with reference to Fig. 6. Fig. 6 shows wiring when correcting the timing of the receiving system of the radar system 200. In the figure, solid arrows represent analog signals, and dashed arrows represent digital signals. The radar system 200 includes antenna devices #1-#n that transmit a transmission signal (FMCW signal) and receive an echo signal reflected from a target, and a signal distributor 14 that distributes the transmission signal of antenna device #1 used for a calibration signal to antenna devices #2-#n.

[0047] The configuration of antenna devices #2 to #n is the same as that of embodiment 1. The signal switch 5 of antenna device #1, which uses the transmission signal as the calibration signal, is not connected to the signal distributor 14. Furthermore, the transmission signal generator 10 of antenna device #1 outputs the transmission signal as a calibration signal, and the directional coupler 6 extracts a part of the calibration signal amplified by the power amplifier 8 and outputs it to the signal distributor 14. The signal distributor 14 distributes the calibration signal to antenna devices other than antenna device #1. The distributed calibration signal is input to the signal switch 5 of each antenna device. When the receiving unit 11 of the antenna devices other than antenna device #1 receives a reception trigger signal output from the correction control unit 12 at the same timing for all antenna devices, the receiving unit 11 performs reception processing on the calibration signal. The receiving unit 11 outputs a reception digital signal of the calibration signal to the correction control unit 12.

[0048] 6, the transmission signal of antenna device #1 is used as the calibration signal, but the antenna device using the transmission signal as the calibration signal can be switched to another antenna device by changing the connections of directional coupler 6 that inputs the calibration signal to signal distributor 14, the destination of the calibration signal distributed by signal distributor 14, and the destination of the received digital signal of correction control unit 12. Hereinafter, the antenna device using the transmission signal as the calibration signal is referred to as the calibration antenna device.

[0049] The correction control units 12 of the antenna devices #3 to #n send the received digital signal of the calibration signal to the correction control units 12 of the antenna devices #2 to #n-1, respectively. The correction control unit 12 of the antenna device #n-1 adjusts the receiving timing to that of the antenna device #n based on the received digital signal of the calibration signal received from the antenna device #n and the received digital signal of the calibration signal received from its own receiving unit 11. The correction control unit 12 of the antenna device #n-2 adjusts the receiving timing to that of the antenna device #n-1 based on the received digital signal of the calibration signal received from the antenna device #n-1 and the received digital signal of the calibration signal received from its own receiving unit 11. By repeating this process, the correction control unit 12 of the antenna device #2 adjusts the receiving timing to that of the antenna device #3 based on the received digital signal of the calibration signal received from the antenna device #3 and the received digital signal of the calibration signal received from its own receiving unit 11, and the receiving timing of the antenna devices #2 to #n can be adjusted. These processes do not allow the reception timing of antenna device #1, which is the calibration antenna device, to be aligned, so the calibration antenna device is switched to an antenna device other than #1 and the same process is performed on antenna device #1 to align the reception timing of all antenna devices.

[0050] Next, the timing correction of the transmission system will be described with reference to FIG. 7. FIG. 7 shows wiring when the timing of the transmission system of the radar system 200 is corrected. When the timing of the transmission system is corrected, the signal distributor 14 is not connected to each antenna device. The radar system 200 corrects the timing of the transmission system after the timing of the reception system is corrected. When the transmission signal generator 10 of the antenna devices #1 to #n receives a transmission trigger signal output from the correction control unit 12 at the same timing in all the antenna devices, the transmission signal generator 10 outputs a transmission signal that is an FMCW signal. The transmission signal output from the transmission signal generator 10 is amplified by the power amplifier 8, a part of which is extracted by the directional coupler 6, and input to the signal switcher 5. The antenna devices #1 to #n control the signal switcher 5 in the transmission return direction, and input the transmission signal to the low noise amplifier 9 via the directional coupler 7. When the receiving unit 11 receives a reception trigger signal output from the correction control unit 12 at a timing in which the delay difference of the reception system is corrected, the receiving unit 11 performs reception processing on the transmission signal. The receiver 11 outputs a received digital signal of the transmission signal to the correction controller 12 .

[0051] The correction control units 12 of the antenna devices #1 to #n-1 each receive a digital signal of a transmission signal from the correction control units 12 of the antenna devices #2 to #n. Based on the digital signal of a transmission signal input from the receiving unit 11 and the digital signal of a transmission signal that the correction control units 12 of the antenna devices #1 to #n-1 each calculate the reception phase of two systems, that is, the correction control unit 12 itself and the antenna device that has received the digital signal of a transmission signal, and calculates the phase difference between the two systems. The correction control unit 12 calculates the delay difference of the transmission system between the two systems based on the slope of the phase difference between the two systems with respect to time. The correction control unit 12 corrects the timing of the transmission system between the two systems by adjusting the timing of the transmission trigger signal output to the transmission signal generator 10 based on the calculated delay difference of the transmission system between the two systems. By correcting the timing of the transmission system between the two systems from the antenna device #n-1 and antenna device #n to the antenna device #2 and antenna device #1 in sequence, the transmission timing of all the antenna devices can be matched.

[0052] After correcting the timing of the reception system and the transmission system, the radar system 200 starts operating as a radar. The processing of the radar system 200 while operating as a radar is the same as in the first embodiment, and therefore a description thereof will be omitted.

[0053] The flow of the reception system timing correction process executed by the radar system 200 will be described with reference to Fig. 8. The reception system timing correction process starts, for example, when the radar system 200 is started up or when a timing correction instruction is input to the radar system 200. The radar system 200 changes the connection to wiring for reception system timing correction (step S41). In the example of wiring for reception system timing correction shown in Fig. 6, antenna device #1 is the calibration antenna device.

[0054] As shown in FIG. 8, antenna devices #1 to #n control signal switch 2 to switch to the termination direction (step S42). Signal switch 4 is controlled to switch to the termination direction (step S43). Signal switch 5 is controlled to switch to the calibration signal direction (step S44). Transmission signal generator 10 of the calibration antenna device outputs a transmission signal as a calibration signal (step S45). The calibration signal output from transmission signal generator 10 of the calibration antenna device is distributed to each antenna device by signal distributor 14, and then input to signal switch 5 of each antenna device. The electrical length from signal distributor 14 to each signal switch 5 is the same.

[0055] The calibration signal output from the signal switch 5 is input to the low-noise amplifier 9 via the directional coupler 7 and amplified. In response to a reception trigger signal output from the correction control unit 12 at the same timing to all the antenna devices, the receiving unit 11 performs reception processing on the calibration signal output from the low-noise amplifier 9 (step S46). The receiving unit 11 outputs a received digital signal of the calibration signal to the correction control unit 12.

[0056] The correction control unit 12 of an antenna device other than the calibration antenna device receives the received digital signal of the calibration signal from the correction control unit 12 of the corresponding other antenna device. Based on the received digital signal of the calibration signal input from the receiving unit 11 and the received digital signal of the calibration signal received from the corresponding other antenna device, the correction control unit 12 calculates the reception phases of two systems, that is, its own system and the antenna device that received the received digital signal of the calibration signal (step S47), and calculates the phase difference between the two systems (step S48).

[0057] The correction control unit 12 calculates the delay difference between the two receiving systems based on the gradient of the phase difference between the two systems with respect to time (step S49). The correction control unit 12 adjusts the timing of the reception trigger signal output to the receiving unit 11 based on the calculated delay difference between the two receiving systems, thereby correcting the timing of the reception systems between the two systems (step S50). If there is an antenna device other than the calibration antenna device whose reception system timing has not been corrected (step S51; NO), the process returns to step S46, and steps S46 to S50 are repeated. By repeatedly executing steps S46 to S50 and correcting the timing of the reception systems between the two systems in order, it is possible to match the reception timing between all antenna devices other than the calibration antenna device.

[0058] When the timing of the reception systems of all antenna devices other than the calibration antenna device has been corrected (step S51; YES), the radar system 200 switches the calibration antenna device to another antenna device (step S52). The transmission signal generator 10 of the calibration antenna device outputs a transmission signal as a calibration signal (step S53). The calibration signal output from the transmission signal generator 10 of the calibration antenna device is distributed to each antenna device by the signal distributor 14, and then input to the signal switch 5 of each antenna device.

[0059] The calibration signal output from the signal switch 5 is input to the low-noise amplifier 9 via the directional coupler 7 and amplified. In response to the reception trigger signal output from the correction control unit 12, the receiving unit 11 of the original calibration antenna device performs reception processing on the calibration signal output from the low-noise amplifier 9 (step S54). The receiving unit 11 outputs a received digital signal of the calibration signal to the correction control unit 12.

[0060] The correction control unit 12 of the original calibration antenna device receives the received digital signal of the calibration signal from the correction control unit 12 of the corresponding other antenna device. The correction control unit 12 of the original calibration antenna device calculates the reception phases of two systems, that is, its own system and the antenna device that received the received digital signal of the calibration signal, based on the received digital signal of the calibration signal output from the receiving unit 11 and the received digital signal of the calibration signal received from the correction control unit 12 of the corresponding other antenna device (step S55), and calculates the phase difference between the two systems (step S56).

[0061] The correction control unit 12 calculates the delay difference between the two receiving systems based on the gradient of the phase difference between the two systems with respect to time (step S57). The correction control unit 12 corrects the timing of the receiving systems between the two systems by adjusting the timing of the receiving trigger signal to be output to the receiving unit 11 based on the calculated delay difference between the receiving systems between the two systems (step S58), and ends the process.

[0062] Next, the flow of the transmission system timing correction process executed by the radar system 200 will be described with reference to Fig. 9. The transmission system timing correction process starts when the reception system timing correction process is completed. The radar system 200 changes the connection to the wiring for the transmission timing correction (step S61). An example of the wiring for the transmission system timing correction is shown in Fig. 7.

[0063] The antenna devices #1 to #n switch the signal switch 5 to the transmission return direction (step S62). The transmission signal generators 10 of the antenna devices #1 to #n output a transmission signal, which is an FMCW signal, in response to a transmission trigger signal output from the correction control unit 12 at the same timing for all the antenna devices (step S63). The transmission signal output from the transmission signal generator 10 is amplified by the power amplifier 8, and a part of it is extracted by the directional coupler 6 and input to the signal switch 5.

[0064] The transmission signal input to the signal switch 5 is input to the low-noise amplifier 9 via the directional coupler 7 and amplified. In response to a reception trigger signal output from the correction control unit 12 at a timing when the delay difference in the reception system has been corrected, the receiving unit 11 performs reception processing on the transmission signal output from the low-noise amplifier 9 (step S64). The receiving unit 11 outputs a received digital signal of the transmission signal to the correction control unit 12.

[0065] The correction control unit 12 receives a received digital signal of the transmission signal from the correction control unit 12 of the corresponding other antenna device. Based on the received digital signal of the transmission signal input from the receiving unit 11 and the received digital signal of the transmission signal received from the corresponding other antenna device, the correction control unit 12 calculates the reception phases of two systems, that is, itself and the antenna device that received the received digital signal of the transmission signal (step S65), and calculates the phase difference between the two systems (step S66).

[0066] The correction control unit 12 calculates the delay difference between the two transmission systems based on the gradient of the phase difference between the two systems with respect to time (step S67). The correction control unit 12 adjusts the timing of the transmission trigger signal output to the transmission signal generator 10 based on the calculated delay difference between the transmission systems between the two systems, thereby correcting the timing of the transmission systems between the two systems (step S68). If there is an antenna device whose timing of the transmission system has not been corrected (step S69; NO), the process returns to step S64, and steps S64 to S68 are repeated. In step S64 from the second time onwards, the transmission signal generator 10 of the antenna device whose transmission timing has been corrected outputs a transmission signal that is an FMCW signal in response to the corrected transmission trigger signal. If the timing of the transmission systems of all the antenna devices has been corrected (step S69; YES), the process ends. By repeatedly executing steps S64 to S68 and correcting the timing of the transmission systems between the two systems in order, the transmission timing between all the antenna devices can be matched.

[0067] As described above, according to the second embodiment, by calculating the reception phase of the continuous frequency modulated wave signal and calculating the timing difference based on the gradient of the phase difference between the antenna devices with respect to time, it is possible to accurately correct the timing difference without performing high-speed sampling processing even when there are individual differences in the signal characteristics of each antenna device. Also, according to the second embodiment, the calibration signal generator 13 is not required.

[0068] (Embodiment 3) In the second embodiment, a transmission signal of one system of the antenna devices is used as a calibration signal, the calibration antenna device is switched by changing the connection, and the same process is performed on the original calibration antenna device, thereby synchronizing the reception timing and transmission timing of all the antenna devices. In contrast, in the third embodiment, the calibration antenna device can be switched without changing the connection.

[0069] Fig. 10 shows a configuration example of a radar system 300 according to the third embodiment. In the figure, a solid arrow indicates an analog signal, and a dashed arrow indicates a digital signal. The radar system 300 includes antenna devices #1 to #n that transmit an FMCW signal as a transmission signal and receive an echo signal of the transmission signal reflected from a target, and a signal distributor 14 that distributes the transmission signal of the calibration antenna device to the other antenna devices. In the example of Fig. 10, either the antenna device #1 or the antenna device #n can be the calibration antenna device.

[0070] In addition to the configuration of the second embodiment, antenna device #1 and antenna device #n include a signal switch 15 between directional coupler 6 and signal switch 5 for switching between the calibration signal direction and the transmission return direction. During reception system timing correction, transmission signal generator 10 of the calibration antenna device outputs the transmission signal as a calibration signal, and directional coupler 6 extracts a portion of the calibration signal amplified by power amplifier 8 and outputs it to signal switch 15. The calibration antenna device controls signal switch 15 to switch to the calibration signal direction and inputs the calibration signal to signal distributor 14. Signal distributor 14 distributes the calibration signal to antenna devices other than the calibration antenna device. The distributed calibration signal is input to signal switch 5 of each antenna device.

[0071] In the example of Fig. 10, antenna device #1 is used as the calibration antenna device. The calibration antenna device can be switched to antenna device #n by controlling the signal switch 15 of antenna device #1 to switch to the transmission return direction and controlling the signal switch 15 of antenna device #n to switch to the calibration signal direction.

[0072] When correcting the timing of the transmission system, the calibration antenna device controls signal switch 15 to switch to the transmission return direction. In antenna devices #1 and #n, directional coupler 6 extracts a part of the transmission signal amplified by power amplifier 8 and outputs it to signal switch 15, and the transmission signal that has passed through signal switch 15 and signal switch 5 is input to low-noise amplifier 9 via directional coupler 7. The other configurations are the same as those in the second embodiment.

[0073] The flow of the reception system timing correction process executed by the radar system 300 will be described with reference to FIG. 11. The reception system timing correction process starts, for example, when the radar system 300 is started or when a timing correction instruction is input to the radar system 300. The antenna devices #1 to #n control the signal switch 2 to switch to the terminal direction (step S71). The signal switch 4 is controlled to switch to the terminal direction (step S72). The signal switch 5 is controlled to switch to the calibration signal direction (step S73). The signal switch 15 of the calibration antenna device is controlled to switch to the calibration signal direction (step S74). The transmission signal generator 10 of the calibration antenna device outputs a transmission signal as a calibration signal (step S75). The calibration signal output from the transmission signal generator 10 of the calibration antenna device is distributed to each antenna device by the signal distributor 14, and then input to the signal switch 5 of each antenna device. The electrical length from the signal distributor 14 to each signal switch 5 is the same.

[0074] The calibration signal output from the signal switch 5 is input to the low-noise amplifier 9 via the directional coupler 7 and amplified. In response to a reception trigger signal output from the correction control unit 12 at the same timing to all the antenna devices, the receiving unit 11 performs reception processing on the calibration signal output from the low-noise amplifier 9 (step S76). The receiving unit 11 outputs a received digital signal of the calibration signal to the correction control unit 12.

[0075] The correction control unit 12 of an antenna device other than the calibration antenna device receives the received digital signal of the calibration signal from the correction control unit 12 of the corresponding other antenna device. Based on the received digital signal of the calibration signal output from the receiving unit 11 and the received digital signal of the calibration signal received from the corresponding other antenna device, the correction control unit 12 calculates the reception phase of two systems, that is, its own system and the antenna device that received the received digital signal of the calibration signal (step S77), and calculates the phase difference between the two systems (step S78).

[0076] The correction control unit 12 calculates the delay difference between the two receiving systems based on the gradient of the phase difference between the two systems with respect to time (step S79). The correction control unit 12 adjusts the timing of the receiving trigger signal output to the receiving unit 11 based on the calculated delay difference between the receiving systems between the two systems, thereby correcting the timing of the receiving systems between the two systems (step S80). If there is an antenna device other than the calibration antenna device whose timing of the receiving system has not been corrected (step S81; NO), the process returns to step S76, and steps S76 to S80 are repeated. By repeatedly executing steps S76 to S80 and correcting the timing of the receiving systems between the two systems in order, it is possible to match the receiving timing between all antenna devices other than the calibration antenna device.

[0077] When the timing of the reception systems of all antenna devices other than the calibration antenna device has been corrected (step S81; YES), the radar system 300 controls the signal switch 15 of the other antenna devices to switch to the calibration signal direction, and controls the signal switch 15 of the original calibration antenna device to switch to the transmission return direction, thereby switching the calibration antenna device (step S82). The transmission signal generator 10 of the calibration antenna device outputs the transmission signal as a calibration signal (step S83). The calibration signal output from the transmission signal generator 10 of the calibration antenna device is distributed to each antenna device by the signal distributor 14, and then input to the signal switch 5 of each antenna device.

[0078] The calibration signal output from the signal switch 5 is input to the low-noise amplifier 9 via the directional coupler 7 and amplified. In response to the reception trigger signal output from the correction control unit 12, the receiving unit 11 of the original calibration antenna device performs reception processing on the calibration signal output from the low-noise amplifier 9 (step S84). The receiving unit 11 outputs a received digital signal of the calibration signal to the correction control unit 12.

[0079] The correction control unit 12 of the original calibration antenna device receives the received digital signal of the calibration signal from the correction control unit 12 of the corresponding other antenna device. The correction control unit 12 of the original calibration antenna device calculates the reception phases of two systems, that is, its own system and the antenna device that received the received digital signal of the calibration signal, based on the received digital signal of the calibration signal output from the receiving unit 11 and the received digital signal of the calibration signal received from the correction control unit 12 of the corresponding other antenna device (step S85), and calculates the phase difference between the two systems (step S86).

[0080] The correction control unit 12 calculates the delay difference between the two receiving systems based on the gradient of the phase difference between the two systems with respect to time (step S87). The correction control unit 12 corrects the timing of the receiving systems between the two systems by adjusting the timing of the reception trigger signal to be output to the receiving unit 11 based on the calculated delay difference between the receiving systems between the two systems (step S88), and ends the process.

[0081] Next, the flow of the transmission system timing correction process executed by the radar system 300 will be described with reference to Fig. 12. The transmission system timing correction process starts when the reception system timing correction process is completed. The radar system 300 controls the signal switch 15 of the calibration antenna device to switch to the transmission return direction (step S91).

[0082] The antenna devices #1 to #n switch the signal switch 5 to the transmission return direction (step S92). The transmission signal generators 10 of the antenna devices #1 to #n output a transmission signal, which is an FMCW signal, in response to a transmission trigger signal output from the correction control unit 12 at the same timing for all the antenna devices (step S93). The transmission signal output from the transmission signal generator 10 is amplified by the power amplifier 8, and a part of it is extracted by the directional coupler 6 and input to the signal switch 5.

[0083] The transmission signal input to the signal switch 5 is input to the low-noise amplifier 9 via the directional coupler 7 and amplified. In response to a reception trigger signal output from the correction control unit 12 at a timing when the delay difference in the reception system is corrected, the receiving unit 11 performs reception processing on the transmission signal output from the low-noise amplifier 9 (step S94). The receiving unit 11 outputs a received digital signal of the transmission signal to the correction control unit 12.

[0084] The correction control unit 12 receives a received digital signal of the transmission signal from the correction control unit 12 of the corresponding other antenna device. Based on the received digital signal of the transmission signal output from the receiving unit 11 and the received digital signal of the transmission signal received from the corresponding other antenna device, the correction control unit 12 calculates the reception phases of two systems, that is, itself and the antenna device that has received the received digital signal of the calibration signal (step S95), and calculates the phase difference between the two systems (step S96).

[0085] The correction control unit 12 calculates the delay difference between the two systems based on the gradient of the phase difference between the two systems with respect to time (step S97). The correction control unit 12 adjusts the timing of the transmission trigger signal output to the transmission signal generator 10 based on the calculated delay difference between the two systems, thereby correcting the timing of the transmission systems between the two systems (step S98). If there is an antenna device whose timing of the transmission system has not been corrected (step S99; NO), the process returns to step S94, and steps S94 to S98 are repeated. In step S94 from the second time onwards, the transmission signal generator 10 of the antenna device whose transmission timing has been corrected outputs a transmission signal that is an FMCW signal in response to the corrected transmission trigger signal. If the timing of the transmission systems of all the antenna devices has been corrected (step S99; YES), the process ends. By repeatedly executing steps S94 to S98 and correcting the timing of the transmission systems between the two systems in order, the transmission timing between all the antenna devices can be matched.

[0086] As described above, according to the third embodiment, by calculating the reception phase of the continuous frequency modulated wave signal and calculating the timing difference based on the gradient of the phase difference with respect to time between the antenna devices, it is possible to accurately correct the timing difference without performing high-speed sampling processing even when there are individual differences in the signal characteristics of each antenna device. Furthermore, according to the third embodiment, the calibration signal generator 13 is not necessary, and the calibration antenna device can be switched without changing the connection.

[0087] In the above embodiment, an example has been shown in which the present disclosure is applied to a multiple-input multiple-output (MIMO) radar, but the present disclosure is not limited to this, and may also be applied to a single-input multi-output (SIMO) radar.

[0088] In the above embodiment, an example has been described in which the antenna devices #1 to #n control the signal switcher 5 to switch between the transmission signal and the calibration signal and input the signal to the low-noise amplifier 9, but the present disclosure is not limited to this. For example, the transmission signal and the calibration signal may be input to the low-noise amplifier 9 via a directional coupler, and the antenna devices #1 to #n may control the timing at which they output the transmission signal and the calibration signal.

[0089] In the above embodiment, an example has been shown in which each of the antenna devices #1 to #n includes a correction control unit 12, but the present disclosure is not limited to this. For example, only one correction control unit 12 may be included. In that case, the single integrated correction control unit 12 receives signals from each receiving unit 11 and outputs signals to each receiving unit 11 and each transmission signal generator 10.

[0090] In the above embodiment, an example has been shown in which the calibration signal is distributed and transmitted by signal distributor 14, but the present disclosure is not limited to this. For example, the calibration signal may be transmitted directly to antenna devices #1 to #n from calibration signal generator 13 having multiple output channels using cables of the same electrical length.

[0091] In the above embodiment, the correction control unit 12 measures the phases of two points in a stable time period in the calibration signal and the FMCW signal, which is the transmission signal, and calculates the gradient of the phase difference between the two antenna devices with respect to time, but the present disclosure is not limited to this. For example, the phase of the FMCW signal may be measured after it is determined that the calibration signal and the FMCW signal, which is the transmission signal, are in a steady state. The steady state may be determined when a predetermined time has elapsed since the calibration signal generator 13 and the transmission signal generator 10 are started, or the phase of the FMCW signal may be measured multiple times, and the steady state may be determined when the measured phase difference of the FMCW signal is equal to or less than a predetermined threshold.

[0092] In the above embodiment, an example has been described in which the correction control unit 12 corrects the timing of outputting the reception trigger signal and the timing of outputting the transmission trigger signal, but the present disclosure is not limited to this. For example, only the timing of outputting the reception trigger signal may be corrected.

[0093] Although the preferred embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims.

[0094] Various aspects of the present disclosure are summarized below as appendices.

[0095] (Appendix 1) A radar system comprising: a plurality of antenna devices that transmit a transmission signal and receive an echo signal reflected from a target; and a calibration signal generator that outputs a calibration signal to the plurality of antenna devices, Each of the plurality of antenna devices includes: a transmission signal generator that outputs a transmission signal, which is a continuous frequency modulated wave signal, in response to a transmission trigger signal; a receiving section that, in response to a receiving trigger signal, performs receiving processing on the transmission signal or the calibration signal to generate a received digital signal; a correction control unit that corrects the timings of outputting the transmission trigger signal and the reception trigger signal before outputting them; Equipped with The correction control unit is calculating a phase of the received digital signal generated by executing the reception processing on the calibration signal, and correcting a timing for outputting the reception trigger signal based on a slope of a phase difference of the received digital signal between the antenna devices with respect to time; calculating a phase of the received digital signal generated by executing the reception processing on the transmission signal, and correcting a timing for outputting the transmission trigger signal based on a gradient with respect to time of a phase difference of the received digital signal between the plurality of antenna devices; Radar system. (Appendix 2) a signal switcher for switching the transmission signal or the calibration signal input to the receiving unit, 2. The radar system of claim 1. (Appendix 3) The correction control unit receives information regarding the phase of the received digital signal from a correction control unit other than itself. 3. A radar system as claimed in claim 1 or 2. (Appendix 4) The correction control unit is calculating a delay difference with respect to time of the received digital signals between the plurality of antenna devices based on a gradient with respect to time of the phase difference of the received digital signals between the plurality of antenna devices, and correcting output timings of the reception trigger signal and the transmission trigger signal based on the calculated delay difference; 4. The radar system of claim 3. (Appendix 5) The correction control unit is repeating a process of correcting output timings of the reception trigger signal and the transmission trigger signal based on a gradient with respect to time of a phase difference of the reception digital signal between two antenna devices sequentially selected from the plurality of antenna devices, thereby matching reception timings and transmission timings in all of the plurality of antenna devices; 5. A radar system as claimed in claim 3 or 4. (Appendix 6) a power amplifier for amplifying the transmission signal; a transmitting side directional coupler that extracts a part of the transmission signal amplified by the power amplifier; a receiving-side directional coupler for combining the calibration signal or the amplified transmission signal with the echo signal; a low noise amplifier for amplifying a signal output from the receiving side directional coupler; Further comprising: 6. A radar system as claimed in any one of claims 1 to 5. (Appendix 7) using the transmission signal generator in one of the plurality of antenna devices as a calibration signal generator; 7. A radar system as claimed in any one of claims 1 to 6. (Appendix 8) a signal distributor that distributes the calibration signal output from the calibration signal generator to the plurality of antenna devices; 8. A radar system as claimed in any one of claims 1 to 7. (Appendix 9) The electrical lengths from the signal distributor to the plurality of antenna devices are all the same. 9. The radar system of claim 8. (Appendix 10) The correction control unit is measuring a phase of the received digital signal when it is determined that the received digital signal is in a steady state; 10. A radar system as claimed in any one of claims 1 to 9. (Appendix 11) 1. A radar system comprising: a plurality of antenna devices for receiving echo signals reflected from a target; and a calibration signal generator for outputting a calibration signal to the plurality of antenna devices, Each of the plurality of antenna devices includes: a receiving section that, in response to a receiving trigger signal, performs a receiving process on the calibration signal to generate a receiving digital signal; a correction control unit that corrects the timing of outputting the reception trigger signal before outputting it; Equipped with The correction control unit is calculating a phase of the received digital signal generated by executing the reception processing on the calibration signal, and correcting a timing for outputting the reception trigger signal based on a gradient with respect to time of a phase difference of the received digital signal between the plurality of antenna devices; Radar system. (Appendix 12) 1. A timing adjustment method performed by a radar system having a plurality of antenna devices that receive echo signals reflected from a target, and a calibration signal generator that outputs a calibration signal to the plurality of antenna devices, comprising: The radar system includes: calculating a phase of a received digital signal generated by performing a reception process on the calibration signal, and correcting a timing of receiving the echo signal based on a gradient with respect to time of a phase difference of the received digital signal between the plurality of antenna devices; How to adjust the timing. [Explanation of symbols]

[0096] 1 Antenna, 2, 4, 5, 15 Signal switch, 3 Circulator, 6, 7 Directional coupler, 8 Power amplifier, 9 Low noise amplifier, 10 Transmission signal generator, 11 Receiver, 12 Correction control section, 13 Calibration signal generator, 14 Signal distributor, 100, 200, 300 Radar system.

Claims

1. A radar system comprising a plurality of antenna devices that transmit a transmission signal and receive echo signals reflected from a target, and a calibration signal generator that outputs a calibration signal to the plurality of antenna devices, Each of the aforementioned multiple antenna devices is, A transmit signal generator that outputs a transmit signal, which is a frequency-continuous modulated wave signal, in response to a transmit trigger signal, A receiving unit that, in response to a received trigger signal, performs reception processing on the transmitted signal or the calibration signal to generate a received digital signal, A correction control unit that corrects the output timing of the transmit trigger signal and the receive trigger signal before outputting them, Equipped with, The correction control unit, The phase of the received digital signal generated by performing the reception process on the calibration signal is calculated, and the output timing of the received trigger signal is corrected based on the slope of the phase difference of the received digital signals with respect to time among the plurality of antenna devices. The phase of the received digital signal generated by performing the reception process on the transmitted signal is calculated, and the output timing of the transmitted trigger signal is corrected based on the slope of the phase difference of the received digital signal with respect to time among the plurality of antenna devices. Radar system.

2. The receiving unit further includes a signal switcher for switching between the transmission signal or the calibration signal input to the receiving unit. The radar system according to claim 1.

3. The correction control unit receives information regarding the phase of the received digital signal from another correction control unit. The radar system according to claim 1 or 2.

4. The correction control unit, Based on the slope of the phase difference of the received digital signal between the plurality of antenna devices with respect to time, the delay difference of the received digital signal between the plurality of antenna devices with respect to time is calculated, and the output timing of the received trigger signal and the transmitted trigger signal are corrected based on the calculated delay difference. The radar system according to claim 3.

5. The correction control unit, By repeatedly correcting the output timing of the receive trigger signal and the transmit trigger signal based on the slope of the phase difference of the received digital signal with respect to time between two antenna devices selected sequentially from the plurality of antenna devices, the receive timing and transmit timing are synchronized for all of the plurality of antenna devices. The radar system according to claim 3.

6. A power amplifier that amplifies the aforementioned transmission signal, A transmitter-side directional coupler that extracts a portion of the transmitted signal amplified by the power amplifier, A receiver-side directional coupler that couples the calibration signal or the amplified transmission signal with the echo signal, A low-noise amplifier that amplifies the signal output from the receiving directional coupler, Furthermore, The radar system according to claim 1 or 2.

7. The transmitting signal generator in any one of the aforementioned multiple antenna devices is used as a calibration signal generator. The radar system according to claim 1 or 2.

8. The system further includes a signal distributor that distributes the calibration signal output from the calibration signal generator to the plurality of antenna devices. The radar system according to claim 1 or 2.

9. The electrical lengths from the signal distributor to the multiple antenna devices are all the same. The radar system according to claim 8.

10. The correction control unit, When it is determined that the received digital signal is in a steady state, the phase of the received digital signal is measured. The radar system according to claim 1 or 2.

11. A radar system comprising a plurality of antenna devices that receive echo signals reflected from a target, and a calibration signal generator that outputs calibration signals to the plurality of antenna devices, Each of the aforementioned multiple antenna devices is, A receiving unit that, in response to a received trigger signal, performs reception processing on the calibration signal to generate a received digital signal, A correction control unit that corrects the output timing of the received trigger signal before outputting it, Equipped with, The correction control unit, The phase of the received digital signal generated by performing the reception process on the calibration signal is calculated, and the output timing of the received trigger signal is corrected based on the slope of the phase difference of the received digital signals with respect to time among the plurality of antenna devices. Radar system.

12. A timing adjustment method performed by a radar system having a plurality of antenna devices that receive echo signals reflected from a target, and a calibration signal generator that outputs calibration signals to the plurality of antenna devices, The aforementioned radar system, The phase of the received digital signal generated by performing a reception process on the calibration signal is calculated, and the reception timing of the echo signal is corrected based on the slope of the phase difference of the received digital signals with respect to time among the multiple antenna devices. Timing adjustment method.

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