JP2021148744A - Radar device and control method of radar device - Google Patents

Abstract

To improve reception sensitivity of a radar device by suppressing interference of a CW signal.SOLUTION: A radar device 10 includes: a transmission part 12 for transmitting a transmission signal obtained by pulse-modulating a carrier from a transmission antenna 14; a reception part 16 for down-converting a reception signal received by a reception antenna 17 by a carrier; a reception filter 20 for removing components lower than a predetermined frequency from the down-converted reception signal and outputting the signal; and a synchronization transmission mode for synchronizing a frequency fC of a carrier to a frequency fI of an interference signal such that a frequency difference becomes smaller than a predetermined frequency and for generating a transmission signal on the basis of a frequency difference fΔ between an interference signal and a carrier calculated based on a reception signal outputted from the reception filter 20.SELECTED DRAWING: Figure 3

Description

The present invention relates to a radar device and a method for controlling the radar device.

Conventionally, as a countermeasure against radar signal interference in a radar device (hereinafter, also referred to as "pulse radar") that outputs a radar signal by a pulse method, as disclosed in Patent Documents 1 and 2, for example, a pulse as a transmission signal. A staggered method is known in which the signal transmission cycle is not constant.

Specifically, the radar device of Patent Document 1 is provided with a circuit capable of arbitrarily selecting the repetition order of the stagger trigger and an interference elimination circuit, thereby eliminating interference even for interference signals having the same stagger ratio and the same average repetition frequency. It is possible to do. The radar device of Patent Document 2 can suppress the generation of a virtual image by selecting a transmission timing that does not overlap with other radar devices mounted on the own vehicle from a plurality of transmission timing information. ing.

Japanese Unexamined Patent Publication No. 60-100775 JP-A-2018-119934

By the way, in a frequency band such as the ISM (Industry Science and Medical) band in which a band is not allocated exclusively for radar, a signal of an arbitrary frequency or modulation method may exist as an interference wave. For example, a Doppler sensor used as a motion sensor for detecting a moving object installed in an outdoor vending machine or an automatic door uses a CW (Continuous Wave) signal in the 24 GHz band. Therefore, the signal output from the Doppler sensor becomes an interference signal with respect to the radar signal of the pulse radar using the 24 GHz band installed in a moving body such as an automobile.

On the other hand, the stagger method as an interference countermeasure technique disclosed in Patent Documents 1 and 2 described above is a technique assuming a radar signal of the same type (pulse) as an interference signal. That is, the above-mentioned anti-interference technique is a technique for preventing interference of radar signals of other pulse radars with respect to radar signals of pulse radar.

In general, the stagger method is a technique for taking the correlation between pulses, outputting only the correlated signal as a target signal, and removing the uncorrelated signal as an interference signal. Therefore, the above-mentioned Doppler sensor outputs the signal. The effect of sufficiently removing the CW signal may not be obtained.

For example, when the difference between the carrier frequency of an in-vehicle pulse radar and the carrier frequency of a Doppler sensor installed in a vending machine or the like is small (for example, about 1 MHz), the transmission cycle of the radar signal output from the pulse radar is staggered. Even if it is changed by the method, the phase of the received signal received by the pulse radar cannot be randomized, so that the interference of the CW signal of the Doppler sensor cannot be suppressed, and the reception sensitivity of the pulse radar, that is, the object. There is a risk that the measurement accuracy of the speed and the distance to the object will decrease.

The present invention is for solving the above-mentioned problems, and an object of the present invention is to suppress interference of CW signals and improve the reception sensitivity of a radar device.

The radar device according to a typical embodiment of the present invention includes an oscillating unit that generates a carrier which is a CW signal, a transmitting unit that transmits a pulse signal obtained by pulse-modulating the carrier as a transmitting signal, and a receiving antenna. Receives the reflected signal of the transmission signal as a reception signal and down-converts the reception signal using the carrier, and removes components lower than a predetermined frequency from the reception signal down-converted by the reception unit. The frequency difference between the interference signal that interferes with the reflected signal and the carrier is calculated based on the reception filter output by A transmission mode for transmitting a signal is determined, and the oscillation unit and a data processing control unit that controls the transmission unit are provided based on the determined transmission mode. In the transmission mode, the frequency difference is the predetermined value. It is characterized by including a tuned transmission mode in which the frequency of the carrier is tuned to the frequency of the interference signal to generate the transmission signal so as to be smaller than the frequency of.

According to one aspect of the present invention, it is possible to suppress the interference of the CW signal and improve the reception sensitivity of the radar device.

It is a figure which shows the implementation example of the radar system which concerns on embodiment of this invention. It is a figure which shows the structural example of the radar system which concerns on embodiment of this invention. It is a figure which shows the structural example of the radar apparatus which concerns on embodiment of this invention. It is a figure which shows the functional block composition of the data processing control part in the radar apparatus which concerns on Embodiment 1. FIG. It is a figure which shows an example of the determination method of presence / absence of a CW interference signal by the radar apparatus which concerns on Embodiment 1. FIG. It is a figure which shows an example of the determination method of presence / absence of a CW interference signal by the radar apparatus which concerns on Embodiment 1. FIG. It is a figure for demonstrating the frequency difference fΔ. It is a figure for demonstrating the frequency difference fΔ. It is a figure which shows the frequency spectrum of the received signal at the time of transmitting a signal in a tuned transmission mode. It is a figure which shows the frequency spectrum of the received signal at the time of transmitting a signal in a staggered transmission mode. It is a flow chart which shows the flow of processing by the radar apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the functional block composition of the data processing control part in the radar apparatus which concerns on Embodiment 2. FIG. It is a figure for demonstrating the setting method of the interference prevention transmission mode which concerns on Embodiment 2. FIG. It is a figure which shows an example of the frequency determination information 360A in the radar apparatus which concerns on Embodiment 2. FIG. It is a flow chart which shows the flow of the process by the radar apparatus 10 which concerns on Embodiment 2. FIG. It is a flow chart which shows the flow of the process by the radar apparatus 10 which concerns on Embodiment 2. FIG. It is a figure which shows the functional block composition of the data processing control part in the radar apparatus which concerns on Embodiment 3. FIG. It is a figure for demonstrating the setting method of the interference prevention transmission mode which concerns on Embodiment 3. It is a figure which shows an example of the frequency determination information 360B in the radar apparatus which concerns on Embodiment 3. FIG. It is a flow chart which shows the flow of processing by the radar apparatus which concerns on Embodiment 3. FIG. It is a flow chart which shows the flow of processing by the radar apparatus which concerns on Embodiment 3. FIG. It is a flow chart which shows the flow of processing by the radar apparatus which concerns on Embodiment 3. FIG. It is a flow chart which shows the flow of processing by the radar apparatus which concerns on Embodiment 3. FIG.

1. 1. Outline of Embodiment First, an outline of a typical embodiment of the invention disclosed in the present application will be described. In the following description, as an example, reference numerals on drawings corresponding to the components of the invention are described in parentheses.

[1] The radar device (10, 10-1, 10-2) according to a typical embodiment of the present invention has an oscillating unit (11) that generates a carrier which is a CW signal and pulse-modulated the carrier. A transmission unit (12) that transmits a pulse signal as a transmission signal from a transmission antenna and a reception antenna (17) receive a reflection signal of the transmission signal as a reception signal, and down-convert the reception signal using the carrier. Based on the unit (16), the reception filter (20) that removes components lower than a predetermined frequency from the reception signal down-converted by the reception unit and outputs the signal, and the reception signal output from the reception filter. , The frequency difference (fΔ) between the interference signal that interferes with the reflected signal and the carrier is calculated, and the transmission mode for transmitting the transmission signal is determined based on the frequency difference, and the determined transmission mode is set. The oscillation unit and the data processing control unit (15) for controlling the transmission unit are provided based on the above, and the transmission mode sets the frequency (fC) of the carrier so that the frequency difference becomes smaller than the predetermined frequency. It is characterized by including a tuned transmission mode in which the transmission signal is generated by tuning to the frequency (fI) of the interference signal.

[2] In the radar device (10) according to the above [1], and the transmission mode includes a stagger transmission mode that generates the transmission signal so that the repetition period of the pulse signal is unequal. The data processing control unit may switch between the tuning transmission mode and the stagger transmission mode based on the frequency difference.

[3] In the radar device (10) according to the above [2], the data processing control unit (15) sets the transmission mode to the synchronized transmission mode when the frequency difference is smaller than the first threshold value (A). When the frequency difference is larger than the first threshold value, the transmission mode may be set to the stagger transmission mode.

[4] In the radar device (10A, 10B) according to the above [1] or [2], when the data processing control unit (15A, 15B) tunes the frequency of the carrier wave to the frequency of the interference signal. When the occupied bandwidth (OBW) of the transmission signal does not exceed a predetermined frequency range, the transmission mode may be set to the tuning transmission mode.

[5] In the radar device (10A, 10B) according to the above [4], the data processing control unit (15A, 15B) has the transmission mode when the frequency difference is larger than a predetermined threshold value (A). May be set to the staggered transmission mode.

[6] In the radar device (10A, 10B) according to the above [4] or [5], when the data processing control unit (15A, 15B) tunes the frequency of the carrier wave to the frequency of the interference signal. When the occupied bandwidth (OBW) of the transmission signal exceeds the predetermined frequency range, the frequency of the carrier wave is controlled so that the frequency difference becomes large, and the transmission mode is set to the stagger transmission mode. You may.

[7] In the radar device (10B) according to any one of the above [4] to [6], the data processing control unit (15B) tunes the frequency of the carrier to the frequency of the interference signal. When the occupied bandwidth (OBW) of the transmitted signal exceeds the predetermined frequency range (fR), the pulse width of the transmitted signal is increased and the occupied bandwidth of the transmitted signal after the pulse width is increased. The transmission mode may be determined based on the relationship between the bandwidth (OBWx) and the predetermined frequency range (fR).

[8] In the radar device (10, 10A, 10B) according to any one of the above [1] to [7], the data processing control unit (15B) is the reception signal output from the reception filter. A frequency analysis may be performed on the data, the presence or absence of the interference signal may be determined based on the analysis result, and the frequency difference may be calculated when it is determined that the interference signal exists.

[9] In the radar device (10, 10A, 10B) according to the above [8], the data processing control unit (15B) has a signal strength of a second threshold value (Mth) based on the analysis result by the frequency analysis. When the frequency component exceeding the above is present, it may be determined that the interference signal is present.

[10] In the radar device (10, 10A, 10B) according to the above [9], the second threshold value may be determined based on the signal intensity at each frequency component of the reflected signal.

[11] In the radar device (10, 10A, 10B) according to any one of the above [2] to [10], in the transmission mode, the carrier wave having a constant frequency is subjected to a predetermined pulse period and pulse width. The data processing control unit (15, 15A, 15B) further includes a normal transmission mode for generating the transmission signal by performing pulse modulation in the above, when the transmission mode is the tuning transmission mode or the stagger transmission mode. In addition, when the measurement environment of the radar device satisfies the predetermined conditions (Tth, Lth), the transmission mode may be switched to the normal transmission mode.

[12] In the control method of the radar device according to the typical embodiment of the present invention, an oscillating unit that generates a carrier wave which is a CW signal and a pulse signal obtained by pulse-modulating the carrier wave are transmitted from a transmission antenna as a transmission signal. A predetermined reception unit receives the reflected signal of the transmission signal as a reception signal by the transmission unit and the reception antenna, and down-converts the reception signal using the carrier wave, and the reception signal down-converted by the reception unit. A control method of a radar device having a reception filter that removes components lower than the frequency and outputs the signal, and a data processing control unit that controls the oscillation unit and the transmission unit based on the reception signal output from the reception filter. Is. This control method is based on the first step (S7) of causing the data processing control unit to calculate the frequency difference between the interference signal interfering with the reflected signal and the carrier, and the data processing control unit based on the frequency difference. The second step (S7 to S8) for determining the transmission mode for transmitting the transmission signal, and the first step for causing the data processing control unit to control the oscillation unit and the transmission unit based on the determined transmission mode. Including three steps (S8, S9), the transmission mode tunes the frequency of the carrier to the frequency of the interference signal so that the frequency difference becomes smaller than the predetermined frequency to generate the transmission signal. It is characterized by including a transmission mode.

2. Specific Examples of Embodiments Hereinafter, specific examples of embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals will be given to the components common to each embodiment, and the repeated description will be omitted. In addition, it should be noted that the drawings are schematic, and the dimensional relationship of each element, the ratio of each element, and the like may differ from the reality. Even between drawings, there may be parts where the relationship and ratio of dimensions are different from each other.

<< Embodiment 1 >>
FIG. 1 is a diagram showing an implementation example of a radar system according to an embodiment of the present invention.

The radar system 1 according to the present embodiment is, for example, a radar system for a vehicle. As shown in FIG. 1, the radar devices 10-1 and 10-2 constituting the radar system 1 are, for example, pulse radars, which are arranged on the left and right sides of the rear portion of the vehicle C, respectively. The radar devices 10-1 and 10-2 have a detection area behind the vehicle C, and detect that a target as a detection target (for example, another vehicle, a bicycle, a person, etc.) exists in the detection area. The ECU 50 is notified. The ECU 50 controls an alarm device (not shown) and issues an alarm when, for example, a target may come into contact with or collide with the own vehicle.

FIG. 2 is a diagram showing a configuration example of a radar system according to an embodiment of the present invention.

As shown in FIG. 2, the radar system 1 includes an ECU (Electronic Control Unit) 30 as a host device and radar devices 10-1 and 10-2. The ECU 50 and the radar devices 10-1 and 10-2 are connected by communication lines 41 and 42 so that they can communicate with each other.

Although the ECU 50 is taken as an example of the higher-level device in FIG. 2, the device has a function of recognizing its own ID (Identification) in the network and controlling other devices via the communication lines 41 and 42. If so, a device other than the ECU may be used.

The ECU 50 controls each part of the vehicle, detects a target based on the information supplied from the radar devices 10-1 and 10-2 via the communication lines 41 and 42, and issues a warning or the like as necessary. ..

The radar devices 10-1 and 10-2 irradiate the target to be detected with a pulse signal, detect the target based on the reflected signal, and transmit the target to the ECU 50 via the communication lines 41 and 42. Further, the radar devices 10-1 and 10-2 are connected by communication lines 41 and 42, one of which operates as a master and the other of which operates as a slave.

FIG. 3 is a diagram showing a configuration example of a radar device according to an embodiment of the present invention. Since the radar devices 10-1 and 10-2 have the same configuration, the radar devices 10-1 and 10-2 will be referred to as "radar device 10" below.

As shown in FIG. 3, the radar device 10 includes an oscillation unit 11, a transmission unit 12, a data processing control unit 15, a reception unit 16, a reception filter 20, and an A / D (Analog to Digital) conversion unit (ADC) 21. It is provided as a main component.

The oscillating unit 11 generates a CW (Continuous Wave) signal having a predetermined frequency and supplies it to the transmitting unit 12 and the receiving unit 16. The oscillator 11 is, for example, a local oscillator.

The transmission unit 12 has a modulation unit 13 and a transmission antenna 14. The transmission unit 12 pulse-modulates the CW signal supplied from the oscillation unit 11 as a carrier wave signal by the modulation unit 13 and transmits it to the target via the transmission antenna 14.

The modulation unit 13 is controlled by the data processing control unit 15. The modulation unit 13 pulse-modulates the CW signal supplied from the oscillation unit 11 based on the pulse signal supplied from the data processing control unit 15, generates a transmission signal (pulse signal), and supplies the transmission signal (pulse signal) to the transmission antenna 14. .. The transmitting antenna 14 transmits the pulse signal supplied from the modulation unit 13 toward the outside (target).

The receiving unit 16 has a receiving antenna 17, an amplifying unit 18, and a demodulating unit 19. The receiving unit 16 receives the signal transmitted from the transmitting antenna 14 and reflected by the target, performs demodulation processing, and then outputs the signal to the A / D conversion unit 21.

The receiving antenna 17 is transmitted from the transmitting antenna 14, receives the reflected signal from the target, and supplies the reflected signal to the amplification unit 18. The amplification unit 18 is, for example, a low noise amplifier (LNA). The amplification unit 18 amplifies the signal (received signal) received by the transmission antenna 14 with a predetermined gain and outputs it to the demodulation unit 19. The gain of the amplification unit 18 may be variably controlled by the data processing control unit 15.

The demodulation unit 19 demodulates the received signal supplied from the amplification unit 18 using the CW signal supplied from the oscillation unit 11 and outputs it. In other words, the demodulation unit 19 down-converts the reception signal amplified by the amplification unit 18 based on the CW signal supplied from the oscillation unit 11 and supplies it to the reception filter 20.

The receiving unit 16 may have a plurality of antennas (for example, four antennas) as the receiving antenna 17. In this case, the receiving unit 16 selects any one of the plurality of antennas constituting the receiving antenna 17, and supplies the signal received by the selected antenna to the amplification unit 18.

The reception filter 20 is a filter circuit that removes components lower than a predetermined frequency from the reception signal supplied from the reception unit 16. The reception filter 20 is, for example, a high-pass filter (HPF). The reception filter 20 removes a frequency component below the cutoff frequency (for example, 1 MHz or less) from the reception signal supplied from the reception unit 16 and supplies the frequency component to the A / D conversion unit 21. As the reception filter 20, a known one having a filter function for removing components lower than a predetermined frequency from the reception signal supplied from the reception unit 16 can be used. For example, a bandpass filter (BPF) is used. can do.

The A / D conversion unit 21 is a circuit that samples the reception signal supplied from the reception filter 20 at a predetermined cycle and converts it into a digital signal. The A / D conversion unit 21 converts the received signal down-converted by the demodulation unit 19 and from which the low frequency component has been removed by the reception filter 20 into a digital signal and supplies it to the data processing control unit 15. Further, the A / D conversion unit 21 determines whether or not the input signal exceeds the input voltage range of the A / D conversion unit 21, and the input signal is in the input voltage range of the A / D conversion unit 21. If it exceeds, an overrange signal indicating that the input signal is saturated is output.

The data processing control unit 15 comprehensively controls each component (circuit) constituting the radar device 10. The data processing control unit 15 includes, for example, a program processing device such as an MCU (Micro Control Unit), an FPGA (Field Programmable Gate Array), and a DSP (Digital Signal Processor).

The data processing control unit 15 controls the oscillation unit 11 and the modulation unit 13 to pulse-modulate a carrier signal (CW signal) having a specified frequency based on a specified pulse period and pulse width, and transmit antenna 14 Send from.

Further, the data processing control unit 15 controls the receiving unit 16 and the A / D conversion unit 21 to input the received signal received and demodulated by the receiving unit 16 via the A / D conversion unit 21 and input the received signal. By executing arithmetic processing on the received data, the target is detected and notified to the ECU 50 which is a higher-level device.

Further, the data processing control unit 15 determines the presence or absence of an external CW signal (hereinafter, also referred to as “CW interference signal”) that interferes with the reflected signal of the transmission signal (pulse signal) output from the transmission unit 12. When the CW interference signal is present, the transmission signal is output from the transmission unit 12 after performing processing for preventing the reception sensitivity of the radar device 10 from deteriorating.

Specifically, the data processing control unit 15 calculates the frequency difference between the CW signal as the carrier wave generated by the oscillation unit 11 and the CW interference signal based on the reception signal output from the reception filter (HPF) 20. At the same time, the transmission mode for transmitting the pulse signal from the transmission unit 12 is determined based on the calculated frequency difference, and the oscillation unit 11 and the transmission unit 12 are controlled based on the determined transmission mode.

Here, the radar device 10 according to the first embodiment has a normal transmission mode and an interference prevention transmission mode as transmission modes.

The normal transmission mode is a mode in which a pulse signal as a transmission signal is generated by performing pulse modulation on a carrier wave having a predetermined frequency set in advance with a predetermined pulse period and pulse width set in advance.

The interference prevention transmission mode is a mode for preventing interference by an external CW signal with respect to a reflected signal from a target. In the present embodiment, the interference prevention transmission mode includes a tuning transmission mode and a stagger transmission mode.

In the tuned transmission mode, the frequency difference between the CW signal as a carrier wave generated by the oscillating unit 11 and the CW interference signal is equal to or less than the cutoff frequency of the reception filter 20 (for example, the frequency difference becomes zero). In this mode, the frequency fC of the carrier wave (CW signal) is tuned to the frequency fI of the CW interference signal to generate a pulse signal as a transmission signal.

The staggered transmission mode is a mode in which a transmission signal is generated by adjusting the transmission timing so that the repetition period of the pulse signal is unequal.

The data processing control unit 15 generates and transmits a pulse signal in the normal transmission mode when the CW interference signal does not exist, and generates a pulse signal in the synchronized transmission mode or the stagger transmission mode when the CW interference signal exists. And send. The data processing control unit 15 switches between the tuning transmission mode and the stagger transmission mode based on the frequency difference.

The data processing control unit 15 has the following functional blocks in order to realize each of the above-mentioned functions.

FIG. 4 is a diagram showing a functional block configuration of the data processing control unit 15 in the radar device 10 according to the first embodiment.

As shown in FIG. 4, the data processing control unit 15 has a signal analysis unit 30, a measurement unit 31, a communication unit 32, an interference determination unit 33, and a frequency difference calculation unit 34 as functional blocks for realizing each of the above-mentioned functions. , A frequency determination unit 35, a storage unit 36, an interference prevention control unit 37, a pulse control unit 38, and a frequency control unit 39.

In the interference prevention control unit 37, the pulse control unit 38, and the frequency control unit 39, for example, the CPU (Central Processing Unit) is a program stored in a storage device such as a ROM (Read Only Memory) and a RAM (Random Access Memory). It is realized by executing various arithmetic processes according to the above.

The signal analysis unit 30, the measurement unit 31, the interference determination unit 33, the frequency difference calculation unit 34, and the frequency determination unit 35 are realized by, for example, program processing by a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), or the like. NS. The communication unit 32 is realized by, for example, an input / output interface circuit mounted on an MCU such as a UART (Universal Asynchronous Receiver Transmitter) or a CAN (Control Area Network).

The signal analysis unit 30 analyzes the received signal (digital signal) supplied from the A / D conversion unit 21. The signal analysis unit 30 analyzes the phase of the received signal based on, for example, the I component and the Q component included in the received signal, and also performs a Fourier transform process to analyze the frequency component of the received signal.

The measuring unit 31 detects the target and measures the speed of the target and the distance to the target based on the analysis result of the signal analysis unit 30. The communication unit 32 exchanges data with the ECU 50 as a higher-level device and another radar device 10 via the communication lines 41 and 42. For example, the communication unit 32 transmits information on the distance to the target and the speed of the target measured by the measurement unit 31 to the ECU 50.

The interference determination unit 33 determines the presence or absence of a CW interference signal based on the frequency analysis result by the signal analysis unit 30.

5A and 5B are diagrams showing an example of a method for determining the presence or absence of a CW interference signal by the radar device 10 according to the first embodiment.

In FIGS. 5A and 5B, the horizontal axis represents frequency and the vertical axis represents signal strength. Reference numeral 400 represents the characteristics of the reflected signal with respect to the transmission signal included in the received signal input from the A / D conversion unit 21 to the data processing control unit 15, and reference numeral 500 represents data processing from the A / D conversion unit 21. It shows the characteristics of the CW interference signal included in the received signal input to the control unit 15.

As shown in FIG. 5A, the interference determination unit 33 determines that a CW interference signal is present when a frequency component whose signal strength exceeds the threshold Mth is present, based on the frequency analysis result by the signal analysis unit 30. The frequency fI of the CW interference signal is detected, and when there is no frequency component whose signal strength exceeds the threshold Mth, it is determined that the CW interference signal does not exist.

The threshold value Mth is a reference value for determining the presence or absence of the CW interference signal. The threshold value Mth may be a fixed value as shown by reference numeral 600, or may be a value (variable value) determined based on the signal intensity in each frequency component of the reflected signal as shown by reference numeral 601. You may.

By setting the threshold value Mth as a fluctuation value based on the signal intensity of each frequency component of the reflected signal, it is possible to reliably detect even a CW interference signal having a small signal intensity, and the detection accuracy of the CW interference signal is improved. It becomes possible.

Further, as shown in FIG. 5B, the presence or absence of the CW interference signal may be determined during the period when the received signal (reflected signal) is not input. According to this, the value of the threshold value Mt can be set to a lower value, and even a CW interference signal having a small signal strength can be reliably detected.

Here, the threshold value Mth, a calculation formula for calculating the threshold value Mth from the signal strength in each frequency component of the reflected signal, and the like are stored in advance in the storage unit 36 as, for example, interference determination information 361.

The frequency difference calculation unit 34 is a difference between the frequency fI of the CW interference signal detected by the interference determination unit 33 and the frequency fC of the carrier wave (CW signal) output from the oscillation unit 11 (hereinafter, also referred to as “frequency difference fΔ””. .) Is calculated.

6A and 6B are diagrams for explaining the frequency difference fΔ.
In FIGS. 6A and 6B, the horizontal axis represents frequency and the vertical axis represents signal strength. Reference numeral 400 represents the characteristics of the reflected signal with respect to the transmission signal included in the received signal input from the A / D conversion unit 21 to the data processing control unit 15, and reference numeral 500 represents data processing from the A / D conversion unit 21. It shows the characteristics of the CW interference signal included in the received signal input to the control unit 15.

FIG. 6A shows a case where the frequency difference fΔ is smaller than the threshold value A described later, and FIG. 6B shows a case where the frequency difference fΔ is larger than the threshold value A.

The received signal input from the A / D conversion unit 21 to the data processing control unit 15 is a signal after being down-converted by the demodulation unit 19. Therefore, as shown in FIGS. 6A and 6B, the frequency component corresponding to the frequency fC of the CW signal as the carrier wave output from the oscillator 11 is 0 Hz, so that the frequency component corresponding to the frequency fI of the CW interference signal is The frequency difference fΔ is obtained as it is.

The frequency determination unit 35 determines the transmission mode based on the determination result by the interference determination unit 33 and the frequency difference fΔ calculated by the frequency difference calculation unit 34. Specifically, when the interference determination unit 33 determines that the CW interference signal exists, the frequency determination unit 35 compares the frequency difference fΔ calculated by the frequency difference calculation unit 34 with the predetermined threshold value A.

The threshold value A is a value that serves as a reference for switching the transmission mode for preventing interference. In other words, the threshold value A corresponds to the frequency difference that can be expected to improve the reception sensitivity by the staggering process. The threshold value A is stored in the storage unit 36 as, for example, frequency determination information 360.

When the frequency difference fΔ is smaller than the predetermined threshold value A as shown in FIG. 6A, the frequency difference calculation unit 34 sets the transmission mode to the synchronized transmission mode. On the other hand, when the frequency difference fΔ is larger than the predetermined threshold value A as shown in FIG. 6B, the frequency difference calculation unit 34 sets the transmission mode to the stagger transmission mode.

Further, when the frequency determination unit 35 detects a change in the measurement environment of the radar device 10 when the transmission mode is the interference prevention transmission mode (tuned transmission mode or stagger transmission mode), the frequency determination unit 35 sets the transmission mode to the normal transmission mode. Switch.

For example, the frequency determination unit 35 switches the transmission mode from the interference prevention transmission mode to the normal transmission mode by using a parameter for detecting a change in the measurement environment of the radar device 10. As the parameters for detecting the change in the measurement environment, a reference value Tth regarding the duration of the interference prevention transmission mode, a reference value Lth regarding the moving distance of the vehicle equipped with the radar device 10, and the like can be exemplified. The reference value Tth and the reference value Lth are stored in the storage unit 36 as, for example, frequency determination information 360.

For example, the frequency determination unit 35 starts timing at the timing when the transmission mode is switched to the synchronized transmission mode or the staggered transmission mode, and when the duration of the synchronized transmission mode or the staggered transmission mode reaches the reference value Tth, the transmission mode To switch to normal transmission mode. Further, the frequency determination unit 35 starts measuring the moving distance of the vehicle (radar device 10) at the timing when the transmission mode is switched to the synchronized transmission mode or the staggered transmission mode, and when the moving distance reaches the reference value Lth, the frequency determination unit 35 starts measuring the moving distance. Switch the transmission mode to the normal transmission mode.

According to this, since the transmission mode can be returned to the normal transmission mode according to the change in the measurement environment of the radar device 10, it is possible to prevent the interference prevention transmission mode from continuing in the measurement environment where interference by the CW interference signal does not occur. can do.

The frequency determination unit 35 may use both the reference value Tth and the reference value Lth in order to detect a change in the measurement environment of the radar device 10, or may use only one of them.

The storage unit 36 stores various parameters necessary for data processing related to generation of a transmission signal by the data processing control unit 15, analysis of a reception signal, switching of a transmission mode, and the like. The storage unit 36 stores, for example, frequency determination information 360 including the above-mentioned threshold value A, reference values Tth, Lth, and the like, and interference determination information 361 including the threshold value Mth and the like.

The interference prevention control unit 37 controls the pulse control unit 38 and the frequency control unit 39 based on the transmission mode determined by the frequency determination unit 35 to generate a desired pulse signal and transmit it as a transmission signal.

Specifically, the interference prevention control unit 37 instructs the frequency control unit 39 to generate a CW signal (carrier wave) having a predetermined frequency fC when the normal transmission mode is selected by the frequency determination unit 35. At the same time, the pulse control unit 38 is instructed to generate a pulse signal having a predetermined pulse period and pulse width.

Further, the interference prevention control unit 37 sets the frequency difference fΔ to be equal to or lower than the cutoff frequency of the reception filter 20 (for example, to be zero) when the tuning transmission mode is selected by the frequency determination unit 35. (2) The frequency fC of the carrier wave is tuned to the frequency fI of the CW interference signal. Specifically, the interference prevention control unit 37 instructs the frequency control unit 39 to generate a carrier wave having a frequency fCX that matches the frequency fI of the CW interference signal.

Further, the interference prevention control unit 37 adjusts the transmission timing of the pulse signal as the transmission signal by the stagger method when the stagger transmission mode is selected by the frequency determination unit 35. Specifically, the interference prevention control unit 37 instructs the pulse control unit 38 so that the repetition period of the pulse signal as the transmission signal is unequal.

The pulse control unit 38 supplies a pulse signal having a pulse period and a pulse width specified by the interference prevention control unit 37 to the modulation unit 13 at a transmission timing specified by the interference prevention control unit 37. The frequency control unit 39 controls the oscillation unit 11 so as to generate a CW signal (carrier wave) having a frequency specified by the interference prevention control unit 37.

FIG. 7A is a diagram showing a frequency spectrum of a received signal when a signal is transmitted in the synchronized transmission mode.

In the figure, the horizontal axis represents frequency and the vertical axis represents signal strength. Reference numeral 400 represents the characteristics of the reflected signal with respect to the transmission signal included in the received signal input from the A / D conversion unit 21 to the data processing control unit 15, and reference numeral 500 represents data processing from the A / D conversion unit 21. It shows the characteristics of the CW interference signal included in the received signal input to the control unit 15.

As described above, in the tuned transmission mode, the frequency fC of the carrier wave is adjusted to tune to the frequency fI of the CW interference signal. Therefore, the frequency spectra of the reflected signal and the CW interference signal included in the received signal are as shown in FIG. 7A.

That is, as shown in FIG. 7A, the frequency component after down-conversion of the CW interference signal included in the received signal moves to around 0 Hz, which is the frequency component after down-conversion of the frequency fCx of the carrier wave tuned to the CW interference signal. ..

As described above, in the radar device 10, a high-pass filter (HPF) as a reception filter 20 is provided between the demodulation unit 19 of the reception unit 16 and the data processing control unit 15, and therefore after down-conversion. The low frequency component of the received signal is removed by the receiving filter 20.

Therefore, as shown in FIG. 7A, when the receiving filter 20 removes the frequency component of the frequency range indicated by the reference numeral 410, the frequency component of the CW interference signal included in the frequency range 410 is removed by the receiving filter 20. Of the received signals, only frequency components larger than the frequency range 410 are input to the signal analysis unit 30 of the data processing control unit 15.

In this way, when the frequency difference fΔ is small, that is, when the CW interference signal and the carrier wave are close to each other, the radar is set by setting the tuning transmission mode and tuning the frequency of the carrier wave to the CW interference signal. The influence of the external CW interference signal on the radar measurement of the device 10 can be suppressed.

FIG. 7B is a diagram showing a frequency spectrum of a received signal when a signal is transmitted in the staggered transmission mode.

In the figure, the horizontal axis represents frequency and the vertical axis represents signal strength. Reference numeral 400 represents the characteristics of the reflected signal with respect to the transmission signal included in the received signal input from the A / D conversion unit 21 to the data processing control unit 15, and reference numeral 500 represents data processing from the A / D conversion unit 21. It shows the characteristics of the CW interference signal included in the received signal input to the control unit 15.

As described above, in the staggered transmission mode, the transmission timing of the transmission signal is adjusted so that the repetition period of the pulse signal is unequal, and the frequency spectra of the reflected signal and the CW interference signal included in the reception signal are shown in FIG. 7B. Will be shown in.

That is, when the frequency difference fΔ is large, the phase of the received signal is randomized by transmitting the transmission signal by the stagger method, and the frequency component of the down-converted CW interference signal is dispersed as shown in FIG. 7B. This makes it possible to reduce the signal strength of the CW interference signal with respect to the signal strength of the reflected signal.

In this way, when the frequency difference fΔ is large, that is, when the CW interference signal and the frequency of the carrier wave are far apart, the transmission timing of the transmission signal is adjusted by the staggering process, so that the radar measurement by the radar device 10 is performed. Interference of an external CW signal can be suppressed.

Next, the processing flow of the radar device 10 according to the first embodiment will be described.

FIG. 8 is a flow chart showing a flow of processing by the radar device 10 according to the first embodiment.

The radar device 10 according to the present embodiment executes the process shown in FIG. 8 every time the engine of the vehicle is started. For example, when the ignition key is turned on to start the engine, the supply of power to the ECU 50 and the radar devices 10-1 and 10-2 shown in FIG. 2 is started, and the radar devices 10-1, 10- 2 starts.

As shown in FIG. 8, after the radar device 10 is started, the normal transmission mode is set as the transmission mode (step S1). In the normal transmission mode, the interference prevention control unit 37 instructs the frequency control unit 39 to generate a carrier wave (CW signal) having a predetermined frequency fC, and also generates a pulse signal having a predetermined pulse period and pulse width. Instruct the pulse control unit 38. As a result, in the radar measurement process (step S2) described later, a transmission signal obtained by pulse-modulating a CW signal having a frequency fC with a predetermined pulse period and pulse width is output from the transmission antenna 14.

Next, the radar device 10 performs radar measurement processing (step S2).
Specifically, first, the transmitting antenna 14 transmits a transmission signal obtained by pulse-modulating a CW signal having a frequency of fC with a predetermined pulse period and pulse width. Then, the receiving antenna 17 receives the reflected signal by the target of the transmission signal. At this time, if the CW interference signal is present in the surrounding environment of the radar device 10, the receiving antenna 17 receives the CW interference signal as well as the reflected signal. The received signal received by the receiving antenna 17 is down-converted by the demodulation unit 19, and then the low frequency component is removed by the reception filter 20 and supplied to the A / D conversion unit 21. The A / D conversion unit 21 converts the supplied received signal into a digital signal and inputs it to the data processing control unit 15, and the data processing control unit 15 is subjected to the digital signal by the A / D conversion unit 21 by the method described above. Perform signal analysis on the received signal converted to. Specifically, the signal analysis unit 30 executes frequency analysis on the received signal as described above, and the measurement unit 31 reaches the target speed and the target based on the analysis result of the signal analysis unit 30. The communication unit 32 measures the distance of the above, and the communication unit 32 transmits the measurement result by the measurement unit 31 to the ECU 50.

Next, the data processing control unit 15 determines whether or not the input received signal is saturated, that is, whether or not the received signal has a signal level that exceeds the input voltage range of the A / D conversion unit 21 (. Step S3).

When the received signal has a signal level exceeding the input voltage range of the A / D conversion unit 21 (step S3: Yes), an overrange signal is output from the A / D conversion unit 21, and the data processing control unit 15 receives the data processing control unit 15. The communication unit 32 outputs a signal indicating that the signal detection performance of the radar device 10 is deteriorated to the ECU 50 or the like (step S5). After that, the data processing control unit 15 returns to step S2.

On the other hand, when the received signal does not have a signal level exceeding the input voltage range of the A / D conversion unit 21 (step S3: No), the data processing control unit 15 is converted into a digital signal by the A / D conversion unit 21. The frequency component of the received signal is analyzed (step S4). Specifically, the signal analysis unit 30 executes frequency analysis on the received signal as described above to extract the frequency component included in the received signal.

Next, the data processing control unit 15 determines whether or not a CW interference signal is present (step S6). Specifically, the interference determination unit 33 determines whether or not the received signal includes a CW interference signal based on the analysis result of the signal analysis unit 30 by the method described above.

If the received signal does not include the CW interference signal, the data processing control unit 15 returns to step S2 and repeatedly executes radar measurement processing, signal analysis, determination of the CW interference signal, and the like in the normal transmission mode. (Steps S2 to S6).

On the other hand, when the received signal includes a CW interference signal, the data processing control unit 15 performs determination processing based on the frequency difference fΔ (step S7). Specifically, as described above, the frequency difference calculation unit 34 differs between the frequency fI of the CW interference signal detected by the interference determination unit 33 and the frequency fC of the CW signal as a carrier wave output from the oscillation unit 11. (Frequency difference fΔ) is calculated, and the frequency determination unit 35 compares the frequency difference fΔ with the threshold value A.

In step S7, when the frequency difference fΔ is smaller than the threshold value A, the data processing control unit 15 sets the transmission mode to the synchronized transmission mode, changes the frequency fC of the carrier wave as described above, and transmits the transmission signal. (Step S8).

On the other hand, in the flow diagram of FIG. 8, when the frequency difference fΔ is equal to or greater than the threshold value A, the data processing control unit 15 sets the transmission mode to the stagger transmission mode and transmits the transmission signal by the stagger method as described above. (Step S9).

After changing the transmission mode from the normal transmission mode to the interference prevention transmission mode in steps S8 and S9, the radar device 10 performs radar measurement processing and detects a target in the same manner as in step S2 (step S10).

Next, the data processing control unit 15 determines whether or not to end the interference prevention transmission mode (step S11). Specifically, the frequency determination unit 35 determines whether or not there is a change in the measurement environment of the radar device 10. More specifically, as described above, the frequency determination unit 35 determines whether or not the duration of the tuning transmission mode or the stagger transmission mode has reached the reference value Tth, or the moving distance of the vehicle has reached the reference value Lth. Judge whether or not.

When the change in the measurement environment of the radar device 10 is not detected (step S11: No), the data processing control unit 15 performs radar measurement processing without changing the current transmission mode to detect the target. (Step S10).

On the other hand, when a change in the measurement environment of the radar device 10 is detected (step S11: Yes), the data processing control unit 15 shifts to step S1 and changes the current transmission mode from the synchronized transmission mode or the stagger transmission mode. The mode is changed to the normal transmission mode, and the above-mentioned series of processes is repeated.

As described above, as described above, the radar device 10 according to the first embodiment sets the tuning transmission mode and the stagger transmission mode based on the frequency difference fΔ between the interference signal and the carrier wave that interfere with the reflected signal of the transmitted pulse signal. Switch.

Specifically, as described above, when the frequency difference between the CW interference signal and the carrier wave of the radar device 10 is small, the tuning transmission mode is set and the frequency of the carrier wave is controlled to match the CW interference signal.

As described above, according to the radar device 10 according to the present embodiment, when the CW interference signal output from the Doppler sensor or the like installed outside the radar device 10 and the frequency difference of the carrier wave are close to each other. The CW interference signal component included in the received signal can be removed by the reception filter 20.

Further, as described above, when the frequency difference between the CW interference signal and the carrier wave of the radar device 10 is large, the transmission timing of the transmission signal is adjusted by the stagger processing.

As described above, according to the radar device 10 according to the present embodiment, when the CW interference signal and the frequency difference of the carrier wave are significantly separated from each other, the phase of the received signal is randomized by stagger processing to randomize the phase of the received signal and the reflected signal. The signal strength of the CW interference signal can be reduced.

As described above, according to the radar device 10 according to the present embodiment, it is possible to suppress the interference of the CW signal and improve the reception sensitivity regardless of the frequency of the CW interference signal.

In the first embodiment described above, a configuration is shown in which the tuning transmission mode and the stagger transmission mode are switched based on the frequency difference fΔ between the interference signal and the carrier that interfere with the reflected signal of the transmitted pulse signal. Instead of switching to the transmission mode, it may be determined whether or not to switch from the normal transmission mode to the synchronized transmission mode based on the frequency difference fΔ between the interference signal and the carrier that interferes with the reflected signal of the transmitted pulse signal. .. In such a case, for example, instead of setting the transmission mode to the stagger transmission mode in step S9, the frequency determination unit 35 sends a signal from the communication unit 32 to the ECU 50 indicating that the detection performance of the radar device 10 is deteriorated. You may send it to.

<< Embodiment 2 >>
FIG. 9 is a diagram showing a functional block configuration of the data processing control unit 15A in the radar device 10A according to the second embodiment.

The radar device 10A according to the second embodiment is a radar device according to the first embodiment in that the transmission mode is switched in consideration of not only the frequency difference fΔ but also the frequency range of the transmission signal that can be irradiated by the radar device. Different from 10.

First, an outline of the method of setting the interference prevention transmission mode according to the second embodiment will be described.

FIG. 10 is a diagram for explaining a method of setting the interference prevention transmission mode according to the second embodiment.

In the figure, the horizontal axis represents frequency and the vertical axis represents signal strength. Reference numeral 450 represents the characteristics of the reflected signal with respect to the transmission signal included in the received signal before down-conversion, and reference numeral 550 represents the characteristics of the CW interference signal included in the received signal before down-conversion.

As shown in FIG. 10, the transmission signal generated by pulse-modulating a carrier wave having a frequency fc has an occupied bandwidth (Occupied Band Width: OBW) proportional to the modulation speed (pulse period and pulse width), and is a transmission signal. The reflected signal to the target has a similar occupied bandwidth.

On the other hand, the frequency range that the radar device can irradiate is from the viewpoint of reducing adverse effects on wireless devices that use other frequency bands, and the performance of each electronic device (for example, amplification unit 18 or ADC 21) of the radar device 10. From the viewpoint of the above, it is preferable to configure the transmission signal (received signal) so as not to exceed a predetermined frequency range. For example, as shown in FIG. 10, when the lower limit frequency that can be irradiated by the radar device is fL and the upper limit frequency is fH, the occupied bandwidth OBW of the transmission signal is within the frequency range fR from the lower limit frequency fL to the upper limit frequency fH. The transmission signal (received signal) of the radar device 10 can be prevented from exceeding the lower limit frequency fL or the upper limit frequency fH.

Therefore, the radar device 10A according to the second embodiment selects an appropriate interference prevention transmission mode so that the occupied bandwidth OBW of the transmission signal does not exceed a predetermined frequency range.

Specifically, the data processing control unit 15A in the radar device 10A sets the transmission mode to the stagger transmission mode when the frequency difference fΔ is equal to or greater than the threshold value A, as in the data processing control unit 15 according to the first embodiment. do. In this case, as described in the first embodiment, the phase of the received signal is randomized by the staggering process, so that the signal strength of the CW interference signal with respect to the reflected signal can be reduced.

Further, in the data processing control unit 15A, when the occupied bandwidth OBW of the transmission signal when the frequency fc of the carrier wave is matched with the frequency fI of the interference signal does not exceed the predetermined frequency range fR (range from fL to fH). The transmission mode is set to the synchronized transmission mode, and when the occupied bandwidth OBW of the transmission signal exceeds the predetermined frequency range fR, the frequency fc of the carrier wave is adjusted so that the frequency difference Δf becomes large, and the transmission is transmitted. Set the mode to stagger transmission mode.

For example, as shown in FIG. 10, when fC <fI, when the carrier wave is shifted in the direction in which the frequency fC increases in order to match the frequency fC of the carrier wave with the frequency fI of the CW interference signal, the frequency The occupied bandwidth OBW of the transmission signal centered on fC also shifts in the direction of increasing frequency. At this time, if the maximum frequency in the occupied bandwidth OBW of the transmission signal does not exceed the upper limit frequency fH, the transmission mode can be set to the synchronized transmission mode.

On the other hand, in FIG. 10, when the carrier wave is shifted in the direction in which the frequency fC increases in order to match the frequency fC of the carrier wave with the frequency fI of the CW interference signal, the maximum frequency in the occupied bandwidth OBW of the transmission signal becomes. When the upper limit frequency fH is exceeded, the transmission mode is not set to the synchronized transmission mode. In this case, the data processing control unit 15A shifts the frequency fC of the carrier wave in the direction in which the frequency difference fΔ becomes larger, and then sets the transmission mode to the stagger transmission mode.

For example, in FIG. 10, the frequency difference fΔ is further widened by shifting the carrier wave in the direction in which the frequency fC becomes smaller. According to this, since the phase of the received signal can be randomized by the staggering process, it is possible to reduce the signal strength of the CW interference signal with respect to the reflected signal.

Next, the specific processing contents by the frequency determination unit 35A in the data processing control unit 15A will be described.

The frequency determination unit 35A is based on the determination result by the interference determination unit 33, the frequency difference fΔ calculated by the frequency difference calculation unit 34, the occupied bandwidth OBW of the transmission signal, and the upper limit frequency fH and the lower limit frequency fL of the transmission signal. To determine the transmission mode.

First, the frequency determination unit 35A calculates the lower adjustment width fLBW and the upper adjustment width fHBW based on the occupied bandwidth OBW of the transmission signal and the upper limit frequency fH and the lower limit frequency fL of the transmission signal.

As shown in FIG. 10, the lower adjustment width fLBW is the maximum adjustment width on the lower limit side where the frequency can be shifted in the irradiable frequency range fR of the transmission signal, and is represented by the following equation (1).

As shown in FIG. 10, the upper adjustment width fHBW is the maximum adjustment width on the upper limit side where the frequency can be shifted in the irradiable frequency range fR of the transmission signal, and is represented by the following equation (2).

Here, the values of the lower limit frequency fL, the upper limit frequency fH, and the occupied bandwidth OBW are stored in advance in the storage unit 36A as frequency determination information 360A, for example. The frequency determination unit 35A uses the values of the lower limit frequency fL, the upper limit frequency fH, and the occupied bandwidth OBW read from the storage unit 36A to obtain the lower adjustment width fLBW and the upper adjustment width from the above equations (1) and (2). Calculate fHBW respectively.

The frequency determination unit 35A determines whether or not the CW interference signal of the carrier frequency fc can be tuned to the frequency fI so that the occupied bandwidth OBW of the transmission signal does not exceed the predetermined frequency range fR.

Specifically, the frequency determination unit 35A compares the lower adjustment width fLBW or the upper adjustment width fHBW with the frequency difference fΔ calculated by the frequency difference calculation unit 34 (first frequency determination process). For example, when fC> fI and fΔ is equal to or less than the lower adjustment width fLBW, it can be determined that the occupied bandwidth OBW of the transmission signal does not exceed the predetermined frequency range fR even if frequency tuning is performed. , The frequency determination unit 35A sets the transmission mode to the synchronized transmission mode. Here, the frequency fCx of the carrier wave after tuning in the case of fC> fI is determined by the following equation (3).

Similarly, when fC <fI and fΔ is equal to or less than the upper adjustment width fHBW, the frequency determination unit 35A sets the transmission mode to the synchronized transmission mode. The frequency fCx of the carrier wave after tuning in the case of fC <fI is determined by the following equation (4).

また、周波数判定部３５Ａは、スタガ処理によって干渉抑制効果が期待できるか否かを判定する。具体的には、周波数判定部３５Ａは、周波数差算出部３４によって算出された周波数差ｆΔと閾値Ａとを比較する（第２周波数判定処理）。周波数判定部３５Ａは、周波数差ｆΔが閾値Ａ以上である場合には、送信モードをスタガ送信モードに設定する。

Further, the frequency determination unit 35A determines whether or not the interference suppression effect can be expected by the stagger processing. Specifically, the frequency determination unit 35A compares the frequency difference fΔ calculated by the frequency difference calculation unit 34 with the threshold value A (second frequency determination process). When the frequency difference fΔ is equal to or greater than the threshold value A, the frequency determination unit 35A sets the transmission mode to the stagger transmission mode.

Further, the frequency determination unit 35A determines whether or not the frequency difference fΔ can be expanded to the threshold value A or more so that the occupied bandwidth OBW of the transmission signal does not exceed the predetermined frequency range fR. Specifically, the frequency determination unit 35A determines the difference (A-fLBW) or (A-fHBW) between the threshold value A and the lower adjustment width fLBW or the upper adjustment width fHBW, and the frequency calculated by the frequency difference calculation unit 34. Compare with the difference fΔ (third frequency determination process). When the frequency difference fΔ is greater than or equal to the difference (A−fLBW) or (A−fHBW), the frequency determination unit 35A changes the frequency fc of the carrier wave so that the frequency difference fΔ becomes larger than the threshold value A. Instruct and set the transmission mode to stagger transmission mode.

Here, the frequency fCx after the change of the carrier wave in the case of fC> fI is determined by the following equation (5).

Further, when fC <fI, the frequency fCx after the change of the carrier wave is determined by the following equation (6).

On the other hand, when the frequency difference fΔ is smaller than the difference (A-fLBW) or (A-fHBW), the influence of the CW interference signal cannot be reduced even if the tuning transmission mode or the stagger transmission mode is set. In this case, the frequency determination unit 35A causes the communication unit 32 to output a signal indicating that the detection performance of the radar device 10A is deteriorated.

FIG. 11 is a diagram showing an example of frequency determination information 360A in the radar device 10A according to the second embodiment.

As shown in FIG. 11, among the parameters included in the frequency determination information 360A, the occupied bandwidth OBW, the lower limit frequency fL, the upper limit frequency fH, the threshold value A, the reference value Tth regarding the duration of the interference prevention transmission mode, and the interference prevention transmission mode. The reference value Lth regarding the moving distance of the vehicle after setting is stored in advance in the storage unit 36A as a fixed value.

Among the parameters included in the frequency determination information 360A, the carrier frequency fC (fCx), the lower adjustment width fLBW, the upper adjustment width fHBW, the CW interference signal frequency fI, and the frequency difference fΔ are the data processing control unit 15A. It is calculated in the storage unit 36A, stored in the storage unit 36A, and updated sequentially.

As shown in FIG. 11, a plurality of occupied bandwidth OBWs may be set according to the ambient temperature of the radar device 10A. In this case, as shown in FIG. 9, the data processing control unit 15A further has a temperature detection unit 40, and the frequency determination unit 35A has an occupied band corresponding to the measured value of the temperature detected by the temperature detection unit 40. The value of the width OBW is read from the storage unit 36A and used for the transmission mode setting process described above. According to this, an appropriate transmission mode can be selected even when the ambient temperature of the radar device 10A changes.

The temperature detection unit 40 can be realized by, for example, an input / output interface circuit or an A / D conversion circuit of the MCU that inputs a detection signal (analog signal) from a temperature sensor provided outside the MCU.

Next, the flow of processing by the radar device 10A according to the second embodiment will be described.

12A and 12B are flow charts showing a flow of processing by the radar device 10A according to the second embodiment.

FIG. 12A shows a flow chart when the frequency fC of the carrier wave is larger than the frequency fI of the CW interference signal (fC> fI), and FIG. 12B shows the frequency fC of the carrier wave larger than the frequency fI of the CW interference signal. The flow chart when it is small (fC <fI) is shown.

Note that the flow charts shown in FIGS. 12A and 12B differ only in the parameters used in the first to third frequency determination processes described later, and are the same in other respects. Therefore, FIGS. 12A and 12B are individually shown. Instead of explaining in, I will explain in a lump.

As shown in FIGS. 12A and 12B, the processes from step S1 to step S6 after the start of the radar device 10A are the same as the process flow of the radar device 10 according to the first embodiment (see FIG. 8).

In step S6, when the received signal includes a CW interference signal, the data processing control unit 15A starts the determination process based on the frequency difference fΔ. Specifically, first, the frequency determination unit 35A executes the above-described first frequency determination process to determine whether or not the frequency difference fΔ is equal to or less than the lower adjustment width fLBW (upper adjustment width fHBW). (Step S70 / Step S70A).

When the frequency difference fΔ is equal to or less than the lower adjustment width fLBW (upper adjustment width fHBW) (S70 / S70A: Yes), even if the frequency fc of the carrier wave is tuned to the frequency fI of the CW interference signal, transmission is performed. Since the occupied bandwidth OBW of the signal does not exceed the predetermined frequency range fR, the frequency determination unit 35A sets the transmission mode to the synchronized transmission mode (steps S8 / S8A).

On the other hand, when the frequency difference fΔ is larger than the lower adjustment width fLBW (upper adjustment width fHBW) (S70 / S70A: No), the frequency determination unit 35A executes the above-described second frequency determination process. It is determined whether or not the frequency difference fΔ is equal to or greater than the threshold value A (step S71 / step S71A).

When the frequency difference fΔ is equal to or greater than the threshold value A (S71 / S71A: Yes), the frequency determination unit 35A sets the transmission mode to the stagger transmission mode (step S8).

On the other hand, when the frequency difference fΔ is smaller than the threshold value A (S71 / S71A: No), the frequency determination unit 35A executes the above-described third frequency determination process, and the frequency difference fΔ is (A−fHBW) or more. It is determined whether or not there is (whether or not the frequency difference fΔ is (A-fLBW) or more) (step S72 / S72A).

When the frequency difference fΔ is smaller than (A-fHBW) (when the frequency difference fΔ is smaller than (A-fLBW)) (S72 / S72A: No), the interference prevention transmission mode (tuned transmission mode or stagger transmission mode) is set. Since the influence of the CW interference signal cannot be reduced even if it is set, the frequency determination unit 35A transmits a signal indicating that the detection performance of the radar device 10A is deteriorated from the communication unit 32 to the ECU 50. (Step S74). After that, the data processing control unit 15A returns to step S2.

On the other hand, when the frequency difference fΔ is (A-fHBW) or more (when the frequency difference fΔ is (A-fLBW) or more) (S72 / S72A: Yes), the frequency determination unit 35A determines that the frequency difference fΔ is The interference prevention control unit 37A is instructed to change the frequency fc of the carrier wave so as to be larger than the threshold value A (step S73). Specifically, the frequency determination unit 35A instructs the interference prevention control unit 37A to change the frequency of the carrier wave according to the above equation (5) or (6). After that, the frequency determination unit 35A sets the transmission mode to the stagger transmission mode (step S8).

The processing after steps S8 and S9 (S9A) in FIGS. 12A and 12B is the same as the processing flow of the radar device 10 according to the first embodiment (see FIG. 8).

As described above, according to the radar device 10A according to the second embodiment, as described above, the transmission mode is determined in consideration of not only the frequency difference fΔ but also the set frequency range fR, so that the frequency of the transmission signal is in the frequency range. It is possible to prevent a decrease in the reception sensitivity of the radar device 10A so as not to exceed fR.

In particular, according to the radar device 10A, when the frequency difference fΔ is not equal to or more than the threshold value A, the transmission mode is set to the stagger transmission mode after changing the frequency fc of the carrier wave so as to widen the frequency difference fΔ. Even in the case of a frequency difference fΔ in which an interference prevention effect cannot be expected due to processing or frequency tuning, it is possible to prevent a decrease in the reception sensitivity of the radar device 10A.

<< Embodiment 3 >>
FIG. 13 is a diagram showing a functional block configuration of the data processing control unit 15B in the radar device 10B according to the third embodiment.

The radar device 10B according to the third embodiment has a function of changing the pulse width of a pulse signal for pulse-modulating a carrier wave in addition to the function of the radar device 10A according to the second embodiment. It is different from the radar device 10A according to 2.

First, an outline of the method of setting the interference prevention transmission mode according to the third embodiment will be described.

FIG. 14 is a diagram for explaining a method of setting the interference prevention transmission mode according to the third embodiment.

In the figure, the horizontal axis represents frequency and the vertical axis represents signal strength. Reference numeral 450 represents the characteristics of the reflected signal with respect to the transmission signal included in the received signal before down-conversion, and reference numeral 550 represents the characteristics of the CW interference signal included in the received signal before down-conversion. Further, in the figure, reference numeral 450x represents the characteristics of the reflected signal included in the received signal before down-conversion when the pulse width of the pulse signal as the transmission signal is wider than that of the pulse signal according to reference numeral 450. ing.

As shown in FIG. 14, in the pulse modulation method, in general, the larger the pulse width of the pulse signal used for modulation, the narrower the occupied bandwidth OBW of the pulse signal (transmission signal) after modulation. That is, as shown in FIG. 14, by expanding the pulse width of the transmission signal, it is possible to expand the lower adjustment width fLBW and the upper adjustment width fHBW.

Therefore, in the radar device 10B according to the third embodiment, when the occupied bandwidth OBW of the transmission signal exceeds the specified frequency range fR when the frequency of the carrier wave is adjusted, the pulse of the pulse signal which is the reference of the pulse modulation is used. By expanding the width, the lower adjustment width fLBW and the upper adjustment width fHBW are expanded, and then the transmission mode is switched from the normal transmission mode to the interference prevention transmission mode.

Specifically, in the data processing control unit 15B of the radar device 10B, the occupied bandwidth OBW of the transmission signal (pulse signal) when the frequency fc of the carrier is matched with the frequency fI of the CW interference signal has a predetermined frequency range fR. If it exceeds, the pulse width of the transmission signal is increased, and the transmission mode is determined based on the relationship between the occupied bandwidth OBWx of the pulse signal with the increased pulse width and the frequency range fR.

More specifically, the frequency determination unit 35B of the data processing control unit 15B first receives the first frequency determination process, the second frequency determination process, and the third frequency, similarly to the frequency determination unit 35A according to the second embodiment. Execute the judgment process.

In the third frequency determination process, the frequency determination unit 35B increases the pulse width of the pulse signal for pulse modulation when the frequency difference fΔ is smaller than the difference (A-fLBW) or (A-fHBW). Instruct the interference prevention control unit 37B. Here, the expansion amount of the pulse width at the time of pulse width expansion is, for example, a fixed value and is stored in the storage unit 36B in advance.

The interference prevention control unit 37B determines the pulse width based on the increase amount of the pulse width stored in the storage unit 36B in response to the instruction of the pulse width expansion from the frequency determination unit 35B, and instructs the pulse control unit 38. .. The pulse control unit 38 generates a pulse signal in response to an instruction from the interference prevention control unit 37B and transmits it to the modulation unit 13. As a result, a pulse signal having a wider pulse width than the initial one is transmitted from the transmission antenna 14 as a transmission signal.

Then, the frequency determination unit 35B performs the first frequency determination process, the second frequency determination process, and the third frequency determination by the same method as in the second embodiment based on the received signal for the transmission signal with the expanded pulse width. Re-execute the process to determine the appropriate anti-interference transmission mode.

FIG. 15 is a diagram showing an example of frequency determination information 360B in the radar device 10B according to the third embodiment.

As described above, the occupied bandwidth OBW of the transmission signal changes according to the pulse width (see FIG. 14). Therefore, as shown in FIG. 15, the radar device 10B according to the second embodiment stores, as the frequency determination information 360B, two types of parameter groups 362 and 363 in the storage unit 36B, one is when the pulse width is not expanded and the other is when the pulse width is expanded. I remember.

When the pulse width is not expanded, the frequency determination unit 35B executes the first to third frequency determination processes using the parameter group 362, and when the pulse width is expanded, the frequency determination unit 35B uses the parameter group 363 to execute the first to third frequencies. Execute frequency determination processing.

The values of the parameter group 362 and the parameter group 363 may differ only in the occupied bandwidths OBW and OBWx, and the other parameters may have the same values.

Next, the flow of processing by the radar device 10B according to the third embodiment will be described.

16A, 16B, 17A, and 17B are flow charts showing a flow of processing by the radar device 10B according to the third embodiment. 16A and 16B show a flow chart when the frequency fC of the carrier wave is larger than the frequency fI of the CW interference signal (fC> fI), and FIGS. 17A and 17B show the frequency fC of the carrier wave interfering with CW. A flow chart is shown when the frequency of the signal is smaller than the frequency fI (fC <fI).

Note that the flow charts shown in FIGS. 16A, 16B, 17A, and 17B differ only in the parameters used in the first to third frequency determination processes described later, and are the same in other respects. 16A and 16B and 17A and 17B are not described individually, but collectively.

As shown in FIGS. 16A, 16B, 17A, and 17B, steps S1 to S11 (including step S8A) and steps S70 to S73 (including S70A, S72A, and S73A) after the start of the radar device 10B. Is the same as the processing flow of the radar device 10A according to the second embodiment (see FIGS. 12A and 12B).

In step S72 (step S72A), when the frequency difference fΔ is smaller than (A-fHBW) (when the frequency difference fΔ is smaller than (A-fLBW)), (S72 / S72A: No), the data processing control unit 15B , Outputs a transmission signal with an expanded pulse width of pulse modulation (step S75).

Specifically, as described above, the frequency determination unit 35B instructs the interference prevention control unit 37B to increase the pulse width of the pulse signal for pulse modulation, and the interference prevention control unit 37B directs the storage unit 36B. The pulse width is determined based on the increase amount of the pulse width stored in the pulse control unit 38, and is instructed to the pulse control unit 38. The pulse control unit 38 generates a pulse signal having a pulse width specified by the interference prevention control unit 37B and transmits it to the modulation unit 13. As a result, a pulse signal having a wider pulse width than the initial one is transmitted from the transmission antenna 14 as a transmission signal.

Next, the frequency determination unit 35B starts the determination process based on the frequency difference fΔ after the pulse width is expanded. Specifically, first, the frequency determination unit 35B executes the above-described first frequency determination process to determine whether or not the frequency difference fΔ is equal to or less than the lower adjustment width fLBWx (upper adjustment width fHBWx) ( Step S70B / Step S70C).

When the frequency difference fΔ is equal to or less than the lower adjustment width fLBWx (upper adjustment width fHBWx) (S70B / S70C: Yes), even if the frequency fc of the carrier wave is tuned to the frequency fI of the CW interference signal, transmission is performed. Since the occupied bandwidth OBWx of the signal does not exceed the predetermined frequency range fR, the frequency determination unit 35B sets the transmission mode to the synchronized transmission mode (steps S9B / S9C).

On the other hand, when the frequency difference fΔ is larger than the lower adjustment width fLBWx (upper adjustment width fHBWx) (S70B / S70C: No), the frequency determination unit 35B executes the above-described second frequency determination process. It is determined whether or not the frequency difference fΔ is equal to or greater than the threshold value A (step S71 / step S71A).

When the frequency difference fΔ is equal to or greater than the threshold value A (S71 / S71A: Yes), the frequency determination unit 35B sets the transmission mode to the stagger transmission mode (step S8B / S8C).

On the other hand, when the frequency difference fΔ is smaller than the threshold value A (S71 / S71A: No), the frequency determination unit 35B executes the above-described third frequency determination process, and the frequency difference fΔ is (A−fHBWx) or more. It is determined whether or not there is (whether or not the frequency difference fΔ is (A−fLBWx) or more) (step S72B / S72C).

When the frequency difference fΔ is smaller than (A-fHBWx) (when the frequency difference fΔ is smaller than (A-fLBWx)) (S72B / S72C: No), the interference prevention transmission mode (tuned transmission mode or stagger transmission mode) is set. Since the influence of the CW interference signal cannot be reduced even if it is set, the frequency determination unit 35B transmits a signal indicating that the detection performance of the radar device 10B is deteriorated from the communication unit 32 to the ECU 50. (Step S74B / S74C). After that, the data processing control unit 15B returns to step S2.

On the other hand, when the frequency difference fΔ is (A-fLBWx) or more (when the frequency difference fΔ is (A-fHBWx) or more) (S72B / S72C: Yes), the frequency determination unit 35B determines that the frequency difference fΔ is The interference prevention control unit 37B is instructed to change the frequency fc of the carrier wave so as to be larger than the threshold value A (steps S73B / S73C). Specifically, the frequency determination unit 35B instructs the interference prevention control unit 37B to change the frequency of the carrier wave according to the above equation (5) or (6). Next, the frequency determination unit 35B sets the transmission mode to the stagger transmission mode (steps S8B / S8C).

After switching to the interference prevention transmission mode when the pulse width is expanded by steps S8B / S8C and S9B / S9C, the radar device 10B performs radar measurement processing and detects a target in the same manner as in step S2 (step S10B). / S10C).

Next, the data processing control unit 15B determines whether or not to end the interference prevention transmission mode when the pulse width is expanded (steps S11B / S11C). Specifically, as described above, the frequency determination unit 35B is based on whether or not the duration of the tuning transmission mode or the stagger transmission mode has reached the reference value Tth after the expansion of the pulse width, or the moving distance of the vehicle. Determine if the value Lth has been reached.

When the change in the measurement environment of the radar device 10B is not detected (step S11B / S11C: No), the data processing control unit 15B performs radar measurement processing without changing the current transmission mode to target. Is detected (step S10B / S10C).

On the other hand, when a change in the measurement environment of the radar device 10B is detected (step S11B / S11C: Yes), the data processing control unit 15B shifts to step S1 to restore the expanded pulse width and at present. The transmission mode of is changed from the synchronous transmission mode or the stagger transmission mode to the normal transmission mode, and the above-mentioned series of processes is repeated.

As described above, the radar device 10B according to the third embodiment can switch the transmission mode from the normal transmission mode to the interference prevention transmission mode after expanding the pulse width of the pulse signal used for pulse modulation as described above. It has become.

According to this, as shown by reference numeral 450x in FIG. 14, by expanding the pulse width of the pulse signal, the occupied bandwidth OBW can be narrowed and the lower adjustment width fLBW and the upper adjustment width fHBW can be expanded. can. As a result, even if the occupied bandwidth OBW of the transmission signal exceeds the specified frequency range fR when the frequency of the carrier wave is adjusted when the pulse width is not expanded, the transmission mode can be changed by expanding the pulse width. It is possible to set to the synchronized transmission mode or the stagger transmission mode.

Therefore, according to the radar device 10B according to the third embodiment, even in an environment where the frequency difference Δf is larger, the reception sensitivity is lowered without the occupied bandwidth OBW of the transmission signal exceeding the specified frequency range fR. Can be prevented.

<< Expansion of embodiment >>
The inventions made by the present inventors have been specifically described above based on the embodiments, but it goes without saying that the present invention is not limited thereto and can be variously modified without departing from the gist thereof. stomach.

For example, the above-mentioned flowchart is a specific example and is not limited to this flowchart. For example, other processes may be inserted between each step, or the processes may be parallelized. For example, the first to third frequency determination processes (steps S70 to S72, S70A to S72A) are not limited to the order of the processes shown in FIGS. 12A and 12B, and the order may be changed. However, by performing the first to third frequency determination processes (steps S70 to S72, S70A to S72A) in the order of the processes shown in FIGS. 12A and 12B, the synchronized transmission mode is executed in preference to the stagger transmission mode. However, it is preferable because the load on the data processing control unit 15 can be further reduced.

1 ... Radar system, 10, 10A, 10B, 10-1, 10-2 ... Radar device, 11 ... Oscillating section, 12 ... Transmitting section, 13 ... Modulating section, 14 ... Transmitting antenna, 15, 15A, 15B ... Data processing Control unit, 16 ... receiver unit, 17 ... reception antenna, 18 ... amplification unit, 19 ... demodulation unit, 20 ... reception filter, 21 ... A / D conversion unit, 30 ... signal analysis unit, 31 ... measurement unit, 32 ... communication Unit, 33 ... Interference determination unit, 34 ... Frequency difference calculation unit, 35, 35A, 35B ... Frequency determination unit, 36, 36A, 36B ... Storage unit, 37, 37A, 37B ... Interference prevention control unit, 38 ... Pulse control unit , 39 ... Frequency control unit, 40 ... Temperature detection unit, 41, 42 ... Communication line, 360, 360A, 360B ... Frequency determination information, 361 ... Interference determination information, 362 ... Parameter group, 363 ... Parameter group.

Claims (12)

An oscillator that generates a carrier wave that is a CW signal,
A transmitter that transmits a pulse signal obtained by pulse-modulating a carrier wave as a transmission signal from a transmission antenna.
A receiving unit that receives the reflected signal of the transmitted signal as a received signal by the receiving antenna and down-converts the received signal using the carrier wave.
A reception filter that removes components lower than a predetermined frequency from the received signal down-converted by the receiving unit and outputs the signal.
A transmission mode for calculating the frequency difference between the interference signal that interferes with the reflected signal and the carrier wave based on the reception signal output from the reception filter, and transmitting the transmission signal based on the frequency difference. A data processing control unit that controls the oscillation unit and the transmission unit based on the determined transmission mode is provided.
The transmission mode includes a tuning transmission mode in which the frequency of the carrier wave is tuned to the frequency of the interference signal to generate the transmission signal so that the frequency difference becomes smaller than the predetermined frequency.
Radar device. The transmission mode includes a staggered transmission mode that generates the transmission signal so that the repetition period of the pulse signal is unequal.
The radar device according to claim 1, wherein the data processing control unit switches between the tuning transmission mode and the stagger transmission mode based on the frequency difference. In the radar device according to claim 2,
The data processing control unit sets the transmission mode to the tuning transmission mode when the frequency difference is smaller than the first threshold value, and sets the transmission mode to the stagger when the frequency difference is larger than the first threshold value. A radar device that sets the transmission mode. In the radar device according to claim 1 or 2.
The data processing control unit sets the transmission mode to the tuning transmission mode when the occupied bandwidth of the transmission signal does not exceed a predetermined frequency range when the frequency of the carrier wave is tuned to the frequency of the interference signal. Radar device to set. In the radar device according to claim 4,
The data processing control unit is a radar device that sets the transmission mode to the stagger transmission mode when the frequency difference is larger than a predetermined threshold value. In the radar apparatus according to claim 4 or 5,
The data processing control unit increases the frequency difference when the occupied bandwidth of the transmission signal exceeds the predetermined frequency range when the frequency of the carrier wave is tuned to the frequency of the interference signal. A radar device that controls the frequency of a carrier wave and sets the transmission mode to the stagger transmission mode. In the radar device according to any one of claims 4 to 6.
The data processing control unit increases the pulse width of the transmission signal when the occupied bandwidth of the transmission signal when the frequency of the carrier is tuned to the frequency of the interference signal exceeds the predetermined frequency range. At the same time, a radar device that determines the transmission mode based on the relationship between the occupied bandwidth of the transmission signal after increasing the pulse width and the predetermined frequency range. In the radar device according to any one of claims 1 to 7.
When the data processing control unit performs frequency analysis on the received signal output from the reception filter, determines the presence or absence of the interference signal based on the analysis result, and determines that the interference signal exists. , A radar device that calculates the frequency difference. In the radar device according to claim 8,
The data processing control unit is a radar device that determines that the interference signal is present when a frequency component whose signal strength exceeds the second threshold value is present based on the analysis result of the frequency analysis. In the radar device according to claim 9,
The second threshold value is a radar device determined based on the signal intensity at each frequency component of the reflected signal. In the radar device according to any one of claims 2 to 10.
The transmission mode further includes a normal transmission mode in which the carrier wave of a constant frequency is pulse-modulated with a predetermined pulse period and pulse width to generate the transmission signal.
The data processing control unit sets the transmission mode to the normal transmission mode when the measurement environment of the radar device satisfies a predetermined condition when the transmission mode is the synchronized transmission mode or the stagger transmission mode. Radar device to switch. An oscillating unit that generates a carrier wave that is a CW signal, a transmitting unit that transmits a pulse signal obtained by pulse-modulating the carrier wave as a transmitting signal from a transmitting antenna, and a receiving antenna that receives a reflected signal of the transmitting signal as a receiving signal. A receiving unit that down-converts a received signal using the carrier wave, a receiving filter that removes a component lower than a predetermined frequency from the received signal down-converted by the receiving unit and outputs the signal, and an output from the receiving filter. A control method for a radar device including a data processing control unit that controls the oscillation unit and the transmission unit based on the received signal.
The first step of causing the data processing control unit to calculate the frequency difference between the interference signal that interferes with the reflected signal and the carrier wave.
A second step of causing the data processing control unit to determine a transmission mode for transmitting the transmission signal based on the frequency difference.
The data processing control unit includes a third step of controlling the oscillation unit and the transmission unit based on the determined transmission mode.
The transmission mode is a control method of a radar device including a tuning transmission mode in which the frequency of the carrier wave is tuned to the frequency of the interference signal so that the frequency difference becomes smaller than the predetermined frequency to generate the transmission signal.

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