JP2004239644A - Radar apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To store Fourier transform data in all reception channels into a storage without providing any large-capacity storages. <P>SOLUTION: A beat signal transformed into digital data is read (step S10) and Fourier transform is executed to the read beat signal (step S20). Based on data expressed by a bit string after the Fourier transform, the peak frequency of a power spectrum is determined (step S30) and the data after the Fourier transform are stored within a bit range corresponding to the peak frequency (step S40), thus restricting the bit range for storing into the storage, reducing a region required for storage, and hence storing the Fourier transform data in all reception channels into the storage without providing the large-capacity storages. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a radar device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an FM-CW (Frequency Modulation-Continuous Wave) radar device which is mounted on an automobile and detects a distance to a forward object, a relative speed, and an azimuth of the object, a beam scanning mechanism for mechanically scanning a fixed beam is provided. There is one in which beam scanning is realized by digital signal processing without having it (for example, see Patent Document 1). In the radar device disclosed in Patent Document 1, beam scanning is realized by applying digital beam forming (hereinafter, referred to as DBF) technology to an FM-CW radar. The DBF converts a received signal of each of a plurality of array antennas into a digital signal, and performs a fast Fourier transform process (hereinafter, referred to as an FFT process) on the signal. Then, the distance to the object, the relative speed, and the azimuth of the object are calculated using the data subjected to the FFT processing.
[0003]
[Patent Document 1]
JP-A-11-133142
[Problems to be solved by the invention]
In the above-described DBF, the digital signal of each reception channel corresponding to each array antenna is subjected to FFT processing of 512 points in each of a frequency increase section (UP section) and a frequency decrease section (DOWN section), and the processing result is obtained. It is temporarily stored in the storage device. In this FFT processing, in-phase component i and quadrature component q are obtained for each of the 512 points, and thus 512 sets of (i, q) data are generated in one section, and 1024 sections of the UP section and the DOWN section are combined. A set of (i, q) data is generated per channel. Further, in order to calculate the azimuth to the object, it is necessary to generate (i, q) data for eight channels and store them in a storage device.
[0005]
As described above, since the storage device used in the conventional radar device needs to store a large amount of (i, q) data, it is necessary to provide a large-capacity storage device. Therefore, it has been difficult to realize an inexpensive radar device.
[0006]
The present invention has been made in view of such a problem, and an object of the present invention is to provide a radar device that can store Fourier transform data of all reception channels without having a large-capacity storage device.
[0007]
[Means for Solving the Problems]
A radar device according to claim 1, wherein a radar signal for generating a transmission signal obtained by applying frequency modulation to a basic signal, radiating the generated transmission signal as a transmission wave, and detecting a reflected wave thereof as a reception signal, A beat signal generating means for generating a beat signal by mixing the signal and the received signal, and performing a Fourier transform process on the beat signal, and converting a Fourier transform data for each frequency included in the beat signal into a bit string comprising a predetermined number of bits. A Fourier transform means for generating a bit range smaller than a predetermined number of bits to be stored in a bit string according to a frequency corresponding to the Fourier transform data; A storage unit for storing Fourier transform data represented by a bit string in a specified bit range, and a Fourier transform stored in the storage unit Characterized in that it comprises a processing means for performing a calculation process of calculating the relative speed between the distance and reflecting object to the reflecting object based on the data.
[0008]
As described above, when the Fourier transform data represented by the bit string having the predetermined number of bits is stored in the storage unit, the radar apparatus of the present invention uses the number of bits of the bit string representing the Fourier transform data in accordance with the frequency corresponding to the data. Also specify a smaller bit range. That is, if the specifications of the radar means (for example, the maximum reflection intensity and the detection method of a detectable reflected wave) and the object to be detected by the radar means (for example, a vehicle) are determined, the frequency band included in the beat signal and its frequency band are determined. Can theoretically calculate the range of the received power of the power spectrum at. Further, since the magnitude of the received power is calculated from the Fourier transform data, the range of possible values of the Fourier transform data can be grasped in advance. As a result, the bit range of the Fourier transform data required for accurate calculation of the distance to the reflecting object and the relative speed can be designated.
[0009]
By this, the bit range of the Fourier transform data to be stored is specified in the bit range necessary for accurate calculation of the distance to the reflecting object and the relative speed, so that excessively accurate Fourier transform data is stored in the storage means. You don't have to. As a result, since the storage capacity of the storage unit can be reduced, all Fourier transform data can be stored without having a large-capacity storage unit.
[0010]
In the radar device according to the second aspect, the radar unit includes a plurality of receiving units that detect a reflected wave as a reception signal, and the processing unit determines a phase difference of a beat signal generated from the reception signal detected by each reception unit. The azimuth of the reflection object is calculated based on the azimuth.
[0011]
As described above, even when the azimuth of the reflecting object is calculated from the phase difference between the signals received by the plurality of receiving units, the bit range of the Fourier transform data to be stored is specified, so that the capacity of the storing unit is reduced. In addition, the Fourier transform data of all reception channels can be stored in the storage unit. As a result, it is possible to calculate the phase difference for each reception channel from the Fourier transform data stored in the storage unit, so that the azimuth of the reflecting object can be calculated.
[0012]
According to the radar device of the third aspect, the bit range specifying means shifts the bit range to be stored in the storage unit from the upper bits to the lower bits as the frequency increases. .
[0013]
That is, as the distance to the reflecting object becomes longer or the relative speed becomes higher, the frequency of the beat signal becomes higher, and the possible value of the received power of the power spectrum at that frequency tends to become smaller. Therefore, the value of the Fourier transform data from which the received power of the power spectrum is calculated also becomes small, and the Fourier transform data represented by a bit string has a value in a lower bit range.
[0014]
Therefore, in order to correspond to the possible value of the Fourier transform data, when the frequency of the beat signal increases, the bit range stored in the storage unit is shifted from upper bits to lower bits. As a result, the stored Fourier transform data covers possible values of the reception power of the power spectrum in each frequency domain.
[0015]
In the radar device according to claim 4, the Fourier transform means generates Fourier transform data including two bit strings of a real part and an imaginary part, and the storage unit stores two bit strings of a real part and an imaginary part. It is characterized by. As described above, by storing the Fourier transform data including the real part and the imaginary part in the storage unit, the distance and the relative speed to the reflecting object and the azimuth of the reflecting object can be determined based on the reception power and phase derived from both. Can be calculated.
[0016]
According to the radar device of the fifth aspect, the bit range designating unit divides the frequency band that can be included in the beat signal into a plurality of regions, and sets the divided frequency regions as storage targets in the storage unit. A power range is specified in advance, and a bit range in a frequency domain to which a frequency corresponding to the Fourier transform data belongs is specified as a bit range to be stored in the storage unit. Thereby, the bit range to be stored in the storage unit can be easily specified from the value of the frequency corresponding to the Fourier transform data.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a radar device according to an embodiment of the present invention will be described with reference to the drawings.
[0018]
FIG. 1 is a block diagram illustrating an overall configuration of a radar device according to the present embodiment. The radar device 1 is used for detecting a vehicle or the like in front of an automobile, and includes a transmission / reception unit 10 and a signal processing unit 20 as shown in FIG. The transmission / reception unit 10 is mounted on the front of the vehicle, and the signal processing unit 20 is mounted at a predetermined position in or near the vehicle interior.
[0019]
The transmission / reception unit 10 includes an oscillator 11, a transmission antenna 12, a reception antenna 13, and a mixer 14. As the oscillator 11, for example, a voltage-controlled oscillator or the like that can change the oscillation frequency by controlling the magnitude of the voltage is used. Modulates the oscillation frequency.
[0020]
The transmission antenna 12 transmits a transmission wave modulated to a predetermined frequency, and the reception antenna 13 receives a reflected wave of the transmission wave radiated from the transmission antenna 12. The mixer 14 is a device that mixes a transmission signal generated by the oscillator 11 and a reception signal received by the reception antenna 103 into one signal (hereinafter, referred to as a beat signal).
[0021]
Here, the measurement principle of the radar device 1 will be described with reference to the drawings. FIG. 2A shows an example of a case where a transmission wave fs is emitted and a reception wave fr which is a reflection wave of the transmission wave fs is received. As shown in FIG. 2A, the transmission wave fs radiated from the transmission antenna 12 is repeatedly radiated every 1 / fm while modulating the frequency within the range of the modulation width ΔF around the frequency f0.
[0022]
On the other hand, the reflected wave of the transmitted wave fs is received by the receiving antenna 13 is the received wave fr, and the received wave fr has a time delay td and a frequency shift with respect to the transmitted wave fs. In the radar device 1 according to the present embodiment, the distance to the reflecting object and the relative speed are derived from the time delay td and the frequency shift.
[0023]
That is, when the relative speed with respect to the reflecting object is zero, the reflected wave with respect to the emitted transmission wave receives a time delay td according to the distance to the reflecting object. On the other hand, the frequency shift is caused by the so-called Doppler effect. That is, when the own vehicle and the reflecting object are relatively moving, the transmission wave fs radiated from the own vehicle has a larger frequency shift amount on the reflecting object side in accordance with the magnitude of the relative speed. . Therefore, the relative speed can be derived from the frequency shift amount.
[0024]
FIG. 2B shows a beat signal in which the transmission wave fs and the reception wave fr are mixed by the mixer 14. As shown in the figure, the beat frequency fbu indicates the amount of frequency shift at each rising portion of the transmission wave fs and the reception wave fr, and the beat frequency fbd indicates the frequency shift amount at each falling portion of the transmission wave fs and the reception wave fr. The amount of frequency shift is shown.
[0025]
By using these two beat frequencies fbu and fbd, a frequency fb corresponding to the distance length and a frequency fd corresponding to the magnitude of the relative speed can be obtained as shown in the following equation. Note that ABS in the following equation indicates an absolute value.
[0026]
## EQU1 ## Frequency fb corresponding to distance = [ABS (fbu) + ABS (fbd)] / 2
[0027]
## EQU2 ## Frequency fd corresponding to relative speed = [ABS (fbu) -ABS (fbd)] / 2
Further, by substituting these frequencies fb and fd into the following equation, the distance to the reflecting object and the relative speed are calculated. C in the following equation indicates the speed of light.
[0028]
## EQU3 ## Distance = C / (4 × ΔF × fm) × fb
[0029]
## EQU4 ## Relative speed = (C / 2 × f0) × fd
In the radar device 1, the azimuth of the reflection object with respect to the host vehicle is measured based on the following principle. As shown in FIG. 3, in the present embodiment, a plurality of (in this embodiment, eight) reflected antennas of the transmitted wave radiated from the transmitting antenna 12 are received by the receiving antennas 13. Then, the direction of the reflection object 100 with respect to the own vehicle is obtained from the reception waves received by the respective reception antennas 13.
[0030]
For example, when a plurality of receiving antennas 13 are arranged in the width direction of the own vehicle and receive reflected waves reflected from a reflecting object present in front of the own vehicle, the plurality of receiving antennas 13 There is almost no time difference. As a result, even in the beat signal input to the A / D converter 22, the received wave is received at the same time, so that there is almost no phase difference.
[0031]
However, as shown in FIG. 3, when a reflected wave reflected from the reflecting object 100 positioned at an angle (dir) with respect to the length direction of the host vehicle is received, the reception of the plurality of receiving antennas 13 A time difference occurs in the arrival times of the received waves, and the time difference appears as a phase difference between beat signals input to the A / D converter 22. Therefore, the direction of the reflecting object with respect to the host vehicle can be obtained from the magnitude of the phase difference.
[0032]
Next, the configuration of the signal processing unit 20 will be described. As shown in FIG. 1, the signal processing unit 20 converts the beat signal from the waveform generator 21 and the mixer 14 for generating a triangular wave signal into digital data (hereinafter, referred to as a digital beat signal). It comprises a converter 22, an FFT 23 and a microcomputer 30.
[0033]
The A / D converter 22 generates 512 digital beat signals by sampling 512 points in each of the rising and falling sections of the triangular wave for each channel (CH) corresponding to the eight receiving antennas 13.
[0034]
The FFT 23 is a device that executes an operation of fast Fourier transform based on a digital beat signal stored in the RAM 33 of the microcomputer 26, and Fourier transform data as an operation result is sent to the microcomputer 26. This Fourier transform data is represented by a 32-bit integer type composed of a real part component (Re) and an imaginary part component (Im).
[0035]
The microcomputer 30 is configured by a ROM 32, a RAM 33, and the like, with a well-known CPU 31 being the center. The microcomputer 30 operates the waveform generator 21, receives the digital beat signal converted by the A / D converter 22, and stores the digital beat signal in the RAM 33. The digital beat signal is stored in a 16-bit integer type.
[0036]
The microcomputer 30 stores the calculation result transmitted from the FFT 23 in the RAM 33 and calculates the distance to the obstacle such as the vehicle, the relative speed, and the azimuth based on the calculation result stored in the RAM 33. Execute the process. When the Fourier transform data transmitted from the FFT 23 is stored in the RAM 33, the microcomputer 30 stores only the 16-bit bit sequence of the 32-bit bit sequence.
[0037]
That is, in order to calculate the azimuth to the preceding vehicle, it is necessary to use the Fourier transform data of the beat signal for eight channels as described above, so that the real part component (Re) and the imaginary part component (Im) of all eight channels are used. Must be stored in the RAM 33. Furthermore, since the Fourier transform data is represented by a high-precision 32-bit integer type, it is necessary to provide a large-capacity RAM to store the Fourier transform data of all 8 channels.
[0038]
The purpose of this embodiment is to store the Fourier transform data of all 8 channels in the RAM without providing a large-capacity RAM. Therefore, in order to achieve this object, when storing the Fourier transform data in the RAM 33, only the 16-bit bit string of the 32-bit bit string is stored.
[0039]
Specifically, a 16-bit bit range is specified for the real part component (Re) and the imaginary part component (Im) of the Fourier transform data, each represented by 32 bits, according to the frequency of the beat signal. It is stored in the RAM 33.
[0040]
For example, when the radar apparatus 1 is mounted on a vehicle and a preceding vehicle (for example, a passenger car or a freight car) is to be detected, the detection target is limited, and thus the reflected wave from the vehicle detected by the radar apparatus 1 is detected. The maximum intensity (in other words, the maximum power obtained when the radar means receives a reflected wave) can be grasped in advance.
[0041]
FIG. 6 is a diagram showing the characteristics of the frequency-power spectrum. Power (db) on the vertical axis corresponds to the magnitude of the intensity of the reflected wave (reception power). Therefore, when the maximum value of the reception power can be grasped in advance, a line of the maximum reception power of the power spectrum, such as the straight line (1) in the figure, can be drawn.
[0042]
In addition, the radar device 1 is applied to an inter-vehicle distance warning (warning is generated when the inter-vehicle distance to a preceding vehicle is equal to or less than a predetermined distance) and an inter-vehicle distance control (control for maintaining a constant inter-vehicle distance to a preceding vehicle). In such a case, the upper limit (for example, 150 m or the like) of the distance to the vehicle ahead to be detected by the radar device 1 is determined. Therefore, the change characteristic of the reception power accompanying the change in the distance to the vehicle detected by the radar device 1 (for example, 0 to 150 m or the like) can be theoretically calculated. Therefore, as indicated by the curve (2) in FIG. 6, the reception power that changes with the change in the distance to the vehicle detected by the radar device 1 can be shown.
[0043]
Furthermore, when the detection target of the radar device 1 is a vehicle, the upper limit (for example, 180 km / h) of the relative speed with respect to the preceding vehicle detected by the radar device 1 is determined. The maximum shift amount of the reflected wave can be calculated theoretically. Therefore, as shown by a curve (3) in FIG. 6, a change in the reception power detected when the relative speed is 180 km / h can be shown.
[0044]
As described above, when an object to be detected by the radar apparatus 1 and a detection method are determined in advance, since the change characteristic of the frequency-power spectrum can be calculated theoretically, a real part component (Re) and an imaginary part that can be obtained as Fourier transform data are obtained. The range of values of component (Im) can be derived from this change characteristic.
[0045]
Then, as shown in FIG. 6, the range of the reflection intensity to be detected by the radar apparatus 1 of the present embodiment is set to about 100 (db) in the reception power. The reason is as follows.
[0046]
The reception power is obtained by the following equation from Fourier transform data composed of a real part component (Re) and an imaginary part component (Im).
[0047]
Power (db) = 20 × {log ₁₀ (Re ² + Im ² ) ^1/2 } = 10 × log ₁₀ (Re ² + Im ² )
At this time, if (Re ² + Im ² ) of the common logarithm in the above equation doubles, Power (db) becomes about six times. Accordingly, 6 (db) can be expressed by one bit, and about 96 (db) can be expressed by 16 bits. Therefore, a reception power in a range of about 100 (db) can be almost covered by a 16-bit bit string.
[0048]
Thus, the range of the received power of the power spectrum corresponding to the reflection intensity to be detected by the radar device 1 can be covered by the 16-bit bit string of the Fourier transform data expressed by 32 bits.
[0049]
Note that, as the frequency of the beat signal increases, the possible range of the reception power of the power spectrum decreases. Therefore, in the 32-bit Fourier transform data, the 16-bit range to be stored is changed from the upper bit to the lower bit. Shift toward
[0050]
First, in the present embodiment, as shown in FIG. 6, the detectable frequency region of the radar device 1 is divided into a plurality of regions (A to C). Then, for the Fourier transform data represented by the 32-bit integer type, as shown in FIG. 7, a bit range to be stored in the RAM corresponding to each of the frequency ranges A to C is set. As shown in FIG. 6, as the frequency increases, the received power of the power spectrum decreases. Therefore, as shown in FIG. 7, the bit range is shifted from upper bits to lower bits. As a result, the Fourier transform data stored in the RAM 33 covers possible values of the reception power of the power spectrum in each frequency domain.
[0051]
Next, a calculation process of the distance, the relative speed, and the azimuth performed by the signal processing unit 20 according to the characteristic portion of the present embodiment will be described with reference to a flowchart illustrated in FIG. First, in step 10, the digital beat signal (16-bit integer type) in the rising part of the first CH is read out of the digital beat signals for each channel (CH) corresponding to the eight receiving antennas 13.
[0052]
In step S20, a Fourier transform of 512 points is performed for the rising portion of the first CH. Thus, Fourier transform data represented by the real part component (Re) and the imaginary part component (Im) is obtained for each of the 512 frequency points. This Fourier transform data is represented by a 32-bit integer type for both the real part component (Re) and the imaginary part component (Im).
[0053]
In step S30, it is determined which of the frequency regions (A to C) shown in FIG. 6 the frequencies corresponding to the real number component (Re) and the imaginary number component (Im) belong to. In step S40, the Fourier transform data of the bit range determined in step S30 is stored in the RAM 33. In step S50, it is determined whether or not the process has been completed for all points in both the rising section and the falling section. If the determination is affirmative, the process proceeds to step S60. If the determination is negative, the process proceeds to step S20, and the above-described process is repeatedly performed.
[0054]
In step S60, it is determined whether or not all the 8 CHs have been completed. If the processing has been completed for all the CHs, the process proceeds to step S70, and the distance and relative speed are calculated based on the Fourier transform data of all the 8 CHs stored in the RAM 33. , The direction is calculated. On the other hand, if the processing has not been completed for all the channels, the process proceeds to step S20, and the above-described process is repeatedly performed.
[0055]
In step S70, a peak appears on the frequency spectrum based on the absolute value of the complex vector of the Fourier transform data including the real part component (Re) and the imaginary part component (Im), that is, the amplitude of the frequency component indicated by the complex vector. All frequency components are detected, and the frequency is specified as a peak frequency. Then, a combination for each peak frequency of the rising section and the falling section is determined.
[0056]
Since the Fourier transform data is obtained by extracting a bit range of 16 bits out of 32 bits, it is necessary to correct the amplitude when obtaining the amplitude. For this correction, it is possible to determine which upper bit to lower bit out of the 32 bits is extracted based on the frequency corresponding to the Fourier transform data. Accordingly, after correcting the real part component (Re) and the imaginary part component (Im) from the value of the frequency, the amplitude of the frequency is obtained.
[0057]
For example, it is assumed that there are three peak frequencies in the rising section shown in FIG. 4A and three peak frequencies in the falling section shown in FIG. At this time, numbers 1, 2, and 3 are assigned to the three peak frequencies in the rising section in ascending order of frequency, and the codes of a, b, and c are assigned to the three peak frequencies in the descending section in order of decreasing frequency. Attached. Then, a combination of peak frequencies is determined in ascending frequency order, and a distance is calculated from the peak frequency of this combination according to the above-described principle.
[0058]
In the combination of the peak frequencies, the combination is determined in ascending order of the peak frequency, but the magnitude of the amplitude may be considered. That is, the accuracy of the combination can be improved by determining the combination by determining the frequency and the amplitude. On the other hand, for the direction, the phase is obtained from the real part component (Re) and the imaginary part component (Im) for 8 CHs, and the direction is calculated from the phase difference between each CH.
[0059]
As described above, when the Fourier transform data represented by the bit string of 32 bits is stored in the RAM 33, the radar device according to the present embodiment sets the 16-bit range to be stored according to the frequency corresponding to the data. specify.
[0060]
As a result, the bit range of the Fourier transform data to be stored is specified in the bit range necessary for accurate calculation of the distance to the reflecting object, the relative speed, the azimuth, and the like. Will not be remembered. As a result, the storage capacity of the RAM 33 can be reduced, so that all Fourier transform data can be stored without having a large-capacity RAM.
[0061]
(Modification)
In the present embodiment, the frequency band detectable by the radar device 1 is divided into a plurality of regions, and a bit range to be stored in the RAM 33 is set for each of the divided frequency regions. A map indicating the correspondence between the frequency and the bit range may be prepared in advance, and the bit range may be derived by applying the frequency to the map.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an overall configuration of a radar device 1 according to an embodiment of the present invention.
FIG. 2A is a diagram illustrating an example of a reception signal when a transmission wave fs is radiated and a reception wave fr that is a reflection wave of the transmission wave fs is received, and FIG. FIG. 3 is a diagram showing an example of a signal obtained by mixing a transmission wave fs and a reception wave fr by a mixer 14.
FIG. 3 is a diagram illustrating a principle of measuring a direction of a reflection object with respect to a host vehicle in the radar device 1 according to the embodiment of the present invention.
FIG. 4A is a diagram illustrating an example of three power spectra in an ascending section; FIG. 4B is a diagram illustrating an example of three power spectra in a descending section;
FIG. 5 is a flowchart illustrating a flow of a calculation process of a distance, a relative speed, and an azimuth executed in the signal processing unit 20 according to the embodiment of the present invention.
FIG. 6 is a diagram illustrating a range of a power spectrum detected by the radar device 1 according to the embodiment of the present invention.
FIG. 7 is a diagram showing a setting example of a bit range to be stored for each frequency domain according to the embodiment of the present invention.
[Explanation of symbols]
1 radar apparatus 10 transmitting / receiving section 20 signal processing section 23 FFT
30 microcomputer 33 RAM

Claims (5)

Radar means for generating a transmission signal obtained by applying frequency modulation to the basic signal, radiating the generated transmission signal as a transmission wave, and detecting a reflected wave thereof as a reception signal,
Beat signal generating means for generating a beat signal by mixing the transmission signal and the reception signal,
Fourier transform means for performing a Fourier transform process on the beat signal and generating Fourier transform data for each frequency included in the beat signal as a bit string composed of a predetermined number of bits,
Bit range specifying means for specifying a bit range smaller than the predetermined number of bits to be stored in the bit string according to a frequency corresponding to the Fourier transform data,
A storage unit that stores the Fourier transform data indicated by a bit string in a bit range specified by the bit range specifying unit;
A radar device comprising: a processing unit configured to execute a calculation process of calculating a distance to a reflective object and a relative speed with respect to the reflective object based on Fourier transform data stored in the storage unit. The radar unit includes a plurality of receiving units that detect the reflected wave as a received signal,
2. The radar apparatus according to claim 1, wherein the processing unit calculates an azimuth of the reflection object based on a phase difference between beat signals generated from the reception signals detected by the reception units. The radar device according to claim 1, wherein the bit range designating unit shifts a bit range to be stored in the storage unit from upper bits to lower bits as the frequency increases. 4. . The Fourier transform means generates Fourier transform data consisting of two bit strings of a real part and an imaginary part,
The radar device according to claim 1, wherein the storage unit stores the two bit strings of the real part and the imaginary part. The bit range designating unit divides a frequency band that can be included in the beat signal into a plurality of regions, designates a bit range to be stored in the storage unit in advance for each of the divided frequency regions, The radar device according to claim 1, wherein a bit range in a frequency domain to which a frequency corresponding to Fourier transform data belongs is designated as a bit range to be stored in the storage unit.

Images