WO2008023726A1

WO2008023726A1 - Radar apparatus and distance measuring method

Info

Publication number: WO2008023726A1
Application number: PCT/JP2007/066259
Authority: WO
Inventors: Tatsuya Ueno; Kazumasa Nomura
Original assignee: Yamatake Corporation
Priority date: 2006-08-22
Filing date: 2007-08-22
Publication date: 2008-02-28
Also published as: JP4437804B2; JP2008051523A

Abstract

A transport signal generating part (1) generates a transport signal that is a pseudo random signal having a substantially non-periodic characteristic. A transmitting part (2) radiates a transport wave obtained by modulating an electromagnetic wave with the transport signal, and a receiving part (3) receives a reflected wave. A phase-only correlation calculating part (5) comprises a first Fourier transforming part that subjects the transport signal and received signal to a one-dimensional discrete Fourier transformation; a combining part that combines the Fourier transport signal with the Fourier received signal; an amplitude suppressing part that suppresses the amplitude of the combined Fourier signal; a second Fourier transforming part that subjects the combined Fourier signal as amplitude suppressed to a one-dimensional discrete Fourier transformation or a one-dimensional discrete inverse Fourier transformation; a delay time determining part that determines, based on the peak position of a correlation signal, a delay time; and a distance calculating part that calculates, based on the delay time, the distance from an object.

Description

Specification

Radar apparatus and distance measuring method

Technical field

[0001] The present invention relates to a radar apparatus and a distance measuring method for measuring a distance to a target.

Background art

Conventionally, a chaos laser radar device has been disclosed in Japanese Patent Application Publication No. 2004-301588 as a radar device that measures the distance to a target by simple signal processing. FIG. 10 is a waveform diagram illustrating the operating principle of the chaotic laser radar device. Chaos laser radar equipment modulates light and radio waves with a transmission signal that is a random signal (chaos signal), irradiates the target with the modulated light and radio waves, and uses the reflected light and radio waves as an electric signal. A received signal is obtained by conversion.

[0003] Next, one point on the time axis of the binarized transmission signal (ST in Fig. 10) converted into binary values of +1 and 1 is set as the reference time, and the first transmission signal ST from this reference time Time Dl, time to second rising edge D2, time to third rising edge D3, n (n is an arbitrary positive integer) time Dn to the first rising edge The received signals SRI, SR2, SR3,..., SRn are generated by shifting the binarized received signal (SR in FIG. 10) by the respective times from D1 to Dn. When n received signals SR1, SR2, SR3,..., SRn are added, a zero cross point appears in the added signal SUM where it corresponds to the time difference between the transmitted signal and the received signal. During the time before and after the zero cross point, the random pulse waveform is averaged and the sum signal SUM converges to zero. When the delay time 100 of the received signal SR with respect to the reference time of the transmission signal ST is obtained based on the position of the zero cross point of the sum signal SUM, this delay time 100 is until light and radio waves are reflected by the target and returned. Therefore, it is possible to calculate the separation from the target based on the delay time 100.

Disclosure of the invention

Problems to be solved by the invention [0004] In the chaotic laser radar device, the received signals are shifted and added by a known time so that the rising edges of the signals are aligned. Therefore, the signal processing is possible regardless of the reception state, and the received signal contains noise. Even in the case of! /, It only affects the peak value of the added signal, so it has the advantage of being excellent in noise resistance.

However, because the chaotic laser radar device has a distance resolution pulse (electromagnetic wave speed / clock frequency), a high-speed circuit that operates at a very high clock frequency is required to improve the resolution. For example, when a high-speed circuit cannot be used due to cost or other reasons, there is a problem that the distance measurement accuracy deteriorates.

[0005] The present invention has been made to solve the above problems, and provides a radar apparatus and a distance measurement method capable of measuring a distance to a target with high accuracy without using a high-speed circuit. The purpose is to do.

Means for solving the problem

[0006] A radar apparatus according to the present invention includes a transmission signal generation unit that generates a transmission signal that is a substantially aperiodic pseudorandom signal, a transmission unit that radiates a transmission wave obtained by modulating an electromagnetic wave with the transmission signal, Receiving means for receiving a reflected wave of the transmitted wave and outputting a received signal; and obtaining a delay time of the received signal with respect to the transmitted signal, and calculating a distance to an object reflecting the transmitted wave based on the delay time A first Fourier transform unit that performs a one-dimensional discrete Fourier transform on the transmission signal and the reception signal, respectively, to generate a Fourier transmission signal and a Fourier reception signal; and A synthesis processing unit configured to combine the Fourier transmission signal and the Fourier reception signal to generate a synthesized Fourier signal; an amplitude suppression processing unit configured to perform amplitude suppression processing of the synthesized Fourier signal; and the amplitude suppression. Based on the second Fourier transform means for generating a correlation signal by applying one of the one-dimensional discrete Fourier transform and the one-dimensional discrete inverse Fourier transform to the composite Fourier signal after the control processing, and the peak position of the correlation signal First delay time detecting means for obtaining the delay time, and distance calculating means for calculating a distance to the object reflecting the transmission wave based on the delay time.

[0007] In addition, the distance measurement method of the present invention provides a transmission signal that is a substantially aperiodic pseudorandom signal. A transmission signal generating step for generating a transmission wave, a transmission step for emitting a transmission wave obtained by modulating an electromagnetic wave with the transmission signal, a reception step for receiving a reflected wave of the transmission wave and outputting a reception signal, and the transmission signal Calculating a distance to an object reflecting the transmission wave based on the delay time, and the calculation step is performed on the transmission signal and the reception signal, respectively. And performing a discrete Fourier transform to obtain the delay time.

The invention's effect

[0008] As described above, according to the present invention, the transmission signal generation means, the transmission means, the reception means, and the calculation means are provided, and the calculation means receives the transmission signal using the phase only correlation method. Since the delay time of the received signal is obtained and the distance to the object reflecting the transmitted wave is calculated based on this delay time, the speed of the circuit is limited as in conventional chaotic laser radar devices and time-of-flight. The distance to the target can be measured with high accuracy

Yes

Brief Description of Drawings

FIG. 1 is a block diagram showing a configuration of a radar apparatus according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the radar apparatus of FIG.

FIG. 3 is a block diagram showing a configuration example of a phase only correlation calculation unit in the first embodiment of the present invention.

FIG. 4 is a flowchart showing the operation of the phase only correlation calculation unit in the first embodiment of the present invention.

FIG. 5 is a diagram showing the relationship between the transmission signal and the sampling timing of the phase only correlation calculation unit in the first embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a radar apparatus according to a second embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration example of a chaos laser radar calculation unit in the second embodiment of the present invention.

FIG. 8 is a flowchart showing the operations of the chaotic laser radar computing unit and the phase-only correlation computing unit in the second embodiment of the present invention.

FIG. 9 shows other transmission signals used in the first and second embodiments of the present invention and the transmission signals. FIG. 6 is a waveform diagram of a random noise signal that is the source of a signal.

FIG. 10 is a waveform diagram illustrating the operating principle of a conventional chaotic laser radar device.

BEST MODE FOR CARRYING OUT THE INVENTION

[0010] Conceptually, when the signal n (t) is a random signal, the correlation with other time series is 0, and the autocorrelation coefficient is 0 except when the lag is 0 (ie, non- Refers to a periodic signal. However, engineering cannot always realize a random signal in such an ideal state, and usually only a signal having a certain degree of autocorrelation (ie, substantially non-periodic) can be obtained. Here, engineering-realizable random signals are collectively referred to as “pseudo-random signals”.

It should be noted that the transmission signal of the present invention has substantially non-periodic force.

If the transmission signal period is τ and the high speed is C, it means that the following equation is satisfied.

T> (2 X Lmax) / C (1)

Lmax in equation (1) is the maximum measurable distance assumed by the radar apparatus of the present invention.

[0011] The technical idea of the present invention is that the pattern of the transmission signal is similar to the pattern of the reception signal reflected back to the target (since the reception signal includes some noise). In order to detect the shift on the time axis of both patterns as the delay time of the received signal with respect to the transmitted signal, the pattern matching method using Fourier transform was applied. is there.

[0012] [First embodiment]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a radar apparatus according to a first embodiment of the present invention. The radar apparatus according to the present embodiment includes a transmission signal generation unit 1 that generates a transmission signal that is a substantially non-periodic pseudo-random signal, and a transmission unit 2 that emits transmission light in which laser light is intensity-modulated with the transmission signal. Then, the receiver 3 that receives the reflected light of the transmitted light and outputs the received signal, the low pass filter (LPF) 4, and the delay time of the received signal with respect to the transmitted signal are obtained, and based on this delay time, the transmitted light And a phase-only correlation calculation unit 5 for calculating the distance to the object reflecting the light. The transmission unit 2 includes a laser diode (LD) 20 and an LD drive circuit 21 that drives the LD 20. An LED may be used instead of the LD.

The receiving unit 3 includes a photodiode (PD) 30 and an amplifier circuit 31 that amplifies a signal output from the PD 30.

[0014] Hereinafter, the operation of the radar apparatus of the present embodiment will be described. Fig. 2 is a flowchart showing the operation of the radar system. The transmission signal generation unit generates a transmission signal that is a pseudo-random signal (step Sl). Specifically, it is well known that thermal noise generated in resistors of electronic circuits, atmospheric noise or cosmic noise, generation of radiation due to decay of radioactive elements, or pseudo-random number generator PRNG mounted on a microcomputer. A pseudo-random signal is obtained by means. Next, a pseudo-random signal is sampled periodically according to the clock pulse, and this sampling value is compared with an appropriate threshold value. If it is small, 0 is held and 1 is held until the next sampling. In this way, a pseudo-random signal (hereinafter sometimes referred to as a random pulse signal) is obtained as a pulse signal in which one of the states 0 and 1 can be generated approximately aperiodically for each clock cycle. In order to reduce the error calculation rate of the phase-only correlation method described later, the transmission signal is preferably a random pulse signal having a trapezoidal pulse rather than a square wave. Converting a square wave to a trapezoidal wave can be realized by a known signal processing technique. At this time, the trapezoidal wave may be a curved substantially trapezoidal wave in which the rising and falling slopes, which are not a perfect trapezoidal wave, are represented by an exponential function using CR, for example. The pseudo-random signal described above may be newly generated every time it is used, or may be stored in advance in a memory and reproduced every time it is used.

[0015] In the phase-only correlation method, it is necessary to use an analog signal as a transmission signal. On the other hand, in the chaotic laser radar described later, the transmission signal has a steep and reproducible rise in nature. It is necessary to use a signal such as By using either a trapezoidal wave or a substantially trapezoidal wave, the phase-only correlation method and the chaotic laser radar can be performed with relatively simple means (for example, by adding a first-order delay circuit such as a CR circuit to the output of a random noise signal). It is possible to make the transmission signal suitable for both systems.

[0016] The LD drive circuit 21 of the transmission unit 2 drives the LD 20 in accordance with the transmission signal, so that the transmission light, which is a Norse-shaped laser beam whose intensity is modulated in accordance with the transmission signal, is output from the LD 20. (Step S2). This transmitted light is irradiated as parallel light by a projection lens (not shown).

[0017] The transmission light emitted from the transmission unit 2 is reflected by an object in front of the transmission unit 2 (hereinafter referred to as a target object 10), and a part of the reflected light is collected by a light receiving lens (not shown). Then, it enters the PD 30 of the receiver 3.

The PD 30 converts the incident light into a current, and the amplifier circuit 31 converts the output current of the PD 30 into a voltage, amplifies it, and outputs it as a received signal (step S3).

LPF 4 removes a high-frequency component of the reception signal output from reception unit 3.

Next, the phase only correlation calculation unit 5 receives the transmission signal generated by the transmission signal generation unit 1 and the reception signal that has passed through the LPF 4 to obtain the delay time of the reception signal with respect to the transmission signal, and based on this delay time. The distance to the target 10 is calculated (step S4). The phase-only correlation calculation unit 5 uses the phase-only correlation method as a method for obtaining the delay time of the received signal with respect to the transmitted signal.

[0019] The phase only correlation method is a cross-correlation algorithm that focuses on the phase of a signal. The force S that gives the amplitude spectrum and phase spectrum when the signal is Fourier-transformed, of which the phase spectrum stores information related to the signal intensity change, that is, the shape of the signal. Not included. The phase-only correlation method is a cross-correlation algorithm that removes amplitude information (or decreases the weight of amplitude information) and uses only phase information (or increases the weight of phase information) in the correlation value calculation process. Hereinafter, this phase-only correlation method will be described in more detail.

FIG. 3 is a block diagram showing a configuration example of the phase only correlation calculation unit 5, and FIG. 4 is a flowchart showing the operation of the phase only correlation calculation unit 5. The phase only correlation calculation unit 5 includes an input unit 50, a first Fourier transform unit 51, a synthesis processing unit 52, an amplitude suppression processing unit 53, a second Fourier transform unit 54, and a delay time detection unit 55. And a distance calculation unit 56.

[0021] First, the input unit 50 performs AD conversion on each of the transmission signal and the reception signal (step S100 in FIG. 4). At this time, as shown in FIG. 5, the AD conversion sampling period 500 is required to be shorter than the trapezoidal wave length 502 of the transmission signal 501. In other words, the transmission signal 501 is generated such that the trapezoidal wave length 502 is longer than the sampling period 500. The Further, in order to properly capture the shape of the trapezoidal wave, it is desirable that the rise time 503 and the fall time 504 of the transmission signal 501 are longer than the sampling period 500. Note that reference numeral 505 in FIG. 5 denotes a sampling timing.

[0022] Subsequently, the first Fourier transform unit 51 performs one-dimensional discrete Fourier transform (DFT) on the transmission signal and the reception signal captured by the input unit 50 (step S101). As a result, data on the time axis is converted into data on the frequency axis. Hereinafter, the transmission signal and the reception signal after Fourier transform are called the Fourier transmission signal and the Fourier reception signal, respectively.

Next, the synthesis processing unit 52 synthesizes the Fourier transmission signal and the Fourier reception signal to obtain a synthesized Fourier signal (step S 102). Here, the synthesized Fourier signal is expressed as AXBXe ^{j (e Φ)} , where the Fourier received signal is AXe ^je and the Fourier transmitted signal is BXe ^] . Where A and Β are amplitude spectra and θ and φ are phase spectra, both of which are functions in the frequency (Fourier) space. This synthesized Fourier signal AXBXe ^{j (e Φ)} is expressed by the following equation.

AXBXe —) = AXBXcos (θ-) + j XAXBXsin (θ-)

••• (2)

[0024] And AXe] ^e = a + j β, BXe ^J = α + j β, Α = ² + / 3 ² ) ^1/2 , Β =

2 2 1 1

(α ₂ ² + β Υ ² , θ φ = tan— ¹ (/ 3, a ₂ ).

Thus, a synthesized Fourier signal can be obtained. AXBXe ^ —) = AXBX _e ^je X) + j (

a synthesized Fourier signal may be obtained as aXβ-aXβ).

2 1 1 2

[0025] The amplitude suppression processing unit 53 performs amplitude suppression processing of the synthesized Fourier signal (step S103). In this embodiment, logarithmic (log) processing is performed as amplitude suppression processing. That is, the amplitude suppression processing unit 53 takes the logarithm of the synthesized Fourier signal AXBXe ^{i (e Φ} ) and takes it as log (AXB) Xe ^{i (} ^Θ — ^Φ) , thereby obtaining the amplitude AX の of the synthesized Fourier signal as log Suppress to (AX Β) (AX B> log (AXB)). A process for obtaining the square root of the synthesized Fourier signal may be performed as the amplitude suppression process. In addition to logarithmic processing and square root processing, any processing can be used as long as the amplitude can be suppressed! /.

[0026] In the synthesized Fourier signal subjected to the amplitude suppression process, the intensity difference between the transmission signal and the reception signal is caused. The effect is smaller. In other words, by performing the amplitude suppression process, the spectrum intensity of the synthesized Fourier signal is suppressed, so there are no outstanding values, and more information becomes effective. In addition, by performing the amplitude suppression process, a characteristic part that is information necessary for deriving the delay time is more emphasized.

Next, the second Fourier transform unit 54 performs one-dimensional discrete Fourier transform (DFT) on the synthesized Fourier signal after the amplitude suppression process (step S104). By this one-dimensional discrete Fourier transform, data on the frequency axis is converted into data on the time axis, and a correlation signal is obtained. Note that the second Fourier transform unit 54 may perform a one-dimensional discrete inverse Fourier transform instead of performing the one-dimensional discrete Fourier transform.

In the correlation signal (data related to the time axis) output from the second Fourier transform unit 54, an amplitude peak appears at a position corresponding to the time difference between the transmission signal and the reception signal. The delay time detector 55 obtains the delay time of the received signal with respect to the transmission signal based on the peak position of the correlation signal (step S105). At this time, the delay time detection unit 55 obtains the delay of the received signal by obtaining the peak position with a precision of a fraction of the sampling period 500 to a few tenths using the internal method for the correlation signal. Time can be calculated with high accuracy

Yes

[0029] When the delay time detected by the delay time detector 55 is d [s], the distance to the target 10 is L [m], and the speed of light is C [m / s], the following relationship holds.

d = (2 X L) / C (3)

The distance calculation unit 56 calculates the distance L to the target object 10 using the equation (3) from the delay time d detected by the delay time detection unit 55 (step S106).

[0030] As described above, in the present embodiment, by using the phase-only correlation method, the delay time of the reception signal with respect to the transmission signal can be detected with high accuracy. The distance to the target can be measured with high accuracy without being limited by the circuit speed as in the case of time-of-flight.

[0031] [Second Embodiment]

Next, a second embodiment of the present invention will be described. FIG. 6 is a block diagram showing the configuration of the radar apparatus according to the second embodiment of the present invention. The same components as those in FIG. is there. The radar apparatus according to the present embodiment includes a transmission signal generation unit 1, a transmission unit 2, a reception unit 3, an LPF 4, a phase only correlation calculation unit 5, and a binary signal that binarizes the transmission signal and the reception signal. And a chaos laser radar operation unit 7 for obtaining a delay time of the reception signal with respect to the transmission signal by the chaos laser radar system.

[0032] The operations of the transmission signal generator 1, the transmitter 2, the receiver 3, and the LPF 4 are the same as those in the first embodiment.

The binarization circuit 6 converts the transmission signal output from the transmission signal generation unit 1 into a binary value of +1 and 1, and similarly converts the reception signal that has passed through the LPF 4 into a binary value. The received signal that passed through LPF4 is used to reduce noise.

FIG. 7 is a block diagram showing a configuration example of the chaos laser radar calculation unit 7, and FIG. 8 is a flowchart showing the operations of the force male laser radar calculation unit 7 and the phase-only correlation calculation unit 5. The chaos laser radar calculation unit 7 includes an edge detection unit 70, a shift register 71, an addition processing unit 72, and a delay time detection unit 73. The phase-only correlation calculation unit 5 receives the transmission signal generated by the transmission signal generation unit 1 and the reception signal that has passed through the LPF 4, and the chaos laser radar calculation unit 7 is binarized by the binarization circuit 6. Send signal and receive signal are input

[0034] First, the edge detection unit 70 of the chaos laser radar calculation unit 7 performs the binarized transmission signal.

A certain point on the time axis of (ST in Fig. 10) is set as the reference time, the time Dl from this reference time to the first rising edge of the transmission signal ST, the time D 2 to the second rising edge, and the third Time D3, n (n is an arbitrary positive integer) th rising force S Time Dn until the rising edge is detected. Then, the shift register 71 generates received signals SRI, SR2, SR3,..., SRn obtained by shifting the binarized received signal (SR in FIG. 10) by each time from D1 to Dn. (Fig. 8, step S200).

The addition processing unit 72 performs calorie calculation on the n received signals SRI, SR2, SR3,..., SRn generated by the shift register 71 (step S201). As a result, the calorie calculation signal SUM as shown in Fig. 10 is obtained. In this sum signal SUM, a zero cross point appears at a position corresponding to the time difference between the transmission signal and the reception signal.

The delay time detection unit 73 obtains the delay time of the reception signal with respect to the reference time of the transmission signal based on the position of the zero cross point of the addition signal SUM (step S202). And The delay time detection unit 73 notifies the phase-only correlation calculation unit 5 of the detected delay time. Note that the added signal SUM in Fig. 10 shows the waveform when processed for continuous time for ease of description. However, since the received signal is actually processed discretely, the added signal is also shown in the figure. It becomes a discrete value like SUM 'of 10. 101 in FIG. 10 is a sampling timing.

[0036] The input unit 50, the first Fourier transform unit 51, the synthesis processing unit 52, the amplitude suppression processing unit 53, the second Fourier transform unit 54, and the delay time detection unit 55 of the phase only correlation calculation unit 5 are delayed. Only in the predetermined time range centered on the delay time detected by the time detector 73, the processing described in steps S100 to S105 in FIG. 4 is executed to obtain the delay time of the received signal with respect to the transmission signal (step S203). ).

The distance calculation unit 56 calculates the distance L to the target 10 in the same manner as Step S106 in FIG. 4 (Step S204).

As described above, in this embodiment, the delay time of the received signal is obtained by the phase-only correlation method only for a predetermined time range centered on the delay time detected by the chaotic laser radar method. The calculation amount of the limited correlation calculation unit 5 can be reduced. In addition, the phase-only correlation method can be combined with the power chaotic laser radar method, which has the disadvantage of being vulnerable to noise, to realize a radar device with excellent noise resistance. In this embodiment, since the improvement of the distance measurement accuracy is realized by the phase-only correlation calculation unit 5, it is not necessary to use a high-speed circuit for the chaos laser radar calculation unit 7.

[0038] In the first and second embodiments, light is used as the carrier wave of the transmission signal. However, the present invention is not limited to this, and other electromagnetic waves such as radio waves may be used.

In the first and second embodiments, one random noise signal having a trapezoidal waveform or a substantially trapezoidal waveform is used as the transmission signal, but a random noise signal having a sinusoidal pulse (sine wave and random pulse) is used. (Integrated signal with pulse signal) When a sine wave is used, it is easy to generate a transmission signal, and it is possible to limit the frequency band processed by the phase-only correlation method, thereby reducing the possibility of erroneous calculation of the delay time by the phase-only correlation method. Therefore, it is possible to realize a radar apparatus that achieves both noise resistance and high resolution. Figure 9 shows the waveforms of the random noise signal and transmission signal in this case. In this case, LPF4 Instead, a narrow-band bandpass filter can be used. From the viewpoint of the sampling theorem, the clock and sampling period of the random noise signal must be higher than the frequency twice that of the sine wave. It is more preferable if it is more than 4 times the frequency of the sine wave!

[0039] In the phase-only correlation method, the position shift is converted into a phase shift proportional to the frequency. For example, when “frequency” = C / “wavelength 10 cm”, the lcm deviation corresponds to 36 °, and for “double frequency” = C / “wavelength 5 cm,” the same lcm corresponds to a 72 ° deviation ( Where C is the distance traveled in unit time of electromagnetic waves). To calculate the displacement, the proportional coefficient of frequency and phase at this time is obtained.

If the frequency of the transmitted signal includes various frequencies as in the general phase-only correlation method, noise and the received signal cannot be separated when calculating the proportional coefficient of the phase difference with respect to the frequency! The proportionality coefficient is obtained from the result including the phase shift of noise.

On the other hand, as shown in FIG. 9, when an integrated signal of a sine wave of a single frequency and a random noise signal is used as a transmission signal, the received signal is passed through a bandpass filter (BPF) and noise is received. Since the shift can be removed, the calculation accuracy of the slope is improved. However, there is only information on the phase shift at one point on the frequency axis, so when the number of measurement points decreases, it is weak against noise and includes elements.

When using an integrated signal of a sine half wave obtained by folding a single frequency sine wave at 0 and a random pulse signal as the transmission signal, it is also possible to remove the noise by passing the received signal through the BPF. In addition, since the number of measurement points increases, the calculation accuracy of the slope improves. Furthermore, if the sine wave to be integrated with the random pulse signal is a plurality of sine waves of different frequencies, the number of measurement points can be further increased, and the slope calculation accuracy can be further improved. Industrial applicability

[0041] The present invention can be applied to a radar apparatus such as an automobile collision prevention sensor.

Claims

The scope of the claims

[1] A transmission signal generating unit that generates a transmission signal that is a substantially aperiodic pseudorandom signal, a transmission unit that radiates a transmission wave obtained by modulating an electromagnetic wave with the transmission signal,

Receiving means for receiving a reflected wave of the transmission wave and outputting a reception signal;

Calculating a delay time of the reception signal with respect to the transmission signal, and calculating a distance to an object reflecting the transmission wave based on the delay time;

The computing means is

First Fourier transform means for performing a one-dimensional discrete Fourier transform on each of the transmission signal and the reception signal to generate a Fourier transmission signal and a Fourier reception signal;

Combining processing means for generating a combined Fourier signal by combining the Fourier transmission signal and the Fourier reception signal;

Amplitude suppression processing means for performing amplitude suppression processing of the synthesized Fourier signal;

A second Fourier transform means for generating a correlation signal by applying one of a one-dimensional discrete Fourier transform and a one-dimensional discrete inverse Fourier transform to the synthesized Fourier signal after the amplitude suppression processing;

First delay time detection means for obtaining the delay time based on a peak position of the correlation signal;

A radar apparatus comprising: distance calculation means for calculating a distance to an object reflecting the transmission wave based on the delay time.

[2] The radar device according to claim 1,

The radar apparatus according to claim 1, wherein the transmission signal is a random pulse signal having one of a trapezoidal waveform and a substantially trapezoidal waveform.

[3] The radar device according to claim 1,

The transmission device is a random pulse signal having a sinusoidal pulse.

[4] The radar device according to claim 1,

And binarization means for binarizing the transmission signal and the reception signal to generate a binary transmission signal and a binary reception signal, respectively. Edge detection means for detecting each time from a reference time of the binarized transmission signal to a plurality of rising edges;

A shift register that generates a plurality of reception signals obtained by shifting the binarized reception signal by a plurality of times detected by the edge detection unit;

Addition processing means for adding a plurality of reception signals generated by the shift register to generate an addition signal;

Second delay time detecting means for determining a delay time of the binarized reception signal with respect to a reference time of the binarized transmission signal based on a position of a zero cross point of the addition signal! / The first Fourier transform means, the synthesis processing means, the amplitude suppression processing means, the second Fourier transform means, and the first delay time detection means are the delay times detected by the second delay time detection means. A radar apparatus, wherein a delay time of the reception signal with respect to the transmission signal is obtained only in a predetermined time range centered.

[5] A transmission signal generation step of generating a transmission signal that is a substantially aperiodic pseudorandom signal;

A transmission step of radiating a transmission wave obtained by modulating an electromagnetic wave with the transmission signal; a reception step of receiving a reflected wave of the transmission wave and outputting a reception signal; and obtaining a delay time of the reception signal with respect to the transmission signal, A calculation step for calculating the distance to the object reflecting the transmission wave based on the delay time,

The calculation step includes a step of performing discrete Fourier transform on each of the transmission signal and the reception signal to obtain the delay time.