JP2013137268A - Fmcw radar system - Google Patents

Abstract

An FMCW radar system capable of preventing a decrease in target detection accuracy caused by a fluctuation in phase of a leak wave is provided.
A transmission unit for generating a transmission wave radiated to a target TG, an antenna for receiving a reflected wave by radiating the transmission wave in the air, and reception for extracting information on the TG based on the reception wave. Unit 4 and antenna sharing unit 5 that outputs a transmission wave to an antenna and outputs a reception wave to a reception unit. The transmission unit includes a local signal generation unit 21, a chirp signal generation unit 22, and a transmission-side mixer 23. , A transmission side control unit 24, and a reception unit that generates a beat wave from a leak wave and a reception wave as a transmission wave, an HPF 42 that removes a low frequency component of the beat wave, and an HPF output An error correction unit 43 that corrects an error caused by the frequency characteristic of the reflection phase at the input end of the included antenna 3 and a target information extraction unit 44 that extracts information about TG from the corrected signal are provided.
[Selection] Figure 3

Description

  The present invention relates to an FMCW radar system, and more particularly to an FMCW radar system in which an antenna is used for both transmission and reception and a two-terminal single-ended mixer is applied as a receiving-side mixer.

An FMCW (Frequency Modulated Continuous Wave) radar system is known as one type of radar system.
This FMCW radar system not only can measure the distance to the target, but can also detect the relative speed of the target from the frequency difference between the transmitted wave and the received wave caused by the Doppler effect. An on-vehicle FMCW radar system has already been proposed (see, for example, Patent Document 1).

  In order to simplify the system configuration, the FMCW radar system according to the above proposal includes a configuration in which an antenna is used for both transmission and reception and a two-terminal single-ended mixer is used as a mixer.

JP 2007-024890 A

  FIG. 12 is a schematic configuration diagram and a waveform graph of the radar system disclosed in Patent Document 1, wherein (a) is a schematic configuration, (b) is a transmission / reception timing, (c) is a transmission wave waveform, (D) shows a transmission wave mixer output waveform, and (e) shows a high-pass filter output waveform.

  That is, the FMCW radar system disclosed in Patent Document 1 includes a transmission unit 2, an antenna 3, a reception unit 4, and an antenna sharing unit 5, as shown in FIG. An end-type receiving side mixer 41 and a high-pass filter (hereinafter referred to as “HPF”) 42 are included.

The transmission unit 2 generates a chirp signal whose frequency changes within a predetermined range every predetermined period T as shown by the solid line in (b) and (c), and goes from the antenna 3 to the target TG via the antenna sharing unit 5. Radiate.
A reflected wave that is a transmitted wave reflected by the target TG is received as a received wave by the antenna 3 and supplied to the receiving-side mixer 41.

  The reception-side mixer 41 has a function of generating a beat wave by mixing a local signal and a reception wave. However, if one antenna is used for both transmission and reception and a part of the transmission wave is used as a local signal, Challenges arise.

  That is, not all of the transmitted wave is supplied to the antenna 3, but a part of the transmitted wave is reflected at the antenna input end and becomes a leaky wave and leaks to the receiving-side mixer 41. However, since it has a large power, it becomes an obstacle to beat wave generation, and reception sensitivity is lowered.

In order to solve this problem, Patent Document 1 also describes that the reception-side mixer 41 is a single-ended type and a leak wave is used as a local signal.
In this case, the receiving side mixer 41 outputs the beat wave shown in FIG.

Here, since the receiving side mixer 41 is of a single end type, a direct current component is generated at the output of the receiving side mixer 41.
Since this DC component narrows the dynamic range in the process of extracting the target information from the beat wave, the DC component is removed by the HPF 42, and the target information is detected from the beat wave whose DC component is zero as shown in (e). Is extracted.
That is, when a two-terminal single-ended mixer is applied as the receiving-side mixer 41, it is necessary to install the HPF 42 at the subsequent stage.

However, in a radar system that uses a leak wave as a local signal, the reflection frequency characteristics at the antenna input end may affect the detection accuracy.
The reflection frequency characteristic at the antenna input end includes an amplitude characteristic and a phase characteristic. Although the amplitude characteristic can be configured to be substantially flat, it is difficult to intentionally adjust the phase characteristic.
Therefore, there arises a problem that the detection accuracy of the target is lowered due to the fluctuation of the phase of the leak wave.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an FMCW radar system capable of preventing a decrease in target detection accuracy due to a variation in the phase of a leak wave used as a local signal. To do.

  An FMCW radar system according to the present invention generates a transmission wave that radiates toward a target, and receives a reflected wave, which is a transmission wave radiated in the air and reflected by the target, as a received wave. An FMCW radar system comprising: an antenna; a receiving unit that extracts information about the target based on the received wave; and an antenna sharing unit that outputs the transmission wave to the antenna and outputs the received wave to the receiving unit. The transmission unit includes a local signal generation unit that generates a local signal, a chirp signal generation unit that generates a chirp signal, and a transmission-side mixer that mixes the local signal and the chirp signal into the transmission wave. And a transmission-side control unit that controls the local signal generation unit and the transmission signal generation unit, and the reception unit transmits the transmission Is a reception-side mixer that generates a beat wave by mixing the leaked wave reflected by the input end of the antenna and the received wave, and a high-pass that removes the low-frequency component of the beat wave and generates a target information signal An error correction unit that corrects an error caused by the frequency characteristic of the reflection phase of the input end of the antenna included in the target information signal, and generates a corrected signal, and extracts information about the target from the corrected signal And a target information extraction unit.

  According to the above configuration, it is possible to extract the target information after correcting the error due to the frequency characteristic of the reflection phase shift at the antenna input end.

  In the FMCW radar system according to the present invention, the error correction unit converts the target information signal into a frequency domain target information signal, and a negative frequency portion of the frequency domain target information signal is replaced with zero. Based on a zero permutation unit that outputs a region correction target signal, an inverse conversion unit that reversely converts the frequency domain correction target signal into a time domain correction target signal, and a frequency characteristic of a reflection phase of the antenna input terminal measured in advance A correction coefficient calculation unit that calculates a correction coefficient; and a multiplication unit that multiplies the time domain correction target signal by the correction coefficient and outputs a time domain corrected signal.

  According to the above configuration, it is possible to accurately correct an error caused by the frequency characteristic of the reflection phase shift at the antenna input end.

  In the FMCW radar system according to the present invention, the error correction unit shifts the phase of the target information signal by 90 degrees in the entire frequency range and outputs an imaginary number component of the time domain correction target signal, and the target information A delay unit that delays a signal by a phase shift processing time in the phase shift unit and outputs a real component of a time domain correction target signal; a correction coefficient calculation unit that calculates a correction coefficient based on the reflection characteristics measured in advance; A time domain correction target beat wave obtained by synthesizing an imaginary number component and a real number component of the time domain correction target signal, and a multiplication unit that multiplies the correction coefficient and outputs a time domain corrected signal.

  According to the above configuration, it is possible to correct an error caused by the frequency characteristic of the reflection phase at the antenna input end in the time domain.

  The FMCW radar system according to the present invention includes a transmission / reception start command output unit in which the transmission-side control unit intermittently outputs a transmission / reception start command, and the chirp signal generation unit has an amplitude of zero after reading the transmission / reception start command. An amplitude increasing signal that gradually increases to a predetermined amplitude, a chirp signal whose frequency continuously changes in a predetermined range at the predetermined amplitude, and an amplitude decreasing transmission signal whose amplitude gradually decreases from the predetermined amplitude to zero It has a configuration that outputs sequentially.

  According to the above configuration, even in an FMCW radar system that transmits and receives intermittently, it is possible to correct an error caused by the frequency characteristic of the reflection phase at the antenna input end.

  A control program for an FMCW radar system according to the present invention includes: a transmission unit that generates a transmission wave that radiates toward a target; and a reflected wave that is a transmission wave that radiates the transmission wave in the air and is reflected by the target. An antenna that receives the received wave; a receiving unit that extracts information on the target based on the received wave; an antenna sharing unit that outputs the transmitted wave to the antenna and outputs the received wave to the receiving unit; A control unit that controls the transmission unit and the reception unit, wherein the transmission unit generates a local signal that generates a local signal, a chirp signal generation unit that generates a chirp signal, the local signal, and the A transmission-side mixer that mixes chirp signals into the transmission wave, and the reception unit reflects the transmission wave at the input end of the antenna sharing unit. A control program for an FMCW radar system, comprising: a receiving-side mixer that generates a beat wave by mixing the leaked wave and the received wave; and a high-pass filter that removes a low-frequency component of the beat wave, The control unit corrects an error caused by the frequency characteristic of the reflection phase at the input end of the antenna included in the target information signal, generates an corrected signal, and information about the target from the corrected signal. It has the structure which functions as a target information extraction part to extract.

  According to the present invention, there is provided an FMCW radar system capable of preventing deterioration of target detection capability even when a two-terminal single-ended mixer is applied as a receiving-side mixer and intermittent transmission / reception is performed with one antenna. The

It is an example of the frequency characteristic of the reflection phase of an antenna input terminal. It is a distance profile when the amplitude is changed to 0, π / 4, π / 2, and π. It is a functional block diagram of the FMCW radar system concerning the present invention. It is a hardware block diagram of the FMCW radar system which concerns on this invention. It is a functional block diagram of the correction | amendment part and target information extraction part which concern on the 1st Embodiment of this invention. It is a conceptual diagram of zero padding. It is a graph which shows the effect of the 1st example. It is a functional block diagram of the correction | amendment part which concerns on the 2nd Embodiment of this invention. It is a functional block diagram of the target information extraction part and 2nd correction | amendment part which concern on the 3rd Embodiment of this invention. It is a waveform graph at the time of performing alternately the beam direction control and transmission / reception of an antenna with the FMCW radar system which concerns on this invention. It is a graph which shows the time change of the transmission signal produced | generated by a chirp signal generation | occurrence | production part. It is a schematic block diagram and a waveform diagram of a conventional FMCW radar system.

First, the influence of the frequency characteristics of the reflection phase at the antenna input end is examined.
In the FMCW radar, assuming that the center frequency of the chirp signal, which is a transmission wave, is f _C , the sweep bandwidth is B, and the sweep time is T, the frequency f (t) of the transmission wave is expressed by [Equation 1].

  The phase of the transmission wave is obtained by time-integrating the angular frequency and can be expressed by [Equation 2].

  If the distance from the FMCW radar to the target is R, the phase of the received wave can be expressed by [Equation 3].

  On the other hand, the leaky wave generated when the transmission signal is reflected at the antenna input end is affected by the frequency characteristics of the reflection phase at the antenna input end, so the phase of the leaky wave is expressed by [Equation 4] and [Equation 5]. The

  The phase of the beat wave obtained by mixing this leak wave as a local signal with the received signal is the phase difference between the received signal and the leak signal, and can be expressed by [Equation 6].

In other words, when using a leaky wave as a local signal, the beat wave is also affected by the frequency characteristics of the reflection phase at the antenna input end, unlike when the transmission signal is branched to be a local signal or has an independent local oscillator circuit. It is understood that it receives.
The instantaneous angular frequency of the beat wave is expressed by [Expression 7] obtained by time-differentiating [Expression 6].

Here, the first term on the right side is the frequency of the beat wave determined by the distance to the target, and the second term on the right side shows the influence of the frequency characteristic of the reflection phase at the antenna input end.
If the frequency characteristic of the reflection phase at the antenna input end is flat, the second term on the right side becomes zero. However, generally, the frequency characteristic of the impedance at the antenna input end is not flat, so the second term does not become zero.

For this reason, when detecting the distance from the spectrum (distance profile) obtained by Fourier transform of the beat wave to the target, the peak becomes unclear and the resolution may be lowered.
Here, in order to examine the influence of the leak wave by specific numerical values, the frequency characteristic of the reflection phase at the antenna input end is modeled by [Equation 8].

For the frequency characteristic of the reflection phase at the antenna input end, it is sufficient to use a simple model whose first derivative is a monotone increasing function or a monotone decreasing function.
Here, FIG. 1 shows the frequency characteristics of the reflection phase of the antenna input end when A = π / 4 and T = 2.73 (microseconds), and the transmission signal f (t) is the center frequency f _C. Sometimes the maximum phase.

FIG. 2 shows distance profiles when A = 0, π / 4, π / 2, and π. When A = 0, the frequency characteristic of the reflection phase at the antenna input end is flat.
As can be seen from FIG. 2, when A = π / 4, the shape of the distance profile hardly changes although the side rope slightly rises. When A = π / 2, the gain decreases by about 1 dB and the side lobe also increases. When A = π, the gain decreases by about 4 dB, the shape of the distance profile changes greatly, and the influence is great.
Hereinafter, a method for avoiding the influence of the frequency characteristic of the reflection phase at the antenna input end will be described with reference to an embodiment.

FIG. 3 is a functional block diagram of the FMCW radar system according to the present invention.
That is, the FMCW radar system 1 according to the present invention receives a transmission unit 2 that generates a transmission wave radiated toward the target TG, and a reflected wave that is a transmission wave that is radiated in the air and reflected by the target TG. An antenna 3 that receives as a signal, a receiving unit 4 that extracts information about the target based on the received signal, and an antenna sharing unit 5 that outputs a transmission wave to the antenna 3 and outputs a reception wave to the receiving unit 4 are provided.

  The transmission unit 2 includes a local signal generation unit 21 that generates a local signal, a chirp signal generation unit 22 that generates a chirp signal, a transmission-side mixer 23 that mixes the local signal and the chirp signal to generate a transmission wave, A transmission-side control unit 24 that controls the local signal generation unit 21 and the chirp signal generation unit 22.

  The reception unit 4 includes a high-frequency amplification unit 40 that amplifies the leak wave and the reception signal, a two-terminal single-ended reception-side mixer 41 that generates a beat wave by mixing the leak wave and the reception signal, and a beat wave An HPF 42 that removes low frequency components, an error correction unit 43 that corrects an error caused by the frequency characteristic of the reflection phase of the antenna input included in the target information signal and generates a corrected signal, and the target from the corrected signal A target information extraction unit for extracting information.

FIG. 4 is a hardware configuration diagram of the FMCW radar system according to the present invention.
That is, the FMCW radar system 1 according to the present invention includes a local signal generation unit 21, a transmission-side mixer 23, an antenna 3, a reception-side mixer 41, an HPF 42, an antenna sharing unit 5, and a microcomputer 6.
The chirp signal generation unit 22, the transmission side control unit 24, the error correction unit 43, and the target information extraction unit 44 are configured by software by a program incorporated in the microcomputer 6.

  The microcomputer 6 has a configuration in which, for example, a CPU 61, a memory 63, an operation unit 64, a target information display unit 65, and a radar interface (I / F) 66 are coupled to each other around a bus 61.

  Here, the CPU 62 executes a control program for controlling the operation of the FMCW radar system 1, and the memory 63 stores the control program and the processing result of the CPU 62. The operation unit 64 and the target information display are displayed. The unit 65 functions as a man-machine I / F, and the radar I / F 66 operates with respect to the local signal generation unit 21, the transmission side mixer 23, the antenna 3, the reception side mixer 41, the HPF 42, and the antenna sharing unit 5. This is for outputting commands and taking in feedback signals from these to the microcomputer 6.

[First Embodiment]
FIG. 5 is a functional block diagram of the error correction unit 43 and the target information extraction unit 44 according to the first embodiment of the present invention. The error correction unit 43 is a stage subsequent to the HPF 42, and the target information extraction unit 44 is an error. It is arranged at the subsequent stage of the correction unit 43.
The error correction unit 43 includes an FFT unit 431, a zero padding unit 432, an IFFT unit 433, a correction coefficient calculation unit 434, and a multiplication unit 435.
Note that the forward conversion unit, the zero substitution unit, and the inverse conversion unit in the claims correspond to the FFT unit 431, the zero padding unit 432, and the IFFT unit 433, respectively.

As described above, the correction unit 43 and the target information extraction unit 44 are configured in software in the CPU 62.
The FFT unit 431 reads the beat wave s _IF (t), which is the output of the HPF 42, via the radar I / F 66, and performs Fourier transform to convert it into a frequency domain signal.
Here, the beat wave s _IF (t) is a cosine wave having a phase expressed by [Equation 6], and can be expressed by [Equation 9].

The Fourier transform S _IF (f) of [Equation 8] is expressed by [Equation 10].

The zero padding unit 432 replaces the negative part of the frequency f of S _IF (f) with zero (zero padding).
Zero padding is a process of replacing the value of the portion where the frequency f is negative (portion surrounded by a thick frame) with zero as shown in the conceptual diagram of FIG.

The IFFT unit 433 performs inverse Fourier transform on the signal S ′ _IF (f) after zero padding to obtain a time domain signal.
The signal after the inverse Fourier transform, that is, the output s ′ _IF (t) of the IFFT unit 433 is expressed by [Equation 12].

  The correction coefficient calculation unit 434 calculates the correction coefficient h (t) from [Equation 13] based on the frequency characteristic of the reflection phase at the antenna input end.

The reflection frequency characteristic Φ _A (f) at the antenna input end can be measured using a vector network analyzer or the like.
Then, the multiplication unit 435 multiplies the signal s ′ _IF (t) after the inverse Fourier return and the correction coefficient h (t), and outputs a corrected signal s ″ _IF (t) expressed by [Equation 14]. .

As can be seen from [Equation 14], the corrected signal s ″ _IF (t) does not include the frequency characteristic component of the reflection phase at the antenna input end.
The target information extraction unit 44 re-Fourier-transforms the corrected signal s ″ _IF (t), thereby obtaining an accurate distance profile that eliminates the influence of the frequency characteristic of the reflection phase at the antenna input end.
The accurate distance profile is output to the target information display unit 65.

FIG. 7 is a graph showing the effect of the present embodiment, and shows a distance profile (ideal profile) when the reflection frequency characteristic of the antenna input end is flat, a distance profile before correction, and a distance profile after correction.
In FIG. 7, the corrected distance profile matches the ideal profile, and it can be understood that the correction according to the present invention is effective.

[Second Embodiment]
FIG. 8 is a functional block diagram of the error correction unit 43 and the target information extraction unit 44 according to the second embodiment of the present invention. The error correction unit 43 includes a delay unit 436, an FIR filter unit 437, and a correction coefficient calculation. A unit 434 and a multiplication unit 435 are included.
The FIR filter unit 437 reads the beat wave s _IF (t) that is the output of the HPF 42 via the radar I / F 66, delays the phase by 90 degrees over the entire frequency band, and performs the inverse Fourier transform in the first embodiment. A signal corresponding to the imaginary part of the time domain is calculated.

The delay unit 436 delays the target information signal s _IF (t), which is the output of the HPF 42, by a time corresponding to the calculation time in the FIR filter unit 437, and the time domain real number after zero padding in the first embodiment. A signal corresponding to the part is calculated.
Note that the delay unit and the phase shift unit in the claims correspond to the delay unit 436 and the FIR filter unit 437, respectively.
Subsequent processing in the correction coefficient calculation unit 434, multiplication unit 435, and target information extraction unit 44 is the same as that in the first embodiment, and a description thereof will be omitted.
In the second embodiment, the target information signal is processed in the time domain, and finally converted into the frequency domain to obtain a distance profile.

[Third Embodiment]
In the first embodiment, after zero padding in the frequency domain, the signal is once converted into a time domain signal, multiplied by a correction coefficient, and converted to the frequency domain again.
As is well known, since time domain multiplication is the same as frequency domain convolution, the frequency domain signal after zero padding and the Fourier transform of the reflected frequency characteristic of the antenna input terminal expressed by [Equation 5] are calculated. An accurate distance profile can also be obtained by convolution integration.

FIG. 9 is a functional block diagram of the target information extraction unit 44 and the second error correction unit 45 according to the third embodiment of the present invention.
In other words, the target information extraction unit 44 is arranged downstream of the HPF 42, and the second error correction unit 45 is arranged downstream of the target information extraction unit 44.

The second error correction unit 45 includes a zero padding unit 432, a frequency domain correction coefficient calculation unit 451, and a convolution integration unit 452.
The target information extraction unit 44 converts the target information signal s _IF (t), which is the output of the HPF 42, into a signal in the frequency domain S _IF (f) expressed by [Equation 9].
The zero padding unit 432 of the second correction unit 45 is the same as that of the first embodiment, and performs zero padding represented by [Equation 10] on the frequency domain signal represented by [Equation 9]. The signal S ′ _IF (f) after zero padding is output.

The frequency domain correction coefficient calculation unit 451 calculates the frequency domain correction coefficient H (f) based on the frequency characteristic Φ _A (f) of the reflection phase shift at the antenna input end.
The convolution integration unit 452 performs convolution integration of the signal S ′ _IF (f) after zero padding and the frequency domain correction coefficient H (f) to obtain the frequency characteristic Φ _A (f) of the reflection phase shift at the antenna input end. An accurate distance profile from which the error caused by the error is removed is output.
In the third embodiment, the target information signal is processed in the frequency domain, and an accurate distance profile can be obtained directly.

[Fourth Embodiment]
The FMCW radar system described in the above embodiment is based on the premise that the antenna directivity is fixed. However, the present invention is also applicable to an FMCW radar system that alternately performs antenna beam direction control and transmission / reception. Is possible.

  FIG. 10 is a waveform graph when the beam direction control of the antenna and transmission / reception are alternately executed in the FMCW radar system according to the present invention, where (A) shows the transmission / reception timing, (B) shows the transmission wave waveform, (C) shows the output waveform of the receiving side mixer, and (D) shows the output waveform of the HPF.

That is, when the antenna beam direction control and the transmission / reception are performed alternately, the DC component of the output of the reception-side mixer 41 changes stepwise at the transmission start time and the transmission end time.
Since the step-like change of the DC component includes a high-frequency component, a pulse-like waveform (ringing) is generated at the output of the HPF 42.
For this reason, the beat wave is buried in the ringing, and the target detection capability may be reduced.

  Therefore, in order to avoid a decrease in target detection capability due to ringing, the present applicant has already proposed that an amplitude increasing signal is added before the chirp signal and an amplitude decreasing signal is added after the chirp signal (particularly, Application No. 2011-037272).

FIG. 11 is a graph showing temporal changes in the transmission signal generated by the chirp signal generator 22, wherein (E) shows the waveform, (F) shows the frequency, and (G) shows the temporal change in amplitude. .
That is, when an amplitude increase signal is generated, the frequency of the transmission signal is (f _c -B / 2), and the amplitude gradually increases from zero to a predetermined amplitude A.
When the chirp signal is generated, the amplitude of the transmission signal is maintained at a predetermined amplitude A, and the frequency changes with time from the initial frequency (f _c −B / 2) to the final frequency (f _c + B / 2).
When the amplitude gradually decreasing signal is generated, the frequency of the transmission signal is (f _c + B / 2), and the amplitude gradually decreases from the predetermined amplitude A to zero.

  By applying the first to third embodiments to such an FMCW radar system that alternately executes beam direction control and transmission / reception of antennas, detection due to ringing caused by intermittent transmission / reception is performed. Not only can the reduction in capability be suppressed, but also the reduction in detection capability due to the frequency characteristic of the reflection phase at the antenna input end can be reduced.

  The FMCW radar system according to the present invention can prevent deterioration of target detection capability even when a leak wave is used as a local signal, and is industrially useful.

DESCRIPTION OF SYMBOLS 1 ... FMCW radar system 2 ... Transmitter 3 ... Antenna 4 ... Receiver 5 ... Antenna shared unit 6 ... Microcomputer 21 ... Local signal generator 22 ... chirp signal generator 23 ... transmitter mixer 24 ... transmitter controller 40 ... high frequency amplifier 41 ... receiver mixer 42 ... HPF
43 ... Error correction unit 44 ... Target information extraction unit 61 ... Bus 62 ... CPU
63 ... Memory 64 ... Operation unit 65 ... Target information display unit 66 ... Radar interface

Claims (5)

A transmitter for generating a transmission wave radiated toward the target;
An antenna that radiates the transmitted wave into the air and receives a reflected wave that is a transmitted wave reflected by the target as a received wave;
A receiving unit that extracts information on the target based on the received wave;
An FMCW radar system comprising: an antenna sharing unit that outputs the transmission wave to the antenna and outputs the reception wave to the reception unit;
The transmitter comprises a local signal generator for generating a local signal, a chirp signal generator for generating a chirp signal, a transmitter mixer for mixing the local signal and the chirp signal into the transmission wave, and the local signal A signal generation unit and a transmission side control unit for controlling the chirp signal generation unit,
The receiving unit removes a low-frequency component of the beat wave, and a receiving-side mixer that generates a beat wave by mixing the leaked wave generated when the transmitted wave is reflected at the input end of the antenna and the received wave. A high-pass filter that generates a target information signal, an error correction unit that corrects an error caused by a frequency characteristic of a reflection phase of the input end of the antenna included in the target information signal, and generates a corrected signal; A FMCW radar system comprising: a target information extraction unit that extracts information about the target from a signal. The error correction unit is
A forward conversion unit for converting the target information signal into a frequency domain target information signal;
Replacing the negative frequency part of the frequency domain target information signal with zero and outputting a frequency domain correction target signal; and
An inverse transform unit that inversely transforms the frequency domain correction target signal into a time domain correction target signal;
A correction coefficient calculation unit that calculates a correction coefficient based on the frequency characteristic of the reflection phase of the antenna input terminal measured in advance;
The FMCW radar system according to claim 1, further comprising: a multiplication unit that multiplies the time domain correction target signal and the correction coefficient and outputs a time domain corrected signal. The error correction unit is
A phase shift unit that shifts the phase of the target information signal by 90 degrees in the entire frequency range, and outputs an imaginary component of the time domain correction target signal;
A delay unit that delays the target information signal by a phase shift processing time in the phase shift unit and outputs a real component of a time domain correction target signal;
A correction coefficient calculation unit that calculates a correction coefficient based on the reflection characteristics measured in advance;
The multiplication part which multiplies the said correction coefficient by the time domain correction object beat wave which synthesize | combined the imaginary number component and the real number component of the said time domain correction object signal, and outputs the signal after a time domain correction | amendment. FMCW radar system. The transmission-side control unit includes a transmission / reception start command output unit that intermittently outputs a transmission / reception start command,
The chirp signal generation unit, after reading the transmission / reception start command, an amplitude gradually increasing signal whose amplitude gradually increases from zero to a predetermined amplitude, a chirp signal whose frequency continuously changes in a predetermined range at the predetermined amplitude, The FMCW radar system according to any one of claims 1 to 3, wherein an amplitude gradually decreasing transmission signal whose amplitude gradually decreases from the predetermined amplitude to zero is sequentially output. A transmitter for generating a transmission wave radiated toward the target;
An antenna that radiates the transmitted wave into the air and receives a reflected wave that is a transmitted wave reflected by the target as a received wave;
A receiving unit that extracts information on the target based on the received wave;
An antenna sharing unit that outputs the transmission wave to the antenna and outputs the reception wave to the reception unit;
A control unit for controlling the transmission unit and the reception unit,
The transmission unit includes a local signal generation unit that generates a local signal, a chirp signal generation unit that generates a chirp signal, and a transmission-side mixer that mixes the local signal and the chirp signal into the transmission wave. ,
The reception unit removes a low-frequency component of the beat wave, and a reception-side mixer that generates a beat wave by mixing the leaked wave generated by reflection of the transmission wave at the input end of the antenna and the reception wave A control program for an FMCW radar system comprising a high-pass filter,
The control unit corrects an error caused by the frequency characteristic of the reflection phase of the input end of the antenna included in the target information signal, generates an corrected signal, and information on the target from the corrected signal FMCW radar system control program for functioning as a target information extraction unit for extracting

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