CN108776330B - High-precision calibration method and device for multiple receiving channels of FMCW radar - Google Patents
High-precision calibration method and device for multiple receiving channels of FMCW radar Download PDFInfo
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Abstract
The application discloses a high-precision calibration method and device for multiple receiving channels of an FMCW radar.
Description
Technical Field
The application relates to the technical field of radars, in particular to a high-precision calibration method and device for multiple receiving channels of an FMCW radar.
Background
Frequency Modulated Continuous Wave (FMCW) is a high-precision radar ranging technology, the basic principle is that the transmitted Wave is a high-Frequency continuous Wave, the Frequency of the transmitted Wave changes along with the time according to the rule of a triangular Wave, the Frequency of a return Wave received by a radar is the same as the change rule of the transmitted Frequency, the change rules are all the rules of the triangular Wave, and the target distance can be calculated by utilizing the time difference of the return Wave signals. Because the FMCW technology has the advantages of no distance blind area, high resolution, low transmitting power and the like, the FMCW technology is widely applied to the related fields of industrial measurement and control, security protection, missile guidance, meteorological detection, through-wall detection, mine detection systems, collision avoidance systems and the like.
With the increasing requirements for the signal processing of multi-receiving channel diversity or target angle measurement, the importance of the calibration of multiple receiving channels is more and more prominent, and for multi-channel radar angle measurement, as shown in fig. 5 to 7, the position of the target at the angle θ in the normal direction of the radar antenna, assuming two receiver channels, receiving channel a and receiving channel B, whose characteristics are identical, the delay of the signal from the antenna entrance to the output of the receiver is identical, and the gain of the signal is also identical, then the two receiving channels measure the phase difference
Then, the target is easily obtainedAs shown in fig. 5 to 7, since the difference in the path length from the plane wave reflected from the target to the antenna entrance is Δ R and the distance between the two antennas is d, the relationship between the phase difference and the path length difference can be obtained by combining Δ R and d · sin θ
The azimuth angle of the target can be obtained
Although the above process of obtaining the target azimuth is not complicated, the above calculation result of the target azimuth is accurate on the premise that the delays of the two receiving channels to the received signals are consistent and the phase differenceThe calculation is generally obtained by calculation after orthogonal decomposition of signals, which also requires that the receiving gains of two channels are completely consistent, but due to the discreteness of devices and PCB manufacturing errors, it is impossible to realize that the group delay and the gain of two receiving channels are completely consistent for a receiving link composed of analog circuits, and if the consistency of the receiving channels cannot meet the requirements, the performance of an advanced signal processing algorithm realized by means of multi-channel receiving is reduced or even fails, so that a high-precision calibration method needs to be provided for calibrating the analog channels, and the target detection capability and the angle measurement precision are improved.
Disclosure of Invention
The embodiment of the application provides a high-precision calibration method and device for multiple receiving channels of an FMCW radar, and solves the technical problem that a method for carrying out high-precision calibration on the multiple receiving channels of the radar and improving target detection capability and angle measurement precision is absent in the prior art.
In view of this, the first aspect of the present application provides a method for calibrating multiple receive channels of an FMCW radar with high precision, the method comprising:
101. acquiring a first echo signal of a standard receiving channel and a second echo signal of a calibration receiving channel when a plane where a radar wave reflector and a receiving antenna are located is away from a first preset distance;
102. obtaining a first gain of the first echo signal and a second gain of the second echo signal, and obtaining a first phase error phi of the first echo signal and the second echo signal by taking a quotient of the second gain and the first gain as an amplitude compensation factor1And presetting a complex carrier factor e-j2πτktWherein tau is the time delay of the target echo of the calibration receiving channel relative to the standard receiving channel,
is the slope of the FMCW signal;
103. when the radar wave reflector is away from the plane by a second preset distance, acquiring a third echo signal of the standard receiving channel and a fourth echo signal of the calibration receiving channel, wherein the second preset distance is not equal to the first preset distance;
104. obtaining a second phase error phi of the third echo signal and the fourth echo signal2According to said first phase error phi1And said second phase error phi2Calculating a phase compensation factor by a phase compensation factor calculation formula
T is the sum of the two-way path time delay of the radar detection target echo and the delay on the standard receiving channel, T1For the sum of the two-way path delay of the echo of the radar wave reflector at the first preset distance and the delay on the standard receiving channel, T2The delay sum of the two-way path delay of the echo of the radar wave reflector at the second preset distance and the delay on the standard receiving channel is obtained;
105. and the amplitude compensation factor is multiplied by the standard signal amplitude of the standard receiving channel to calibrate the amplitude of the calibration channel signal, the complex carrier factor is multiplied by the time domain signal of the calibration channel to calibrate the range gate of the calibration channel signal, and the difference between the phase of the standard channel signal and the phase compensation factor is taken as the phase of the calibration channel signal to calibrate the phase of the calibration channel signal.
Preferably, after step 104 and before step 105, the method further comprises:
106. storing the amplitude compensation factor, the complex carrier factor, and the phase compensation factor.
Preferably, step 102 specifically includes:
obtaining a first gain of the first echo signal and a second gain of the second echo signal, taking a quotient of the second gain and the first gain as an amplitude compensation factor, performing Fourier transform on the first echo signal and the second echo signal to respectively obtain a first Fourier transform signal and a second Fourier transform signal, and taking a phase difference of the first Fourier transform signal and the second Fourier transform signal as a first phase error phi1And presetting a complex carrier factor e-j2πτktWherein tau is the time delay of the target echo of the calibration receiving channel relative to the standard receiving channel,
is the slope of the FMCW signal.
Preferably, step 104 specifically includes:
fourier transformation is carried out on the third echo signal and the fourth echo signal to respectively obtain a third Fourier transformation signal and a fourth Fourier transformation, and the phase difference between the third Fourier transformation signal and the fourth Fourier transformation signal is taken as a second phase error phi2According to said first phase error phi1And said second phase error phi2Calculating a phase compensation factor by a phase compensation factor calculation formula
T is the sum of the two-way path time delay of the radar detection target echo and the delay on the standard receiving channel, T1For the two-way path of the echo of the radar wave reflector at the first preset distanceSum of time delay and delay on standard receiving channel, T2The sum of the two-way path delay of the echo of the radar wave reflector at the second preset distance and the delay on the standard receiving channel.
The second aspect of the present application provides a high-precision calibration apparatus for multiple receiving channels of an FMCW radar, the apparatus comprising:
the device comprises a first acquisition module, a second acquisition module and a calibration module, wherein the first acquisition module is used for acquiring a first echo signal of a standard receiving channel and a second echo signal of a calibration receiving channel when a plane where a radar wave reflector and a receiving antenna are located is away from a first preset distance;
a second obtaining module, configured to obtain a first gain of the first echo signal and a second gain of the second echo signal, and obtain a first phase error Φ of the first echo signal and the second echo signal by taking a quotient of the second gain and the first gain as an amplitude compensation factor1And presetting a complex carrier factor e-j2πτktWherein tau is the time delay of the target echo of the calibration receiving channel relative to the standard receiving channel,
is the slope of the FMCW signal;
a third obtaining module, configured to obtain a third echo signal of the standard receiving channel and a fourth echo signal of the calibration receiving channel when the radar wave reflector is away from the plane by a second preset distance, where the second preset distance is not equal to the first preset distance;
a fourth obtaining module, configured to obtain a second phase error phi of the third echo signal and the fourth echo signal2According to said first phase error phi1And said second phase error phi2Calculating a phase compensation factor by a phase compensation factor calculation formulaT is the sum of the two-way path time delay of the radar detection target echo and the delay on the standard receiving channel, T1For the sum of the two-way path delay of the echo of the radar wave reflector at the first preset distance and the delay on the standard receiving channel, T2The delay sum of the two-way path delay of the echo of the radar wave reflector at the second preset distance and the delay on the standard receiving channel is obtained;
and the calibration module is used for calibrating the amplitude of the calibration channel signal by multiplying the amplitude compensation factor by the amplitude of the standard signal of the standard receiving channel, calibrating the range gate of the calibration channel signal by multiplying the complex carrier factor by the time domain signal of the calibration channel, and calibrating the phase of the calibration channel signal by taking the difference between the phase of the standard channel signal and the phase compensation factor as the phase of the calibration channel signal.
Preferably, the apparatus further comprises:
and the storage module is used for storing the amplitude compensation factor, the complex carrier factor and the phase compensation factor.
Preferably, the second obtaining module is specifically configured to:
obtaining a first gain of the first echo signal and a second gain of the second echo signal, taking a quotient of the second gain and the first gain as an amplitude compensation factor, performing Fourier transform on the first echo signal and the second echo signal to respectively obtain a first Fourier transform signal and a second Fourier transform signal, and taking a phase difference of the first Fourier transform signal and the second Fourier transform signal as a first phase error phi1And presetting a complex carrier factor e-j2πτktWherein tau is the time delay of the target echo of the calibration receiving channel relative to the standard receiving channel,
is the slope of the FMCW signal.
Preferably, the fourth obtaining module is specifically configured to:
fourier transform is carried out on the third echo signal and the fourth echo signal to respectively obtain a third Fourier transform signal and a fourth Fourier transform, and the third Fourier transform signal and the fourth Fourier transform are processedA phase difference between the third Fourier transform signal and the fourth Fourier transform signal is used as a second phase error phi2According to said first phase error phi1And said second phase error phi2Calculating a phase compensation factor by a phase compensation factor calculation formula
T is the sum of the two-way path time delay of the radar detection target echo and the delay on the standard receiving channel, T1For the sum of the two-way path delay of the echo of the radar wave reflector at the first preset distance and the delay on the standard receiving channel, T2The sum of the two-way path delay of the echo of the radar wave reflector at the second preset distance and the delay on the standard receiving channel.
A third aspect of the present application provides a computer-readable storage medium for storing program code for executing any one of the above-mentioned methods for high-precision calibration of multiple receive channels of an FMCW radar.
A fourth aspect of the present application provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform any one of the above-described methods of high-precision calibration of FMCW radar multiple receive channels.
According to the technical scheme, the method has the following advantages:
the application provides a high-precision calibration method for multiple receiving channels of an FMCW radar, which includes the steps of obtaining a first echo signal of a standard receiving channel and a second echo signal of a calibration receiving channel when a radar wave reflector is away from a plane where a receiving antenna is located by a first preset distance, calculating a low first phase error of the first echo signal and the second echo signal by taking a quotient of a second gain and the first gain as an amplitude compensation factor according to the first echo signal and the second echo signal, presetting a complex carrier factor, obtaining a third echo signal of the standard receiving channel and a fourth echo signal of the calibration receiving channel when the radar wave reflector is away from the plane where the receiving antenna is located by a second preset distance, calculating a second phase error according to the third echo signal and the fourth echo signal, and calculating a phase compensation factor according to the first phase error and the second phase error through a phase compensation factor calculation formula, the amplitude compensation factor is multiplied by the standard signal amplitude of the standard receiving channel to calibrate the signal amplitude of the calibration channel, so that the consistency of gain can be ensured; the complex carrier factor is multiplied by the time domain signal of the calibration channel to calibrate the range gate of the calibration channel signal, and the frequency domain frequency shift of the signal can be equivalent to the time domain carrier shift, so that the time domain signal of the calibration channel is multiplied by the complex carrier factor, and then the time domain signal is converted into the frequency domain signal, and the range gate error between the standard receiving channel and the calibration receiving channel can be compensated; the difference between the phase of the standard channel signal and the phase compensation factor is used as the phase of the calibration channel signal to calibrate the phase of the calibration channel signal, so that the consistency of the phases is ensured. According to the method, the amplitude compensation factor, the complex carrier factor and the phase compensation factor are calculated, and the amplitude calibration, the range gate calibration and the phase calibration are respectively carried out on the signals of the calibration channel through the amplitude compensation factor, the complex carrier factor and the phase compensation factor, so that the multichannel consistency is ensured, the target detection capability and the angle measurement capability of the radar are improved, and the technical problem that the existing method for carrying out high-precision calibration on multiple receiving channels of the radar and improving the target detection capability and the angle measurement precision is lacked is solved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
FIG. 1 is a schematic flowchart of an embodiment of a method for calibrating multiple receiving channels of an FMCW radar with high accuracy according to the present disclosure;
FIG. 2 is a schematic flow chart of another embodiment of a method for calibrating multiple receiving channels of an FMCW radar in a high-precision manner according to the present disclosure;
FIG. 3 is a schematic structural diagram of a high-precision calibration device for multiple receiving channels of an FMCW radar provided by the present application;
FIG. 4 is a multi-channel calibration schematic diagram of a high-precision calibration method for multiple receiving channels of an FMCW radar provided by the present application;
FIG. 5 is a schematic block diagram of an FMCW radar circuit;
FIG. 6 is a schematic diagram of the transmitted signal and the echo signal of the FMCW radar ranging principle;
fig. 7 is a schematic diagram of the principle of angle measurement of two receiving channels.
Detailed Description
In order to make the technical solutions of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The application designs a high-precision calibration method and device for multiple receiving channels of an FMCW radar, which are characterized in that by calculating an amplitude compensation factor, a complex carrier factor and a phase compensation factor, the amplitude calibration, the range gate calibration and the phase calibration are respectively carried out on signals of a calibration channel through the amplitude compensation factor, the complex carrier factor and the phase compensation factor, the calibration precision of multiple channels is ensured, the target detection capability and the angle measurement capability of the radar are improved, and the technical problem that the existing method for carrying out high-precision calibration on the multiple receiving channels of the radar and improving the target detection capability and the angle measurement precision is lacked is solved.
For easy understanding, please refer to fig. 1 and 4, an embodiment of a method for calibrating multiple receive channels of an FMCW radar with high precision provided by the present application includes:
step 101: and acquiring a first echo signal of a standard receiving channel and a second echo signal of a calibration receiving channel when the radar wave reflector is away from the plane where the receiving antenna is located by a first preset distance.
It should be noted that, for a system with N (N ≧ 2) receiving channels, one channel needs to be selected as a standard receiving channel, and responses of other N-1 receiving channels and the standard receiving channel are calibrated to achieve the purpose of consistent responses of all receiving channels, and without loss of generality, in the embodiment of the present application, taking two receiving channels as an example, as shown in fig. 4, a receiving channel a is a standard receiving channel, a receiving channel B is a calibrated receiving channel, a radar wave reflector is placed in a normal direction of a radar antenna, and a center of the radar wave reflector is aligned with a center of the receiving antenna, a distance between the radar wave reflector and the receiving antenna satisfies a far-field condition, and a transmitting signal of a target is a far-field condition
Gain of the receiving channel A is
Gain of receiving channel B is
The first echo signal received by the receiving channel a and the second echo signal received by the receiving channel B are respectively the baseband signals after down-conversion
And
wherein tau is the time delay of the target echo of the calibration receiving channel relative to the standard receiving channel,is the slope of FMCW signal, T is the sum of the two-way path delay of radar detection target echo and the delay on the standard receiving channel.
Step 102: obtaining a first gain of the first echo signal and a second gain of the second echo signal, and dividing the second gain by the second gainObtaining a first phase error phi of the first echo signal and the second echo signal as an amplitude compensation factor1And presetting a complex carrier factor e-j2πτktWherein tau is the time delay of the target echo of the calibration receiving channel relative to the standard receiving channel,
is the slope of the FMCW signal.
It should be noted that, after obtaining the first echo signal and the second echo signal, the first gain of the first echo signal and the second gain of the second echo signal may be directly obtained, in this embodiment of the application, a quotient of the second gain of the second echo signal and the first gain of the first echo signal is used as an amplitude compensation factor, a difference between a phase of the first echo signal and a phase of the second echo signal is calculated, and a first phase error Φ may be obtained1While presetting a complex carrier factor e for calibrating a two-channel range gate-j2πτktWherein tau is the time delay of the target echo of the calibration receiving channel relative to the standard receiving channel,
is the slope of the FMCW signal.
Step 103: and when the radar wave reflector is away from the plane by a second preset distance, acquiring a third echo signal of the standard receiving channel and a fourth echo signal of the calibration receiving channel, wherein the second preset distance is not equal to the first preset distance.
It should be noted that the first phase error phi obtained in step 1021With initial frequency f of FMCWminThe method also relates to the signal slope k of FMCW, the two-way path delay of the target echo detected by radar, the sum T of the delay on the receiver channel A and the delay tau of the receiving channel B relative to the target echo of the receiving channel A, wherein tau is caused by the hardware inconsistency of the receiving antenna and the receiving channel, for example, the path delay caused by the routing difference of PCB or the internal process of components and parts, and the delay tau on each channel is fixed (the error caused by temperature is not considered, and the error caused by temperature is not considered) for a manufactured circuit productThe error influence caused by the degree is small and can be ignored), and the error can be measured by measuring instruments such as a frequency spectrograph. According to the conventional multi-channel angle measurement principle, as shown in fig. 5 to 7, the azimuth angle is calculated in the manner of
It can be seen that the calculation of the azimuth is only phase difference from the multipaths
The azimuth angle is in one-to-one correspondence with the phase difference under the condition that the inter-channel distance d is fixed, the azimuth angle of the target can be determined through the phase difference, and actually, the azimuth angle determination mode is inaccurate, because the distance between the target and the receiving channel also affects the phase of the received signal, therefore, the target distance needs to be taken into account to realize accurate calibration of the phase of the multi-channel received signal, therefore, the third echo signal of the standard receiving channel and the fourth echo signal of the calibration receiving channel are added when the radar wave reflector is obtained to be away from the plane by a second preset distance, wherein the second preset distance is not equal to the first preset distance, and the first preset distance and the second preset distance in the embodiment of the present application can be set according to practical application, and are not specifically limited herein.
104, obtaining a second phase error phi of the third echo signal and the fourth echo signal2According to the first phase error phi1And a second phase error phi2Calculating a phase compensation factor by a phase compensation factor calculation formula
T is the sum of the two-way path time delay of the radar detection target echo and the delay on the standard receiving channel, T1For the sum of the two-way path delay of the echo of the radar wave reflector at the first preset distance and the delay on the standard receiving channel, T2For the two-way path delay of the echo of the radar wave reflector at the second preset distance and on the standard receiving channelThe sum of the delays of (1).
It should be noted that, in this embodiment of the application, after the third echo signal and the fourth echo signal are obtained, in the same way, the same signal processing as the first echo signal and the second echo signal may be performed on the third echo signal and the fourth echo signal, so as to obtain a second phase error Φ of the third echo signal and the fourth echo signal2By adjusting the first phase error phi1And the second phase error phi2The calculation formulas are simultaneous, and a phase compensation factor calculation formula can be obtained
T is the sum of the two-way path time delay of the radar detection target echo and the delay on the standard receiving channel, T1For the sum of the two-way path delay of the echo of the radar wave reflector at the first preset distance and the delay on the standard receiving channel, T2The sum of the two-way path delay of the echo of the radar wave reflector at the second preset distance and the delay on the standard receiving channel. The phase compensation factor can be calculated according to a phase compensation factor calculation formula, obviously, the phase compensation factor is only related to the sum of the first phase error, the second phase error and the two-way path delay of the radar detection target echo and the delay on the standard receiving channel, and is not related to the delay tau of the receiving channel B relative to the target echo of the receiving channel A.
And 105, multiplying the amplitude compensation factor by the standard signal amplitude of the standard receiving channel to calibrate the amplitude of the calibration channel signal, multiplying the complex carrier factor by the time domain signal of the calibration channel to calibrate the range gate of the calibration channel signal, and taking the difference between the phase of the standard channel signal and the phase compensation factor as the phase of the calibration channel signal to calibrate the phase of the calibration channel signal.
It should be noted that, in the embodiment of the present application, the amplitude compensation factor is multiplied by the standard signal amplitude of the standard receiving channel to calibrate the signal amplitude of the calibration channel, so that the consistency of the gain can be ensured; the complex carrier factor is multiplied by the time domain signal of the calibration channel to calibrate the range gate of the calibration channel signal, and the frequency domain frequency shift of the signal can be equivalent to the time domain carrier shift, so that the time domain signal of the calibration channel is multiplied by the complex carrier factor, and then the time domain signal is converted into the frequency domain signal, and the range gate error between the standard receiving channel and the calibration receiving channel can be compensated; the difference between the phase of the standard channel signal and the phase compensation factor is used as the phase of the calibration channel signal to calibrate the phase of the calibration channel signal, so that the consistency of the phases is ensured.
The embodiment of the application provides a high-precision calibration method for multiple receiving channels of an FMCW radar, which includes obtaining a first echo signal of a standard receiving channel and a second echo signal of a calibration receiving channel when a radar wave reflector is away from a plane where a receiving antenna is located by a first preset distance, calculating a first phase error of the first echo signal and the second echo signal by taking a quotient of a second gain and the first gain as an amplitude compensation factor according to the first echo signal and the second echo signal, presetting a complex carrier factor, obtaining a third echo signal of the standard receiving channel and a fourth echo signal of the calibration receiving channel when the radar wave reflector is away from the plane where the receiving antenna is located by a second preset distance, calculating a second phase error according to the third echo signal and the fourth echo signal, calculating a phase compensation factor according to the first phase error and the second phase error through a phase compensation factor calculation formula, the amplitude compensation factor is multiplied by the standard signal amplitude of the standard receiving channel to calibrate the signal amplitude of the calibration channel, so that the consistency of gain can be ensured; the complex carrier factor is multiplied by the time domain signal of the calibration channel to calibrate the range gate of the calibration channel signal, and the frequency domain frequency shift of the signal can be equivalent to the time domain carrier shift, so that the time domain signal of the calibration channel is multiplied by the complex carrier factor, and then the time domain signal is converted into the frequency domain signal, and the range gate error between the standard receiving channel and the calibration receiving channel can be compensated; the difference between the phase of the standard channel signal and the phase compensation factor is used as the phase of the calibration channel signal to calibrate the phase of the calibration channel signal, so that the consistency of the phases is ensured. According to the method, the amplitude compensation factor, the complex carrier factor and the phase compensation factor are calculated, and the amplitude calibration, the range gate calibration and the phase calibration are respectively carried out on the signals of the calibration channel through the amplitude compensation factor, the complex carrier factor and the phase compensation factor, so that the multichannel consistency is ensured, the target detection capability and the angle measurement capability of the radar are improved, and the technical problem that the existing method for carrying out high-precision calibration on multiple receiving channels of the radar and improving the target detection capability and the angle measurement precision is lacked is solved.
For easy understanding, please refer to fig. 2 and fig. 4, another embodiment of the present application provides a method for calibrating multiple receive channels of an FMCW radar with high precision, including:
It should be noted that step 201 is identical to step 101, and will not be described in detail here.
It should be noted that, when the pulse radar tracks an aerial target, a range gate of a specific time zone is set, only the radar echo received in the time zone is analyzed, and the radar echo earlier or later than the time zone is not considered. As can be seen from the first echo signal and the second echo signal, the receiving channel B increases the delay τ compared to the receiving channel A, and the delay τ causes the same test object to pass throughAfter the two receiving channels are processed, the two receiving channels appear on different range gates, and the phases are different, so that the receiving channels are easy to cause inconsistent detection of the target distance, the diversity receiving effect cannot be achieved, and the azimuth angle of the target cannot be obtained through the target signal phase information of the two channels. In the embodiment of the present application, when the first echo signal is obtained
And
then, Fourier transform is respectively carried out on the first echo signal and the second echo signal to obtain a first Fourier transform signal
And a second Fourier transform signalObviously, the target signal of the reception channel B is delayed by τ k from the target signal of the reception channel A, the gain of which is that of the reception channel A
The phase of the receiving channel B is rotated more than that of the receiving channel AAnd (4) radian. For the delay tau k generated after the fourier transform is performed on the signals received by the two receiving channels, the time domain signals can be subjected to inverse complex modulation before the fourier transform, that is, the frequency shift of the frequency domain can be removed, and the complex carrier factor of the complex modulation is set as e-j2πτktThen, the second echo signal of the reception channel B is multiplied by a complex carrier factor e-j2πτktI.e. by
After Fourier transform, it can be obtained
For the impulse response function, the valid value is only when f is equal to Tk, and all other positions are 0, i.e. the distance gates of the signals of the two receiving channels are at the same position, so that the distance offset is compensated.
And 203, acquiring a third echo signal of the standard receiving channel and a fourth echo signal of the calibration receiving channel when the radar wave reflector is away from the plane by a second preset distance, wherein the second preset distance is not equal to the first preset distance.
It should be noted that step 203 is identical to step 103, and detailed description thereof is omitted here.
As can be seen from the description of step 202, the phase of the reception channel B is rotated more than that of the reception channel a
Radian, then the first phase error can be defined as phi1＝2πτfmin-πkτ2-2πkT1τ, it can be seen that the first phase error includes a fixed constant component 2 π τ fmin-πkτ2Distance-2 pi kT relative to target1τ. Then the radar wave reflector is arranged at a second preset distance which is different from the first preset distance in the normal direction of the plane of the receiving antenna, and a second phase error phi of the echo signals of the two receiving channels corresponding to the second preset distance can be obtained in the same way2＝2πτfmin-πkτ2-2πkT2τ, the first phase error and the second phase error are simultaneously obtained
Thus, the phase compensation factor can be derived
The detection of the target distance is the module value accumulation detection, so that the accumulation performance can not be reduced due to the phase error, and the target can be accumulated only on the same range gate, so that on the basis of solving the target distance, when the target direction is detected, only the phase error calibration needs to be carried out on the detected target point, and the data obtained after the calibration can be used for accurately detecting the target direction.
It should be noted that, in the embodiment of the present application, after obtaining the stored amplitude compensation factor, the complex carrier factor, and the phase compensation factor, the stored amplitude compensation factor, the stored complex carrier factor, and the stored phase compensation factor may be stored in the nonvolatile storage unit.
And step 206, the amplitude compensation factor is multiplied by the standard signal amplitude of the standard receiving channel to calibrate the amplitude of the calibration channel signal, the complex carrier factor is multiplied by the time domain signal of the calibration channel to calibrate the range gate of the calibration channel signal, and the difference between the phase of the standard channel signal and the phase compensation factor is used as the phase of the calibration channel signal to calibrate the phase of the calibration channel signal.
It should be noted that step 206 is identical to step 105, and will not be described in detail here.
For easy understanding, please refer to fig. 3, the present application provides an embodiment of a high-precision calibration apparatus for multiple receive channels of an FMCW radar, including:
the first obtaining module 301 is configured to obtain a first echo signal of a standard receiving channel and a second echo signal of a calibration receiving channel when a distance between the radar wave reflector and a plane where the receiving antenna is located is a first preset distance.
A second obtaining module 302, configured to obtain a first gain of the first echo signal and a second gain of the second echo signal, and obtain a first phase error phi of the first echo signal and the second echo signal by taking a quotient of the second gain and the first gain as an amplitude compensation factor1And presetting a complex carrier factor e-j2πτktWherein tau is the time delay of the target echo of the calibration receiving channel relative to the standard receiving channel,
is the slope of the FMCW signal.
A third obtaining module 303, configured to obtain a third echo signal of the standard receiving channel and a fourth echo signal of the calibration receiving channel when the radar wave reflector is away from the plane by a second preset distance, where the second preset distance is not equal to the first preset distance.
A fourth obtaining module 304 for obtaining a second phase error phi of the third echo signal and the fourth echo signal2According to the first phase error phi1And a second phase error phi2Calculating a phase compensation factor by a phase compensation factor calculation formulaT is the sum of the two-way path time delay of the radar detection target echo and the delay on the standard receiving channel, T1For the sum of the two-way path delay of the echo of the radar wave reflector at the first preset distance and the delay on the standard receiving channel, T2The sum of the two-way path delay of the echo of the radar wave reflector at the second preset distance and the delay on the standard receiving channel.
The calibration module 305 is configured to multiply the amplitude compensation factor by the standard signal amplitude of the standard receiving channel to calibrate the amplitude of the calibration channel signal, multiply the complex carrier factor by the time domain signal of the calibration channel to calibrate the range gate of the calibration channel signal, and use the difference between the phase of the standard channel signal and the phase compensation factor as the phase of the calibration channel signal to calibrate the phase of the calibration channel signal.
Further, the apparatus further comprises:
a storage module 306 for storing the amplitude compensation factor, the complex carrier factor and the phase compensation factor.
Further, the second obtaining module 302 is specifically configured to:
obtaining a first gain of a first echo signal and a second gain of a second echo signal, taking a quotient of the second gain and the first gain as an amplitude compensation factor, performing Fourier transform on the first echo signal and the second echo signal to respectively obtain a first Fourier transform signal and a second Fourier transform signal, and taking a phase difference of the first Fourier transform signal and the second Fourier transform signal as a first phase error phi1And presetting a complex carrier factor e-j2πτktWherein tau is the time delay of the target echo of the calibration receiving channel relative to the standard receiving channel,
is the slope of the FMCW signal.
Further, the fourth obtaining module 304 is specifically configured to:
fourier transformation is carried out on the third echo signal and the fourth echo signal to respectively obtain a third Fourier transformation signal and a fourth Fourier transformation, and the phase difference between the third Fourier transformation signal and the fourth Fourier transformation signal is taken as a second phase error phi2According to the first phase error phi1And a second phase error phi2Calculating a phase compensation factor by a phase compensation factor calculation formula
T is radar detectionTwo-way path delay of target echo and sum of delay on standard receiving channel, T1For the sum of the two-way path delay of the echo of the radar wave reflector at the first preset distance and the delay on the standard receiving channel, T2The sum of the two-way path delay of the echo of the radar wave reflector at the second preset distance and the delay on the standard receiving channel.
The present application further provides an embodiment of a computer-readable storage medium, which is configured to store program codes for performing any one of the foregoing methods for calibrating multiple receiving channels of an FMCW radar with high precision.
The present application further provides an embodiment of a computer program product comprising instructions, which when run on a computer, causes the computer to perform any one of the above-mentioned methods for high-precision calibration of multiple receive channels of an FMCW radar.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described apparatuses, devices and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
The terms "first," "second," "third," "fourth," and the like in the description of the application and the above-described figures, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, apparatus, article, or device that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or device.
In the several embodiments provided in the present application, it should be understood that the disclosed apparatus, device and method may be implemented in other manners. For example, the above-described device embodiments are merely illustrative, and for example, the division of the units is only one type of logical function division, and other division manners may be available in actual implementation, for example, a plurality of units or components may be combined or integrated into another device, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be substantially implemented or contributed to by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.
Claims (9)
1. A high-precision calibration method for multiple receiving channels of an FMCW radar is characterized by comprising the following steps:
101. acquiring a first echo signal of a standard receiving channel and a second echo signal of a calibration receiving channel when a plane where a radar wave reflector and a receiving antenna are located is away from a first preset distance;
102. obtaining a first gain of the first echo signal and a second gain of the second echo signal, taking a quotient of the second gain and the first gain as an amplitude compensation factor, and obtaining a first phase error phi of the first echo signal and the second echo signal1And presetting a complex carrier factor e-j2πτktWherein tau is the time delay of the target echo of the calibration receiving channel relative to the standard receiving channel,is the slope of the FMCW signal;
103. when the radar wave reflector is away from the plane by a second preset distance, acquiring a third echo signal of the standard receiving channel and a fourth echo signal of the calibration receiving channel, wherein the second preset distance is not equal to the first preset distance;
104. obtaining the third echo signal and the stationSecond phase error phi of the fourth echo signal2According to said first phase error phi1And said second phase error phi2Calculating a phase compensation factor by a phase compensation factor calculation formula
T is the sum of the two-way path time delay of the radar detection target echo and the delay on the standard receiving channel, T1For the sum of the two-way path delay of the echo of the radar wave reflector at the first preset distance and the delay on the standard receiving channel, T2The delay sum of the two-way path delay of the echo of the radar wave reflector at the second preset distance and the delay on the standard receiving channel is obtained;
105. and the amplitude compensation factor is multiplied by the standard signal amplitude of the standard receiving channel to calibrate the amplitude of the signal of the calibration receiving channel, the complex carrier factor is multiplied by the time domain signal of the calibration receiving channel to calibrate the range gate of the signal of the calibration receiving channel, and the difference between the phase of the signal of the standard receiving channel and the phase compensation factor is taken as the phase of the signal of the calibration receiving channel to calibrate the phase of the signal of the calibration receiving channel.
2. The method for calibrating FMCW radar multiple receive channels to a high accuracy as set forth in claim 1, wherein step 104 is followed by step 105, further comprising:
106. storing the amplitude compensation factor, the complex carrier factor, and the phase compensation factor.
3. The method for calibrating the FMCW radar multiple receive channels with high accuracy as set forth in claim 1, wherein step 102 specifically comprises:
fourier transformation is carried out on the first echo signal and the second echo signal to respectively obtain a first Fourier transformation signal and a second Fourier transformation signal, and the phases of the first Fourier transformation signal and the second Fourier transformation signal are usedThe difference being taken as the first phase error phi1。
4. The method for calibrating FMCW radar multiple receive channels with high accuracy as set forth in claim 1, wherein step 104 includes:
fourier transformation is carried out on the third echo signal and the fourth echo signal to respectively obtain a third Fourier transformation signal and a fourth Fourier transformation, and the phase difference between the third Fourier transformation signal and the fourth Fourier transformation signal is taken as a second phase error phi2According to said first phase error phi1And said second phase error phi2And calculating the phase compensation factor through a phase compensation factor calculation formula.
5. A high-precision calibration device for multiple receiving channels of an FMCW radar is characterized by comprising the following components:
the device comprises a first acquisition module, a second acquisition module and a calibration module, wherein the first acquisition module is used for acquiring a first echo signal of a standard receiving channel and a second echo signal of a calibration receiving channel when a plane where a radar wave reflector and a receiving antenna are located is away from a first preset distance;
a second obtaining module, configured to obtain a first gain of the first echo signal and a second gain of the second echo signal, and obtain a first phase error Φ of the first echo signal and the second echo signal by using a quotient of the second gain and the first gain as an amplitude compensation factor1And presetting a complex carrier factor e-j2πτktWherein tau is the time delay of the target echo of the calibration receiving channel relative to the standard receiving channel,
is the slope of the FMCW signal;
a third obtaining module, configured to obtain a third echo signal of the standard receiving channel and a fourth echo signal of the calibration receiving channel when the radar wave reflector is away from the plane by a second preset distance, where the second preset distance is not equal to the first preset distance;
a fourth obtaining module, configured to obtain a second phase error Φ of the third echo signal and the fourth echo signal2According to said first phase error phi1And said second phase error phi2Calculating a phase compensation factor by a phase compensation factor calculation formula
T is the sum of the two-way path time delay of the radar detection target echo and the delay on the standard receiving channel, T1For the sum of the two-way path delay of the echo of the radar wave reflector at the first preset distance and the delay on the standard receiving channel, T2The delay sum of the two-way path delay of the echo of the radar wave reflector at the second preset distance and the delay on the standard receiving channel is obtained;
and the calibration module is used for calibrating the amplitude of the signal of the calibration receiving channel by multiplying the amplitude compensation factor by the amplitude of the standard signal of the standard receiving channel, calibrating the range gate of the signal of the calibration receiving channel by multiplying the complex carrier factor by the time domain signal of the calibration receiving channel, and calibrating the phase of the signal of the calibration receiving channel by taking the difference between the phase of the signal of the standard receiving channel and the phase compensation factor as the phase of the signal of the calibration receiving channel.
6. The FMCW radar multiple receive channel high accuracy calibration apparatus as set forth in claim 5, further including:
and the storage module is used for storing the amplitude compensation factor, the complex carrier factor and the phase compensation factor.
7. The FMCW radar multi-receive channel high accuracy calibration apparatus as set forth in claim 5, wherein the second acquisition module is further configured to:
fourier transformation is carried out on the first echo signal and the second echo signal to respectively obtain first Fourier transformationConverting the signal and a second Fourier transform signal, and taking the phase difference of the first Fourier transform signal and the second Fourier transform signal as a first phase error phi1。
8. The FMCW radar multi-receive channel high accuracy calibration apparatus as set forth in claim 5, wherein the fourth acquisition module is further configured to:
fourier transformation is carried out on the third echo signal and the fourth echo signal to respectively obtain a third Fourier transformation signal and a fourth Fourier transformation, and the phase difference between the third Fourier transformation signal and the fourth Fourier transformation signal is taken as a second phase error phi2According to said first phase error phi1And said second phase error phi2And calculating the phase compensation factor through a phase compensation factor calculation formula.
9. A computer-readable storage medium for storing program code for performing the method for high-precision calibration of radar multiple receive channels of any one of claims 1-4.
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| CN111679254B (en) * | 2020-05-13 | 2022-03-25 | 苏州理工雷科传感技术有限公司 | Multichannel calibration method for linear frequency modulation signal MIMO radar system |
| CN111624598B (en) * | 2020-06-11 | 2023-07-18 | 石家庄铁道大学 | Millimeter wave radar-based structure dynamic deformation measurement signal processing method |
| CN111901261B (en) * | 2020-07-03 | 2022-04-05 | 锐迪科创微电子（北京）有限公司 | Method and device for calibrating amplitude offset and storage medium |
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| CN112946589B (en) * | 2021-02-01 | 2022-09-06 | 上海交通大学 | Phase self-calibration method for motion measurement of asynchronous FMCW radar system |
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