CN114096873A - Linear frequency sweep correction method, device, storage medium and system - Google Patents
Linear frequency sweep correction method, device, storage medium and system Download PDFInfo
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- CN114096873A CN114096873A CN202080004310.4A CN202080004310A CN114096873A CN 114096873 A CN114096873 A CN 114096873A CN 202080004310 A CN202080004310 A CN 202080004310A CN 114096873 A CN114096873 A CN 114096873A
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
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Abstract
The embodiment of the application discloses a linear frequency sweep correction method, a linear frequency sweep correction device, a storage medium and a linear frequency sweep correction system, wherein the method comprises the following steps: generating a first drive current signal; pre-correcting the first driving current signal to obtain a target driving current signal; determining the target drive current signal as a linearly swept drive signal. By adopting the embodiment of the application, the first driving current signal can be corrected to generate the target driving current signal meeting the sweep frequency linearity requirement under the condition of ensuring low cost and real-time requirement.
Description
The present application relates to the field of computer technologies, and in particular, to a linear frequency sweep correction method, apparatus, storage medium, and system.
The laser radar is a radar system that detects a characteristic amount such as a position and a velocity of a target by emitting a laser beam. The ranging principle of the FMCW laser radar is that continuous waves with linearly changing frequency are transmitted in a frequency sweep period to serve as outgoing signals, one part of the outgoing signals serve as local oscillation signals, the other part of the outgoing signals are outgoing outwards for detection, a certain frequency difference exists between echo signals returned after being reflected by an object and the local oscillation signals, and distance information between a detected target and the radar can be obtained by measuring the frequency difference. Laser radar is widely applied to the fields of automatic driving, robots, aviation mapping and the like due to the characteristics of long detection distance and high ranging precision.
Wherein, emitting continuous wave with linearly changing frequency in the sweep frequency period can be understood as laser linear sweep frequency. The energy of the beat frequency spectrum of the linear swept frequency signal is concentrated at the signal frequency. However, in practical situations, the nonlinearity of the sweep frequency will cause the frequency spectrum of the beat frequency signal to widen, which leads to the decrease of the accuracy of measuring distance and speed, and simultaneously, the signal amplitude of the adjacent frequency point due to the energy spread also decreases, which leads to the decrease of the signal-to-noise ratio, which leads to the decrease of the maximum range measurement range of the system. Therefore, it is particularly important for the FMCW lidar system to improve the linearity of the frequency sweep of the frequency-swept optical source.
At present, various methods exist for overcoming the frequency sweep nonlinearity of a laser radar system, the system structure is complex, and the requirement of high linearity is difficult to meet.
Disclosure of Invention
The embodiment of the application provides a linear frequency sweep correction method, a linear frequency sweep correction device, a storage medium and a linear frequency sweep correction system, and under the condition that low cost and real-time requirements are guaranteed, a first driving current signal can be corrected to generate a target driving current signal meeting the requirement of frequency sweep linearity. The technical scheme is as follows:
in a first aspect, an embodiment of the present application provides a linear frequency sweep correction method, where the method includes:
generating a first drive current signal;
pre-correcting the first driving current signal to obtain a target driving current signal;
determining the target drive current signal as a linearly swept drive signal.
In a second aspect, an embodiment of the present application provides a linear frequency sweep correction method, where the method includes:
generating a first drive current signal;
performing iterative approximation correction on the first driving current signal to obtain a target driving current signal;
determining the target drive current signal as a linearly swept drive signal.
In a third aspect, an embodiment of the present application provides a linear frequency sweep correction apparatus, where the apparatus includes:
the signal generation module is used for generating a first driving current signal;
the pre-correction module is used for pre-correcting the first driving current signal to obtain a target driving current signal;
and the signal determination module is used for determining the target driving current signal as a linear swept frequency driving signal.
In a fourth aspect, an embodiment of the present application provides a linear frequency sweep correction apparatus, where the apparatus includes:
the signal generation module is used for generating a first driving current signal;
the iterative correction module is used for carrying out iterative approximation correction on the first driving current signal to obtain a target driving current signal;
and the signal determination module is used for determining the target driving current signal as a linear swept frequency driving signal.
In a fifth aspect, an embodiment of the present application provides a computer storage medium storing a plurality of instructions, the instructions being adapted to be loaded by a processor and to execute the linear sweep correction method described above.
In a sixth aspect, an embodiment of the present application provides a laser linear frequency sweep correction system, which may include: a processor and a memory; wherein the memory stores a computer program adapted to be loaded by the processor and to perform the linear sweep frequency correction method described above.
The beneficial effects brought by the technical scheme provided by some embodiments of the application at least comprise:
in one or more embodiments of the present application, a target driving current signal meeting the requirement of frequency sweep linearity is obtained by pre-correcting a first driving current signal, or an iterative approach correction is performed on the first driving current signal to obtain a target driving current signal meeting the requirement of frequency sweep linearity, without adding other hardware and additional algorithms in an actual FMCW system, under the condition of ensuring low cost and real-time requirements, the first driving current signal can be corrected to generate a target driving current signal meeting the requirement of frequency sweep linearity, and during actual operation, a laser is swept according to a correction waveform as a driving signal.
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is an exemplary schematic diagram of an FMCW ranging principle provided in an embodiment of the present application;
FIG. 2 is a schematic diagram of time-frequency waveforms of a linear frequency sweep and a non-linear frequency sweep provided by an embodiment of the present application;
FIG. 3 is an exemplary diagram of a linear frequency amplitude waveform and a non-linear frequency waveform provided by an embodiment of the present application;
fig. 4 is a schematic flowchart of a linear frequency sweep correction method according to an embodiment of the present application;
fig. 5 is a schematic flow chart of a signal pre-correction method according to an embodiment of the present application;
fig. 6 is a schematic structural diagram of a laser linear frequency sweep correction system according to an embodiment of the present disclosure;
fig. 7 is a schematic flowchart of a linear frequency sweep correction method according to an embodiment of the present application;
FIG. 8 is a flowchart illustrating a method for iterative approximation correction of a signal according to an embodiment of the present disclosure;
fig. 9 is a schematic flowchart of a linear frequency sweep correction method according to an embodiment of the present application;
fig. 10 is a schematic structural diagram of a linear frequency sweep correction apparatus according to an embodiment of the present application;
fig. 11 is a schematic structural diagram of a linear frequency sweep correction apparatus according to an embodiment of the present application;
fig. 12 is a schematic structural diagram of a laser linear frequency sweep correction system according to an embodiment of the present application.
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 of the 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.
In the description of the present application, it is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In the description of the present application, it is noted that, unless explicitly stated or limited otherwise, "including" and "having" and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art. Further, in the description of the present application, "a plurality" means two or more unless otherwise specified. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.
For a laser radar, such as a Frequency Modulated Continuous Wave (FMCW) laser radar, speed measurement and distance measurement are realized by a coherent detection principle, a system transmits Continuous laser with linearly changing Frequency (triangular Wave or sawtooth Wave) in a Frequency sweep period, echo light reflected by an object interferes with local oscillator light on a reference arm, a generated beat signal is detected by a photoelectric detector, and the distance and the speed of a target are calculated by measuring the Frequency of the beat signal. As shown in FIG. 1, the center wavelength of the swept laser is λ, the sweep period is T, the sweep bandwidth is B, and the beat signal is fb-And fb+Then the distance of the target can be obtained
And velocity
The FMCW laser radar belongs to a continuous wave laser radar based on coherent detection. A light source with continuously changed frequency is needed, the sweep frequency range is usually from hundreds of MHz to dozens of GHz, generally triangular waves are used for modulation, and the modulation frequency is generally from 10kHz to 100 kHz. And FMCW laser radar has higher requirements on the continuity and the linearity of an emergent signal, so that the difference between a local oscillation signal and an echo signal is stable, and other variables caused by waveform change nonlinearity are avoided. As a light source, a current-modulated Distributed Feedback (DFB) semiconductor laser or an External Cavity semiconductor laser (ECDL) may be generally used.
FMCW has the principle of utilizing coherent detection, the range finding precision is high; compared with a direct detection mode, the anti-interference performance is strong; speed and distance can be measured simultaneously; and continuous light emission, does not need very high peak power, and the system has low power consumption, is safe to human eyes, and the like, and is widely applied to the fields of automatic driving, robots, aviation mapping and the like.
According to different frequency modulation principles, frequency-modulated lasers are classified into mechanical frequency modulation, temperature frequency modulation, current frequency-modulated lasers and the like, but in any mode, the change of laser output frequency is realized by controlling the change of the cavity length, the temperature, the carrier concentration and the like of a resonant cavity of the laser through external driving current. As shown in fig. 2, the driving current is a triangular wave, and ideally, the frequency should strictly change linearly with time, but in reality, the laser output frequency is not linearly related to the driving current, so that the sweep frequency of the frequency-modulated laser has nonlinearity. Maximum frequency deviation | delta f in frequency sweep rangemaxThe smaller the ratio of | to the sweep range B, the better the sweep linearity.
Wherein linearity is defined as the maximum frequency offset | Δ f over the sweep rangemaxThe ratio of L to the sweep range B, i.e. L ═ Δ fmax|/B
The smaller L, the better the linearity.
The beat frequency spectrum of a strictly linear swept frequency signal is shown in fig. 3(a), where the energy is concentrated at the signal frequency. However, in practical situations, the nonlinearity of the frequency sweep will cause the spectrum of the beat frequency signal to widen, as shown in fig. 3(b), which causes the accuracy of measuring distance and speed to decrease, and at the same time, the signal amplitude of the frequency point that the energy spreads to nearby decreases, which causes the signal-to-noise ratio to decrease, and causes the maximum range of the system to decrease. Therefore, it is particularly important for the FMCW system to improve the linearity of the frequency sweep of the swept-frequency light source.
The linear frequency sweep correction method provided by the embodiment of the present application is described in detail below with reference to specific embodiments. The method may be implemented in dependence on a computer program, operable on a linear sweep correction device based on the von neumann architecture. The computer program may be integrated into the application or may run as a separate tool-like application. The linear frequency sweep correction device in the embodiment of the application can be a laser linear frequency sweep system, and the laser is a frequency modulation laser.
Please refer to fig. 4, which is a flowchart illustrating a linear frequency sweep calibration method according to an embodiment of the present application. Including pre-calibration, as shown in fig. 4, the method of the embodiments of the present application may include the steps of:
s101, generating a first driving current signal;
in order to ensure the sweep linearity of the laser, the modulation signal needs to be adjusted.
Specifically, the first driving current signal is an initial modulation signal for loading to the laser. Wherein the first driving current signal I can be generated using an arbitrary waveform generator (e.g., a function signal generator)1(t)。
S102, pre-correcting the first driving current signal to obtain a target driving current signal;
assuming that under linear modulation (triangular wave), i.e. when the modulation signal is i (t) ═ k × t + b, the frequency time function of the laser output is f (t) ═ f [ i (t) ] ═ f (k × t + b); as mentioned above, since the frequency of the laser output and the first drive current signal are not linear, f (t) is a non-linear function.
If the modulated signal is converted to I' (t) ═ f-1(k t + b), the frequency time function of the laser output is f ' (t) f ' [ I ' (t)]＝f[f -1(k*t+b)]K × t + b, it is clear that f' (t) is a linear function.
Therefore, the drive current signal can be corrected into an inverse function of a laser frequency time function under linear modulation to realize the pre-correction of linearity, and the pre-corrected modulation signal is a target drive current signal.
For a specific pre-calibration process, see S201 and S202, as shown in fig. 5:
s201, acquiring a first time frequency function corresponding to the first driving current signal;
fig. 6 is a schematic diagram of a linear frequency sweep system of a laser, in which an arbitrary waveform generator is used to randomly generate a first driving current signal, and input the first driving current signal to a frequency-modulated laser, so as to inject a rated working current into the laser, so that the laser emits light normally. The output of the laser passes through the Mach-ZehnderAn Interferometer (Mach-Zehnder Interferometer) generates an optical beat frequency signal, the optical beat frequency signal is measured by a balanced detector, a beat frequency time domain signal is obtained through a data acquisition unit (or an oscilloscope), the time domain signal is processed and analyzed through an upper computer, for example, the upper computer is used for carrying out Hilbert transform or Fourier transform on the time domain signal of the balanced detector, or an optical frequency discriminator is adopted, and a first time frequency function f is obtained through calculation1(t)。
S202, calculating an inverse function of the first time frequency function, and taking the inverse function as a target driving current signal.
The first driving current signal is
And S103, determining the target driving current signal as a linear swept frequency driving signal.
And S104, storing the driving signal of the linear frequency sweep.
The driving signal is stored in an FMCW system, and when the FMCW system works actually, the linearity requirement can be met by using the correction waveform as the driving signal to sweep the laser.
In the embodiment of the application, the target driving current signal meeting the sweep frequency linearity requirement can be obtained by pre-correcting the first driving current signal. The first drive current signal can be corrected to generate a target drive current signal meeting the sweep linearity requirement without adding other hardware and additional algorithms in an actual FMCW system under the condition of ensuring low cost and real-time requirements, and the laser is swept according to the correction waveform as the drive signal during actual work.
Please refer to fig. 7, which is a flowchart illustrating a linear frequency sweep calibration method according to an embodiment of the present application. Including iterative approximation correction, as shown in fig. 7, the method of the embodiment of the present application may include the steps of:
s301, generating a first driving current signal;
it will be appreciated that the first drive current signalIs a randomly generated initial current signal for loading onto the laser. May be generated by a random generator. Wherein the first driving current signal I can be generated using an arbitrary waveform generator (e.g., a function signal generator)1(t)。
S302, performing iterative approximation correction on the first driving current signal to obtain a target driving current signal;
the specific iterative approximation correction process can be seen in S401 and S405, as shown in fig. 8:
s401, acquiring a first time frequency function corresponding to the first driving current signal and a theoretical time frequency function;
as shown in FIG. 6, a pre-corrected output signal I is first used1(t) initial input signal I as an iterative approximation correctionk(t), using any waveform generator to sweep frequency and drive the laser, using the output of the laser to generate an optical beat frequency signal through a Mach-Zehnder interferometer, measuring the optical beat frequency signal by using a balance detector, obtaining a beat frequency time domain signal through a data acquisition unit (or an oscilloscope), using an upper computer to perform frequency domain transformation on the time domain signal of the balance detector, and calculating to obtain Ik(t) corresponding first time-frequency function fk(t) of (d). At the same time, the theoretical time-frequency function f (t) is calculated. Wherein F (t) is a linear function.
S402, calculating a difference value between the theoretical time frequency function and the first time frequency function, and taking the difference value as an error function;
and performing iterative approximation correction on the first driving current signal based on the error function and the linearity threshold value to obtain a target driving current signal after iterative approximation correction.
In particular, the error function ek(t)＝F(t)-f k(t)。
S403, when the maximum value of the absolute value of the error function is smaller than a linearity threshold value, taking the second driving current signal as a target driving current signal;
the threshold of linearity is L when max | ek(t)|<When L is higher, f is shownk(t) can meet the linear sweep frequency requirement, then the second drive current signal I1And (t) is the driving signal of the linear frequency sweep.
S404, when the maximum value of the absolute value of the error function is not less than the linearity threshold, adjusting the first driving current signal to generate a second driving current signal;
when the maximum value of the absolute value of the error function is not less than the linearity threshold value, calculating the product of the error function and a preset weight;
when max | ek(t) | is equal to or greater than L, indicating that fk(t) if the linear sweep frequency requirement cannot be met, the first drive current signal I needs to be adjusted continuouslyk(t) of (d). Specifically, a.e is calculatedk(t), wherein a is the coefficient of the driving current error with frequency.
Second drive current signal Ik+1(t)＝I k(t)+a·e k(t)
S405, the second driving current signal is used as the first driving current signal, and the step of obtaining the first time frequency function corresponding to the first driving current signal and the theoretical time frequency function is executed.
The modified signal Ik+1(t) inputting the value laser as a new input waveform, repeating the above steps until the frequency error is a function of time ekThe maximum value of (t) is less than the linearity index L required by the system.
And S303, determining the target driving current signal as a linear swept frequency driving signal.
And S304, storing the driving signal of the linear frequency sweep.
The driving signal is stored in an FMCW system, and when the FMCW system works actually, the linearity requirement can be met by using the correction waveform as the driving signal to sweep the laser.
In the embodiment of the application, the target driving current signal meeting the sweep frequency linearity requirement is obtained by performing iterative approximation correction on the first driving current signal. The first drive current signal can be corrected to generate a target drive current signal meeting the sweep linearity requirement without adding other hardware and additional algorithms in an actual FMCW system under the condition of ensuring low cost and real-time requirements, and the laser is swept according to the correction waveform as the drive signal during actual work. Compared with the traditional open-loop correction method, the correction effect does not depend on the numerical model of the frequency-modulated laser, and the linearity L <0.001 can be achieved by the method through an iterative approximation method.
Referring to fig. 9, a schematic flow chart of a linear frequency sweep correction method provided in the embodiment of the present application includes pre-correction and iterative approximation correction, and as shown in fig. 9, the method in the embodiment of the present application may include the following steps:
s501, generating a first driving current signal;
specifically, the first driving current signal is an initial modulation signal for loading to the laser. Wherein the first driving current signal I can be generated using an arbitrary waveform generator (e.g., a function signal generator)1(t)。
As shown in fig. 6, the purpose of the whole system is to obtain a corrected driving current waveform i (t) at a preset chirp frequency, and to ensure that a frequency-time curve f (t) output by the laser meets the linearity requirement under the modulation of the driving current waveform. Wherein an arbitrary waveform generator (function signal generator) is used to generate the modulation signal I1(t) is applied to a frequency-modulated laser.
S502, pre-correcting the first driving current signal to obtain a second driving current signal;
the pre-calibration principle can be seen in S102, which is not described herein.
In particular, the output I of the laser1And (t) generating an optical beat frequency signal by a Mach-Zehnder Interferometer, measuring by using a balanced detector, acquiring a beat frequency time domain signal by using a data acquisition unit (or an oscilloscope), and processing and analyzing the time domain signal by using an upper computer to generate a new modulation waveform, namely a second driving current signal I' (t).
Generally, the pre-correction method can only primarily improve the sweep linearity of the laser, and reduce the sweep linearity L to about 0.05, but cannot further improve the linearity. The specific reasons are that: the pre-correction process is to consider the frequency-current impulse response function as an ideal delta function, and in practical situations, due to the laser frequency modulation principle, the response bandwidth cannot be infinite, so the frequency-current impulse response function cannot be completely considered as the ideal delta function. And further improvement of linearity is realized through iterative approximation correction.
S503, carrying out iterative approximation correction on the second driving current signal to obtain a target driving current signal;
first, the second drive current signal I' (t) of the output of the pre-calibration module is used as the initial input waveform I of the iterative approximation modulekAnd (t) performing sweep frequency driving on the laser by using an arbitrary waveform generator. Then, the upper computer is used for carrying out time domain-frequency domain transformation (such as Hilbert transformation) on the time domain signal of the balance detector, and a frequency-time curve f is obtained through calculationk(t) of (d). Then calculating the actual frequency-time function fk(t) frequency error versus time function e of the frequency versus time function F (t) of the ideal linear sweepk(t)＝F(t)-f k(t) of (d). Determining a frequency error versus time function ek(t) whether the maximum value is less than the linearity index L required by the system, if so, driving current I at the momentk(t) is the correction waveform to be acquired; if not, then it is necessary to follow the error-time function ek(t) for the drive current Ik(t) performing iterative correction, wherein the corrected drive current signal is Ik+1(t)＝I k(t)+a·e k(t)。
Wherein a is the coefficient of the driving current along with the frequency error, and the corrected waveform Ik+1(t) substituting the new input waveform into the iterative approximation module, and repeating the above steps until the frequency error is a time function ekThe maximum value of (t) is less than the linearity index L required by the system.
And S504, determining the target driving current signal as a linear frequency sweep driving signal.
And S505, storing the driving signal of the linear frequency sweep.
The driving signal is stored in an FMCW system, and when the FMCW system works actually, the linearity requirement can be met by using the correction waveform as the driving signal to sweep the laser.
In one or more embodiments of the present application, a first driving current signal is pre-corrected, and a second driving current signal after pre-correction is subjected to iterative approximation correction, so that a target driving current signal meeting the requirement of frequency sweep linearity can be obtained, without adding other hardware and additional algorithms in an actual FMCW system, and under the condition of ensuring low cost and real-time requirements, the first driving current signal can be corrected to generate a target driving current signal meeting the requirement of frequency sweep linearity, and during actual operation, a laser is subjected to frequency sweep by using a correction waveform as a driving signal.
The following are embodiments of the apparatus of the present application that may be used to perform embodiments of the method of the present application. For details which are not disclosed in the embodiments of the apparatus of the present application, reference is made to the embodiments of the method of the present application.
Please refer to fig. 10, which shows a schematic structural diagram of a linear frequency sweep correction apparatus according to an exemplary embodiment of the present application. The linear sweep correction device may be implemented as all or part of the laser in software, hardware, or a combination of both. The apparatus 1 comprises a signal generation module 11, a pre-correction module 12 and a signal determination module 13.
A signal generating module 11, configured to generate a first driving current signal;
the pre-correction module 12 is configured to pre-correct the first driving current signal to obtain a target driving current signal;
a signal determining module 13, configured to determine the target driving current signal as a linear swept driving signal.
Optionally, the pre-correction module 12 is specifically configured to:
acquiring a first time frequency function corresponding to the first driving current signal;
and calculating an inverse function of the first time-frequency function, and taking the inverse function as a second driving current signal.
Optionally, the signal determining module 13 is further configured to:
and when the inverse function is a linear function, determining the second driving current signal as a driving signal of a linear frequency sweep.
Optionally, the apparatus further comprises:
and the signal storage module 14 is used for storing the driving signal of the linear frequency sweep.
It should be noted that, when the linear frequency sweep correction apparatus provided in the foregoing embodiment executes the linear frequency sweep correction method, only the division of the functional modules is illustrated, and in practical applications, the functions may be distributed by different functional modules according to needs, that is, the internal structure of the device is divided into different functional modules, so as to complete all or part of the functions described above. In addition, the linear frequency sweep correction device and the linear frequency sweep correction method provided by the above embodiments belong to the same concept, and the details of the implementation process are referred to as method embodiments, which are not described herein again.
The above-mentioned serial numbers of the embodiments of the present application are merely for description and do not represent the merits of the embodiments.
In the embodiment of the application, the target driving current signal meeting the sweep frequency linearity requirement can be obtained by pre-correcting the first driving current signal. The first drive current signal can be corrected to generate a target drive current signal meeting the sweep linearity requirement without adding other hardware and additional algorithms in an actual FMCW system under the condition of ensuring low cost and real-time requirements, and the laser is swept according to the correction waveform as the drive signal during actual work.
Please refer to fig. 11, which shows a schematic structural diagram of a linear frequency sweep correction apparatus according to an exemplary embodiment of the present application. The linear sweep correction device may be implemented as all or part of the laser in software, hardware, or a combination of both. The apparatus 2 comprises a signal generation module 21, an iterative correction module 22 and a signal determination module 23.
A signal generation module 21 that generates a first drive current signal;
the iterative correction module 22 is configured to perform iterative approximation correction on the first driving current signal to obtain a target driving current signal;
a signal determination module 23, configured to determine the target driving current signal as a linear swept driving signal.
Optionally, the iterative correction module 22 is specifically configured to:
acquiring a second time frequency function corresponding to the second driving current signal and a theoretical time frequency function;
calculating a difference value between the theoretical time-frequency function and the second time-frequency function, and taking the difference value as an error function;
and performing iterative approximation correction on the second driving current signal based on the error function and the linearity threshold value to obtain a target driving current signal after iterative approximation correction.
Optionally, the iterative correction module 22 is specifically configured to:
when the maximum value of the absolute value of the error function is smaller than a linearity threshold value, taking the second driving current signal as a target driving current signal;
when the maximum value of the absolute value of the error function is not smaller than the linearity threshold value, adjusting the second driving current signal to generate a third driving current signal;
and taking the third driving current signal as the second driving current signal, and executing the step of obtaining a second time frequency function corresponding to the second driving current signal and a theoretical time frequency function.
Optionally, the iterative correction module 22 is specifically configured to:
when the maximum value of the absolute value of the error function is not less than the linearity threshold value, calculating the product of the error function and a preset weight;
determining a sum of the product and the second drive current signal as a third drive current signal.
Optionally, the apparatus further comprises:
and a signal storage module 24, configured to store the driving signal of the linear frequency sweep.
It should be noted that, when the linear frequency sweep correction apparatus provided in the foregoing embodiment executes the linear frequency sweep correction method, only the division of the functional modules is illustrated, and in practical applications, the functions may be distributed by different functional modules according to needs, that is, the internal structure of the device is divided into different functional modules, so as to complete all or part of the functions described above. In addition, the linear frequency sweep correction device and the linear frequency sweep correction method provided by the above embodiments belong to the same concept, and the details of the implementation process are referred to as method embodiments, which are not described herein again.
The above-mentioned serial numbers of the embodiments of the present application are merely for description and do not represent the merits of the embodiments.
In the embodiment of the application, the target driving current signal meeting the sweep frequency linearity requirement is obtained by performing iterative approximation correction on the first driving current signal. The first drive current signal can be corrected to generate a target drive current signal meeting the sweep frequency linearity requirement without adding other hardware and additional algorithms in an actual FMCW system under the condition of ensuring low cost and real-time requirements, and the laser is swept according to the corrected waveform as the drive signal during actual work. Compared with the traditional open-loop correction method, the correction effect does not depend on the numerical model of the frequency-modulated laser, and the linearity L <0.001 can be achieved by the method through an iterative approximation method.
An embodiment of the present application further provides a computer storage medium, where the computer storage medium may store a plurality of instructions, where the instructions are suitable for being loaded by a processor and executing the application monitoring method according to the embodiments shown in fig. 4 to 9, and a specific execution process may refer to specific descriptions of the embodiments shown in fig. 4 to 9, which is not described herein again.
Fig. 12 shows a von neumann based linear sweep correction system 12 running the linear sweep correction method described above. Specifically, an external input interface 1001, a processor 1002, a memory 1003, and an output interface 1004 connected through a system bus may be included. The external input interface 1001 may include a touch screen 10016, and optionally a network interface 10018. Memory 1003 can include external memory 10032 (e.g., a hard disk, optical or floppy disk, etc.) and internal memory 10034. Output interfaces 1004 may include devices such as a display 10042 and speakers 10044.
In the present embodiment, the method is executed based on a computer program, the program file of which is stored in the external memory 10032 of the computer system 10 based on the von neumann architecture, loaded into the internal memory 10034 at the time of execution, and then compiled into machine code and then transferred to the processor 1002 to be executed, so that a signal generation module, a pre-correction module, an iterative correction module, a signal determination module, and a signal storage module are logically formed in the computer system 10 based on the von neumann architecture. In the execution process of the linear sweep frequency correction method, the input parameters are received through the external input interface 1001, transferred to the memory 1003 for buffering, and then input into the processor 1002 for processing, and the processed result data is buffered in the memory 1003 for subsequent processing or transferred to the output interface 1004 for outputting.
In one or more embodiments of the present application, a target driving current signal meeting the requirement of frequency sweep linearity is obtained by pre-correcting a first driving current signal, or an iterative approach correction is performed on the first driving current signal to obtain a target driving current signal meeting the requirement of frequency sweep linearity, without adding other hardware and additional algorithms in an actual FMCW system, under the condition of ensuring low cost and real-time requirements, the first driving current signal can be corrected to generate a target driving current signal meeting the requirement of frequency sweep linearity, and during actual operation, a laser is swept according to a correction waveform as a driving signal.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a read-only memory or a random access memory.
The above disclosure is only for the purpose of illustrating the preferred embodiments of the present application and is not to be construed as limiting the scope of the present application, so that the present application is not limited thereto, and all equivalent variations and modifications can be made to the present application.
Claims (11)
- A linear frequency sweep correction method, the method comprising:generating a first drive current signal;pre-correcting the first driving current signal to obtain a target driving current signal;determining the target drive current signal as a linearly swept drive signal.
- The method of claim 1, wherein pre-correcting the first driving current signal to obtain a target driving current signal comprises:acquiring a first time frequency function corresponding to the first driving current signal;and calculating an inverse function of the first time frequency function, and taking the inverse function as a target driving current signal.
- The method of claim 2, wherein said calculating an inverse function of said first time-frequency function as a target drive current signal further comprises:and when the inverse function is a linear function, determining the target driving current signal as a driving signal of a linear frequency sweep.
- The method of claim 1, wherein after determining the target drive current signal as a linear swept drive signal, further comprising:and storing the driving signal of the linear frequency sweep.
- A linear frequency sweep correction method, the method comprising:generating a first drive current signal;performing iterative approximation correction on the first driving current signal to obtain a target driving current signal;determining the target drive current signal as a linearly swept drive signal.
- The method of claim 5, wherein the performing iterative approximation correction on the first drive current signal to obtain a target drive current signal comprises:acquiring a first time frequency function corresponding to the first driving current signal and a theoretical time frequency function;calculating a difference value between the theoretical time frequency function and the first time frequency function, and taking the difference value as an error function;and performing iterative approximation correction on the first driving current signal based on the error function and the linearity threshold value to obtain a target driving current signal after iterative approximation correction.
- The method of claim 6, wherein performing iterative approximation correction on the first driving current signal based on the error function and a linearity threshold to obtain an iteratively approximated corrected target driving current signal comprises:when the maximum value of the absolute value of the error function is smaller than a linearity threshold value, taking the first driving current signal as a target driving current signal;when the maximum value of the absolute value of the error function is not smaller than the linearity threshold value, adjusting the first driving current signal to generate a second driving current signal;and taking the second driving current signal as the first driving current signal, and executing the step of obtaining a second time frequency function corresponding to the first driving current signal and a theoretical time frequency function.
- The method of claim 7, wherein adjusting the first drive current signal to generate a second drive current signal when the maximum value of the absolute value of the error function is not less than the linearity threshold comprises:when the maximum value of the absolute value of the error function is not less than the linearity threshold value, calculating the product of the error function and a preset weight;determining a sum of the product and the first drive current signal as a second drive current signal.
- The method of claim 5, wherein after determining the target drive current signal as a linear swept drive signal, further comprising:and storing the driving signal of the linear frequency sweep.
- A computer storage medium having stored thereon a plurality of instructions adapted to be loaded by a processor and to perform the method of any of claims 1 to 4 or 5 to 9.
- A laser linear frequency sweep correction system, comprising: a processor and a memory; wherein the memory stores a computer program adapted to be loaded by the processor and to perform the method of any of claims 1 to 4 or 5 to 9.
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| CN115236634A (en) * | 2022-06-23 | 2022-10-25 | 中国电子科技集团公司第十一研究所 | Method and device for correcting laser linear frequency modulation signal in laser radar |
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| CN206132085U (en) * | 2016-06-08 | 2017-04-26 | 江苏骏龙光电科技股份有限公司 | Optical frequency scanning non -linearity correction system |
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| CN115236634B (en) * | 2022-06-23 | 2024-06-14 | 中国电子科技集团公司第十一研究所 | Correction method and device for laser linear frequency modulation signals in laser radar |
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