A linear frequency sweep correction method, device, storage medium and system

Abstract

Embodiments of the present application disclose a linear frequency sweep correction method, apparatus, storage medium, and system. The method includes generating a first drive current signal; pre-correcting the first drive current signal to obtain a target drive current signal; and determining the target drive current signal as the drive signal for the linear frequency sweep. Using the embodiments of the present application, the first drive current signal can be corrected to generate a target drive current signal that meets frequency sweep linearity requirements while ensuring low cost and real-time performance.

Description

Technical Field

[0001] The present application relates to the field of computer technology, and in particular to a linear frequency sweep correction method, device, storage medium, and system. Background Art

[0002] LiDAR is a radar system that uses laser beams to detect target characteristics such as position and velocity. The FMCW LiDAR ranging principle uses a continuous wave with a linearly varying frequency within a frequency sweep cycle as the output signal. A portion of the output signal serves as the local oscillator signal, while the remainder is transmitted outward for detection. After being reflected by an object, the returned echo signal has a certain frequency difference with the local oscillator signal. By measuring this frequency difference, the distance between the detected target and the radar can be determined. Due to its long detection range and high ranging accuracy, LiDAR is widely used in autonomous driving, robotics, aerial surveying and mapping, and other fields.

[0003] The linear frequency sweep of a laser can be understood as a continuous wave that emits a linearly varying frequency within a sweep cycle. The energy of the beat frequency spectrum of a linearly swept signal is concentrated at the signal frequency. However, in practice, the nonlinearity of the sweep will cause the beat frequency spectrum to broaden, resulting in reduced ranging and velocity measurement accuracy. Furthermore, as the energy diffuses to nearby frequency points, the signal amplitude also decreases, causing a drop in the signal-to-noise ratio and reducing the system's maximum ranging range. Therefore, improving the sweep linearity of the swept light source is particularly important for FMCW lidar systems.

[0004] Currently, there are many methods to overcome the nonlinearity of the laser radar system's frequency sweeping. However, the system structures are complex and it is difficult to meet the requirements of high linearity. Summary of the Invention

[0005] The present invention provides a linear sweep correction method, device, storage medium, and system that can correct a first drive current signal to generate a target drive current signal that meets sweep linearity requirements while ensuring low cost and real-time performance. The technical solution is as follows:

[0006] In a first aspect, an embodiment of the present application provides a linear frequency sweep correction method, the method comprising:

[0007] generating a first driving current signal;

[0008] Pre-correcting the first driving current signal to obtain a target driving current signal;

[0009] The target driving current signal is determined as a linear frequency swept driving signal.

[0010] In a second aspect, an embodiment of the present application provides a linear frequency sweep correction method, the method comprising:

[0011] generating a first driving current signal;

[0012] performing iterative approximation correction on the first driving current signal to obtain a target driving current signal;

[0013] The target driving current signal is determined as a linear frequency swept driving signal.

[0014] In a third aspect, an embodiment of the present application provides a linear frequency sweep correction device, the device comprising:

[0015] A signal generating module, configured to generate a first driving current signal;

[0016] a pre-correction module, configured to pre-correct the first drive current signal to obtain a target drive current signal;

[0017] The signal determination module is configured to determine the target driving current signal as a linear frequency sweeping driving signal.

[0018] In a fourth aspect, an embodiment of the present application provides a linear frequency sweep correction device, the device comprising:

[0019] A signal generating module, configured to generate a first driving current signal;

[0020] an iterative correction module, configured to perform iterative approximation correction on the first drive current signal to obtain a target drive current signal;

[0021] The signal determination module is configured to determine the target driving current signal as a linear frequency sweeping driving signal.

[0022] In a fifth aspect, an embodiment of the present application provides a computer storage medium, wherein the computer storage medium stores a plurality of instructions, wherein the instructions are suitable for being loaded by a processor and executing the above-mentioned linear frequency sweep correction method.

[0023] 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, and the computer program is suitable for being loaded by the processor and executing the above-mentioned linear frequency sweep correction method.

[0024] The beneficial effects of the technical solutions provided by some embodiments of the present application include at least:

[0025] In one or more embodiments of the present application, the first drive current signal is pre-corrected to obtain a target drive current signal that meets the sweep linearity requirement, or the first drive current signal is iteratively approximated and corrected to obtain a target drive current signal that meets the sweep linearity requirement. There is no need to add other hardware and additional algorithms to the actual FMCW system. While ensuring low cost and real-time requirements, the first drive current signal can be corrected to generate a target drive current signal that meets the sweep linearity requirement. During actual operation, the laser can be swept according to the corrected waveform as the drive signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 This is a schematic diagram illustrating an example of an FMCW ranging principle provided in an embodiment of the present application;

[0028] Figure 2 This is a schematic diagram of a time-frequency waveform of a linear frequency sweep and a nonlinear frequency sweep provided in an embodiment of the present application;

[0029] Figure 3 This is an example schematic diagram of a linear frequency amplitude waveform and a nonlinear frequency waveform provided in an embodiment of the present application;

[0030] Figure 4 1 is a flow chart of a linear frequency sweep correction method provided in an embodiment of the present application;

[0031] Figure 5 This is a flow chart of a signal pre-correction method provided in an embodiment of the present application;

[0032] Figure 6 1 is a schematic structural diagram of a laser linear frequency sweep correction system provided in an embodiment of the present application;

[0033] Figure 7 1 is a flow chart of a linear frequency sweep correction method provided in an embodiment of the present application;

[0034] Figure 8 1 is a flow chart of a signal iterative approximation correction method provided in an embodiment of the present application;

[0035] Figure 9 1 is a flow chart of a linear frequency sweep correction method provided in an embodiment of the present application;

[0036] Figure 10 1 is a schematic structural diagram of a linear frequency sweep correction device provided in an embodiment of the present application;

[0037] Figure 11 1 is a schematic structural diagram of a linear frequency sweep correction device provided in an embodiment of the present application;

[0038] Figure 12 This is a structural diagram of a laser linear frequency sweep correction system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0040] In the description of this application, it should be understood that the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance. In the description of this application, it should be noted that, unless otherwise expressly specified and limited, "including" and "having" and any variations thereof,

[0041] It is intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units that are inherent to these processes, methods, products or devices. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances. In addition, in the description of this application, unless otherwise specified, "multiple" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the previous and subsequent associated objects are in an "or" relationship.

[0042] For laser radar, such as frequency modulated continuous wave FMCW (Frequency Modulated Continuous Wave, FMCW) laser radar, speed and distance measurement are achieved through the principle of coherent detection. The system emits a continuous laser with a linearly changing frequency (triangle wave or sawtooth wave) during the sweep cycle. The echo light reflected by the object interferes with the local oscillator light on the reference arm, and the generated beat frequency signal is detected by the photodetector. The distance and speed of the target are calculated by measuring the frequency of the beat frequency signal. Figure 1As shown, the central wavelength of the swept laser is λ, the sweep period is T, the sweep bandwidth is B, and the beat frequency signal is f b- and f b+ , the distance to the target can be obtained and speed

[0043] FMCW LiDAR is a type of continuous wave LiDAR based on coherent detection. It requires a light source with continuously changing frequency. The sweep frequency range is usually from several hundred MHz to several tens of GHz. It is generally modulated using a triangle wave, and the modulation frequency is generally between 10kHz and 100kHz. In addition, FMCW LiDAR has high requirements for the continuity and linearity of the output signal, so that the difference between the local oscillator signal and the echo signal is stable to avoid the introduction of other variables due to nonlinear waveform changes. Current-modulated distributed feedback (DFB) semiconductor lasers or external cavity diode lasers (ECDL) are usually used as light sources.

[0044] FMCW utilizes the principle of coherent detection, resulting in high ranging accuracy. Compared with direct detection, it has strong anti-interference capabilities and can simultaneously measure speed and distance. It also features continuous light emission, does not require very high peak power, has low system power consumption, and is eye-safe. It is widely used in autonomous driving, robotics, aerial surveying, and other fields.

[0045] According to the different frequency modulation principles, frequency modulated lasers are divided into mechanical frequency modulation, temperature frequency modulation and current frequency modulation lasers, but no matter which method is used, the laser output frequency is changed by controlling the laser's resonant cavity length, temperature and carrier concentration through external driving current. Figure 2 As shown, the driving current is a triangular wave. Ideally, the frequency should change strictly linearly with time. However, in reality, the laser output frequency is not linearly related to the driving current. Therefore, the frequency sweep of the frequency modulated laser is nonlinear. When the maximum frequency deviation |Δf max The smaller the ratio of | to the sweep range B, the better the sweep linearity.

[0046] The linearity is defined as the maximum frequency deviation |Δf within the frequency sweep range. max The ratio of | to the sweep range B, that is, L = |Δf max The smaller | / BL is, the better the linearity is.

[0047] The beat frequency spectrum of a strictly linear sweep signal is as follows: Figure 3 As shown in (a), the energy is concentrated on the signal frequency. However, in practice, the nonlinearity of the frequency sweep will cause the spectrum of the beat frequency signal to be broadened, as shown in Figure 3As shown in (b), this results in a decrease in ranging and velocity measurement accuracy. At the same time, as energy spreads to nearby frequency points, the signal amplitude also decreases, causing a decrease in the signal-to-noise ratio and reducing the system's maximum ranging range. Therefore, improving the swept frequency linearity of the swept frequency source is particularly important for FMCW systems.

[0048] The linear frequency sweep correction method provided in the embodiments of the present application is described in detail below with reference to specific examples. This method can be implemented using a computer program and can be run on a linear frequency sweep correction device based on the von Neumann architecture. The computer program can be integrated into an application or run as a standalone tool application. The linear frequency sweep correction device in the embodiments of the present application can be a laser linear frequency sweep system, wherein the laser is a frequency modulated laser.

[0049] See Figure 4 , is a flow chart of a linear sweep frequency correction method provided in an embodiment of the present application. Including pre-correction, such as Figure 4 As shown, the method of the embodiment of the present application may include the following steps:

[0050] S101, generating a first driving current signal;

[0051] In order to ensure the linearity of the laser's frequency sweep, the modulation signal needs to be adjusted.

[0052] Specifically, the first driving current signal is an initial modulation signal, which is applied to the laser. An arbitrary waveform generator (such as a function signal generator) can be used to generate the first driving current signal I1 (t).

[0053] S102, pre-correcting the first driving current signal to obtain a target driving current signal;

[0054] Assuming linear modulation (triangle wave), that is, 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 linearly related, f(t) is a nonlinear function.

[0055] If the modulated signal is transformed into I'(t) = f -1 (k*t+b), then the frequency-time function of the laser output is f′(t)=f′[I′(t)]=f[f -1 (k*t+b)]=k*t+b. Obviously, f′(t) is a linear function at this time.

[0056] Therefore, the driving current signal can be corrected into an inverse function of the laser frequency-time function under linear modulation to achieve pre-correction of linearity. The pre-corrected modulation signal is the target driving current signal.

[0057] The specific pre-correction process can be found in S201 and S202. Figure 5 As shown:

[0058] S201, obtaining a first time-frequency function corresponding to the first driving current signal;

[0059] like Figure 6 The figure shows a schematic diagram of a laser linear frequency sweep system, in which an arbitrary waveform generator is used to randomly generate a first drive current signal and input it into the frequency-modulated laser, injecting the rated operating current into the laser to enable normal laser emission. The laser output passes through a Mach-Zehnder interferometer to generate an optical beat signal, which is measured with a balanced detector. The beat signal is then acquired using a data acquisition device (or oscilloscope). The time-domain signal is then processed and analyzed by a host computer, such as by performing a Hilbert transform or Fourier transform on the balanced detector's time-domain signal, or by using an optical frequency discriminator to calculate the first time-frequency function f1(t).

[0060] S202: Calculate an inverse function of the first time-frequency function, and use the inverse function as a target driving current signal.

[0061] The first driving current signal is

[0062] S103: Determine the target driving current signal as a linear frequency sweeping driving signal.

[0063] S104: storing the linear frequency sweep driving signal.

[0064] The driving signal is stored in the FMCW system. During actual operation, the linearity requirement can be met by sweeping the laser frequency according to the correction waveform as the driving signal.

[0065] In the embodiments of the present application, a target drive current signal that meets the sweep linearity requirements can be obtained by pre-correcting the first drive current signal. Without adding additional hardware or algorithms to the actual FMCW system, the first drive current signal can be corrected to generate a target drive current signal that meets the sweep linearity requirements while ensuring low cost and real-time performance. During actual operation, the laser can be swept using the corrected waveform as the drive signal.

[0066] See Figure 7 , is a flow chart of a linear sweep correction method provided in an embodiment of the present application. Including iterative approximation correction, such as Figure 7 As shown, the method of the embodiment of the present application may include the following steps:

[0067] S301, generating a first driving current signal;

[0068] It is understood that the first drive current signal is a randomly generated initial current signal for loading onto the laser. It can be generated by a random generator. An arbitrary waveform generator (such as a function signal generator) can be used to generate the first drive current signal I1(t).

[0069] S302, performing iterative approximation correction on the first driving current signal to obtain a target driving current signal;

[0070] The specific iterative approximation correction process can be found in S401 and S405. Figure 8 As shown:

[0071] S401, obtaining a first time-frequency function and a theoretical time-frequency function corresponding to the first driving current signal;

[0072] like Figure 6 As shown in the figure, the pre-corrected output signal I1(t) is first used as the initial input signal Ik(t) for iterative approximation correction, and the laser is swept and driven by an arbitrary waveform generator. The output of the laser passes through a Mach-Zehnder interferometer to generate an optical beat signal, which is measured by a balanced detector. The beat signal is obtained by a data acquisition device (or oscilloscope), and the time domain signal of the balanced detector is transformed into the frequency domain by a host computer to calculate I k (t) corresponds to the first time-frequency function f k (t). At the same time, the theoretical time-frequency function F(t) is calculated. Wherein, F(t) is a linear function.

[0073] S402, calculating a difference between the theoretical time-frequency function and the first time-frequency function, and using the difference as an error function;

[0074] Based on the error function and the linearity threshold, an iterative approximation correction is performed on the first driving current signal to obtain a target driving current signal after iterative approximation correction.

[0075] Specifically, the error function e k (t) = F(t) - f k (t).

[0076] S403: When the maximum absolute value of the error function is less than a linearity threshold, use the second driving current signal as a target driving current signal;

[0077] The linearity threshold is L, when max|e k (t)|<L, indicating f k(t) can meet the linear frequency sweep requirement, then the second driving current signal I1(t) is the driving signal of the linear frequency sweep.

[0078] S404, when the maximum 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;

[0079] When the maximum absolute value of the error function is not less than the linearity threshold, calculating the product of the error function and a preset weight;

[0080] When max|e k (t)|≥L, indicating that f k (t) If the linear sweep requirement is still not met, it is necessary to continue adjusting the first drive current signal I k (t). Specifically, calculate a·e k (t), where a is the coefficient of the drive current with frequency error.

[0081] The second driving current signal I k+1 (t) = I k (t)+a·e k (t)

[0082] S405 : Using the second driving current signal as the first driving current signal, and executing the step of acquiring the first time-frequency function and the theoretical time-frequency function corresponding to the first driving current signal.

[0083] The corrected signal I k+1 (t) is used as the new input waveform and input into the laser. The above steps are repeated until the frequency error-time function e k The maximum value of (t) is smaller than the linearity index L required by the system.

[0084] S303: Determine the target driving current signal as a linear frequency sweeping driving signal.

[0085] S304: Store the linear frequency sweep driving signal.

[0086] The driving signal is stored in the FMCW system. During actual operation, the linearity requirement can be met by sweeping the laser frequency according to the correction waveform as the driving signal.

[0087] In an embodiment of the present application, the first drive current signal is iteratively approximated and corrected to obtain a target drive current signal that meets the sweep linearity requirements. There is no need to add other hardware and additional algorithms to the actual FMCW system. While ensuring low cost and real-time requirements, the first drive current signal can be corrected to generate a target drive current signal that meets the sweep linearity requirements. During actual operation, the laser can be swept according to the corrected waveform as the drive signal. Compared with the traditional open-loop correction method, the correction effect does not depend on the numerical model of the frequency modulated laser. This method can achieve a linearity of L < 0.001 through an iterative approximation method.

[0088] See Figure 9 , is a flow chart of a linear sweep correction method provided in an embodiment of the present application, including pre-correction and iterative approximation correction, such as Figure 9 As shown, the method of the embodiment of the present application may include the following steps:

[0089] S501, generating a first driving current signal;

[0090] Specifically, the first driving current signal is an initial modulation signal, which is applied to the laser. An arbitrary waveform generator (such as a function signal generator) can be used to generate the first driving current signal I1 (t).

[0091] like Figure 6 The laser linear frequency sweep correction system shown in the figure is designed to obtain a corrected drive current waveform I(t) at a preset chirp frequency, ensuring that the laser output frequency-time curve f(t) meets linearity requirements under the modulation of this drive waveform. An arbitrary waveform generator (function signal generator) is used to generate the modulation signal I1(t) and apply it to the frequency-modulated laser.

[0092] S502, pre-correcting the first driving current signal to obtain a second driving current signal;

[0093] The principle of pre-correction can be found in S102 and will not be described in detail here.

[0094] Specifically, the laser output I1(t) generates an optical beat signal through a Mach-Zehnder Interferometer, which is measured with a balanced detector. The beat frequency time domain signal is obtained through a data acquisition device (or oscilloscope). The host computer processes and analyzes the time domain signal to generate a new modulation waveform, namely the second drive current signal I′(t).

[0095] Typically, this pre-correction method can only initially improve the laser's frequency sweep linearity, reducing the sweep linearity L to around 0.05, but cannot further improve linearity. This is because the pre-correction process considers the frequency-current impulse response function to be an ideal delta function. In reality, due to the principle of laser frequency modulation, the response bandwidth cannot be infinite, so the frequency-current impulse response function cannot be completely considered an ideal delta function. Iterative approximation correction is required to further improve linearity.

[0096] S503, performing iterative approximation correction on the second driving current signal to obtain a target driving current signal;

[0097] First, the second driving current signal I′(t) output by the pre-calibration module is used as the initial input waveform I of the iterative approximation module. k (t), and use an arbitrary waveform generator to sweep the laser. Then use the host computer to perform a time domain-frequency domain transformation (such as Hilbert transform) on the time domain signal of the balanced detector to calculate the frequency-time curve f k (t). Then calculate the actual frequency-time function f k The frequency error between the frequency-time function F(t) and the ideal linear sweep frequency-time function e(t) k (t) = F(t) - f k (t). Determine the frequency error-time function e k Is the maximum value of (t) less than the linearity index L required by the system? If so, then the driving current I k (t) is the correction waveform you want to obtain; if it is not satisfied, you need to use the error-time function e k (t) for driving current I k (t) Iterative correction is performed, and the corrected driving current signal is I k+1 (t) = I k (t)+a·e k (t).

[0098] Where a is the coefficient of the drive current with frequency error, and the corrected waveform I k+1 (t) is used as the new input waveform and substituted into the iterative approximation module. The above steps are repeated until the frequency error-time function e k The maximum value of (t) is smaller than the linearity index L required by the system.

[0099] S504: Determine the target driving current signal as a linear frequency sweeping driving signal.

[0100] S505: Store the linear frequency sweep driving signal.

[0101] The driving signal is stored in the FMCW system. During actual operation, the linearity requirement can be met by sweeping the laser frequency according to the correction waveform as the driving signal.

[0102] In one or more embodiments of the present application, by pre-correcting the first drive current signal and then performing iterative approximation correction on the pre-corrected second drive current signal, a target drive current signal that meets the frequency sweep linearity requirements can be obtained. There is no need to add other hardware and additional algorithms to the actual FMCW system. While ensuring low cost and real-time requirements, the first drive current signal can be corrected to generate a target drive current signal that meets the frequency sweep linearity requirements. During actual operation, the laser can be swept according to the corrected waveform as the drive signal.

[0103] The following are device embodiments of the present application, which can be used to implement the method embodiments of the present application. For details not disclosed in the device embodiments of the present application, please refer to the method embodiments of the present application.

[0104] See Figure 10 , which shows a schematic diagram of the structure of a linear frequency sweep correction device provided by an exemplary embodiment of the present application. The linear frequency sweep correction device can be implemented as all or part of a laser through software, hardware, or a combination of both. The device 1 includes a signal generation module 11, a pre-correction module 12, and a signal determination module 13.

[0105] A signal generating module 11 is configured to generate a first driving current signal;

[0106] a pre-correction module 12, configured to pre-correct the first driving current signal to obtain a target driving current signal;

[0107] The signal determination module 13 is configured to determine the target driving current signal as a linear frequency sweeping driving signal.

[0108] Optionally, the pre-correction module 12 is specifically configured to:

[0109] Acquire a first time-frequency function corresponding to the first driving current signal;

[0110] An inverse function of the first time-frequency function is calculated, and the inverse function is used as a second driving current signal.

[0111] Optionally, the signal determination module 13 is further configured to:

[0112] When the inverse function is a linear function, the second driving current signal is determined as a linearly swept driving signal.

[0113] Optionally, the device further includes:

[0114] The signal storage module 14 is configured to store the linear frequency sweep driving signal.

[0115] It should be noted that the linear frequency sweep correction device provided in the above embodiment, when executing the linear frequency sweep correction method, is merely illustrated by the division of the aforementioned functional modules. In actual applications, the aforementioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to perform all or part of the functions described above. Furthermore, the linear frequency sweep correction device provided in the above embodiment and the linear frequency sweep correction method embodiment are based on the same concept. The implementation process is detailed in the method embodiment and will not be repeated here.

[0116] The serial numbers of the above embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0117] In the embodiments of the present application, a target drive current signal that meets the sweep linearity requirements can be obtained by pre-correcting the first drive current signal. Without adding additional hardware or algorithms to the actual FMCW system, the first drive current signal can be corrected to generate a target drive current signal that meets the sweep linearity requirements while ensuring low cost and real-time performance. During actual operation, the laser can be swept using the corrected waveform as the drive signal.

[0118] See Figure 11 , which shows a schematic diagram of the structure of a linear frequency sweep correction device provided by an exemplary embodiment of the present application. The linear frequency sweep correction device can be implemented as all or part of a laser through software, hardware, or a combination of both. The device 2 includes a signal generation module 21, an iterative correction module 22, and a signal determination module 23.

[0119] A signal generating module 21 generates a first driving current signal;

[0120] an iterative correction module 22, configured to perform iterative approximation correction on the first driving current signal to obtain a target driving current signal;

[0121] The signal determination module 23 is configured to determine the target driving current signal as a linear frequency sweeping driving signal.

[0122] Optionally, the iterative correction module 22 is specifically configured to:

[0123] Acquire a second time-frequency function corresponding to the second driving current signal and a theoretical time-frequency function;

[0124] Calculating a difference between the theoretical time-frequency function and the second time-frequency function, and using the difference as an error function;

[0125] Based on the error function and the linearity threshold, an iterative approximation correction is performed on the second driving current signal to obtain a target driving current signal after iterative approximation correction.

[0126] Optionally, the iterative correction module 22 is specifically configured to:

[0127] When the maximum absolute value of the error function is less than a linearity threshold, taking the second driving current signal as a target driving current signal;

[0128] When the maximum absolute value of the error function is not less than the linearity threshold, adjusting the second driving current signal to generate a third driving current signal;

[0129] The third driving current signal is used as the second driving current signal, and the steps of obtaining the second time-frequency function and the theoretical time-frequency function corresponding to the second driving current signal are performed.

[0130] Optionally, the iterative correction module 22 is specifically configured to:

[0131] When the maximum absolute value of the error function is not less than the linearity threshold, calculating the product of the error function and a preset weight;

[0132] A sum of the product and the second driving current signal is determined as a third driving current signal.

[0133] Optionally, the device further includes:

[0134] The signal storage module 24 is used to store the linear frequency sweep driving signal.

[0135] It should be noted that the linear frequency sweep correction device provided in the above embodiment, when executing the linear frequency sweep correction method, is merely illustrated by the division of the aforementioned functional modules. In actual applications, the aforementioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to perform all or part of the functions described above. Furthermore, the linear frequency sweep correction device provided in the above embodiment and the linear frequency sweep correction method embodiment are based on the same concept. The implementation process is detailed in the method embodiment and will not be repeated here.

[0136] The serial numbers of the above embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0137] In an embodiment of the present application, the first drive current signal is iteratively approximated and corrected to obtain a target drive current signal that meets the sweep linearity requirements. There is no need to add other hardware and additional algorithms to the actual FMCW system. While ensuring low cost and real-time requirements, the first drive current signal can be corrected to generate a target drive current signal that meets the sweep linearity requirements. During actual operation, the laser can be swept according to the corrected waveform as the drive signal. Compared with the traditional open-loop correction method, the correction effect does not depend on the numerical model of the frequency modulated laser. This method can achieve a linearity of L < 0.001 through an iterative approximation method.

[0138] The present application also provides a computer storage medium that can store multiple instructions, which are suitable for being loaded and executed by a processor as described above. Figure 4-Figure 9 The application monitoring method of the embodiment shown, the specific execution process can be found in Figure 4-Figure 9 The detailed description of the illustrated embodiment will not be repeated here.

[0139] Figure 12 A linear frequency sweep correction system 12 based on a von Neumann architecture is presented, which implements the aforementioned linear frequency sweep correction method. Specifically, the system may include an external input interface 1001, a processor 1002, a memory 1003, and an output interface 1004 connected via a system bus. The external input interface 1001 may include a touch screen 10016 and, optionally, a network interface 10018. The memory 1003 may include an external memory 10032 (e.g., a hard disk, optical disk, or floppy disk) and an internal memory 10034. The output interface 1004 may include devices such as a display screen 10042 and a speaker / speaker 10044.

[0140] In this embodiment, the operation of this method is based on a computer program. The program file of this computer program is stored in the external memory 10032 of the aforementioned computer system 10 based on the von Neumann architecture. During operation, it is loaded into the internal memory 10034, then compiled into machine code and transmitted to the processor 1002 for execution, thereby forming a logical signal generation module, a pre-correction module, an iterative correction module, a signal determination module, and a signal storage module in the computer system 10 based on the von Neumann architecture. During the execution of the above-mentioned linear frequency sweep correction method, the input parameters are received through the external input interface 1001, transmitted to the memory 1003 for buffering, and then input to the processor 1002 for processing. The result data of the processing is either buffered in the memory 1003 for subsequent processing or transmitted to the output interface 1004 for output.

[0141] In one or more embodiments of the present application, the first drive current signal is pre-corrected to obtain a target drive current signal that meets the sweep linearity requirement, or the first drive current signal is iteratively approximated and corrected to obtain a target drive current signal that meets the sweep linearity requirement. There is no need to add other hardware and additional algorithms to the actual FMCW system. While ensuring low cost and real-time requirements, the first drive current signal can be corrected to generate a target drive current signal that meets the sweep linearity requirement. During actual operation, the laser can be swept according to the corrected waveform as the drive signal.

[0142] Those skilled in the art will appreciate that all or part of the processes in the above-described method embodiments can be implemented by instructing related hardware through a computer program. The program can be stored in a computer-readable storage medium, and when executed, the program can include the processes in the above-described method embodiments. The storage medium can be a magnetic disk, an optical disk, a read-only memory, or a random access memory.

[0143] The above disclosure is only a preferred embodiment of the present application, and certainly cannot be used to limit the scope of rights of the present application. Therefore, equivalent changes made according to the claims of the present application are still within the scope covered by the present application.

Claims

1. A linear frequency sweep correction method, characterized in that: The method comprises: generating a first driving 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 linear frequency sweep drive signal; The iterative approximation correction of the first driving current signal to obtain a target driving current signal includes: Acquire a first time-frequency function and a theoretical time-frequency function corresponding to the first driving current signal; Calculating a difference between the theoretical time-frequency function and the first time-frequency function, and using the difference as an error function; performing iterative approximation correction on the first drive current signal based on the error function and the linearity threshold to obtain a target drive current signal after iterative approximation correction; The iterative approximation correction is performed on the first drive current signal based on the error function and the linearity threshold to obtain a target drive current signal after iterative approximation correction, including: When the maximum absolute value of the error function is not less than the linearity threshold, calculating the product of the error function and a preset weight; determining a sum of the product and the first driving current signal as a second driving current signal; The second driving current signal is used as the first driving current signal, and the steps of obtaining the second time-frequency function corresponding to the first driving current signal and the theoretical time-frequency function are performed.

2. The method according to claim 1, characterized in that The iterative approximation correction is performed on the first drive current signal based on the error function and the linearity threshold to obtain a target drive current signal after iterative approximation correction, including: When the maximum absolute value of the error function is less than a linearity threshold, the first driving current signal is used as a target driving current signal.

3. The method according to claim 1, characterized in that After determining the target driving current signal as a linear frequency sweep driving signal, the method further includes: The linear frequency sweep driving signal is stored.

4. A computer storage medium, characterized in that The computer storage medium stores a plurality of instructions, and the instructions are suitable for being loaded by a processor and executing the method according to any one of claims 1 to 3.

5. A laser linear sweep frequency correction system, characterized in that: include: A processor and a memory; wherein the memory stores a computer program, and the computer program is suitable for being loaded by the processor and executing the method according to any one of claims 1 to 3.

Images