Signal correction method and device and ranging system

Abstract

The invention relates to the technical field of laser ranging, in particular to a signal correction method and device and a ranging system. The method comprises the steps that a driving signal is output to a light source unit in the current round, the light source unit is subjected to frequency modulation through the driving signal to generate a modulated light signal, and the driving signal in the first round is standard triangular wave or sawtooth wave voltage; determining the time-frequency distribution of the modulated light signal, determining the sweep frequency nonlinearity of the time-frequency distribution, and determining the current mapping relation between the output and the input of the light source unit based on the time-frequency distribution and the driving signal; if the nonlinearity is greater than or equal to a preset threshold value, determining a pre-distortion input signal, and updating the driving signal based on the pre-distortion input signal to execute a next round of iteration; and if the nonlinearity is smaller than a preset threshold value, inputting the driving signal in the current round into a light source unit in the ranging system for ranging. The target driving signal enabling the light source to generate the target light signal can be efficiently determined, so that the distance measurement precision is ensured.

Description

Technical Field

[0001] The present application relates to the technical field of laser ranging, and in particular to a signal correction method, device and ranging system. Background Art

[0002] At present, the swept frequency coherent ranging radar based on current injection is widely used in many fields such as unmanned driving, high-precision assembly, and aerospace surveying and mapping due to its non-contact measurement, large modulation bandwidth, fast sweeping speed, and anti-electromagnetic interference. The principle of swept frequency coherent ranging is that the light source is modulated by the injected current signal to output a swept frequency modulated light signal. The modulated light signal is used to detect the object to be measured, and the interference beat signal is generated by receiving the signal reflected by the object to be measured. The interference beat signal can be analyzed to determine the distance to the object to be measured.

[0003] The ranging accuracy of the frequency-sweeping coherent ranging method is related to the frequency-sweeping linearity of the optical signal. Since there is a non-linear relationship between the modulated optical signal output by the light source and the current signal injected into the light source, and when the ranging system is actually used for testing, circuit noise and temperature changes of components will also lead to nonlinearity, which will cause the spectrum of the obtained interference beat signal to be broadened to varying degrees, thus affecting the ranging accuracy. In related technologies, a black box iteration method is often used to obtain the current signal injected into the light source, but the black box iteration method does not pay attention to the relationship between input and output, so it requires more iterations and takes a long time.

[0004] Therefore, when using a ranging system for ranging, how to efficiently determine a target driving signal that can cause a light source to generate a target light signal is an urgent problem to be solved. Summary of the invention

[0005] Based on this, it is necessary to provide a signal correction method, device and ranging system that can efficiently determine the input current signal that can enable the light source to generate a target driving signal in order to solve the above technical problems.

[0006] In a first aspect, the present application provides a signal correction method, the method being executed by a processing unit of a ranging system, the method comprising:

[0007] In the current round, a driving signal is output to the light source unit, so that the light source unit is frequency modulated by the driving signal to generate a modulated light signal, wherein in the first round, the driving signal is a standard triangular wave voltage or a sawtooth wave-like voltage;

[0008] Determining the time-frequency distribution of the modulated light signal, determining the frequency sweep nonlinearity of the time-frequency distribution, and determining a current mapping relationship between the output and the input of the light source unit based on the time-frequency distribution and the driving signal;

[0009] If the nonlinearity is greater than or equal to a preset threshold, a predistortion input signal is determined based on a current mapping relationship between the output and the input of the light source unit, and the drive signal is updated based on the predistortion input signal to perform a next round of iteration;

[0010] If the nonlinearity is less than a preset threshold, the driving signal in the current round is used as a target driving signal, and the target driving signal is used to input into the light source unit in the ranging system for ranging.

[0011] In one embodiment, the driving signal includes N input points, any of the input points includes a current and a corresponding moment, the time-frequency distribution includes N output points, any of the output points includes a frequency and a corresponding moment; and determining a current mapping relationship between the output and the input of the light source unit based on the time-frequency distribution and the driving signal includes:

[0012] Fitting is performed based on the N input points and the N output points to determine a current mapping relationship between the output and the input of the light source unit.

[0013] In one embodiment, determining the swept frequency nonlinearity of the time-frequency distribution includes:

[0014] The frequency sweep nonlinearity of the time-frequency distribution is determined according to the time-frequency distribution and an ideal time-frequency distribution, wherein the ideal time-frequency distribution is obtained based on a linear fitting of the time-frequency distribution.

[0015] In a second aspect, the present application further provides a signal correction device, the device comprising a drive signal output module, a time-frequency distribution determination module, an iteration control module and a target drive signal determination module, wherein:

[0016] A driving signal output module, used for outputting a driving signal to the light source unit in the current round, so that the light source unit is frequency modulated by the driving signal to generate a modulated light signal, wherein the driving signal is a standard triangle wave voltage or a sawtooth wave-like voltage in the first round;

[0017] A time-frequency distribution determination module, used to determine the time-frequency distribution of the modulated light signal, determine the frequency sweep nonlinearity of the time-frequency distribution, and determine the current mapping relationship between the output and input of the light source unit based on the time-frequency distribution and the driving signal;

[0018] an iterative control module, for determining a predistortion input signal based on a current mapping relationship between an output and an input of the light source unit, and updating the drive signal based on the predistortion input signal to perform a next round of iteration if the nonlinearity is greater than or equal to a preset threshold;

[0019] The target driving signal determination module is used to use the driving signal in the current round as the target driving signal if the nonlinearity is less than a preset threshold value. The target driving signal is used to input the light source unit in the ranging system for ranging.

[0020] In a third aspect, the present application further provides a ranging system, the system comprising a light source unit, a monitoring unit and a processing unit, wherein:

[0021] The light source unit can be modulated by an input driving signal to output a modulated light signal;

[0022] The monitoring unit is connected to the output end of the light source unit and is capable of collecting the modulated light signal;

[0023] The processing unit is connected to the output end of the monitoring unit, the output end of the processing unit is connected to the input end of the light source unit, and the processing unit executes the signal correction method as described in the first aspect above.

[0024] In one embodiment, the system further comprises a measuring unit, wherein:

[0025] The input end of the measuring unit is connected to the output end of the light source unit, and the output end of the measuring unit is connected to the input end of the processing unit;

[0026] The measuring unit is capable of outputting the modulated light signal to the object to be measured, acquiring a reflection signal reflected by the object to be measured, and generating a beat signal containing distance information of the object to be measured based on the reflection signal and the modulated light signal;

[0027] The processing unit can receive and analyze the beat frequency signal to obtain distance information.

[0028] In one of the embodiments, the monitoring unit preprocesses the modulated optical signal to obtain a time-frequency distribution, and the preprocessing includes low-pass filtering, Hilbert transform, and phase unwrapping.

[0029] In one of the embodiments, the measuring unit couples the modulated light signal and the reflected signal to obtain a beat frequency signal.

[0030] In one embodiment, the output end of the light source unit is connected to a beam splitting device, wherein:

[0031] The beam splitting device includes an isolator and a first coupler; the modulated optical signal output by the light source unit is isolated by the isolator, and the isolated modulated optical signal is divided into two signals by the first coupler, one of which is input into the measuring unit, and the other is input into the monitoring unit.

[0032] In one embodiment, the monitoring unit comprises an interferometer, a detector and a filter, wherein:

[0033] The modulated optical signal is interfered by the interferometer to generate an interference beat frequency signal; the detector converts the interference beat frequency signal into an electrical beat frequency signal, and the electrical beat frequency signal is filtered by the filter and then output to the processing unit.

[0034] The above-mentioned signal correction method, device and ranging system use the theoretical driving signal corresponding to the target time-frequency distribution based on the actual needs of the user as the driving signal in the first round to input the light source unit for iteration. In each iteration process, the actual mapping relationship between the output and input of the light source unit and the nonlinearity of the time-frequency distribution of the modulated light signal actually output are determined, and then the theoretical driving signal corresponding to the modulated light signal actually output by the light source unit is determined by reverse thinking, that is, the determined pre-distortion signal, and then the pre-distortion signal is used as the driving signal for the next round of iteration for iteration. That is, the scheme of the present application is to continuously iterate based on the relationship between the actual output and theoretical input of the light source unit, and determine the input-output relationship by calculating the time-frequency distribution of the modulated light signal generated under different inputs, so that the input current signal that can make the light source generate the target driving signal can be efficiently obtained; the obtained current signal is used as the driving signal to output the light source unit of the ranging system so that the light source unit generates the target light signal, and a higher-precision ranging can be performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] FIG1 is a diagram showing an application environment of a signal correction method according to an embodiment;

[0037] FIG2 is a schematic flow chart of a signal correction method in one embodiment;

[0038] FIG3 is a logical diagram of the cyclic iteration process;

[0039] FIG4 is a block diagram of a signal correction device in one embodiment;

[0040] FIG5 is a schematic diagram of the structure of a distance measurement system in one embodiment.

[0041] Reference numerals

[0042] 1. Light source unit; 2. Monitoring unit; 3. Processing unit; 4. Measuring unit; 5. Beam splitting device. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0044] In the related technology, the principle of swept frequency coherent ranging is that the light source is modulated by the injected current signal to output a modulated light signal, wherein the frequency of the modulated light signal is related to the current signal; the modulated light signal is used to detect the object to be measured, and the interference beat frequency signal is generated by processing the signal reflected by the object to be measured, and the interference beat frequency signal can be analyzed to determine the distance to the object to be measured.

[0045] The ranging accuracy of the frequency-sweeping coherent ranging method is related to the frequency-sweeping linearity of the optical signal. However, when the ranging system is actually used for testing, the modulated optical signal output by the light source and the current signal injected into the light source are not always linear. At the same time, circuit noise and temperature changes of components will also lead to nonlinearity, which will cause the spectrum of the obtained interference beat signal to be broadened to varying degrees, thus affecting the ranging accuracy. In related technologies, a black box iteration method is often used to obtain the current signal injected into the light source. However, the black box iteration method does not pay attention to the relationship between input and output, so it requires more iterations and takes a long time.

[0046] For example, when the user needs the light source to output a modulated light signal of frequency B for distance measurement, based on the theoretical relationship between the output and input of the light source, it can be deduced that the theoretical driving signal that needs to be input to the light source is driving signal A; however, due to the influence of temperature or other interference, nonlinearity will also occur. When the theoretical driving signal A is actually input to the light source, the output of the light source is not a standard light signal of frequency B, and there will be a large deviation. For example, the output of the light source is a light signal of frequency B1. When using the light signal of frequency B1 for distance measurement, the accuracy of distance measurement is low.

[0047] The signal correction method provided in the embodiment of the present application can be applied to the measurement system shown in Figure 1. The measurement system includes a light source unit, a measurement unit, a monitoring unit and a processing unit; the processing unit can input a driving signal to the light source unit, the light source unit is modulated by the driving signal to generate a modulated light signal, and the modulated light signal passes through the measurement unit to detect the object to be measured for distance measurement; the monitoring unit collects the modulated light signal and transmits it to the processing unit; the processing unit processes the modulated light signal to obtain the time-frequency distribution of the modulated signal, and the processing unit can determine the nonlinearity of the time-frequency distribution, thereby realizing signal correction.

[0048] In an exemplary embodiment, as shown in FIG2 , a signal correction method is provided, and the method is applied to the processing unit of the measurement system in FIG1 as an example for explanation. The method includes steps 10 to 40; the specific steps of an iterative process include steps 10 to 40, and the signal correction method in the present application includes at least one iterative process; wherein:

[0049] Step 10: In the current round, output a driving signal to the light source unit so that the light source unit is frequency modulated by the driving signal to generate a modulated light signal. In the first round, the driving signal is a standard triangle wave voltage or a sawtooth wave voltage.

[0050] For the embodiment of the present application, the light source unit can modulate the light signal based on the input driving signal, and then output the modulated light signal, wherein the driving signal is a current signal. Under actual conditions (not considering noise interference and temperature changes), there is a nonlinear relationship between the current signal input to the light source and the frequency of the modulated light signal obtained after the light source is modulated. During the first round of iterations, the driving signal output to the light source unit is determined based on the actual needs of the user. In the embodiment of the present application, the driving signal can be a standard triangle wave voltage or a sawtooth wave voltage.

[0051] The user determines the target light signal with a target time-frequency distribution based on actual needs. For example, when the user uses the ranging system in this application to measure distance, the user expects the light source unit to output a modulated light signal with a triangular waveform. In the first iteration, the driving signal output by the processing unit to the light source unit should be a current signal corresponding to the triangular waveform. Therefore, in this application, the signal type of the driving signal output by the processing unit to the light source unit in the first iteration is not specifically limited.

[0052] Furthermore, the processing unit can directly output the corresponding current signal as a driving signal to the light source unit; the processing unit can also output the corresponding current parameters to the light source unit, so that the current generating device in the light source unit generates the corresponding current signal as the driving signal of the light source unit based on the current parameters.

[0053] Step 20: determine the time-frequency distribution of the modulated light signal, determine the frequency sweep nonlinearity of the time-frequency distribution, and determine the current mapping relationship between the output and input of the light source unit based on the time-frequency distribution and the driving signal.

[0054] For the embodiments of the present application, the characteristics of the modulated light signal can be described by its time-frequency distribution. The output of the modulated light signal corresponds to the input drive signal in time series, and the current change of the drive signal corresponds to the frequency change of the modulated light signal. The time-frequency distribution is the correspondence between the frequency and time of the modulated light signal; if the drive signal of the input light source unit is a continuous analog current signal, the time-frequency distribution of the modulated light signal is also a continuous analog signal, and at this time, the time-frequency distribution is a continuous curve. If the drive signal of the input light source unit is a discontinuous current signal, the time-frequency distribution of the modulated light signal is also not continuous.

[0055] Specifically, the current mapping relationship between the output and input of the light source unit is the actual mapping relationship between the frequency of the modulated light signal and the current of the driving signal; the current mapping relationship between the output and input of the light source unit can be determined by the time-frequency distribution of the driving signal and the modulated light signal. The time-frequency distribution is an actual output, and the linearity of the time-frequency distribution is determined based on the time-frequency distribution and the ideal time-frequency distribution. The specific determination steps will be described in detail in the subsequent content. Among them, the lower the nonlinearity, the closer the response relationship between the parameters representing the two signals is to linearity, and vice versa.

[0056] Step 30: If the nonlinearity is greater than or equal to the preset threshold, a predistortion input signal is determined based on the current mapping relationship between the output and input of the light source unit, and the driving signal is updated based on the predistortion input signal to perform the next round of iteration.

[0057] For the embodiment of the present application, under actual conditions (without considering noise interference and temperature changes), there is a nonlinear relationship between the current signal input to the light source and the frequency of the modulated light signal obtained after the light source is modulated. Based on the output and input of the light source unit, and based on the time-frequency distribution of the modulated light signal actually output by the light source unit, the drive signal input to the light source unit under theoretical conditions, that is, the pre-distortion signal, can be calculated. Further, referring to FIG. 3 , if the nonlinearity of the actual output of the light source unit, that is, the nonlinearity of the time-frequency distribution of the modulated light signal output by the light source unit, is greater than or equal to a preset threshold, it indicates that the drive signal in the current round is unavailable, and therefore the pre-distortion signal needs to be input as a new drive signal into the light source unit for the next round of iteration.

[0058] Step 40: If the nonlinearity is less than a preset threshold, the driving signal in the current round is used as a target driving signal, and the target driving signal is used to input the light source unit in the ranging system for ranging.

[0059] For the embodiment of the present application, referring to FIG3 , if the nonlinearity of the actual output of the light source unit, that is, the nonlinearity of the time-frequency distribution of the modulated light signal output by the light source unit, is less than a preset threshold value, it indicates that the driving signal in the current round is available; that is, once the time-frequency distribution of the target modulated light signal is determined, an actual driving signal can be determined through the current mapping relationship between the output and input of the light source unit, and then, the user sets the processing unit to output the actual driving signal to the light source unit to obtain a modulated light signal with the required frequency as the target time-frequency distribution to perform ranging work on the object to be measured.

[0060] In the embodiment of the present application, referring to FIG3, the theoretical driving signal corresponding to the target time-frequency distribution based on the actual needs of the user is input as the driving signal in the first round to the light source unit for iteration. In each iteration process, the actual mapping relationship between the output and input of the light source unit and the nonlinearity of the time-frequency distribution of the modulated light signal actually output are determined, and then the theoretical driving signal corresponding to the modulated light signal actually output by the light source unit is determined by reverse thinking, that is, the determined pre-distortion signal, and then the pre-distortion signal is used as the driving signal for the next round of iteration for iteration. That is, the scheme of the present application is to continuously iterate based on the relationship between the actual output and theoretical input of the light source unit, and the input-output relationship is determined by calculating the time-frequency distribution of the modulated light signal generated under different inputs, so that the input current signal that can make the light source generate the target driving signal can be efficiently obtained; the obtained current signal is output as the driving signal to the light source unit of the ranging system so that the light source unit generates the target light signal, and a higher precision ranging can be performed, thereby improving the defect of poor ranging accuracy caused by the nonlinearity of the light source.

[0061] In one embodiment, in the first round of iterations, the driving signal includes N input points, any input point includes current and corresponding time, and the time-frequency distribution includes N output points, any output point includes frequency and corresponding time. In step 20 of each round, based on the time-frequency distribution and the driving signal, the current mapping relationship between the output and input of the light source unit is determined, specifically including: fitting based on the N input points and the N output points to determine the current mapping relationship between the output and input of the light source unit.

[0062] Specifically, fitting can be performed by any of polynomial regression fitting, support vector machine fitting, and multi-layer perceptron model to determine the current mapping relationship between the output and input of the light source unit; the input drive signal and the output time-frequency distribution are imported into MATLAB (Matrix Laboratory) software, and the corresponding fitting function is selected to perform fitting processing. Of course, MATLAB software is only one possible fitting method, and the specific fitting method is not specifically limited in the embodiments of this application.

[0063] In one embodiment, determining the swept frequency nonlinearity of the time-frequency distribution may specifically include: determining the swept frequency nonlinearity of the time-frequency distribution according to the time-frequency distribution and the ideal time-frequency distribution.

[0064] Specifically, the light source unit outputs a modulated light signal, and the monitoring unit inputs the modulated light signal into the interferometer to obtain an interference signal. , further to the interference signal Perform Hilbert transform , and perform inverse tangent and unwrapping on the result of the division to determine the phase of the interference signal ; Due to the delay of the monitoring unit Therefore, the frequency and phase of the interference signal can be considered to be proportional, that is, the frequency of the interference signal is determined by the phase of the interference signal. .

[0065] Specifically, the phase determination method of the interference signal can be expressed by formula (1), and the frequency determination method can be expressed by formula (2):

[0066] Formula (I);

[0067] Formula (II).

[0068] Furthermore, under the condition that the input signal of the light source unit is the same driving signal: it is assumed that f is a sequence with a length of i, representing the actual output frequency, that is, the time-frequency distribution. is a sequence of length i, i.e., the ideal time-frequency distribution, which is obtained by fitting the time-frequency distribution once, where the length i is the number of input points, and also the number of output points, i.e., N. That is, the sequence f contains i output points. ,(p=1,2,…i); sequence There are i output points in . Then the nonlinearity between the output and output of the light source unit is It can be determined by the root mean square error of the residual between the actual output of the light source unit and the theoretical output (ideal time-frequency distribution), as expressed in formula (III):

[0069] Formula (III).

[0070] In one embodiment, the theoretical linear relationship between the input and output of the light source unit can be expressed by the following formula (iv) to formula (vi), where:

[0071] Formula (IV);

[0072] Formula (V);

[0073] Formula (VI).

[0074] in, is the current bias (the driving signal input to the light source unit), is the time, m is the modulation depth (the voltage input is converted into current input to drive the light source), represents the polynomial coefficients, is also a polynomial coefficient. is the frequency of the actual output modulated optical signal, is the frequency of the theoretical linear output modulated optical signal, is the theoretical driving signal (current signal); where, Represents the iteration round. In the 0th iteration, when the input driving signal is a triangular waveform, .

[0075] in, is the 0th iteration, is the sawtooth wave generating function; where, is the bias current, is the modulation amplitude of the current.

[0076] It should be understood that, although the steps in the flowcharts involved in the above embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above embodiments may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0077] Based on the same inventive concept, the embodiment of the present application also provides a signal correction device for implementing the signal correction method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more signal correction device embodiments provided below can refer to the limitations on the signal correction method above, and will not be repeated here.

[0078] In an exemplary embodiment, as shown in FIG4 , a signal correction device is provided, including a drive signal output module 401, a time-frequency distribution determination module 402, an iteration control module 403 and a target drive signal determination module 404, wherein:

[0079] A driving signal output module 401 is used to output a driving signal to the light source unit in the current round, so that the light source unit is frequency modulated by the driving signal to generate a modulated light signal. In the first round, the driving signal is a standard triangle wave voltage or a sawtooth wave voltage.

[0080] The time-frequency distribution determination module 402 is used to determine the time-frequency distribution of the modulated optical signal, determine the frequency sweep nonlinearity of the time-frequency distribution, and determine the current mapping relationship between the output and input of the light source unit based on the time-frequency distribution and the driving signal;

[0081] The iteration control module 403 is used to determine the predistortion input signal based on the current mapping relationship between the output and the input of the light source unit, and update the driving signal based on the predistortion input signal to perform the next iteration if the nonlinearity is greater than or equal to the preset threshold;

[0082] The target driving signal determination module 404 is used to use the driving signal in the current round as the target driving signal if the nonlinearity is less than a preset threshold value. The target driving signal is used to input the light source unit in the ranging system for ranging.

[0083] In the embodiment of the present application, the device uses the theoretical driving signal corresponding to the target time-frequency distribution based on the actual needs of the user as the driving signal in the first round to input the light source unit for iteration. In each iteration process, the actual mapping relationship between the output and input of the light source unit and the nonlinearity of the time-frequency distribution of the modulated light signal actually output are determined, and then the theoretical driving signal corresponding to the modulated light signal actually output by the light source unit is determined by reverse thinking, that is, the determined pre-distortion signal, and then the pre-distortion signal is used as the driving signal for the next round of iteration for iteration. That is, the scheme of the present application is to continuously iterate based on the relationship between the actual output and theoretical input of the light source unit, and the input-output relationship is determined by calculating the time-frequency distribution of the modulated light signal generated under different inputs, so that the input current signal that can make the light source generate the target driving signal can be efficiently obtained; the obtained current signal is used as the driving signal to output the light source unit of the ranging system so that the light source unit generates the target light signal, and a higher precision ranging can be performed.

[0084] In one embodiment, the driving signal includes N input points, any input point includes current and corresponding time, the time-frequency distribution includes N output points, any output point includes frequency and corresponding time; the time-frequency distribution determination module 402 is specifically used to:

[0085] Fitting is performed based on the N input points and the N output points to determine a current mapping relationship between the output and the input of the light source unit.

[0086] In one embodiment, the time-frequency distribution determination module 402 is further configured to:

[0087] The frequency sweep nonlinearity of the time-frequency distribution is determined according to the time-frequency distribution and the ideal time-frequency distribution. The ideal time-frequency distribution is obtained based on the fitting of the time-frequency distribution.

[0088] Each module in the above-mentioned signal correction device can be implemented in whole or in part by software, hardware and a combination thereof. Each of the above-mentioned modules can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute the operations corresponding to each of the above modules.

[0089] In an exemplary embodiment, as shown in FIG5 , a distance measurement system is provided, the system comprising a light source unit 1, a monitoring unit 2, a processing unit 3 and a measuring unit 4, wherein:

[0090] The light source unit 1 can be modulated by the input driving signal and output a modulated light signal; the monitoring unit 2 is connected to the output end of the light source unit 1, can receive the modulated light signal, and output it to the processing unit 3; the processing unit 3 is connected to the output end of the monitoring unit 2, and the output end of the processing unit 3 is connected to the input end of the light source unit 1. The input end of the measuring unit 4 is connected to the output end of the light source unit 1, and the output end of the measuring unit 4 is connected to the input end of the processing unit 3; the measuring unit 4 can output the modulated light signal to the object to be measured, and obtain the reflection signal reflected by the object to be measured, and generate a beat signal containing the distance information of the object to be measured based on the reflection signal and the modulated light signal; the processing unit 3 can receive the beat signal and analyze it to obtain the distance information; further, the processing unit 3 is also configured to be able to perform the steps in the above-mentioned signal correction method embodiment.

[0091] Further referring to FIG. 4 , the light source unit 1 includes a tunable light source, a laser current driver, and a laser temperature control; wherein the laser current driver can generate a corresponding current input tunable light source based on the driving signal (current signal) output by the monitoring unit 2. The laser temperature control can monitor the temperature of the tunable light source and generate a temperature signal. The tunable light source can generate a laser and generate a modulated light signal output under the modulation of the current.

[0092] In one embodiment, the modulated light signal output by the light source unit 1 is divided into two paths after passing through the beam splitter 5, one path is input into the measuring unit 4 to detect the object to be measured; the other path is input into the monitoring unit 2. The beam splitter 5 includes an isolator and a first coupler; the modulated light signal is first isolated by the isolator to reduce interference and noise in the transmission process of the modulation tube signal, so that the modulated light signal remains stable. The first coupler can split the modulated light signal into two signals.

[0093] In one embodiment, the measuring unit 4 includes a second coupler for beam splitting and an output path for inputting a modulated optical signal, and also includes a coupling path for coupling signals. The second coupler is used to split the modulated optical signal input to the measuring unit 4 into two paths, one path is output to the output path, and the other path is output to the coupling path as a reference signal. The output path includes a circulator and a collimator; the modulated optical signal enters the collimator after passing through the circulator, and the collimator collimates the modulated optical signal and then outputs it to the object to be measured.

[0094] The coupling path includes a detector and a third coupler for signal coupling, wherein the third coupler can couple the reference signal and the reflected signal reflected by the object to be measured into the same optical fiber for interference to obtain an interference signal, and the interference signal is converted into a beat frequency signal by the detector. The detector is a photoelectric detector that can convert an optical signal into a corresponding electrical signal. The beat frequency signal output by the detector is output to the processing unit 3, and the processing unit 3 analyzes the beat frequency signal to determine the distance between the object to be measured and the object to be measured.

[0095] In one embodiment, the monitoring unit 2 includes an interferometer, a detector, and a filter; wherein the interferometer may be an unequal-arm Mach-Zehnder interferometer, or other types of interferometers, such as a Sagnac interferometer or a Michelson interferometer. In the embodiment of the present application, the specific type of the interferometer is not specifically limited. The modulated optical signal input to the monitoring unit 2 is input to the interferometer for interference, thereby generating an interference beat signal; the interference beat signal is converted by the detector to obtain an electrical beat signal, and the electrical beat signal is filtered by the filter to obtain a filtered signal.

[0096] In one embodiment, the monitoring unit 2 may further include a processor that can perform Hilbert transform and phase unwrapping on the filtered signal to generate a time-frequency distribution corresponding to the interference signal; the generated time-frequency distribution is output to the processing unit 3.

[0097] In another embodiment, no processor is provided in the monitoring unit 2, and the monitoring unit 2 outputs the filtered signal to the processing unit 3, and the processing unit 3 performs Hilbert transform and phase unwrapping on the filtered signal to generate a time-frequency distribution corresponding to the interference signal.

[0098] In one embodiment, the processing unit 3 includes a processor and an acquisition card, wherein the acquisition card is used to acquire the beat frequency signal output by the measurement unit 4; the acquisition card is also used to acquire the filtered signal output by the monitoring unit 2 or the time-frequency distribution obtained by processing the filtered signal.

[0099] The processor of the processing unit 3 can analyze the beat frequency signal sent by the measuring unit 4 to obtain the distance to the object to be measured; the processor can also perform Albert transform and phase unwrapping on the filtered signal sent by the monitoring unit 2, thereby generating a time-frequency distribution corresponding to the interference signal; the processor can also execute the steps of the signal correction method in the above-mentioned signal correction method embodiment, thereby realizing the correction of the signal.

[0100] A person of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0101] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0102] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A signal correction method, characterized in that: The method is performed by a processing unit of a ranging system, and the method includes: In the current round, a driving signal is output to the light source unit, so that the light source unit is frequency modulated by the driving signal to generate a modulated light signal, wherein in the first round, the driving signal is a standard triangular wave voltage or a sawtooth wave-like voltage; Determining the time-frequency distribution of the modulated light signal, and determining the frequency sweep nonlinearity of the time-frequency distribution, and determining a current mapping relationship between the output and the input of the light source unit based on the time-frequency distribution and the driving signal; If the nonlinearity is greater than or equal to a preset threshold, a predistortion input signal is determined based on a current mapping relationship between the output and the input of the light source unit, and the drive signal is updated based on the predistortion input signal to perform a next round of iteration; If the nonlinearity is less than a preset threshold, the driving signal in the current round is used as a target driving signal, and the target driving signal is used to input into the light source unit in the ranging system for ranging.

2. The method according to claim 1, characterized in that: The driving signal includes N input points, any of which includes a current amplitude and a corresponding time, and the time-frequency distribution includes N output points, any of which includes an offset of a light frequency of a modulated light signal output by a light source unit and a corresponding time; Determining a current mapping relationship between an output and an input of the light source unit based on the time-frequency distribution and the driving signal includes: Fitting is performed based on the N input points and the N output points to determine a current mapping relationship between the output and the input of the light source unit.

3. The method according to claim 2, characterized in that The step of determining the frequency sweep nonlinearity of the time-frequency distribution comprises: The frequency sweep nonlinearity of the time-frequency distribution is determined according to the time-frequency distribution and an ideal time-frequency distribution, wherein the ideal time-frequency distribution is obtained based on a linear fitting of the time-frequency distribution.

4. A signal correction device, characterized in that: The device comprises a driving signal output module, a time-frequency distribution determination module, an iteration control module and a target driving signal determination module, wherein: A driving signal output module, used for outputting a driving signal to the light source unit in the current round, so that the light source unit is frequency modulated by the driving signal to generate a modulated light signal, wherein the driving signal is a standard triangle wave voltage or a sawtooth wave-like voltage in the first round; A time-frequency distribution determination module, used to determine the time-frequency distribution of the modulated light signal, determine the frequency sweep nonlinearity of the time-frequency distribution, and determine the current mapping relationship between the output and input of the light source unit based on the time-frequency distribution and the driving signal; an iterative control module, for determining a predistortion input signal based on a current mapping relationship between an output and an input of the light source unit, and updating the drive signal based on the predistortion input signal to perform a next round of iteration if the nonlinearity is greater than or equal to a preset threshold; The target driving signal determination module is used to use the driving signal in the current round as the target driving signal if the nonlinearity is less than a preset threshold value. The target driving signal is used to input the light source unit in the ranging system for ranging.

5. A distance measurement system, characterized in that: The system comprises a light source unit (1), a monitoring unit (2) and a processing unit (3), wherein: The light source unit (1) can be frequency modulated by an input driving signal to output a modulated light signal; The monitoring unit (2) is connected to the output end of the light source unit (1) and is capable of collecting the modulated light signal; The processing unit (3) is connected to the output end of the monitoring unit (2), the output end of the processing unit (3) is connected to the input end of the light source unit (1), and the processing unit (3) executes the signal correction method according to any one of claims 1 to 3.

6. The system according to claim 5, characterized in that The system further comprises a measuring unit (4), wherein: The input end of the measuring unit (4) is connected to the output end of the light source unit (1), and the output end of the measuring unit (4) is connected to the input end of the processing unit (3); The measuring unit (4) is capable of outputting the modulated light signal to the object to be measured, acquiring a reflection signal reflected by the object to be measured, and generating a beat signal containing distance information of the object to be measured based on the reflection signal and the modulated light signal; The processing unit (3) is capable of receiving and analyzing the beat frequency signal to obtain distance information.

7. The system according to claim 5, characterized in that: The monitoring unit (2) pre-processes the modulated optical signal to obtain a time-frequency distribution, wherein the pre-processing includes low-pass filtering, Hilbert transform and phase unwrapping.

8. The system according to claim 6, characterized in that The measuring unit (4) couples the modulated light signal and the reflected signal to obtain a beat frequency signal.

9. The system according to claim 6, characterized in that The output end of the light source unit (1) is connected to a beam splitting device (5), wherein: The beam splitting device (5) comprises an isolator and a first coupler; the modulated optical signal output by the light source unit (1) is isolated by the isolator, and the isolated modulated optical signal is divided into two signals by the first coupler, one of which is input into the measuring unit (4) and the other is input into the monitoring unit (2).

10. The system according to claim 6 or 9, characterized in that: The monitoring unit (2) comprises an interferometer, a detector and a filter, wherein: The modulated optical signal is interfered by the interferometer to generate an interference beat frequency signal; the detector converts the interference beat frequency signal into an electrical beat frequency signal, and the electrical beat frequency signal is filtered by the filter and then output to the processing unit (3).

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