Signal processing device and method for frequency linearization of FMCW lidar, transmission and reception system of FMCW lidar for frequency linearization, and autonomous vehicle driving method using FMCW lidar comprising transmission and reception system

Abstract

The present invention relates to a signal processing device for frequency linearization of a frequency modulation continuous wave (FMCW) light detection and ranging (LiDAR), comprising: a modulation unit for modulating, into a triangular waveform, a reference signal and a reception signal received through an interferometer of the FMCW LiDAR; a correction unit which generates a distorted triangular waveform by transforming the triangular waveform of the reception signal, and which generates a phase signal by unwrapping the distorted triangular waveform; and a comparison unit for measuring linearity by comparing the phase signal to the reference signal, wherein the modulation unit modulates the phase signal into a triangular waveform, and the comparison unit compares the triangular waveform of the phase signal to the triangular waveform of the reference signal so as to repeatedly measure the linearity until a single frequency is generated.

Description

Signal processing device and method for frequency linearization of FMCW lidar, transmission and reception system of FMCW lidar for frequency linearization, and autonomous driving method of vehicle using FMCW lidar including transmission and reception system

[0001] The present invention relates to a frequency linearization technology of FMCW (frequency modulation continuous wave) LiDAR (light detection and ranging) and autonomous driving for vehicles using the same.

[0002] Lidar is a technology that illuminates a target with a laser beam and measures the time it takes for the laser to reflect off the target and reach a detector, thereby determining the distance to the target and obtaining a three-dimensional image based on this. In Lidar technology, transmission signal modulation methods include pulse, FMCW, and FSK (frequency shift keying). Each modulation method determines the method for extracting the target's speed and distance.

[0003] Pulsed lidar technology requires high-power lasers or highly sensitive detectors for long-distance measurements, which can be expensive and affect eye safety, and can lead to cross-talk between multiple lidar signals.

[0004] In contrast, FMCW lidar is a lidar that transmits a continuous wave signal while simultaneously receiving a reflected wave signal from a target. At this time, FMCW lidar extracts relative distance and relative velocity information of the target by using the beat frequency, which is the difference frequency component of the transmitted and received signals. Since it uses a laser interferometer to detect the target signal, it is relatively simple to implement and is not affected by the external environment, so much research has been conducted on it as a vehicle collision avoidance system.

[0005] A factor that directly affects the signal-to-noise ratio (SNR) of FMCW lidar and its resulting maximum measurement range performance is the linearity of the laser's frequency modulation, and various technologies are being studied to secure this linearity.

[0006] In an embodiment of the present invention, a signal processing technique for frequency linearization of an FMCW lidar is proposed, which generates a distorted waveform in a stage prior to generating a phase signal, and performs infinite repetition of linearity of the waveform based on the generated distorted waveform to obtain a single frequency with secured linearity.

[0007] In an embodiment of the present invention, a method for autonomous driving a vehicle using an FMCW lidar including a signal processing device for frequency linearization is proposed.

[0008] According to an embodiment of the present invention, a signal processing device for frequency linearization of an FMCW (frequency modulation continuous wave) LiDAR (light detection and ranging) comprises: a modulation unit for modulating a reference signal and a reception signal received through an interferometer of the FMCW LiDAR into a triangular waveform; a correction unit for generating a distorted triangular waveform by converting the triangular waveform of the reception signal and generating a phase signal by unwrapping the distorted triangular waveform; and a comparison unit for measuring linearity by comparing the phase signal with the reference signal; wherein the modulation unit modulates the phase signal into a triangular waveform, and the comparison unit repeatedly performs the measurement of linearity by comparing the triangular waveform of the phase signal with the triangular waveform of the reference signal until a single frequency is generated.

[0009] Here, the correction unit can generate the distorted triangular waveform by Hilbert transforming the triangular waveform of the received signal.

[0010] Additionally, the correction unit can generate the distorted triangular waveform by converting the received signal into a quadrature imaginary component.

[0011] Additionally, the correction unit can generate the phase signal by converting the distorted triangular waveform into an in-phase real component.

[0012] According to an embodiment of the present invention, a signal processing method performed in a signal processing device for frequency linearization of an FMCW lidar, comprising: a step of modulating a reference signal and a reception signal received through an interferometer of the FMCW lidar into a triangular waveform; a step of converting the triangular waveform of the reception signal to generate a distorted triangular waveform; a step of unwrapping the distorted triangular waveform to generate a phase signal; and a step of comparing the phase signal with the reference signal to measure linearity; wherein the modulating step includes a step of modulating the phase signal into a triangular waveform, and the measuring step includes a step of repeatedly performing a step of comparing the triangular waveform of the phase signal with the triangular waveform of the reference signal to measure linearity until a single frequency is generated.

[0013] According to an embodiment of the present invention, a transmission and reception system of an FMCW lidar for frequency linearization can be provided, including: a transmission unit for transmitting an optical signal; an interferometer including an optical splitter, an optical delay element, and an optical combiner, and for converting and reflecting the optical signal and outputting the converted and reflected optical signal; a reception unit for receiving a reception signal of an in-phase real component from the optical signal that has passed through the interferometer; and a signal processing device for modulating the reception signal and a separate reference signal into a triangular waveform, converting the triangular waveform of the reception signal to generate a distorted triangular waveform, unwrapping the distorted triangular waveform to generate a phase signal, and comparing the phase signal with the reference signal to measure linearity; wherein the signal processing device modulates the phase signal into a triangular waveform, compares the triangular waveform of the phase signal with the triangular waveform of the reference signal, and repeatedly performs the measurement of linearity until a single frequency is generated.

[0014] Here, the signal processing device can generate the distorted triangular waveform by Hilbert transforming the triangular waveform of the received signal.

[0015] Additionally, the signal processing device can generate the distorted triangular waveform by converting the received signal into an orthogonal phase imaginary component.

[0016] Additionally, the signal processing device can generate the phase signal by converting the distorted triangular waveform into in-phase real components.

[0017] Additionally, the interferometer may include a Mach-Zehnder interferometer.

[0018] According to an embodiment of the present invention, a method for autonomous driving a vehicle using a transmission / reception system of an FMCW lidar may include: a step of transmitting the optical signal from the FMCW lidar; a step of receiving a reflection signal in which the optical signal is reflected from an object; a step of obtaining information about the object based on the optical signal and the reflection signal; and a step of controlling the driving direction and speed of the vehicle based on the information about the object.

[0019] According to an embodiment of the present invention, there is provided a computer-readable recording medium storing a computer program, the computer program including instructions for causing a processor to perform a signal processing method performed in a signal processing device for frequency linearization of an FMCW lidar, the method including the steps of: modulating a reference signal and a received signal received through an interferometer of the FMCW lidar into a triangular waveform; generating a distorted triangular waveform by converting the triangular waveform of the received signal; generating a phase signal by unwrapping the distorted triangular waveform; and measuring linearity by comparing the phase signal with the reference signal; wherein the modulating step may include the step of modulating the phase signal into a triangular waveform, and the measuring step may include the step of repeatedly performing the step of measuring linearity by comparing the triangular waveform of the phase signal with the triangular waveform of the reference signal until a single frequency is generated.

[0020] According to an embodiment of the present invention, there is provided a computer program stored in a computer-readable recording medium, wherein the computer program includes instructions for causing a processor to perform a signal processing method performed in a signal processing device for frequency linearization of an FMCW lidar, the method comprising: a step of modulating a reference signal and a reception signal received through an interferometer of the FMCW lidar into a triangular waveform; a step of converting the triangular waveform of the reception signal to generate a distorted triangular waveform; a step of unwrapping the distorted triangular waveform to generate a phase signal; and a step of comparing the phase signal with the reference signal to measure linearity; wherein the step of modulating may include a step of modulating the phase signal into a triangular waveform, and the step of measuring may include a step of repeatedly performing a step of comparing the triangular waveform of the phase signal with the triangular waveform of the reference signal to measure linearity until a single frequency is generated.

[0021] According to an embodiment of the present invention, by generating a distorted waveform in a stage prior to generating a phase signal and performing infinite repetition of the linearity of the waveform based on the generated waveform to obtain a single frequency with secured linearity, the frequency linearity of an FMCW lidar can be reliably secured and high resolution can be provided without using an expensive external modulation method.

[0022] FIG. 1 is a schematic block diagram of a transmission / reception system of an FMCW lidar for frequency linearization according to an embodiment of the present invention.

[0023] FIG. 2 is a block diagram illustrating a signal processing device for frequency linearization according to an embodiment of the present invention, and is an example of a function of a signal processing device of a transmission / reception system of the FMCW lidar of FIG. 1.

[0024] FIG. 3 is a flowchart exemplarily illustrating a signal processing process of an FMCW lidar performed in a signal processing device for frequency linearization according to an embodiment of the present invention.

[0025] FIG. 4 and FIG. 5 are comparative graphs of triangular waveforms output through a signal processing device for frequency linearization according to an embodiment of the present invention.

[0026] In an embodiment of the present invention, a signal processing technique is proposed that can reliably secure the frequency linearity of an FMCW lidar and provide high resolution without using an expensive external modulation method by generating a distorted waveform in a stage prior to generating a phase signal, and performing infinite repetitions of the linearity of the waveform based on the generated distorted waveform to obtain a single frequency with secured linearity.

[0027] The advantages and features of the present invention, and the methods for achieving them, will become clearer with reference to the embodiments described in detail below with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various forms. These embodiments are provided solely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the scope of the present invention is defined solely by the claims.

[0028] In describing embodiments of the present invention, specific descriptions of known functions or configurations will be omitted unless actually necessary. Furthermore, the terms described below are defined based on their functions in the embodiments of the present invention and may vary depending on the intent or custom of the user or operator. Therefore, their definitions should be based on the overall content of this specification.

[0029] Common frequency modulation methods include direct modulation and external modulation. External modulation, while not significantly altering optical performance, is expensive and not mass-producible. Direct modulation, while very affordable, suffers from nonlinear changes in optical performance.

[0030] For example, assuming that a bit signal is obtained by modulating light with a triangular waveform for a certain signal, the distance value must be constant. However, in the case of the direct modulation method, the refractive index of the laser resonator is changed using voltage / current, thereby changing the wavelength of the resonating light and modulating the output frequency. However, the way the refractive index actually changes causes the signal to change nonlinearly due to the Kerr effect and the Pockels effect.

[0031] Therefore, even if a typical triangular waveform is applied to the current, the actual light is modulated into a distorted waveform rather than a triangular waveform. If linearity differs, multiple frequency components are observed in a single bit signal, which inevitably reduces resolution.

[0032] Accordingly, in an embodiment of the present invention, a signal processing technique is proposed that can reliably secure the frequency linearity of an FMCW lidar and provide high resolution without using an expensive external modulation method by generating a distorted waveform in a stage prior to generating a phase signal, and performing infinite repetition of the linearity of the waveform based on the generated distorted waveform to obtain a single frequency with secured linearity.

[0033] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0034] FIG. 1 is a schematic block diagram of a transmission / reception system (1) of an FMCW lidar for frequency linearization according to an embodiment of the present invention.

[0035] As illustrated in Fig. 1, the transmission / reception system (1) of an FMCW lidar for frequency linearization may include an optical phase-locked loop, and may include a transmitter (10), an interferometer (20), a first receiver (30), a second receiver (32), and a signal processing device (100).

[0036] The transmitter (10) can output laser pulse light, and this transmitter (10) can include, for example, a laser diode (LD). In addition, the transmitter (10) can transmit light having various wavelengths. For example, the light transmitted by the transmitter (10) can have a wavelength smaller than that of RF (radio frequency). With this configuration, the transmitter (10) emits high optical energy, and thus the receiver can receive reflected light having high energy. Accordingly, high-resolution spatial information can be obtained, and thus the lidar device can be used to utilize 3D spatial information.

[0037] The interferometer (20) may include an optical splitter, an optical delay element, an optical combiner, etc. (not shown), and may receive a portion of an optical signal separated from the transmitter (10), convert and reflect the optical signal, and output the optical signal. For example, the interferometer (20) may separate light into two paths using an optical splitter, insert an optical delay element into one path to delay the phase, and then combine them again through an optical combiner to output the light. This output light may be detected by a receiving end (photo diode, PD), amplified by an amplifier, and then input to a mixer (not shown).

[0038] Such an interferometer (20) may include, for example, a Mach-Zehnder interferometer.

[0039] The beat signals of the FMCW lidar's transmission and reception signals can ultimately be identified as sine waves. To confirm the above signals, a Mach-Zehnder interferometer is configured to directly input the optical signal from the LD to the PD, rather than the signal reflected from a target, so that the current triangular waveform can be confirmed. In the present invention, the Mach-Zehnder interferometer can be configured separately from an external interferometer.

[0040] The first receiver (30) can perform FFT processing on a signal optically coupled through the waveguide of the interferometer (20) into a first impulse signal in the real part on the complex plane. This first impulse signal may be an in-phase real component.

[0041] The second receiver (32) can FFT-process the signal optically coupled through the waveguide of the interferometer (20) into a second impulse signal in the imaginary part on the complex plane. This second impulse signal may be a quadrature imaginary component.

[0042] A signal processing device (100) according to an embodiment of the present invention can modulate the reception signals of the first receiving unit (30) and the second receiving unit (32) and a separate reference signal into a triangular waveform, convert the triangular waveform of the reception signal to generate a distorted triangular waveform, unwrap the distorted triangular waveform to generate a phase signal, and compare the phase signal with the reference signal to measure linearity. This signal processing device (100) can repeatedly perform the measurement of linearity by modulating the phase signal into a triangular waveform and comparing the triangular waveform of the phase signal with the triangular waveform of the reference signal until a single frequency is generated.

[0043] This signal processing device (100) can generate a distorted triangular waveform by Hilbert transforming the triangular waveform of the received signal, and can generate a distorted triangular waveform by converting the received signal into an orthogonal phase imaginary component. In addition, the signal processing device (100) can generate a phase signal by converting the distorted triangular waveform into an in-phase real component.

[0044] By applying a delay along the optical path with the configuration of Figure 1 and obtaining a beat signal, we can verify that only one calculated frequency is output. However, observing the wavelength sweep with an OSA to confirm direct modulation of the laser generally results in poor resolution, making proper observation difficult.

[0045] In an embodiment of the present invention, for example, since it was not possible to directly measure a change of 2.5 pm with a resolution of 10 pm, the frequency modulation width was measured by predicting the change per 1 mA using the slope.

[0046] By measuring the triangular waveform with voltage, the current change can be predicted along with the LI curve, and the modulation caused by the actual current value can be confirmed. This is configured as a system that continuously monitors the internal monitor PD periodically.

[0047] Looking at the output graph, we can see that the sine wave has a certain frequency content, confirming that the signal is as predicted by the initial calculation. However, the FFT signal shows that it is not a single signal, but rather a very wide frequency range.

[0048] To reduce this wide frequency range, the optical linearity can be measured independently using the Hilbert transform and phase unwrapping methods, and then an infinite loop can be run to obtain a single linear bit signal.

[0049] The Hilbert transform is a linear operator that shifts the frequency of an input signal by -90 or 90 degrees. In other words, the Hilbert transform of a cosine function becomes a sine function.

[0050] The reason why the Hilbert transform is important in the present invention is that by taking the arc tangent of two sine waves with a 90 degree phase difference, the θ of tanθ can be found.

[0051] In other words, the phase value can be obtained by taking the arc tangent of the sine wave of the existing bit signal and the sine wave obtained by Hilbert transform. The phase obtained in this way is a sine wave with an amplitude of (-ð, ð), so it is difficult to distinguish linearity. Therefore, phase unwrapping is the process of releasing the phase value at regular intervals.

[0052] FIG. 2 is a block diagram for exemplarily explaining the function of the signal processing device (100) of the transmission / reception system (1) of the FMCW lidar of FIG. 1 as a signal processing device for frequency linearization according to an embodiment of the present invention.

[0053] As illustrated in FIG. 2, a signal processing device (100) for frequency linearization of an FMCW lidar may include a modulation unit (110), a correction unit (120), and a comparison unit (130).

[0054] The modulation unit (110) can modulate the reference signal and the received signal received through the interferometer (20) of the FMCW lidar into a triangular waveform.

[0055] The correction unit (120) can generate a distorted triangular waveform by transforming the triangular waveform of the received signal, and can generate a phase signal by unwrapping the distorted triangular waveform. Here, the correction unit (120) can generate a distorted triangular waveform by Hilbert transforming the triangular waveform of the received signal, and can generate a distorted triangular waveform by converting the received signal into an orthogonal phase imaginary component. In addition, the correction unit (120) can generate a phase signal by converting the distorted triangular waveform into an in-phase real component.

[0056] The comparison unit (130) can measure linearity by comparing the phase signal with the reference signal. The modulation unit (110) can modulate the phase signal into a triangular waveform, and therefore the comparison unit (130) can repeatedly perform linearity measurement by comparing the triangular waveform of the phase signal with the triangular waveform of the reference signal until a single frequency is generated.

[0057] Hereinafter, the signal processing process of the FMCW lidar according to the embodiment of the present invention, together with the above-described configuration, will be described in detail with reference to the flowchart of the attached FIG. 3.

[0058] FIG. 3 is a flowchart exemplarily explaining a signal processing process of an FMCW lidar performed in a signal processing device (100) for frequency linearization according to an embodiment of the present invention.

[0059] As illustrated in FIG. 3, the signal processing device (100) can modulate the reference signal and the received signal received through the interferometer (20) of the FMCW lidar into a triangular waveform, and then convert the triangular waveform of the received signal to generate a distorted triangular waveform (S100). The step of generating the distorted triangular waveform may include a step of Hilbert transforming the triangular waveform of the received signal, and a step of converting the received signal into a quadrature imaginary component.

[0060] Thereafter, the signal processing device (100) can generate a phase signal by unwrapping the distorted triangular waveform in step (S100) (S102). The step of generating the phase signal may include a step of converting the distorted triangular waveform into in-phase real components to generate the phase signal.

[0061] Thereafter, the signal processing device (100) can measure linearity by comparing the phase signal and the reference signal (S104, S106).

[0062] At this time, the modulating step (S100) may include a step of modulating the phase signal into a triangular waveform, and thus the signal processing device (100) can measure linearity between the triangular waveforms by comparing the triangular waveform of the phase signal with the triangular waveform of the reference signal.

[0063] These steps for linearity measurement (S100 to S106) can be repeated until a single frequency is generated (S108).

[0064] Figures 4 and 5 are comparative graphs of triangular waveforms output through a signal processing device (100) for frequency linearization according to an embodiment of the present invention. In Figures 4 and 5, a represents a reference signal, and b represents a received signal.

[0065] For example, as a result of measuring the linearity of step (S106), if it is assumed that a bit signal is obtained by modulating light with a triangular waveform for a certain signal as in FIG. 4, the distance value (e.g., 3 MHz) must be constant. However, in the case of the direct modulation method, the refractive index of the laser resonator is changed using voltage / current, thereby changing the wavelength of the resonating light and modulating the output frequency. However, in reality, the way the refractive index changes may cause the signal to change nonlinearly as in FIG. 5 due to the Kerr effect and the Pockelsson effect.

[0066] In an embodiment of the present invention, the distorted triangular waveform is reinserted, the optical linearity is measured again, and the above steps are repeated until the desired linearity is secured through infinite repetition and a single frequency is observed.

[0067] By repeating the above algorithm infinitely to maximize linearity, a single frequency can be obtained.

[0068] The transmission / reception system applied to the present invention can be configured separately from the FMCW receiving terminal, thereby securing the linearity of the transmission beam and the linearity of the reference light of the receiving terminal, thereby obtaining a single frequency of the beat signal.

[0069] According to the embodiment of the present invention as described above, a distorted waveform is generated in a stage prior to generating a phase signal, and based on this, linearity of the waveform is infinitely repeated to obtain a single frequency with secured linearity, thereby reliably securing the frequency linearity of the FMCW lidar and providing high resolution without using an expensive external modulation method.

[0070] Meanwhile, in an embodiment of the present invention, the signal processing method for frequency linearization as described in FIGS. 1 to 5 can be applied to an autonomous vehicle equipped with an FMCW lidar. A method for autonomous driving of a vehicle using an FMCW lidar to which the signal processing method for frequency linearization according to an embodiment of the present invention is applied may include a step of transmitting an optical signal from the FMCW lidar, a step of receiving a reflection signal in which the transmitted optical signal is reflected from an object, a step of acquiring information about the object based on the optical signal and the reflection signal, and a step of controlling the driving direction and speed of the vehicle based on the information about the object.

[0071] The combination of each block of the attached block diagram and each step of the flowchart may be performed by computer program instructions. These computer program instructions may be implemented in a processor of a general-purpose computer, special-purpose computer, or other programmable data processing device, such that the instructions, when executed by the processor of the computer or other programmable data processing device, create a means for performing the functions described in each block of the block diagram.

[0072] These computer program instructions may also be stored in a computer-usable or computer-readable recording medium (or memory) that can direct a computer or other programmable data processing equipment to implement a function in a specific manner, so that the instructions stored in the computer-usable or computer-readable recording medium (or memory) can also produce a manufactured item that includes instruction means for performing the function described in each block of the block diagram.

[0073] And, since the computer program instructions can also be installed on a computer or other programmable data processing equipment, a series of operation steps are performed on the computer or other programmable data processing equipment to create a process that is executed by the computer, so that the instructions that execute the computer or other programmable data processing equipment can also provide steps for executing the functions described in each block of the block diagram.

[0074] Additionally, each block may represent a module, segment, or portion of code that includes at least one executable instruction for performing a specific logical function(s). It should also be noted that in some alternative embodiments, the functions described in the blocks may occur out of order. For example, two blocks depicted in succession may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on their respective functions.

[0075] The present invention can reliably secure the frequency linearity of an FMCW lidar while providing high resolution without using an expensive external modulation method, and is expected to be usefully utilized in various types of correction algorithms and interferometric systems having delay lines.

Claims

1. In a signal processing device for frequency linearization of FMCW (frequency modulation continuous wave) LiDAR (light detection and ranging), A modulation unit that modulates the reference signal and the received signal received through the interferometer of the FMCW lidar into a triangular waveform; A correction unit that converts the triangular waveform of the received signal to generate a distorted triangular waveform and unwraps the distorted triangular waveform to generate a phase signal; and A comparison unit for measuring linearity by comparing the phase signal and the reference signal; The above modulation unit modulates the phase signal into a triangular waveform, The above comparison unit is a signal processing device for frequency linearization of an FMCW lidar, which compares the triangular waveform of the phase signal with the triangular waveform of the reference signal and repeatedly performs the measurement of linearity until a single frequency is generated.

2. In paragraph 1, The above correction unit is a signal processing device for frequency linearization of an FMCW lidar that generates the distorted triangular waveform by performing a Hilbert transform on the triangular waveform of the received signal.

3. In paragraph 2, The above correction unit is a signal processing device for frequency linearization of an FMCW lidar that converts the received signal into a quadrature imaginary component to generate the distorted triangular waveform.

4. In paragraph 2, The above correction unit is a signal processing device for frequency linearization of an FMCW lidar that converts the distorted triangular waveform into an in-phase real component to generate the phase signal.

5. In a signal processing method performed in a signal processing device for frequency linearization of FMCW lidar, A step of modulating the reference signal and the received signal received through the interferometer of the FMCW lidar into a triangular waveform; A step of converting the triangular waveform of the above-described received signal to generate a distorted triangular waveform; A step of generating a phase signal by unwrapping the distorted triangle waveform; and A step of measuring linearity by comparing the phase signal and the reference signal; including, The above modulating step includes a step of modulating the phase signal into a triangular waveform, A signal processing method for frequency linearization of an FMCW lidar, wherein the measuring step includes a step of repeatedly performing the step of measuring linearity by comparing the triangular waveform of the phase signal with the triangular waveform of the reference signal until a single frequency is generated.

6. In paragraph 5, A signal processing method for frequency linearization of an FMCW lidar, wherein the step of generating the distorted triangular waveform includes the step of Hilbert transforming the triangular waveform of the received signal.

7. In paragraph 6, A signal processing method for frequency linearization of an FMCW lidar, wherein the step of generating the distorted triangular waveform includes the step of converting the received signal into a quadrature imaginary component.

8. In paragraph 6, A signal processing method for frequency linearization of an FMCW lidar, wherein the step of generating the phase signal includes the step of converting the distorted triangular waveform into in-phase real components to generate the phase signal.

9. A transmitter for transmitting an optical signal; An interferometer comprising an optical splitter, an optical delay element, and an optical combiner, and converting and reflecting the optical signal to output it; A receiving unit for receiving a reception signal of an in-phase real component from an optical signal passing through the above interferometer; and A signal processing device that modulates the received signal and a separate reference signal into a triangular waveform, converts the triangular waveform of the received signal to generate a distorted triangular waveform, unwraps the distorted triangular waveform to generate a phase signal, and measures linearity by comparing the phase signal and the reference signal; A transmission / reception system of an FMCW lidar for frequency linearization in which the signal processing device modulates the phase signal into a triangular waveform, compares the triangular waveform of the phase signal with the triangular waveform of the reference signal, and repeatedly performs measurement of the linearity until a single frequency is generated.

10. In paragraph 9, The above signal processing device is a transmission / reception system of an FMCW lidar for frequency linearization that generates the distorted triangular waveform by Hilbert transforming the triangular waveform of the received signal.

11. In paragraph 10, The signal processing device is a transmission / reception system of an FMCW lidar for frequency linearization that converts the received signal into an orthogonal phase imaginary component to generate the distorted triangular waveform.

12. In paragraph 10, The above signal processing device is a transmission / reception system of an FMCW lidar for frequency linearization that converts the distorted triangular waveform into in-phase real components to generate the phase signal.

13. In paragraph 9, The above interferometer is a transmission / reception system of an FMCW lidar for frequency linearization including a Mach-Zehnder interferometer.

14. A vehicle autonomous driving method using the transmission and reception system of the FMCW lidar described in Article 9, A step of transmitting the optical signal from the FMCW lidar; A step of receiving a reflection signal in which the above optical signal is reflected from an object; A step of obtaining information of the object based on the optical signal and the reflected signal; and A vehicle autonomous driving method, comprising: a step of controlling the driving direction and speed of the vehicle based on information of the object.

15. A computer-readable recording medium storing a computer program, The above computer program, Includes instructions for causing a processor to perform a signal processing method performed in a signal processing device for frequency linearization of an FMCW lidar, The above method, A step of modulating the reference signal and the received signal received through the interferometer of the FMCW lidar into a triangular waveform; A step of converting the triangular waveform of the above-described received signal to generate a distorted triangular waveform; A step of generating a phase signal by unwrapping the distorted triangle waveform; and A step of measuring linearity by comparing the phase signal and the reference signal; including, The above modulating step includes a step of modulating the phase signal into a triangular waveform, A computer-readable recording medium comprising a step of repeatedly performing the step of measuring linearity by comparing the triangular waveform of the phase signal with the triangular waveform of the reference signal until a single frequency is generated.

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