LIDAR DISTRIBUTION DEVICE, DETECTION SYSTEM, AND DETECTION METHOD

Abstract

A lidar sending device, a detection system, and a detection method are provided for filtering out false targets from multiple targets. Frequency swept optical signals with different slopes are introduced, and the frequency sweep slopes of the different frequency swept optical signals have opposite signs in a period, and the absolute values ​​of the frequency sweep slopes are not equal. For multiple real targets, coherent detection is performed in at least two periods corresponding to the different frequency swept optical signals separately. The range and velocity of the real targets obtained by the operation using the different frequency swept optical signals do not change, and the range and velocity of the false targets change. Therefore, the range and velocity of the real targets are determined using the same coherent detection results of the multiple frequency swept optical signals. This allows the virtual targets to be filtered out without increasing the detection time. In addition, no velocity ambiguity occurs even when an I receiver or a Q receiver is used, and the cost can be further reduced.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Chinese Patent Application No. 202111637896.0, entitled "LIDAR TRANSMISSION DEVICE, DETECTION SYSTEM, AND DETECTION METHOD," filed with the State Intellectual Property Office of the People's Republic of China on December 29, 2021, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the field of optical communication technology, and in particular to a LIDAR emission device, detection system, and detection method. [Background technology]

[0003] Coherent LIDAR may use the characteristics of the linear frequency modulation signal to beat the local oscillator signal with the echo signal to generate a frequency mixing signal that varies with the distance and velocity of the detected object, and may calculate the distance and velocity information of the detected object based on the frequency of the frequency mixing signal. LIDAR is relatively directional and has a small emitted light spot. However, when the emitted light reaches an object at a relatively long distance, the light spot will diverge due to the relatively long distance. This causes the emitted light signal to illuminate multiple objects and generate multiple echo signals. After coherent detection is performed on each of the multiple echo signals with the local oscillator signal, multiple targets are located, but false targets cannot be excluded from the multiple targets. Summary of the Invention [Means for solving the problem]

[0004] Embodiments of the present application provide a LIDAR dispatch apparatus, detection system, and detection method for filtering out false targets from multiple targets.

[0005] According to a first aspect, an embodiment of the present application provides a lidar transmission device including a frequency swept signal source and a multiplexer / demultiplexer component. The frequency swept signal source transmits N frequency swept optical signals, where N is an integer greater than 1. In the N frequency swept optical signals in a first time period, the frequency sweep slope of the first frequency swept optical signal and the frequency sweep slope of the second frequency swept optical signal have opposite signs, the absolute value of the frequency sweep slope of the first frequency swept optical signal is different from the absolute value of the frequency sweep slope of the second frequency swept optical signal, or the frequency sweep slope of the first frequency swept optical signal is not zero and the frequency sweep slope of the second frequency swept optical signal is zero. The N frequency swept optical signals have different frequencies. The multiplexer / demultiplexer component is configured to multiplex the N frequency swept optical signals to obtain a radar transmission signal, demultiplex the radar transmission signal to obtain a local oscillator signal and a detection signal, transmit the detection signal using an antenna, and send the local oscillator signal to a receiving device of the lidar. According to the above solution, frequency swept optical signals with different slopes are introduced. In this case, for multiple real targets, coherent detection is performed in at least two periods corresponding separately to different frequency swept optical signals. The range and velocity of the real target obtained by the operation using the different frequency swept optical signals do not change, while the range and velocity of the false target change. Therefore, the range and velocity of the real target are determined using the same coherent detection results of the multiple frequency swept optical signals. This allows the virtual target to be excluded without increasing the detection time.

[0006] In a possible design, the first frequency swept optical signal and the second frequency swept optical signal are periodic frequency swept optical signals.

[0007] In a possible design, the signal period of the first frequency swept optical signal is M times the signal period of the second frequency swept optical signal, or the signal period of the second frequency swept optical signal is M times the signal period of the first frequency swept optical signal, where M is a positive integer.

[0008] In a possible design, the signal period of the first frequency-swept optical signal is K times the detection period of the lidar, or the signal period of the second frequency-swept optical signal is K times the detection period of the lidar, where K is a positive integer. In the above design, since multiple detections are performed in one signal period, the detection efficiency can be improved and the detection delay can be reduced.

[0009] In a possible design, in one target signal period, the frequency sweep slope of the first frequency sweep signal in the first period is opposite in sign to the frequency sweep slope of the first frequency sweep signal in the second period, the frequency sweep slope of the second frequency sweep signal in the first period is opposite in sign to the frequency sweep slope of the second frequency sweep signal in the second period, the frequency sweep slope of the first frequency sweep signal in the first period is different from the frequency sweep slope of the second frequency sweep signal in the second period, and the frequency sweep slope of the second frequency sweep signal in the first period is different from the frequency sweep slope of the first frequency sweep signal in the second period. The target signal period is the maximum signal period between the signal period of the first frequency sweep optical signal and the signal period of the second frequency sweep optical signal. In the above design, the frequency sweep slopes of the frequency sweep optical signals in the two periods are different. To avoid acquiring the same intermediate frequency signal generated by the beat frequency between the local oscillator signal and the different frequency swept optical signals that beat, the accuracy of rejecting false targets is further improved.

[0010] In a possible design, the minimum frequency difference between the first frequency swept optical signal and the second frequency swept optical signal is related to the receiving bandwidth of the antenna. In the above design, the frequency range of each frequency swept optical signal is determined based on the receiving bandwidth of the antenna, so that the generation of unnecessary beat frequency signals can be reduced and the accuracy of the calculation results can be improved. Furthermore, there is no need to use a computationally complex algorithm to distinguish and remove the unnecessary beat frequency signals. This further reduces the calculation complexity and reduces the processing resources used.

[0011] In a possible design, the minimum frequency difference between the first and second frequency swept optical signals satisfies the following condition: min(|f1-f2|)>|fR1|+|fR2|+fOE

[0012] f1 represents the frequency sweep range of the first frequency swept optical signal, f2 represents the frequency sweep range of the second frequency swept optical signal, fR1 represents the maximum frequency shift amount of the echo signal of the first frequency swept optical signal relative to the local oscillator signal of the first frequency swept optical signal, fR2 represents the maximum frequency shift amount of the echo signal of the second frequency swept optical signal relative to the local oscillator signal of the second frequency swept optical signal, and fOE represents the receiving bandwidth of the antenna. The above design provides a specific scheme for determining the frequency difference between the frequency swept optical signals, and is simple to implement. In addition, the generation of unwanted beat frequency signals can be prevented, and the accuracy of the calculation results can be improved. Furthermore, there is no need to use a computationally complex algorithm to distinguish and remove unwanted beat frequency signals. This further reduces the computational complexity and reduces the processing resources used.

[0013] In a possible design, the first frequency sweep signal and the second frequency sweep signal may be:

number

[0014] In a possible design, the waveform of the first frequency swept optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave. If the frequency sweep slope of the second frequency swept optical signal is non-zero, the waveform of the second frequency swept optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave.

[0015] In possible designs, the wavelength variation ranges of the N frequency swept optical signals are different, or the polarization directions of the N frequency swept optical signals are different.

[0016] In a possible design, the frequency swept signal source includes N frequency swept lasers, and the frequency swept lasers are configured to transmit frequency swept optical signals whose wavelengths change periodically. In the above design, the wavelengths of the optical signals transmitted by different frequency swept lasers are adjusted, so that the frequency ranges of the frequency swept optical signals transmitted by different frequency swept lasers are different, and the frequency sweep slope meets the requirements.

[0017] In a possible design, the frequency swept signal source includes a laser, a modulator, a radio frequency amplifier, and a frequency swept drive signal source. The frequency swept drive signal source is configured to generate N frequency swept signals whose frequencies change periodically, and the frequency swept signals are input to the modulator after being amplified by the radio frequency amplifier. The laser is configured to transmit a laser signal. The modulator is configured to modulate the N amplified frequency swept signals onto the laser signal to obtain N frequency swept optical signals. The above design provides a method of generating N frequency swept optical signals that meet the requirements through external modulation. A frequency swept electrical signal that meets the frequency requirements is generated by digital signal processing, and then the frequency swept electrical signal is modulated onto the laser signal transmitted by the laser, which is simple to implement.

[0018] In a possible design, the frequency swept signal source includes N frequency swept signal transmitting components. Any one of the N frequency swept optical signal transmitting components includes a frequency swept drive signal source, a laser, a modulator, and a radio frequency amplifier. The frequency swept drive signal source is configured to generate one frequency swept signal whose frequency changes periodically, and the frequency swept signal is amplified by the radio frequency amplifier and then input to the modulator. The laser is configured to transmit a laser signal. The modulator is configured to modulate the amplified frequency swept signal onto a laser signal to obtain one frequency swept optical signal. The wavelengths of the laser signals transmitted by the lasers included in the different frequency swept signal transmitting components are different, and / or the frequency ranges of the frequency swept signals generated by the frequency swept drive signal sources included in the different frequency swept signal transmitting components are different. The above design provides a scheme for generating N frequency swept optical signals by using N frequency swept signal transmitting components, so that N frequency swept optical signals that meet requirements are generated relatively easily.

[0019] In a possible design, the frequency sweep signal source includes a laser, an optical frequency comb, N micro-ring modulators, and N frequency sweep drive signal sources. The laser is configured to transmit a laser signal. The optical frequency comb is configured to process the laser signal to obtain optical signals of N wavelengths. The N frequency sweep drive signal sources are connected to the N micro-ring modulators in one-to-one correspondence. The N micro-ring modulators are sequentially connected in series in the optical path of the optical signals of the N wavelengths. The first micro-ring modulator is configured to modulate a frequency sweep signal output by the first frequency sweep drive signal source, the frequency range of which changes periodically, onto an optical signal of a wavelength corresponding to the first micro-ring modulator. The N micro-ring modulators correspond one-to-one to the N wavelengths, and the frequency ranges of the frequency sweep signals output by different frequency sweep drive signal sources are different. The above design provides a scheme for generating N frequency swept optical signals by combining an optical frequency comb and N micro-ring modulators, and is relatively simple to implement.

[0020] In a possible design, the multiplexer / demultiplexer component includes a coupler, for example a directional coupler.

[0021] In a possible design, the N frequency-swept optical signals have different polarization directions, and the multiplexer / demultiplexer component includes a polarization beam combiner and a polarization-maintaining coupler. The polarization beam combiner is configured to perform beam combining on the N frequency-swept optical signals based on the polarization directions of the N frequency-swept optical signals to obtain a radar transmit signal. The polarization-maintaining coupler is configured to demultiplex the radar transmit signal to obtain a local oscillator signal and a detection signal.

[0022] According to a second aspect, an embodiment of the present application provides a LIDAR detection system, including a LIDAR transmitter according to any one of the first aspect or the design of the first aspect, and a LIDAR receiver, the receiver configured to receive a local oscillator signal from the transmitter and an echo signal of the detection signal transmitted by the transmitter, perform frequency mixing of the echo signal and the local oscillator signal to generate a frequency-mixed signal, and obtain positioning information of the detected object based on the frequency-mixed signal.

[0023] In a possible design, the receiving device may obtain positioning information of the detected object through IQ detection.

[0024] In a possible design, the receiving device includes a 90-degree frequency mixer, a first photodetector, a second photodetector, a first analog-to-digital converter, a second analog-to-digital converter, and a signal processor. The 90-degree frequency mixer is configured to perform frequency mixing on an echo signal received from the antenna, which is a detection signal, and a local oscillator signal to generate a frequency-mixed signal, split the frequency-mixed signal into a first signal and a second signal, and send the first signal to the first photodetector and send the second signal to the second photodetector. The first photodetector is configured to perform detection on the first signal and output the first signal to the first analog-to-digital converter for analog-to-digital conversion. The second photodetector is configured to perform detection on the second signal and output the second signal to the second analog-to-digital converter for analog-to-digital conversion. The signal processor is configured to process the digital signal output by the first analog-to-digital converter and the digital signal output by the second analog-to-digital converter to obtain positioning information of the detected object. In the above design, positive and negative frequency information can be distinguished by IQ detection, so that the processing algorithm is simple and the requirements for the processing performance of the signal processor are relatively low.

[0025] In a possible design, the receiving device may obtain positioning information of the detected object through I detection or Q detection.

[0026] In a possible design, the receiving device includes a 180-degree frequency mixer, a third photodetector, a third analog-to-digital converter, and a signal processor. The 180-degree frequency mixer is configured to perform frequency mixing on the echo signal received from the antenna, which is the detection signal, and the local oscillator signal to generate a frequency-mixed signal, and send the frequency-mixed signal to the third photodetector. The third photodetector is configured to perform detection on the frequency-mixed signal, and output the frequency-mixed signal to the third analog-to-digital converter for analog-to-digital conversion. The signal processor is configured to process the digital signal output by the third analog-to-digital converter to obtain positioning information of the detected object. In the above design, an I receiver or a Q receiver is used, and multiple frequency-swept optical signals are multiplexed to form a transmission signal. Since the distance and speed of the real target do not change, the local oscillator signal of each frequency swept optical signal may generate the echo signal and beat of each frequency swept optical signal to calculate the frequency mixed signal, and then the frequency components of the distance and the frequency components of the speed are determined separately using the equations corresponding to different cases, that is, three calculation results can be obtained based on each frequency swept optical signal. In this case, the same result is the final calculation result in the multiple calculation results. This can resolve the ambiguity of the detection speed caused by the inability to determine a specific correct result in the calculation results corresponding to the equations corresponding to multiple cases when using the existing I receiver or Q receiver.

[0027] According to a third aspect, an embodiment of the present application provides a lidar-based detection method, the method includes the steps of: transmitting N frequency swept optical signals, N being an integer greater than 1, and in the N frequency swept optical signals in a first time period, a frequency sweep slope of the first frequency swept optical signal and a frequency sweep slope of the second frequency swept optical signal have opposite signs, or the frequency sweep slope of the first frequency swept optical signal is not zero, the frequency sweep slope of the second frequency swept optical signal is zero, and the N frequency swept optical signals have different frequencies; multiplexing the N frequency swept optical signals to obtain a radar transmission signal, splitting the radar transmission signal into a local oscillator signal and a detection signal, and transmitting the detection signal using an antenna. Coherent detection is performed on the echo signals of the local oscillator signal and the detection signal to obtain positioning information of the detected object.

[0028] In a possible design, the detection method includes a step of receiving an echo signal of the detection signal from an antenna, performing frequency mixing on the echo signal and a local oscillator signal to generate a frequency mixed signal, and a step of obtaining positioning information of the detected object based on the frequency mixed signal.

[0029] In a possible design, the first frequency swept optical signal and the second frequency swept optical signal are periodic frequency swept optical signals.

[0030] In a possible design, the signal period of the first frequency swept optical signal is M times the signal period of the second frequency swept optical signal, or the signal period of the second frequency swept optical signal is M times the signal period of the first frequency swept optical signal, where M is a positive integer.

[0031] In a possible design, the signal period of the first frequency-swept optical signal is K times the detection period of the lidar, or the signal period of the second frequency-swept optical signal is K times the detection period of the lidar, where K is a positive integer.

[0032] In a possible design, in one target signal period, the frequency sweep slope of the first frequency swept optical signal in the first time period is opposite in sign to the frequency sweep slope of the first frequency swept optical signal in the second time period, the frequency sweep slope of the second frequency swept optical signal in the first time period is opposite in sign to the frequency sweep slope of the second frequency swept optical signal in the second time period, the frequency sweep slope of the first frequency swept optical signal in the first time period is different from the frequency sweep slope of the second frequency swept optical signal in the second time period, and the frequency sweep slope of the second frequency swept optical signal in the first time period is different from the frequency sweep slope of the first frequency swept optical signal in the second time period. The target signal period is the maximum signal period between the signal period of the first frequency swept optical signal and the signal period of the second frequency swept optical signal.

[0033] In a possible design, the minimum frequency difference between the first frequency swept optical signal and the second frequency swept optical signal is related to the reception bandwidth of the antenna.

[0034] In a possible design, the minimum frequency difference between the first and second frequency swept optical signals satisfies the following condition: min(|f1-f2|)>|fR1|+|fR2|+fOE

[0035] f1 represents the frequency sweep range of the first frequency swept optical signal, f2 represents the frequency sweep range of the second frequency swept optical signal, fR1 represents the maximum frequency shift amount of the echo signal of the first frequency swept optical signal relative to the local oscillator signal of the first frequency swept optical signal, fR2 represents the maximum frequency shift amount of the echo signal of the second frequency swept optical signal relative to the local oscillator signal of the second frequency swept optical signal, and fOE represents the receiving bandwidth of the antenna.

[0036] In a possible design, the first frequency sweep signal and the second frequency sweep signal may be:

number

[0037] In a possible design, the waveform of the first frequency swept optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave. If the frequency sweep slope of the second frequency swept optical signal is non-zero, the waveform of the second frequency swept optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave.

[0038] In possible designs, the wavelength variation ranges of the N frequency swept optical signals are different, or the polarization directions of the N frequency swept optical signals are different.

[0039] In the present application, based on the implementation forms provided in the above aspects, the implementation forms can be further combined to provide more implementation forms.

[0040] For the beneficial effects of the second and third aspects, please refer to the relevant explanation of the first aspect.

[0041] In order to describe the technical solutions of the embodiments of the present application more clearly, the following briefly describes the accompanying drawings for illustrating the embodiments. [Brief description of the drawings]

[0042] [Figure 1] FIG. 1 is a diagram of the lidar architecture. [Diagram 2] 2 is a diagram of a local oscillator signal, an echo signal, and a frequency mixed signal. [Diagram 3] FIG. 2 is a diagram of the spectrum of a frequency mixed signal. [Figure 4] FIG. 13 is a diagram of a generated false target. [Diagram 5] FIG. 2 is a diagram showing the waveform of a frequency mixed signal. [Figure 6] FIG. 1 is a diagram of the architecture of a LIDAR detection system according to an embodiment of the present application. [Figure 7] 2 is a waveform diagram of a frequency swept optical signal according to an embodiment of the present application. [Figure 8] 2 is a diagram of waveforms of a first frequency swept optical signal and a second frequency swept optical signal according to an embodiment of the present application. [Figure 9] FIG. 13 is a diagram of a spectrum of a frequency mixing signal for two detection targets according to an embodiment of the present application. [Figure 10] FIG. 2 is a diagram of the distance-velocity solution principle according to an embodiment of the present application. [Figure 11] FIG. 2 is a diagram of an output waveform of a frequency swept optical signal in a polarization multiplexing scheme according to an embodiment of the present application. [Figure 12] FIG. 2 is a diagram of the relationship between detection period and signal period according to an embodiment of the present application. [Figure 13] FIG. 6 is a diagram of the structure of a receiving device 620 according to an embodiment of the present application. [Figure 14] FIG. 6 is a structural diagram of another receiving device 620 according to an embodiment of the present application. [Figure 15A] FIG. 1 is a diagram of the architecture of a detection system according to an embodiment of the present application. [Figure 15B] 1A is a diagram of waveforms of two frequency-swept optical signals and a spectrum of a frequency-mixed signal for one detection target according to an embodiment of the present application. [Figure 16] FIG. 1 is a diagram of the architecture of a detection system according to an embodiment of the present application. [Figure 17] FIG. 1 is a diagram of the architecture of a detection system according to an embodiment of the present application. [Figure 18] FIG. 1 is a diagram of the architecture of a detection system according to an embodiment of the present application. [Figure 19] FIG. 1 is a diagram of the architecture of a detection system according to an embodiment of the present application. [Figure 20] FIG. 2 is a diagram of a scheme for generating a frequency swept drive signal source according to an embodiment of the present application. [Figure 21]FIG. 1 is a diagram of the architecture of a detection system according to an embodiment of the present application. [Figure 22] FIG. 2 is a diagram of a scheme for generating a frequency swept drive signal source according to an embodiment of the present application. [Diagram 23] FIG. 1 is a diagram of the architecture of a detection system according to an embodiment of the present application. [Figure 24] FIG. 1 is a diagram of the architecture of a detection system according to an embodiment of the present application. [Diagram 25] 1 is a schematic flowchart of a LIDAR detection method according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings.

[0044] In the following, some terms used in this application are explained and described. It should be noted that the explanation is intended to facilitate understanding by those skilled in the art, but does not constitute a limitation on the scope of protection claimed in this application.

[0045] (1) The term "at least one" in this application means one or more, i.e., including one, two, three, or more, and "multiple" means more than one, i.e., including two, three, or more. In addition, it should be understood that in the description of this application, terms such as "first" and "second" are used for distinction and explanation only, and should not be understood as indicating or implying relative importance, or as indicating or implying order. "And / or" describes an association relationship between related objects and represents that three relationships may exist. For example, A and / or B may represent the cases where only A is present, where both A and B are present, and where only B is present. Each of A and B may be singular or plural. The character " / " generally represents an "or" relationship between the objects to be associated. "At least one of the following items (parts)" or similar expressions refers to any combination of these items, including any combination of singular items (parts) or multiple items (parts). For example, at least one of a, b, or c may represent a, b, c, ab, ac, bc, or abc, where a, b, and c may be singular or plural.

[0046] (2) Swept frequency signal: A swept frequency signal is a signal whose frequency changes linearly with respect to time.

[0047] (3) Frequency sweep waveform: The frequency sweep waveform is the trajectory of the frequency sweep signal during a frequency sweep.

[0048] (4) Frequency Sweep Slope: The frequency sweep slope is the frequency variation of the frequency sweep signal per unit time, measured in Hz / s.

[0049] Sign of the frequency sweep slope: If the sign of the frequency sweep slope is positive, the frequency increases with time. If the sign of the frequency sweep slope is negative, the frequency decreases with time. If the sign of the frequency sweep slope is 0, the frequency does not change with time. Two frequency sweep slopes with opposite signs mean that one frequency sweep slope has a positive sign and the other frequency sweep slope has a negative sign.

[0050] (5) Guard Bandwidth: When frequency multiplexing is used for signals, there is a certain frequency range between the signals. To prevent interference between signals of different frequencies, the frequency range is not loaded with signals.

[0051] (6) Radar transmission signal: A radar transmission signal is a signal that can be generated by one or more frequency sweep signals and transmitted by a transmitting antenna after frequency multiplexing. A radar transmission signal is usually an optical signal.

[0052] (7) Echo signal: The echo signal is a reflected signal after the transmitted signal reaches the detection object. The echo signal is usually an optical signal.

[0053] (8) Minimum detectable distance of the lidar: Some lidars have blind spots, and objects that are relatively close to the lidar, for example 1m, cannot be detected. The minimum distance of the blind spot is the minimum detectable distance of the lidar. Some lidars do not have blind spots. However, some objects are relatively close to the lidar due to the limitations of the processor accuracy or algorithm, so after the lidar transmits a detection signal and a relatively close object transmits an echo signal, the lidar cannot accurately locate the exact location of the object using the echo signal. Therefore, the minimum distance that can be accurately located is the minimum detectable distance of the lidar.

[0054] This application is applied to LIDAR. The LIDAR can be installed on a vehicle, a ship, or other machine. See FIG. 1. The LIDAR uses a frequency swept signal source to transmit a frequency swept optical signal, which is reflected by the detected object after being irradiated on the detected object, and the reflected echo signal can be received by the receiving end of the LIDAR. In this case, the receiving end of the LIDAR can beat the echo signal with a local oscillator signal to generate one intermediate frequency signal that changes with the distance and velocity of the detected object, and calculate the distance, velocity, reflectivity, and other information of the detected object based on the frequency of the intermediate frequency signal.

[0055] As described in the background art, for a relatively distant object, the light spot of the lidar diverges, so that the emitted light signal generates echo signals of multiple detection targets. In FIG. 2, two detection targets are used as an example. After coherent detection of the two echo signals and the local oscillator signal, multiple frequency mixed signals are generated. As shown in FIG. 2, coherent detection is performed on the echo signal 1 and the local oscillator signal to generate frequency mixed signal 1, and coherent detection is performed on the echo signal 2 and the local oscillator signal to generate frequency mixed signal 2. From FIG. 2, it can be seen that the time can be divided into period 1 and period 2. The frequency sweep slope of the transmission signal or the echo signal is different in different periods. Fourier transform is performed separately on the signals in period 1 and period 2 to obtain the spectrum diagram shown in FIG. 3. When only the echo signal 1 exists, in FIG. 3, the signal spectrum in period 1 only has frequency component 1, and the signal spectrum in period 2 only has frequency component 3.

[0056] Also, a distance-related frequency and a speed-related frequency of the detected target may be determined based on frequency component 1 and frequency component 2 in period 1 and frequency component 3 and frequency component 4 in period 2. Then, a distance of the detected target is further calculated based on the distance-related frequency, and a speed of the detected target is calculated based on the speed-related frequency. Since there are two frequency components in period 1 and two frequency components in period 2, the distances and speeds of four detected targets can be obtained by calculation based on the combination.

[0057] An IQ receiver is used as an example. The relationship between the frequency components in period 1, the frequency components in period 2, the distance-related frequencies, and the velocity-related frequencies satisfies equation (1). f1=-f R +f D , f2=f R +f D Formula (1)

[0058] f1 is the frequency component in period 1, f2 is the frequency component in period 2, f R is the distance-related frequency, f D is the speed related frequency.

[0059] Also, f R and f D may be calculated using equation (2).

number

[0060] The range of the detected target may be determined using equation (3), and the velocity of the detected target may be determined using equation (4).

number

[0061] R represents the distance between the detection target and the lidar, and B represents the frequency sweep bandwidth of the transmitted optical signal.

[0062] where c is the speed of light and T is one period, say period 1 or period 2.

number

[0063] λ represents the light wavelength, and V represents the moving speed of the detection target.

[0064] In this case, the relationship between V, R, f1, and f2 can be determined using Equations (2)-(4). For details, see Equation (5).

number

[0065] Referring to equation (5), to determine the curve of the relationship between the velocity V, the distance R, f1, and f2, refer to FIG. 4. From FIG. 4, it can be seen that in the frequency components 1-4, the two specific components from the frequency mixed signal 1 and the two specific components from the frequency mixed signal 2 cannot be distinguished. Therefore, accurate information of the two detection targets cannot be obtained. It should be understood that even when the I receiver or the Q receiver is used, multiple detection targets cannot be distinguished.

[0066] In some scenarios, when the I receiver or Q receiver is used, the moving speed of a certain detection target is relatively high, and speed ambiguity may occur during the calculation of the speed of the detection target. For example, (1) to (3) in FIG. 5 are diagrams of the frequency changes of the local oscillator signal and the echo signal in three possible cases. In the first possible case shown in (1) in FIG. 5, when the I receiver or Q receiver is used for detection, please refer to (4) in FIG. 5 for the frequency mixing signal in period 1 and the frequency mixing signal in period 2. When the IQ receiver is used for detection, the frequency mixing signal in period 1 and the frequency mixing signal in period 2 can be shown in (7) in FIG. 5. The IQ receiver can distinguish positive and negative frequencies during detection. When the I receiver or Q receiver is used for detection, the I receiver or Q receiver cannot distinguish positive and negative frequencies. Therefore, the relationship among the frequency components in period 1, the frequency components in period 2, the distance-related frequencies, and the velocity-related frequencies should theoretically satisfy the condition shown in equation (6). f1=f R -f D , f2=f R +f D Formula (6)

[0067] In the second possible case shown in (2) of FIG. 5, when the I receiver or the Q receiver is used for detection, the frequency mixing signal in period 1 and the frequency mixing signal in period 2 can be seen in (5) of FIG. 5. When the IQ receiver is used for detection, the frequency mixing signal in period 1 and the frequency mixing signal in period 2 can be seen in (8) of FIG. 5. The IQ receiver can distinguish positive and negative frequencies during detection. When the I receiver or the Q receiver is used for detection, the I receiver or the Q receiver cannot distinguish positive and negative frequencies. Therefore, the relationship between the frequency components in period 1, the frequency components in period 2, the distance-related frequency, and the velocity-related frequency should theoretically satisfy the condition shown in equation (7). f1=-f R +f D , f2=f R +f DFormula (7)

[0068] In the third possible case shown in (3) of FIG. 5, when the I receiver or the Q receiver is used for detection, please refer to (6) of FIG. 5 for the frequency mixing signal in period 1 and the actual frequency mixing signal in period 2. When the IQ receiver is used, the frequency mixing signal in period 1 and the frequency mixing signal in period 2 can be shown in (9) of FIG. 5. The IQ receiver can distinguish positive and negative frequencies during detection. When the I receiver or the Q receiver is used for detection, the I receiver or the Q receiver cannot distinguish positive and negative frequencies. Therefore, the relationship between the frequency components in period 1, the frequency components in period 2, the distance-related frequency, and the velocity-related frequency should theoretically satisfy the condition shown in equation (8). f1=f R -f D , f2=-f R -f D Formula (8)

[0069] Therefore, when the I receiver or the Q receiver is used for detection, if the frequencies f1 and f2 are calculated as shown in equation (6), the actual frequency of the frequency mixed signal and the calculation result may not match, which may lead to inaccurate calculation of the speed and distance. If the frequencies f1 and f2 are calculated separately as shown in equations (6), (7), and (8), the accurate calculation results cannot be distinguished.

[0070] Based on this, the present application provides a lidar sending device, a measuring device, and a detection method, so that simultaneous detection of multiple targets is implemented without increasing the detection duration, and the detection result is relatively accurate. No velocity ambiguity occurs even if an I receiver or a Q receiver is used. In the embodiment of the present application, the detection object is also called a reflector, and the detection object may be any object in the scanning direction of the antenna, for example, a person, a mountain, a vehicle, a tree, or a bridge. The antenna in the embodiment of the present application may be called a scanner, including a transmitting antenna for transmitting an optical signal and a receiving antenna for receiving an optical signal, configured to transmit an optical signal and receive an optical signal.

[0071] 6 is a diagram of the structure of a lidar detection system. The detection system 600 includes a transmitting device 610 and a receiving device 620. The detection system may be used in a distance measuring device or a speed measuring device, for example, an FMCW lidar, a laser velocimeter, a laser range finder, an optical coherence tomography (OCT) device, or an optical frequency domain reflectometer (OFDR) device.

[0072] The sending device 610 may include a frequency swept signal source 611 and a multiplexer / demultiplexer component 612. The frequency swept signal source 611 transmits N frequency swept optical signals, where N is an integer greater than 1. The frequency swept signal source may be generated by direct modulation of a laser (also called internal modulation), or may be generated by externally modulating an optical signal generated by a laser with a modulator. The structure that may be used by the frequency swept signal source will be described in detail below and will not be described in detail herein.

[0073] The N frequency swept signals include at least two frequency swept optical signals having different frequency swept waveforms. The N frequency swept optical signals have different frequency ranges. For ease of distinction, the two frequency swept signals are referred to as a first frequency swept optical signal and a second frequency swept optical signal.

[0074] In a first possible implementation form, the first frequency swept optical signal and the second frequency swept optical signal satisfy at least the following Condition 1 and Condition 2.

[0075] Condition 1: There is at least a period of time during which the frequency sweep slope of the first frequency swept optical signal and the frequency sweep slope of the second frequency swept optical signal have opposite signs. This period of time is referred to herein as the first period. It will be understood that the frequency sweep slope of the first frequency swept optical signal and the frequency sweep slope of the second frequency swept optical signal have opposite signs during the first period of time.

[0076] Condition 2: The absolute value of the frequency sweep slope of the first frequency swept optical signal is different from the absolute value of the frequency sweep slope of the second frequency swept optical signal in the first time period.

[0077] In a second possible implementation form, the first frequency swept optical signal and the second frequency swept optical signal satisfy Condition 3 below.

[0078] Condition 3: There is a specific period during which the frequency sweep slope of one of the first and second frequency swept optical signals is 0 and the frequency sweep slope of the other frequency swept optical signal is not 0. For example, during the first period, the frequency sweep slope of the first frequency swept optical signal is 0 and the frequency sweep slope of the second frequency swept optical signal is not 0. Alternatively, during the first period, the frequency sweep slope of the first frequency swept optical signal is not 0 and the frequency sweep slope of the second frequency swept optical signal is 0.

[0079] In some possible embodiments, the N frequency swept optical signals further satisfy at least one of the following conditions 4 to 7.

[0080] Condition 4: All of the N frequency swept optical signals are periodic frequency swept optical signals, or a certain frequency swept optical signal is a constant frequency signal, i.e., the frequency sweep slope of the frequency swept optical signal is 0. In some embodiments, the signal periods of the N frequency swept optical signals satisfy a number of relationships, and the signal periods may alternatively be multiplied by 1, i.e., the signal periods of the frequency swept optical signals are equal. The first frequency swept optical signal and the second frequency swept optical signal are used as an example. The first frequency swept optical signal and the second frequency swept optical signal are both periodic frequency swept optical signals. For example, the signal periods of the first frequency swept optical signal and the second frequency swept optical signal satisfy a number of relationships. For example, the signal period of the first frequency swept optical signal is M times the signal period of the second frequency swept optical signal, or the signal period of the second frequency swept optical signal is M times the signal period of the first frequency swept optical signal. M may be 1, or may be an integer greater than 1.

[0081] Condition 5: In one target signal period, there are two periods in which the frequency sweep slope of the first frequency swept optical signal and the frequency sweep slope of the second frequency swept optical signal have opposite signs. That is, in addition to the first period in which the frequency sweep slope of the first frequency swept optical signal and the frequency sweep slope of the second frequency swept optical signal have opposite signs, it will be understood that there is at least one period in which the frequency sweep slope of the first frequency swept optical signal and the frequency sweep slope of the second frequency swept optical signal have opposite signs. For ease of distinction, a period other than the first period is called a second period. Here, the target signal period is the maximum value between the signal period of the first frequency swept optical signal and the signal period of the second frequency swept optical signal. For example, the signal period of the first frequency swept optical signal is equal to or greater than the signal period of the second frequency swept optical signal. In a signal period of the first frequency sweep optical signal, a frequency sweep slope of the first frequency sweep signal in the first period and a frequency sweep slope of the first frequency sweep signal in the second period have opposite signs, a frequency sweep slope of the second frequency sweep signal in the first period and a frequency sweep slope of the second frequency sweep signal in the second period have opposite signs, a frequency sweep slope of the first frequency sweep signal in the first period is different from a frequency sweep slope of the second frequency sweep signal in the second period, and a frequency sweep slope of the second frequency sweep signal in the first period is different from a frequency sweep slope of the first frequency sweep signal in the second period.

[0082] Condition 6: There is a guard bandwidth between two frequency swept optical signals with consecutive frequencies among the N frequency swept optical signals. The setting of the guard bandwidth is related to the reception bandwidth of the antenna. The first frequency swept optical signal and the second frequency swept optical signal are used as an example. The first frequency swept optical signal and the second frequency swept optical signal are two frequency swept optical signals with the smallest frequency difference among the N frequency swept optical signals. The smallest frequency difference between the first frequency swept optical signal and the second frequency swept optical signal is related to the reception bandwidth of the antenna.

[0083] For example, the minimum frequency difference between the first frequency swept optical signal and the second frequency swept optical signal satisfies the condition shown in equation (9). min(|f1-f2|)>|fR1|+|fR2|+fOE Equation (9)

[0084] f1 represents the frequency sweep range of the first frequency swept optical signal, f2 represents the frequency sweep range of the second frequency swept optical signal, fR1 represents the maximum frequency shift amount of the echo signal of the first frequency swept optical signal relative to the local oscillator signal of the first frequency swept optical signal, fR2 represents the maximum frequency shift amount of the echo signal of the second frequency swept optical signal relative to the local oscillator signal of the second frequency swept optical signal, and fOE represents the receiving bandwidth of the antenna.

[0085] Condition 7: The frequency sweep gradient of the first frequency swept optical signal and the frequency sweep gradient of the second frequency swept optical signal satisfy the condition shown in equation (10).

number

[0086] round() represents a rounding operation to the nearest integer, K1 represents the absolute value of the frequency sweep slope of the first frequency sweep signal in the first period, K2 represents the absolute value of the frequency sweep slope of the second frequency sweep signal in the first period, R min represents the minimum detectable distance of the lidar, and c represents the speed of light.

[0087] For example, in this embodiment of the present application, the conditions satisfied by the N frequency swept optical signals may include multiple combinations of the above conditions. For example, the N frequency swept optical signals satisfy condition 1+condition 2+condition 6+condition 7. In another example, the N frequency swept optical signals satisfy condition 3+condition 6+condition 7. In another example, the N frequency swept optical signals satisfy condition 1+condition 2+condition 4+condition 5+condition 6+condition 7. In another example, the N frequency swept optical signals satisfy condition 1+condition 2+condition 5+condition 6+condition 7. Other examples will not be listed one by one here.

[0088] In some embodiments, each periodic signal of the N frequency swept optical signals in the present application may use a different frequency swept waveform having a frequency that varies linearly with time, such as a triangular wave, a trapezoidal wave, and a sawtooth wave, or any combination of the above waveforms. In some other embodiments, some frequency swept optical signals may use a constant frequency waveform, i.e., the frequency sweep slope is 0. Figure 7 shows examples of frequency swept waveforms.

[0089] The multiplexer / demultiplexer component 612 multiplexes the N frequency-swept optical signals to obtain a radar transmission signal, demultiplexes the radar transmission signal to obtain a local oscillator signal and a detection signal, transmits the detection signal using an antenna, and sends the local oscillator signal to a lidar receiver 620.

[0090] The receiving device 620 receives the local oscillator signal from the transmitting device 610 and the echo signal of the detection signal transmitted by the transmitting device 610, performs frequency mixing of the echo signal and the local oscillator signal to generate a frequency-mixed signal, and then obtains positioning information of the detected object based on the frequency-mixed signal. For example, the positioning information includes information such as the speed, distance from the LIDAR, and reflectivity of the detected object.

[0091] In some embodiments, the N frequency swept optical signals may be multiplexed in a frequency multiplexing manner or a polarization multiplexing manner. Note that in a polarization multiplexing manner, there is no requirement for the guard bandwidth described in condition 6 above for the N frequency swept optical signals.

[0092] The first frequency swept optical signal and the second frequency swept optical signal are used as an example. The first frequency swept optical signal and the second frequency swept optical signal are multiplexed in a frequency multiplexing manner before transmission. Some possible frequency sweep waveforms of the two frequency swept optical signals are described with reference to FIG. 8. (1)-(3) of FIG. 8 use an example in which the frequency sweep bandwidth of the first frequency swept optical signal is B1 and the frequency sweep bandwidth of the second frequency swept optical signal is B2. There is a guard bandwidth between the first frequency swept optical signal and the second frequency swept optical signal. There are at least two periods in which the signs of the frequency sweep slope of the first frequency swept optical signal and the frequency sweep slope of the second frequency swept optical signal are opposite. In (1)-(3) of FIG. 8, in the first period, the signs of the frequency sweep slope of the first frequency swept optical signal and the frequency sweep slope of the second frequency swept optical signal are opposite, and the absolute values ​​of the frequency sweep slopes are not equal. During the second time period, the frequency sweep slopes of the first and second frequency swept optical signals have opposite signs and are not equal in absolute value. The frequency sweep slope of the first frequency swept optical signal during the first time period is different from the frequency sweep slope of the second frequency swept optical signal during the second time period, and the frequency sweep slope of the second frequency swept optical signal during the first time period is different from the frequency sweep slope of the first frequency swept optical signal during the second time period.

[0093] The first frequency swept optical signal and the second frequency swept optical signal shown in FIG. 8(1) are used as an example to illustrate the effect of accurately acquiring positioning information of multiple targets. Please refer to FIG. 9. Two detection targets are used as an example. The local oscillator signal 1 of the first frequency swept optical signal corresponds to two echo signals, echo signal 1-1 and echo signal 1-2, separately. The local oscillator signal 2 of the second frequency swept optical signal corresponds to two echo signals, echo signal 2-1 and echo signal 2-2, separately. For the spectrum of the frequency mixing signal generated by the local oscillator signal 1 generating the echo signal 1-1 and the echo signal 1-2 beats in the period 1, and the spectrum of the frequency mixing signal generated by the local oscillator signal 2 generating the echo signal 2-1 and the echo signal 2-2 beats in the period 1, please refer to the spectrum of the frequency mixing signal shown in (2) of Fig. 9, which exists when the I receiver is used, and the spectrum of the frequency mixing signal shown in (4) of Fig. 9, which exists when the IQ receiver is used. For the spectrum of the frequency mixing signal generated by the local oscillator signal 1 generating the echo signal 1-1 and the echo signal 1-2 beats in the period 2, and the spectrum of the frequency mixing signal generated by the local oscillator signal 2 generating the echo signal 2-1 and the echo signal 2-2 beats in the period 2, please refer to the spectrum of the frequency mixing signal shown in (3) of Fig. 9, which exists when the I receiver is used, and the spectrum of the frequency mixing signal shown in (5) of Fig. 9, which exists when the IQ receiver is used.

[0094] In some embodiments, when an IQ receiver is used, the velocity and distance of a detected target may be determined according to equations (2)-(4).

[0095] In some other embodiments, when an I receiver or a Q receiver is used, the velocity and distance of the detection target may be calculated according to Equations (6) to (8) with reference to Equations (3) and (4), respectively. In this embodiment of the present application, multiple frequency swept optical signals are used for detection. Then, for the frequency mixed signals obtained by frequency mixing each frequency swept optical signal with a local oscillator signal, the velocity and distance of the detection target may be calculated according to Equations (6) to (8) with reference to Equations (3) and (4).

[0096] Frequency swept optical signals with different slopes are introduced. Therefore, in this case, for the real target, coherent detection is performed in two periods corresponding to different frequency swept optical signals separately. The distance and speed of the real target obtained by the operation with different frequency swept optical signals do not change, and the distance and speed of the false target change. Therefore, as shown in FIG. 10, the speed and distance corresponding to the intersection of the four lines are the speed and distance of the real target. In this embodiment of the present application, the frequency swept signals with different slopes are multiplexed by frequency multiplexing to form a transmission signal, and the transmission signal is used to detect M detection objects. This allows the false target to be eliminated without increasing the detection time.

[0097] When there is a certain guard bandwidth in the frequency domain between different frequency swept optical signals (i.e., when condition 6 is satisfied), it can prevent unnecessary beat frequency signals from being generated. Therefore, it can avoid calculation errors and reduce the complexity of the calculation of the velocity or distance. In this embodiment of the present application, the transmission signal is formed through transmission frequency multiplexing, so that multiple targets are distinguished without increasing the measurement time, and the lidar point rate remains unchanged. In addition, in this embodiment of the present application, an I receiver, a Q receiver, or an IQ receiver can be used. When an I receiver or a Q receiver is used, multiple frequency swept optical signals are multiplexed by frequency multiplexing to form a transmission signal. Since the range and velocity of the real target do not change, the local oscillator signal of each frequency swept optical signal generates an echo signal of each frequency swept optical signal and beats to calculate the frequency mixing signal, and the frequency component of the distance and the frequency component of the velocity are determined according to each of Equations (6) to (8). That is, three calculation results can be obtained based on each frequency swept optical signal. As an example, two frequency swept optical signals are used. Of the two frequency swept optical signal calculation results, the same two results are the final calculation result. This can solve the existing problem of velocity ambiguity that occurs when I or Q receivers are used for detection. In addition, the cost can be reduced by using I or Q receivers compared to using IQ receivers.

[0098] The first frequency swept optical signal and the second frequency swept optical signal are used as another example. The first frequency swept optical signal and the second frequency swept optical signal are multiplexed in a polarization multiplexing manner before transmission. Some possible frequency sweep waveforms of the two frequency swept optical signals are described with reference to FIG. 11. (1)-(3) of FIG. 11 use an example in which the frequency sweep bandwidth of the first frequency swept optical signal is B1 and the frequency sweep bandwidth of the second frequency swept optical signal is B2. There are at least two periods in which the signs of the frequency sweep slope of the first frequency swept optical signal and the frequency sweep slope of the second frequency swept optical signal are opposite. In (1)-(3) of FIG. 11, in the first period, the signs of the frequency sweep slope of the first frequency swept optical signal and the frequency sweep slope of the second frequency swept optical signal are opposite, and the absolute values ​​of the frequency sweep slopes are not equal. During the second time period, the frequency sweep slopes of the first and second frequency swept optical signals have opposite signs and are not equal in absolute value. The frequency sweep slope of the first frequency swept optical signal during the first time period is different from the frequency sweep slope of the second frequency swept optical signal during the second time period, and the frequency sweep slope of the second frequency swept optical signal during the first time period is different from the frequency sweep slope of the first frequency swept optical signal during the second time period.

[0099] In the above solution, frequency swept optical signals with different slopes are multiplexed in a polarization multiplexing manner to form a transmission signal, and the transmission signal is used to detect M detection objects. In this way, false targets can be filtered out without increasing the measurement time, and the point rate of the lidar remains unchanged. In addition, an I receiver, a Q receiver, or an IQ receiver can be used. When an I receiver or a Q receiver is used, multiple frequency swept optical signals are multiplexed by frequency multiplexing to form a transmission signal. Since the distance and speed of the real target do not change, the local oscillator signal of each frequency swept optical signal produces an echo signal of each frequency swept optical signal and beats to calculate a frequency mixing signal, and the frequency components of the distance and the frequency components of the speed are determined according to each of Equations (6) to (8). That is, three calculation results can be obtained based on each frequency swept optical signal. As an example, two frequency swept optical signals are used. Among the calculation results of the two frequency swept optical signals, the same two results are the final calculation result. This can solve the existing problem of velocity ambiguity that occurs when I or Q receivers are used for detection. Furthermore, the cost can be reduced by using I or Q receivers compared to using IQ receivers.

[0100] In some possible implementations, in order to improve detection efficiency and shorten detection time, the signal period of the frequency swept optical signal is K times the detection period of the lidar. Here, the signal period of the frequency swept optical signal may be the maximum signal period among the signal periods of the N frequency swept optical signals. K is a positive integer. The detection period means a period for obtaining the positioning information of the detected object once.

[0101] The first frequency swept optical signal and the second frequency swept optical signal are used as an example. Please refer to FIG. 12. The frequency sweep bandwidth of the first frequency swept optical signal is different from the frequency sweep bandwidth of the second frequency swept optical signal. In the following, an example is used in which the signal periods of the first frequency swept optical signal and the second frequency swept optical signal are the same. In FIG. 12, T represents the detection period. In FIG. 12 (1), the first frequency swept optical signal and the second frequency swept optical signal are both triangular waves, and the signal period is equal to the detection period. In FIG. 12 (2), the first frequency swept optical signal and the second frequency swept optical signal are both trapezoidal waves, and the signal period is twice the detection period. In FIG. 12 (3), the first frequency swept optical signal is a triangular wave, the second frequency swept optical signal is a trapezoidal wave, and the signal period is twice the detection period. In (4) of FIG. 12, the first frequency swept optical signal is a triangular wave, the second frequency swept optical signal is a constant frequency wave, and the signal period is equal to the detection period. FIG. 12 is only used to explain one example of the multiple relationship between the signal period and the detection period. In a specific scenario, the multiple relationship may be configured based on requirements. This is not specifically limited in this embodiment of the present application.

[0102] In the following, possible structures of the sending device 610 and the receiving device 620 in this embodiment of the present application are described with reference to the accompanying drawings, to provide some implementation examples.

[0103] In this embodiment of the present application, the receiving device 620 may be equipped with one or more IQ receivers, I receivers, or Q receivers. As an example, FIG. 13 is a diagram of a possible structure of an IQ receiver. The IQ receiver includes a 90-degree frequency mixer 6201, a first photodetector 6202, a second photodetector 6203, a first analog-to-digital converter 6204, a second analog-to-digital converter 6205, and a signal processor 6206. For example, the receiving device 620 may further include a receiving antenna, which may alternatively be located outside the receiving device 620. It should be noted that the receiving device 620 may further include other components. This is not specifically limited in the present application. The structure of the IQ receiver that can perform IQ detection is applicable to this embodiment of the present application.

[0104] The 90-degree frequency mixer 6201 receives an echo signal from the antenna. The received echo signal includes echo signals corresponding separately to the N frequency swept optical signals. When there are multiple detection objects, each frequency swept optical signal corresponds to multiple echo signals. The 90-degree frequency mixer 6201 further receives a local oscillator signal from the sending device 610. The received local oscillator signal includes local oscillator signals corresponding separately to the N frequency swept optical signals. The 90-degree frequency mixer 6201 frequency mixes the local oscillator signal and the echo signal, and outputs two optical signals, an I component optical signal and a Q component optical signal. The first photodetector 6202 performs optoelectronic detection on the I component optical signal and converts the I component optical signal into a first analog electrical signal. The second photodetector 6203 performs optoelectronic detection on the Q component optical signal and converts the Q component optical signal into a second analog electrical signal. The first analog-to-digital converter 6204 samples the first analog electrical signal and converts the first analog electrical signal into a first digital signal. The second analog-to-digital converter 6205 samples the second analog electrical signal and converts the second analog signal into a second digital signal. Furthermore, the signal processor 6206 processes the first digital signal and the second digital signal to obtain positioning information of the detected object. For example, the first photodetector 6202 and the second photodetector 6203 may use single-ended photodetectors or balanced photodetectors (BPD).

[0105] The signal processor 6206 may include a device having a computing capability such as a digital signal processor (DSP), a central processing unit (CPU), an accelerated processing unit (APU), a graphics processing unit (GPU), a microprocessor, a microcontroller, etc. The signal processor 6206 is configured to process the digital signal obtained by sampling to obtain positioning information such as the speed and distance of the detected target object.

[0106] In this embodiment of the present application, the operation of processing the digital signal obtained by sampling to obtain information such as the speed and distance of the target object may be completed by one or more signal processors 6206, for example, by one or more DSPs, or may be completed by one or more signal processors 6206 in combination with other components, for example, by one DSP in combination with one or more central processing units CPUs together. When processing the digital signal obtained by sampling, the signal processor 6206 may specifically call a computer program stored in a computer-readable storage medium. The computer-readable storage medium may include, but is not limited to, a random access memory (RAM), a read only memory (ROM), an erasable programmable read only memory (EPROM), or a compact disc read only memory (CD ROM), and may be configured within the signal processor 6206 or may be independent of the signal processor 6206.

[0107] As another example, FIG. 14 is a diagram of a possible structure of an I receiver. The I receiver includes a 180-degree frequency mixer 62011, a photodetector 62012, an analog digital converter (ADC) 62013, and a signal processor 62014. The 180-degree frequency mixer 62011 frequency-mixes a local oscillator signal and an echo signal, and outputs an I component optical signal. The photodetector 62012 performs photoelectric detection on the I component optical signal to obtain an analog electrical signal. The analog digital converter 62013 converts the analog electrical signal into a digital signal. Furthermore, the signal processor 62014 processes the digital signal to obtain positioning information of the detected object. For example, the receiving device 620 may further include a receiving antenna, and the receiving antenna may alternatively be disposed outside the receiving device 620. It should be noted that the receiving device 620 may further include other components, which are not specifically limited in this application. Any I-receiver structure capable of performing I-detection is applicable to this embodiment of the present application.

[0108] FIG. 15A is a diagram of a possible structure of the detection system. FIG. 15A uses an example in which the transmission signal is generated in a frequency multiplexing manner for explanation. The frequency swept signal source 611 includes N directly modulated frequency swept lasers. In FIG. 15A, for example, N is 2, and the frequency swept lasers are frequency swept laser 61111 and frequency swept laser 61112. The multiplexer / demultiplexer component 612 includes at least one directional waveguide coupler 6121. The receiver device 620 may use an IQ receiver, an I receiver, or a Q receiver. FIG. 15A uses an example in which one IQ receiver is used, and the IQ receiver uses the structure shown in FIG. 13 as an example. To facilitate explanation, the components of the IQ receiver are not identified.

[0109] Since the wavelength of the frequency swept laser 6111 varies with time, the frequency of the output frequency swept optical signal varies within a set frequency range. Among the N frequency swept lasers 6111, the wavelength variation ranges of different frequency swept lasers 6111 are different.

[0110] The frequency swept laser 61111 outputs a frequency swept optical signal 1, the frequency sweep period of the frequency swept optical signal 1 is T1, and the frequency sweep bandwidth is B1. The wavelength change range of the frequency swept laser 61111 is [λ1, λ2], and the frequency change range of the output frequency swept optical signal 1 is [f1, f2]. The wavelength change range of the frequency swept laser 61112 is [λ3, λ4], and the frequency change range of the output frequency swept optical signal 2 is [f3, f4]. The frequency sweep bandwidth B1 and the frequency sweep bandwidth B2 may be the same or different, and the frequency sweep period T1 and the frequency sweep period T2 may be the same or different, but T1 / T2 or T2 / T1 is a positive integer. 15A, the wavelengths of the laser signals transmitted by frequency swept laser 61111 and frequency swept laser 61112 are adjusted so that output frequency swept optical signal 1 and output frequency swept optical signal 2 satisfy the conditions satisfied by the first frequency swept optical signal and the second frequency swept optical signal. For example, frequency swept optical signal 1 and frequency swept optical signal 2 satisfy condition 1+condition 2+condition 4+condition 5+condition 6+condition 7.

[0111] The frequency swept optical signal 1 and the frequency swept optical signal 2 output by the frequency swept laser 61111 and the frequency swept laser 61112 are combined using a directional waveguide coupler 6121, and two optical signals are output, one optical signal is used as a local oscillator signal, and the other optical signal is used as a detection signal. The powers of the two optical signals may be the same or different. In some embodiments, when the powers of the two optical signals are not equal, one optical signal with a relatively low power may be used as a local oscillator signal, and is used to perform coherent reception on the received signal. The detection signal is one optical signal with a relatively high power, which is transmitted using a scanner and used to detect the detected object. After the detection signal reaches M detected objects, the detection signal is reflected to form M echo signals. After reaching the lidar, the M echo signals are received by the scanner. The M echo signals and one local oscillator signal enter a 90-degree frequency mixer 6201 for optical mixing to obtain a frequency mixed signal. The two optical signals output after frequency mixing are converted into two analog electrical signals by the first photodetector 6202 and the second photodetector 6203, respectively, and then converted into two digital electrical signals by the first analog-to-digital converter 6204 and the second analog-to-digital converter 6205. The two digital signals enter the signal processor 6206 for processing, and finally, information such as the distance and velocity of the M detected objects is output. In some embodiments, before the detection signal is transmitted, an amplification process may be performed first, and then the detection signal is transmitted. For example, the sending device 610 may further include an optical amplifier (not shown), for example, a semiconductor optical amplifier or an optical fiber amplifier. The optical amplifier amplifies and processes the detection signal output by the directional waveguide coupler 3, and then transmits the detection signal using the scanner.

[0112] In the above solution, the wavelength ranges of the different frequency swept lasers are adjusted to implement the frequency swept optical signals in different frequency ranges, and the implementation is simple. The frequency swept optical signals with different slopes are introduced. Therefore, in this case, for a real target, coherent detection is performed in two periods corresponding to different frequency swept optical signals. This can filter out false targets. If there is a certain guard bandwidth in the frequency domain between the different frequency swept optical signals (i.e., if condition 6 is met), it can prevent unwanted beat frequency signals from being generated. Therefore, this can avoid calculation errors and reduce the complexity of the calculation of the velocity or distance. In this embodiment of the present application, the transmission signal is formed through transmission frequency multiplexing, so that multiple targets are distinguished without increasing the measurement time, and the lidar point rate remains unchanged. In addition, in the above solution, the frequency value of the frequency swept optical signal 1 is always smaller than the frequency value of the frequency swept optical signal 2. Therefore, the frequency swept optical signal 1 and the frequency swept optical signal 2 are not confused in the 90-degree frequency mixer 6201 and can be received using the same receiver. This can improve resource utilization and reduce costs.

[0113] For example, see FIG. 15B. The waveforms of the frequency swept optical signal 1 and the frequency swept optical signal 2 are shown in FIG. 15B (1). For the signal waveform and spectrum at the normal rate, see FIG. 15B (2). For the signal waveform and spectrum at the excessively high rate, see FIG. 15B (3). In FIG. 15B, the local oscillator signal of the frequency swept optical signal 1 is called the local oscillator signal 1, the echo signal of the frequency swept optical signal 1 is called the echo signal 1, the local oscillator signal of the frequency swept optical signal 2 is called the local oscillator signal 2, and the echo signal of the frequency swept optical signal 2 is called the echo signal 2. It should be noted that FIG. 15B only uses some waveforms of the frequency swept optical signal 1 and the frequency swept optical signal 2 for explanation, and the principles of other waveforms are similar and will not be described again. 15B(2) and 15B(3), it can be seen that the frequency value of frequency swept optical signal 1 is always smaller than the frequency value of frequency swept optical signal 2. Therefore, in 90 degree frequency mixer 6201, frequency swept optical signal 1 and frequency swept optical signal 2 are not confused with each other.

[0114] FIG. 16 is a diagram of a possible structure of the detection system. For the sake of explanation, FIG. 16 uses an example in which the transmission signal is generated in a frequency multiplexed manner. The frequency swept signal source 611 includes N directly modulated frequency swept lasers. In FIG. 16, for example, N is 2, and the frequency swept lasers are frequency swept laser 61111 and frequency swept laser 61112. The multiplexer / demultiplexer component 612 includes three directional waveguide couplers 6121, which are referred to as directional waveguide coupler 6121-1, directional waveguide coupler 6121-2, and directional waveguide coupler 6121-3, respectively, for ease of differentiation. The receiving device 620 may use two IQ receivers. For ease of explanation, the components of the IQ receivers are not identified.

[0115] The frequency swept laser 61111 outputs a frequency swept optical signal 1. The frequency swept laser 61112 outputs a frequency swept optical signal 2. For the conditions that the frequency swept optical signal 1 and the frequency swept optical signal 2 satisfy, please refer to the description of the embodiment corresponding to FIG. 15A, and the details will not be repeated here. The frequency swept optical signal 1 is output by the directional waveguide coupler 6121-1 and split into two parts. A part of the optical signal is sent to one receiver as a local oscillator signal, and the other part of the optical signal enters the directional waveguide coupler 6121-3. The frequency swept optical signal 2 is output by the directional waveguide coupler 6121-2 and split into two parts. A part of the optical signal is sent to the other receiver as a local oscillator signal, and the other part of the optical signal enters the directional waveguide coupler 6121-3. The detection signal output by the directional waveguide coupler 3 is transmitted by the scanner to detect the detected object. In some embodiments, before the detection signal is transmitted, an amplification process may be performed first, and then the detection signal is transmitted. For example, the sending device 610 may further include an optical amplifier (not shown). The optical amplifier amplifies and processes the detection signal output by the directional waveguide coupler 3, and then transmits the detection signal using the scanner. In some embodiments, the detection system may further include a wavelength division demultiplexer configured to demultiplex the echo signal received from the scanner into two optical signals, and the two optical signals respectively enter two receivers. The processing schemes of the two receivers have been described above, and the details will not be repeated here.

[0116] Two frequency swept optical signals with different wavelength ranges and different slopes are used through frequency multiplexing to form a transmission signal, which is used to detect M detection objects. This can filter out false targets. Furthermore, different IQ receivers are used at the receiving end to perform coherent detection on the different frequency swept optical signals, reducing the computational complexity of the signal processor. In the above embodiment, accurate positioning of multiple detection target objects is implemented without increasing the measurement time, and the lidar point rate remains unchanged.

[0117] In some embodiments, in the detection system shown in FIG. 16, the receiving device 620 may alternatively use two I receivers or two Q receivers, so that no velocity ambiguity occurs and detection costs can be reduced.

[0118] FIG. 17 is a diagram of a possible structure of the detection system. The difference between the embodiment corresponding to FIG. 17 and the embodiment corresponding to FIG. 16 is that in FIG. 17, the multiplexer / demultiplexer components include a wavelength division multiplexer 61211 and a coupler 61212. The frequency swept optical signals 1 to N output by N frequency swept lasers are multiplexed by the wavelength division multiplexer 61211. The optical signal output by the wavelength division multiplexer 61211 is split into two optical signals by the coupler. One optical signal is input to the receiver as a local oscillator signal, and the other optical signal is sent out by the scanner as a detection signal. In some embodiments, before the detection signal is sent, an amplification process may be performed first, and then the detection signal is sent. For example, the sending device 610 may further include an optical amplifier (not shown). The optical amplifier amplifies and processes the detection signal output by the coupler 61212, and then sends the detection signal using the scanner.

[0119] In the above solution, N signals with different frequency swept waveforms are loaded into a laser signal with different wavelength ranges, and frequency multiplexing is performed to generate a transmission signal. In order to filter out false targets, M detection objects are detected simultaneously using the signals. Furthermore, an IQ receiver is used at the receiving end to perform coherent detection on the different frequency swept optical signals, reducing the computational complexity of the signal processor. In the above embodiment, accurate positioning of multiple detection target objects is performed without increasing the measurement time, and the lidar point rate remains unchanged. In some embodiments, in the detection system shown in FIG. 17, the receiving device 620 may alternatively use an I receiver or a Q receiver, and no velocity ambiguity occurs and the detection cost can be reduced.

[0120] Figure 18 is a diagram of a possible structure of a detection system. The difference between the embodiment corresponding to Figure 18 and the embodiment corresponding to Figure 15A is that the receiving device 620 in Figure 15A uses one IQ receiver, and the receiving device 620 in Figure 18 uses one I receiver or Q receiver. In the above solution, no velocity ambiguity occurs, and the detection cost can be reduced.

[0121] FIG. 19 is a diagram of a possible structure of the detection system. In FIG. 19, N frequency swept optical signals are generated by IQ modulating the laser signal transmitted by the laser, and the frequency swept waveforms can be generated by a digital signal processing method. The frequency swept signal source 611 includes a laser 1910, a modulator 1920, a frequency swept drive signal source 1930, and two radio frequency amplifiers. For ease of differentiation, the two radio frequency amplifiers are called radio frequency amplifier 1941 and radio frequency amplifier 1942. FIG. 20 shows the manner in which the sweep drive signal source generates N frequency swept signals. The frequency swept signal 1 to frequency swept signal N are N frequency swept signals with different frequencies, and different up-conversion processes are performed on the frequency swept signals to obtain frequency swept signals whose frequency ranges meet the above conditions. Then, the digital frequency swept signals are converted into analog frequency swept signals by taking the real part and the imaginary part and performing a digital-to-analog conversion process. Furthermore, after radio frequency amplification, the analog frequency swept signal is modulated onto the laser signal transmitted by the laser. After the analog frequency swept signals of different frequency swept frequency ranges are modulated onto the laser signal, frequency swept optical signals of different frequency swept frequency ranges are obtained. The multiplexer / demultiplexer component 612 includes a coupler 1950. The multiplexer / demultiplexer component is configured to demultiplex one optical signal sent by the modulator 1920 and including the N frequency swept optical signals to obtain a local oscillator signal and a detection signal. The coupler 1950 sends the local oscillator signal to the receiving device 620 and transmits the detection signal using a scanner. In some embodiments, before the detection signal is transmitted, an amplification process may be performed first, and then the detection signal is transmitted. For example, the transmitting device 610 may further include an optical amplifier (not shown). The optical amplifier amplifies and processes the detection signal output by the coupler 1950, and then transmits the detection signal using a scanner.

[0122] In this solution, analog frequency swept electrical signals with different frequency sweep slopes and opposite frequency sweep directions are loaded into the laser signal to obtain N frequency swept optical signals whose frequency sweep range meets the requirement. M detection objects are detected using the frequency swept optical signals to filter out false targets. In this embodiment of the present application, the positioning of multiple detection target objects may be performed without increasing the measurement time, and the lidar point rate remains unchanged. In some embodiments, in the detection system shown in FIG. 19, the receiving device 620 may alternatively use an I receiver or a Q receiver, and no velocity ambiguity occurs, and the detection cost can be reduced.

[0123] FIG. 21 is a diagram of a possible structure of the detection system. In FIG. 21, N frequency swept optical signals are generated by IQ modulating the laser signal transmitted by the laser, and the frequency swept waveforms can be generated by a digital signal processing method. In FIG. 21, the frequency swept signal source 611 includes N frequency swept signal transmitting components, which are frequency swept signal transmitting components 1 to N, respectively. Each frequency swept signal transmitting component includes a frequency swept driving signal source 2101, a radio frequency amplifier 2102, a radio frequency amplifier 2103, a laser 2104, and a modulator 2105. The frequency swept driving signal source 2101 generates one frequency swept signal whose frequency changes periodically, and the frequency swept signal is input to the modulator after being amplified by the radio frequency amplifier. The laser 2104 transmits a laser signal. The modulator 2105 modulates the amplified frequency swept signal onto the laser signal to obtain one frequency swept optical signal. Thus, the N frequency swept signal transmitting components generate N frequency swept optical signals. The multiplexer / demultiplexer component 612 includes a coupler 2106 and is configured to perform beam combining processing on the frequency swept optical signals transmitted by the N frequency swept signal transmitting components, and then demultiplex the frequency swept optical signals to obtain a local oscillator signal and a detection signal. The coupler 2106 sends the local oscillator signal to the receiving device 620 and transmits the detection signal using a scanner. In some embodiments, before the detection signal is transmitted, an amplification processing may be performed first, and then the detection signal is transmitted. For example, the transmitting device 610 may further include an optical amplifier (not shown). The optical amplifier amplifies and processes the detection signal output by the coupler 2106, and then transmits the detection signal using a scanner.

[0124] For example, see Fig. 22 for how the frequency sweep driving signal source 2101 generates a frequency sweep signal with a periodically changing frequency. After taking the real and imaginary parts, the digital frequency sweep signal is converted into an analog frequency sweep signal by performing a digital-to-analog conversion process.

[0125] In one example, the wavelengths of the laser signals transmitted by the lasers included in the different frequency swept signal transmitting components are different. In this example, the lasers transmit laser signals of different wavelengths, so that the frequency ranges of the frequency swept optical signals transmitted by the N frequency swept signal transmitting components satisfy the above condition.

[0126] In another example, the frequency ranges of the frequency swept signals generated by the frequency swept drive signal sources included in the different frequency swept signal transmitting components are different. In this example, the frequency swept signal sources generate analog frequency swept electrical signals of different frequency ranges and modulate the analog frequency swept electrical signals onto the laser signal transmitted by the laser such that the frequency ranges of the frequency swept optical signals transmitted by the N frequency swept signal transmitting components satisfy the above condition.

[0127] In yet another example, the wavelengths of the laser signals transmitted by the lasers included in the different frequency swept signal transmitting components are different, and the frequency ranges of the frequency swept signals generated by the frequency swept drive signal sources included in the different frequency swept signal transmitting components are different. In this example, the frequency swept signal sources generate analog frequency swept electrical signals of different frequency ranges, which are correspondingly modulated onto the different wavelength laser signals transmitted separately by the N lasers such that the frequency ranges of the frequency swept optical signals transmitted by the N frequency swept signal transmitting components satisfy the above condition.

[0128] In the above solution, N frequency swept signals that satisfy the condition are generated by digital signal processing, and modulated onto the laser signal to generate N frequency swept optical signals that satisfy the condition to detect M detection objects. This can filter out false targets. There is a certain guard bandwidth in the frequency domain between two adjacent analog frequency swept electrical signals, and as a result, there is a certain guard bandwidth in the frequency domain between two output adjacent frequency swept optical signals. This can prevent the generation of unwanted beat frequency signals. In this embodiment of the present application, the positioning of multiple detection target objects may be performed without increasing the measurement time, and the lidar point rate remains unchanged.

[0129] In some embodiments, in the detection system shown in FIG. 21, the receiver 620 may alternatively use an I receiver or a Q receiver, so that velocity ambiguity does not occur and detection costs can be reduced.

[0130] FIG. 23 is a diagram of a possible structure of the detection system. In FIG. 23, N frequency-swept optical signals are generated by modulating the laser signal transmitted by the laser, and the frequency-swept waveform can be generated by a digital signal processing method. In FIG. 23, the frequency-swept signal source 611 includes a laser 2301, an optical frequency comb 2302, N microring modulators, and N frequency-swept driving signal sources. The N microring modulators are microring modulators 1 to N, and the N frequency-swept driving signal sources are frequency-swept driving signal sources 1 to N. For the principle of generating frequency-swept signals by the frequency-swept driving signal sources, please refer to FIG. 22. Details will not be described again here.

[0131] The laser 2301 transmits a laser signal. The optical frequency comb 2302 processes the laser signal to obtain optical signals of N wavelengths. The N frequency sweep driving signal sources are connected to the N microring modulators in one-to-one correspondence, and the N microring modulators are sequentially connected in series in the optical path of the optical signals of the N wavelengths. The microring modulator i (i=1...N) modulates the frequency sweep signal output by the frequency sweep driving signal source, whose frequency range changes periodically, onto the optical signal of the wavelength corresponding to the microring modulator to obtain N frequency swept optical signals that satisfy the above condition. The N microring modulators correspond one-to-one to the N wavelengths, and the frequency ranges of the frequency swept signals output by different frequency sweep driving signal sources are different. The multiplexer / demultiplexer component 612 may include a directional waveguide coupler 2303, configured to demultiplex the optical signal output by the microring modulator N to obtain a local oscillator signal and a detection signal. The directional waveguide coupler 2303 sends the local oscillator signal to the receiving device 620, and transmits the detection signal using the scanner. In some embodiments, before the detection signal is transmitted, an amplification process may be performed first, and then the detection signal is transmitted. For example, the transmitting device 610 may further include an optical fiber amplifier (not shown). The optical fiber amplifier amplifies the detection signal output by the directional waveguide coupler 2303, and then transmits the detection signal using the scanner.

[0132] In this solution, N frequency swept driving signal sources generate analog frequency swept electrical signals of different frequency ranges, and the laser signal is converted into multiple frequencies of light by using an optical frequency comb, which can also be understood as different wavelengths of light. In addition, N microring modulators respectively modulate N analog frequency swept electrical signals of different frequency ranges onto optical signals of different wavelengths, and the frequency ranges of the generated N frequency swept optical signals satisfy the above condition. The N frequency swept optical signals that satisfy the condition are transmitted to detect M detection objects. This can filter out false targets. There is a certain guard bandwidth in the frequency domain between two adjacent analog frequency swept electrical signals, and as a result, there is a certain guard bandwidth in the frequency domain between two adjacent frequency swept optical signals. This can prevent the generation of unnecessary beat frequency signals. In this embodiment of the present application, the positioning of multiple detection target objects may be performed without increasing the measurement time, and the lidar point rate remains unchanged.

[0133] In some embodiments, in the detection system shown in FIG. 23, the receiver 620 may alternatively use an I receiver or a Q receiver, so that velocity ambiguity does not occur and detection costs can be reduced.

[0134] FIG. 24 is a diagram of a possible structure of the detection system. The frequency swept signal source 611 includes N frequency swept lasers, i.e., frequency swept lasers 1 to N. The polarization directions of the frequency swept optical signals generated by different frequency swept lasers are different. The N frequency swept lasers generate N frequency swept optical signals, and the N optical signals satisfy the above condition. In FIG. 24, the multiplexer / demultiplexer component 612 includes a polarization beam combiner (PBC) 2401 and a polarization-maintaining coupler 2402. The polarization beam combiner 2401 performs beam synthesis processing on the N frequency swept optical signals based on the polarization directions of the N frequency swept optical signals to obtain a radar transmission signal. And the polarization-maintaining coupler 2402 demultiplexes the radar transmission signal to obtain a local oscillator signal and a detection signal. The polarization-maintaining coupler 2402 sends the local oscillator signal to the receiving device 620, and transmits the detection signal using a scanner. In some embodiments, before the detection signal is transmitted, an amplification process may be performed first, and then the detection signal is transmitted. For example, the sending device 610 may further include a polarization-maintaining amplifier (not shown). The polarization-maintaining amplifier amplifies the detection signal output by the polarization-maintaining coupler 2402, and then transmits the detection signal using the scanner.

[0135] In the above solution, frequency-swept optical signals with different gradients are multiplexed in a polarization multiplexing manner to form a transmission signal, which is used to detect M detection objects. In this way, false targets can be filtered out without increasing the measurement time, and the point rate of the lidar remains unchanged. In some embodiments, in the detection system shown in FIG. 24, the receiving device 620 may alternatively use an I receiver or a Q receiver, and no velocity ambiguity occurs, and the detection cost can be reduced.

[0136] Based on the above contents and the same concept, the present application provides a detection method for a lidar. Please refer to the description in Fig. 25. The detection method can be applied to the detection system shown in any of the embodiments in Fig. 15A to Fig. 24. It is also understood that the detection method may be performed based on the detection system shown in any of the embodiments in Fig. 15A to Fig. 24.

[0137] 25 is a schematic flow chart of a LIDAR detection method according to the present application. The detection method includes the following steps:

[0138] 2501: Transmitting N frequency swept optical signals, N being an integer greater than 1, and in the N frequency swept optical signals in a first period, the frequency sweep slope of the first frequency swept optical signal and the frequency sweep slope of the second frequency swept optical signal have opposite signs, or the frequency sweep slope of the first frequency swept optical signal is 0 and the frequency sweep slope of the second frequency swept optical signal is not 0, and the frequencies of the N frequency swept optical signals are different.

[0139] For the conditions that the N frequency swept optical signals must satisfy, please refer to the relevant description above, and the details will not be described again here.

[0140] 2502: Multiplex N frequency-swept optical signals to obtain a radar transmission signal, and split the radar transmission signal into a local oscillator signal and a detection signal.

[0141] 2503: Using an antenna to transmit a detection signal, the local oscillator signal is used for coherent detection together with an echo signal of the detection signal to obtain positioning information of the detected object.

[0142] In a possible design, the detection method may further include:

[0143] 2504: Receive an echo signal of the detection signal from the antenna, and frequency-mix the echo signal with a local oscillator signal to generate a frequency-mixed signal.

[0144] 2505: Obtain positioning information of the detected object based on the frequency mixed signal.

[0145] In a possible implementation, the first frequency swept optical signal and the second frequency swept optical signal are periodic frequency swept optical signals.

[0146] In a possible implementation, the signal period of the first frequency swept optical signal is M times the signal period of the second frequency swept optical signal, or the signal period of the second frequency swept optical signal is M times the signal period of the first frequency swept optical signal, where M is a positive integer.

[0147] In a possible implementation, the signal period of the first frequency-swept optical signal is K times the detection period of the lidar, or the signal period of the second frequency-swept optical signal is K times the detection period of the lidar, where K is a positive integer.

[0148] In a possible implementation, a signal period of the first frequency swept optical signal is equal to or greater than a signal period of the second frequency swept signal, in one signal period of the first frequency swept optical signal, a frequency sweep slope of the first frequency swept signal in the first period is opposite in sign to a frequency sweep slope of the first frequency swept signal in the second period, a frequency sweep slope of the second frequency swept signal in the first period is opposite in sign to a frequency sweep slope of the second frequency swept signal in the second period, a frequency sweep slope of the first frequency swept signal in the first period is different from a frequency sweep slope of the second frequency swept signal in the second period, and a frequency sweep slope of the second frequency swept signal in the first period is different from a frequency sweep slope of the first frequency swept signal in the second period.

[0149] In a possible implementation, the minimum frequency difference between the first frequency swept optical signal and the second frequency swept optical signal is related to the reception bandwidth of the antenna.

[0150] In a possible implementation, the minimum frequency difference between the first and second frequency swept optical signals satisfies the following condition: min(|f1-f2|)>|fR1|+|fR2|+fOE

[0151] f1 represents the frequency sweep range of the first frequency swept optical signal, f2 represents the frequency sweep range of the second frequency swept optical signal, fR1 represents the maximum frequency shift amount of the echo signal of the first frequency swept optical signal relative to the local oscillator signal of the first frequency swept optical signal, fR2 represents the maximum frequency shift amount of the echo signal of the second frequency swept optical signal relative to the local oscillator signal of the second frequency swept optical signal, and fOE represents the receiving bandwidth of the antenna.

[0152] In a possible implementation, the first frequency sweep signal and the second frequency sweep signal are

number

[0153] In a possible implementation, the waveform of the first frequency swept optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave. If the frequency sweep slope of the second frequency swept optical signal is not zero, the waveform of the second frequency swept optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave.

[0154] In possible implementations, the wavelength variation ranges of the N frequency swept optical signals are different, or the polarization directions of the N frequency swept optical signals are different.

[0155] In the embodiments of the present application, if there is no special description and logical contradiction, the terms and / or descriptions between different embodiments are consistent and may be mutually referenced, and the technical features in different embodiments may be combined based on their internal logical relationships to form a new embodiment.

[0156] For convenience of description, for the above methods, please refer to the corresponding descriptions of the above device or system embodiments, and it will be clearly understood by those skilled in the art that the details will not be repeated here.

[0157] Although the present application is described with reference to specific features and embodiments thereof, it is apparent that various modifications and combinations may be made thereto without departing from the scope of the present application. Correspondingly, this specification and the accompanying drawings are merely examples for illustrating the solutions defined in the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the present application.

[0158] It is obvious that those skilled in the art can make various modifications and variations to this application without departing from the scope of this application. This application is intended to cover these modifications and variations of the embodiments of this application as long as they fall within the scope of protection defined by the following claims and their equivalent technologies. [Explanation of symbols]

[0159] 1 Echo signal, frequency mixing signal, frequency swept optical signal, local oscillator signal, frequency components 2 Echo signal, local oscillator signal, output frequency swept optical signal, frequency components 3 Frequency Components, Directional Waveguide Coupler 4 Frequency Components 600 Detection System 610 Delivery device 611 Frequency Sweep Signal Source 612 Multiplexer / Demultiplexer Components 620 Receiving Equipment 1910 Laser 1920 Modulator 1930 Frequency Sweep Drive Signal Source 1941 Radio Frequency Amplifier 1942 Radio Frequency Amplifier 1950 Capra 2101 Frequency Sweep Drive Signal Source 2102 Radio Frequency Amplifier 2103 Radio Frequency Amplifier 2104 Laser 2105 Modulator 2106 Coupler 2301 Laser 2302 Optical Frequency Comb 2303 Directional Waveguide Coupler 2401 Polarization Beam Combiner 2402 Polarization-Maintaining Coupler 6121 Directional Waveguide Coupler 6201 90 degree frequency mixer 6202 First photodetector 6203 Second Photodetector 6204 First Analog-to-Digital Converter 6205 Second Analog-to-Digital Converter 6206 Signal Processor 61111 Frequency Swept Laser 61112 Frequency Swept Laser 61211 Wavelength Division Multiplexer 61212 Coupler 62011 180 degree frequency mixer 62012 Photodetector 62013 Analog to Digital Converter 62014 Signal Processor

Claims

1. A lidar transmission device comprising a frequency swept signal source and multiplexer / demultiplexer components, the frequency swept signal source is configured to transmit N frequency swept optical signals, N being an integer greater than 1; In the N frequency swept optical signals in a first time period, a frequency sweep slope of a first frequency swept optical signal and a frequency sweep slope of a second frequency swept optical signal have opposite signs, or the frequency sweep slope of the first frequency swept optical signal is non-zero and the frequency sweep slope of the second frequency swept optical signal is zero, and the frequencies of the N frequency swept optical signals are different; a transmitter device, the multiplexer / demultiplexer component configured to multiplex the N frequency-swept optical signals to obtain a radar transmission signal, demultiplex the radar transmission signal to obtain a local oscillator signal and a detection signal, transmit the detection signal using an antenna, and transmit the local oscillator signal to a receiver device of the LIDAR.

2. 2. The transmitting apparatus of claim 1, wherein an absolute value of the frequency sweep slope of the first frequency swept optical signal is different from an absolute value of the frequency sweep slope of the second frequency swept optical signal.

3. 3. The transmitting device according to claim 1, wherein the first frequency swept optical signal and the second frequency swept optical signal are periodic frequency swept optical signals.

4. 4. The transmitting device of claim 3, wherein a signal period of the first frequency swept optical signal is M times the signal period of the second frequency swept optical signal, or the signal period of the second frequency swept optical signal is M times the signal period of the first frequency swept optical signal, where M is a positive integer.

5. The transmitting device of claim 3 or 4, wherein the signal period of the first frequency swept optical signal is K times the detection period of the LIDAR, or the signal period of the second frequency swept optical signal is K times the detection period of the LIDAR, where K is a positive integer.

6. in one target signal period, the frequency sweep slope of the first frequency swept optical signal in the first period and the frequency sweep slope of the first frequency swept optical signal in the second period have opposite signs, and the frequency sweep slope of the second frequency swept optical signal in the first period and the frequency sweep slope of the second frequency swept optical signal in the second period have opposite signs; the frequency sweep slope of the first frequency swept optical signal during the first time period is different from the frequency sweep slope of the second frequency swept optical signal during the second time period, and the frequency sweep slope of the second frequency swept optical signal during the first time period is different from the frequency sweep slope of the first frequency swept optical signal during the second time period; 6. The sending device according to claim 3, wherein the target signal period is a maximum signal period between the signal period of the first frequency swept optical signal and the signal period of the second frequency swept optical signal.

7. 7. The sending device of claim 1, wherein a minimum frequency difference between the first and second frequency swept optical signals is related to a reception bandwidth of the antenna.

8. the minimum frequency difference between the first frequency swept optical signal and the second frequency swept optical signal satisfies the following condition: min( |f 1 -f 2 |)>|fR 1 |+|fR 2 |+fOE f 1 represents the frequency sweep range of the first frequency swept optical signal, and f 2 represents the frequency sweep range of the second frequency swept optical signal, and fR 1 represents the maximum frequency shift of the echo signal of the first frequency swept optical signal relative to the local oscillator signal of the first frequency swept optical signal, and fR 28. The sending device of claim 7, wherein fOE represents a maximum frequency shift amount of the echo signal of the second frequency swept optical signal relative to a local oscillator signal of the second frequency swept optical signal, and fOE represents the reception bandwidth of the antenna.

9. The first frequency sweep signal and the second frequency sweep signal are [0010] Fulfilling round() represents the operation of rounding to the nearest integer, and K 1 represents the absolute value of the frequency sweep slope of the first frequency sweep signal during the first time period; K 2 represents the absolute value of the frequency sweep slope of the second frequency sweep signal during the first period, and R min 9. The transmitter of claim 1, wherein ω represents a minimum detectable distance of the lidar, and c represents the speed of light.

10. a waveform of the first frequency swept optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave; 10. The sending device of claim 1, wherein when the frequency sweep slope of the second frequency swept optical signal is not zero, the waveform of the second frequency swept optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave.

11. 11. The transmission device according to claim 1, wherein the N frequency swept optical signals have different wavelength variation ranges or different polarization directions.

12. A lidar detection system, comprising: the lidar sending device according to any one of claims 1 to 11; and the lidar receiving device, A detection system, wherein the receiving device is configured to receive a local oscillator signal from the transmitting device and an echo signal of the detection signal transmitted by the transmitting device, perform frequency mixing of the echo signal and the local oscillator signal to generate a frequency-mixed signal, and obtain positioning information of a detected object based on the frequency-mixed signal.

13. the receiving device includes a quadrature mixer, a first photodetector, a second photodetector, a first analog-to-digital converter, a second analog-to-digital converter, and a signal processor; the 90 degree frequency mixer is configured to perform frequency mixing on the echo signal received from the antenna, which is the detection signal, and the local oscillator signal to generate the frequency mixed signal, split the frequency mixed signal into a first signal and a second signal, send the first signal to the first photodetector, and send the second signal to the second photodetector; the first photodetector is configured to perform detection on the first signal and output the first signal to the first analog-to-digital converter for analog-to-digital conversion; the second photodetector is configured to perform detection on the second signal and output the second signal to the second analog-to-digital converter for analog-to-digital conversion; 13. The system of claim 12, wherein the signal processor is configured to process the digital signal output by the first analog-to-digital converter and the digital signal output by the second analog-to-digital converter to obtain the positioning information of the detected object.

14. the receiving device includes a 180 degree frequency mixer, a third photodetector, a third analog-to-digital converter, and a signal processor; the 180 degree frequency mixer is configured to perform frequency mixing on the echo signal received from the antenna, which is the detection signal, and the local oscillator signal to generate the frequency-mixed signal, and send the frequency-mixed signal to the third photodetector; the third photodetector is configured to perform detection on the frequency-mixed signal and output the frequency-mixed signal to the third analog-to-digital converter for the analog-to-digital conversion; The system of claim 12 , wherein the signal processor is configured to process the digital signal output by the third analog-to-digital converter to obtain the positioning information of the detected object.

15. 1. A LIDAR-based detection method, comprising: transmitting N frequency swept optical signals, N being an integer greater than 1, wherein in the N frequency swept optical signals in a first time period, a frequency sweep slope of a first frequency swept optical signal and a frequency sweep slope of a second frequency swept optical signal have opposite signs, or the frequency sweep slope of the first frequency swept optical signal is zero and the frequency sweep slope of the second frequency swept optical signal is non-zero, and the frequencies of the N frequency swept optical signals are different; multiplexing the N frequency-swept optical signals to obtain a radar transmission signal, splitting the radar transmission signal into a local oscillator signal and a detection signal, and transmitting the detection signal using an antenna; receiving an echo signal of the detection signal from the antenna and performing frequency mixing on the echo signal and the local oscillator signal to generate a frequency mixed signal; obtaining positioning information of a detected object based on the frequency mixed signal; A method comprising:

16. 16. The method of claim 15, wherein an absolute value of the frequency sweep slope of the first frequency swept optical signal is different from an absolute value of the frequency sweep slope of the second frequency swept optical signal.

17. 17. The method of claim 15 or 16, wherein the first frequency swept optical signal and the second frequency swept optical signal are periodic frequency swept optical signals.

18. 18. The method of claim 17, wherein a signal period of the first frequency swept optical signal is M times the signal period of the second frequency swept optical signal, or the signal period of the second frequency swept signal is M times the signal period of the first frequency swept optical signal, where M is a positive integer.

19. 19. The method of claim 17 or 18, wherein the signal period of the first frequency-swept optical signal is K times the detection period of the lidar, or the signal period of the second frequency-swept optical signal is K times the detection period of the lidar, where K is a positive integer.

20. in one target signal period, the frequency sweep slope of the first frequency swept optical signal in the first period and the frequency sweep slope of the first frequency swept optical signal in the second period have opposite signs, and the frequency sweep slope of the second frequency swept optical signal in the first period and the frequency sweep slope of the second frequency swept optical signal in the second period have opposite signs; the frequency sweep slope of the first frequency swept optical signal during the first time period is different from the frequency sweep slope of the second frequency swept optical signal during the second time period, and the frequency sweep slope of the second frequency swept optical signal during the first time period is different from the frequency sweep slope of the first frequency swept optical signal during the second time period; 20. The method of claim 17, wherein the target signal period is a maximum signal period between the signal period of the first frequency swept optical signal and the signal period of the second frequency swept optical signal.

21. 21. The method of claim 15, wherein a minimum frequency difference between the first and second frequency swept optical signals is related to a reception bandwidth of the antenna.

22. the minimum frequency difference between the first frequency swept optical signal and the second frequency swept optical signal satisfies the following condition: min( |f 1 -f 2 |)>|fR 1 |+|fR 2 |+fOE f 1 represents the frequency sweep range of the first frequency swept optical signal, and f 2 represents the frequency sweep range of the second frequency swept optical signal, and fR 1represents the maximum frequency shift of the echo signal of the first frequency swept optical signal relative to the local oscillator signal of the first frequency swept optical signal, and fR 2 22. The method of claim 21, wherein fOE represents a maximum amount of frequency shift of the echo signal of the second frequency swept optical signal relative to a local oscillator signal of the second frequency swept optical signal, and fOE represents the reception bandwidth of the antenna.

23. The first frequency sweep signal and the second frequency sweep signal are [0025] Fulfilling round() represents the operation of rounding to the nearest integer, and K 1 represents the absolute value of the frequency sweep slope of the first frequency sweep signal during the first time period; K 2 represents the absolute value of the frequency sweep slope of the second frequency sweep signal during the first period, and R min 23. The method of claim 15, wherein x represents a minimum detectable distance of the lidar and c represents the speed of light.

24. a waveform of the first frequency swept optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave; 24. The method of claim 15, wherein when the frequency sweep slope of the second frequency swept optical signal is not zero, a waveform of the second frequency swept optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave.

25. 25. The method of claim 15, wherein the N frequency swept optical signals have different wavelength variation ranges or different polarization directions.

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