A transmitting device, detection system and detection method of a lidar

Abstract

A transmitting device, a detection system, and a detection method for a lidar, which can exclude false targets in the case of multiple targets. By introducing swept-frequency optical signals with different slopes, there are time periods in which the signs of the swept-frequency slopes of different swept-frequency optical signals are opposite, and the absolute values of the swept-frequency slopes are also not equal. Multiple real targets are coherently detected in at least two time periods respectively corresponding to different swept-frequency optical signals. Since the distances and speeds of real targets calculated from different swept-frequency optical signals do not change, while the distances and speeds of false targets change, the distances and speeds of real targets are determined by the same results of coherent detection of multiple swept-frequency optical signals, so that false targets can be eliminated without increasing the detection time. And even when using an I receiver or a Q receiver, there will be no velocity ambiguity, and the cost can be further reduced.

Description

[0001] This application is a divisional application. The application number of the original application is 202111637896.0, the filing date of the original application is December 29, 2021, and the entire content of the original application is incorporated herein by reference. Technical Field

[0002] This application relates to the field of optical communication technologies, and particularly to a transmitting device, a detection system, and a detection method for a lidar. Background Art

[0003] For coherent lidars, the characteristics of chirp signals can be utilized to generate a mixed-frequency signal that varies with the distance and speed of the detected object by beating the local oscillator signal and the echo signal. The distance information and speed information of the detected object can be calculated based on the frequency of the mixed-frequency signal. Although lidars have high directivity and small emission spots, when the emitted light reaches an object at a relatively long distance, the spot diverges due to the long distance, so that the emitted optical signal will irradiate multiple objects and generate multiple echo signals. After the multiple echo signals are coherently detected with the local oscillator signal respectively, multiple targets are located, and it is impossible to exclude false targets from the multiple targets. Summary of the Invention

[0004] Embodiments of this application provide a transmitting device, a detection system, and a detection method for a lidar, which can exclude false targets in the case of multiple targets.

[0005] In a first aspect, an embodiment of this application provides a transmitting device for a lidar, including a frequency-swept signal source and a multiplexer / demultiplexer component. The frequency-swept signal source emits N frequency-swept optical signals, where N is an integer greater than 1. In a first time period, the sign of the frequency-swept slope of the first frequency-swept optical signal is opposite to that of the second frequency-swept optical signal among the N frequency-swept optical signals, and the absolute value of the frequency-swept slope of the first frequency-swept optical signal is different from that of the second frequency-swept optical signal, or the frequency-swept slope of the first frequency-swept optical signal is not 0 and the frequency-swept slope of the second frequency-swept optical signal is 0; the frequencies of the N frequency-swept optical signals are different; the multiplexer / demultiplexer component multiplexes the N frequency-swept optical signals to obtain a radar transmission signal, and demultiplexes the radar transmission signal to obtain a local oscillator signal and a detection signal, transmits the detection signal through an antenna, and sends the local oscillator signal to a receiving device of the lidar. Through the above solution, by introducing frequency-swept optical signals with different slopes, multiple real targets are coherently detected in at least two time periods respectively corresponding to different frequency-swept optical signals. Since the distances and speeds of real targets calculated by different frequency-swept optical signals do not change, while the distances and speeds of false targets will change, the distances and speeds of real targets are determined through the same results of coherent detection of multiple frequency-swept optical signals, so that virtual targets can be eliminated without increasing the detection time.

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

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

[0008] In a possible design, the signal period of the first swept-frequency optical signal is K times that of the detection period of the lidar, or the signal period of the second swept-frequency optical signal is K times that of the detection period of the lidar, where K is a positive integer. In the above design, multiple detections are performed within one signal period, which can improve the detection efficiency and reduce the detection delay.

[0009] In a possible design, within a target signal period, the sign of the sweep slope of the first swept-frequency signal in the first time period is opposite to that in the second time period; the sign of the sweep slope of the second swept-frequency signal in the first time period is opposite to that in the second time period; the sweep slope of the first swept-frequency signal in the first time period is different from that of the second swept-frequency signal in the second time period, and the sweep slope of the second swept-frequency signal in the first time period is different from that of the first swept-frequency signal in the second time period. Wherein, the target signal period is the maximum signal period among the signal periods of the first swept-frequency optical signal and the second swept-frequency optical signal. In the above design, the sweep slopes of the swept-frequency optical signals in the two time periods are all different, preventing the intermediate frequency signals obtained by beating different swept-frequency optical signals with the local oscillator signal from being the same, and further improving the accuracy of eliminating false targets.

[0010] In a possible design, the minimum frequency difference between the first swept-frequency optical signal and the second swept-frequency optical signal is related to the receiving bandwidth of the antenna. In the above design, determining the frequency range of each swept-frequency optical signal based on the receiving bandwidth of the antenna can reduce the generation of unwanted beat frequency signals and improve the accuracy of the calculation results. And there is no need to use algorithms with high computational complexity to distinguish and eliminate unwanted beat frequency signals, thereby reducing the computational complexity and the processing resources used.

[0011] In a possible design, the minimum frequency difference between the first swept-frequency optical signal and the second swept-frequency optical signal satisfies the following conditions:

[0012] min(|f1 - f2|) > |fR1| + |fR2| + fOE;

[0013] Among them, 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 value of the 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 value of the 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 method for determining the frequency difference of the frequency-swept optical signal, with simple implementation. And it can prevent the generation of unwanted beat frequency signals, improving the accuracy of the calculation results. And there is no need to use algorithms with high computational complexity to distinguish and eliminate unwanted beat frequency signals, thus reducing the computational complexity and the processing resources used.

[0014] In a possible design, the first frequency-swept signal and the second frequency-swept signal satisfy:

[0015] Or

[0016] Among them, round() represents the rounding operation, K1 represents the absolute value of the frequency sweep slope of the first frequency-swept signal in the first time period, K2 represents the absolute value of the frequency sweep slope of the second frequency-swept signal in the first time period, R min represents the minimum detectable distance of the lidar, and c represents the speed of light. In the above design, the frequency sweep slopes of different frequency-swept optical signals satisfy the conditions shown above. By combining the minimum detectable distance to determine the magnitudes of the frequency sweep slopes of different frequency-swept optical signals, it can prevent the reduction in the accuracy of eliminating false targets caused by a small difference in the frequency sweep slopes of different frequency-swept optical signals, further improving the accuracy of eliminating false targets.

[0017] 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; when the frequency sweep slope of the second frequency-swept optical signal is not 0, the waveform of the second frequency-swept optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave.

[0018] In a possible design, the wavelength change ranges of the N frequency-swept optical signals are different, or the polarization directions of the N frequency-swept optical signals are different.

[0019] In a possible design, the frequency-swept signal source includes N frequency-swept lasers, and the frequency-swept lasers are used to emit frequency-swept optical signals with periodically changing wavelengths. In the above design, by adjusting the wavelengths of the optical signals emitted by different frequency-swept lasers, the frequency ranges of the frequency-swept optical signals emitted by different frequency-swept lasers are made different, so that the frequency sweep slopes meet the requirements.

[0020] In a possible design, the frequency-swept signal source includes a laser, a modulator, a radio frequency amplifier, and a frequency-swept driving signal source; the frequency-swept driving signal source is used to generate N frequency-swept signals with periodic frequency changes, and after being amplified by the radio frequency amplifier, the signals are input into the modulator; the laser is used to emit a laser signal; the modulator is used to modulate the N amplified frequency-swept signals onto the laser signal to obtain N frequency-swept optical signals. In the above design, a method for generating N frequency-swept optical signals that meet the requirements by an external modulation method is provided. By using a digital signal processing method to generate a frequency-swept electrical signal that meets the frequency requirements and then modulating it onto the laser signal emitted by the laser, the implementation is simple.

[0021] 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 driving signal source, a laser, a modulator, and a radio frequency amplifier; the frequency-swept driving signal source is used to generate a frequency-swept signal with periodic frequency changes, and after being amplified by the radio frequency amplifier, the signal is input into the modulator; the laser is used to emit a laser signal; the modulator is used to modulate the amplified frequency-swept signal onto the laser signal to obtain a frequency-swept optical signal; wherein, the wavelengths of the laser signals emitted by the lasers included in different frequency-swept signal transmitting components are different, and / or the frequency ranges of the frequency-swept signals generated by the frequency-swept driving signal sources included in different frequency-swept signal transmitting components are different. In the above design, a method for generating N frequency-swept optical signals by using N frequency-swept signal transmitting components is provided, and it is relatively easy to generate N frequency-swept optical signals that meet the requirements.

[0022] In a possible design, the frequency-swept signal source includes a laser, an optical frequency comb, N micro-ring modulators, and N frequency-swept driving signal sources; the laser is used to emit a laser signal; the optical frequency comb is used to process the laser signal to obtain optical signals with N wavelengths; the N frequency-swept driving signal sources are connected to the N micro-ring modulators in one-to-one correspondence, and the N micro-ring modulators are arranged in series in the optical paths of the optical signals with N wavelengths in sequence; the first micro-ring modulator is used to modulate the frequency-swept signal with a periodically changing frequency range output by the first frequency-swept driving signal source onto the optical signal corresponding to the wavelength of the first micro-ring modulator; wherein, the N micro-ring modulators correspond to the N wavelengths one by one, and the frequency ranges of the frequency-swept signals output by different frequency-swept driving signal sources are different. In the above design, a method for generating N frequency-swept optical signals by combining an optical frequency comb and N micro-ring modulators is provided, and the implementation is relatively simple.

[0023] In a possible design, the multiplexer / demultiplexer component includes a coupler, such as a directional coupler.

[0024] In a possible design, the polarization directions of N swept-frequency optical signals are different, and the multiplexer / demultiplexer component includes a polarization beam combiner and a polarization-maintaining coupler; the polarization beam combiner is configured to combine the N swept-frequency optical signals based on the polarization directions of the N swept-frequency optical signals to obtain a radar transmission signal; the polarization-maintaining coupler is configured to split the radar transmission signal to obtain the local oscillator signal and the detection signal.

[0025] In a second aspect, an embodiment of the present application provides a detection system for a lidar, including the transmission device of the lidar according to the first aspect or any design of the first aspect, and a receiving device of the lidar. The receiving device is configured to receive the local oscillator signal from the sending device and the echo signal of the detection signal sent by the sending device, and perform mixing processing on the echo signal and the local oscillator signal to generate a mixing signal; obtain the positioning information of the detected object according to the mixing signal.

[0026] In a possible design, the receiving device may adopt an IQ detection method to obtain the positioning information of the detected object.

[0027] In a possible design, the receiving device includes a 90-degree 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 mixer is configured to perform mixing processing on the echo signal of the detection signal received from the antenna and the local oscillator signal to generate a mixing signal, divide the mixing signal into a first path signal and a second path signal, and send the first path signal to the first photodetector and the second path signal to the second photodetector; the first photodetector is configured to perform detection processing on the first path signal and then output it to the first analog-to-digital converter for analog-to-digital conversion; the second photodetector is configured to perform detection processing on the second path signal and then output it 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 the positioning information of the detected object. In the above design, by using the IQ detection method, positive and negative frequency information can be distinguished, the processing algorithm is simple, and the processing performance requirements for the signal processor are relatively low.

[0028] In a possible design, the receiving device may adopt an I detection method or a Q detection method to obtain the positioning information of the detected object.

[0029] In a possible design, the receiving device includes a 180-degree mixer, a third photodetector, a third analog-to-digital converter, and a signal processor; the 180-degree mixer is configured to mix the echo signal of the detection signal received from the antenna and the local oscillator signal to generate a mixed signal, and send the mixed signal to the third photodetector; the third photodetector is configured to perform detection processing on the mixed signal and then output it 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 the positioning information of the detected object. In the above design, an I receiver or a Q receiver is used, and the transmitted signal is formed by multiplexing multiple swept optical signals. Since the distance and speed of the real target do not change, the local oscillator signal and the echo signal of each swept optical signal can be used for beat frequency calculation to obtain the mixed signal, and then the frequency component of the distance and the frequency component of the speed can be determined respectively through the corresponding formulas in different cases. That is, three calculation results can be obtained based on each swept optical signal. Then, the same result among the multiple calculation results is the final calculation result, which can solve the problem of speed ambiguity in detection caused by the inability to determine which of the calculation results corresponding to the formulas in multiple cases is the correct result when using an I receiver or a Q receiver in the prior art.

[0030] In a third aspect, an embodiment of the present application provides a detection method based on lidar, including: transmitting N swept optical signals, where N is an integer greater than 1, and in the first time period, the sign of the sweep slope of the first swept optical signal among the N swept optical signals is opposite to the sign of the sweep slope of the second swept optical signal, or the sweep slope of the first swept optical signal is 0 and the sweep slope of the second swept optical signal is not 0; the frequencies of the N swept optical signals are different; combining the N swept optical signals to obtain a radar transmitted signal, and dividing the radar transmitted signal into a local oscillator signal and a detection signal, and transmitting the detection signal through an antenna; the local oscillator signal is used to perform coherent detection with the echo signal of the detection signal to obtain the positioning information of the detected object.

[0031] In a possible design, the detection method may further include: receiving the echo signal of the detection signal from the antenna, and mixing the echo signal and the local oscillator signal to generate a mixed signal; obtaining the positioning information of the detected object according to the mixed signal.

[0032] In a possible design, the first swept optical signal and the second swept optical signal are periodic swept optical signals.

[0033] In a possible design, the signal period of the first swept optical signal is M times the signal period of the second swept optical signal, or the signal period of the second swept optical signal is M times the signal period of the first swept optical signal, where M is a positive integer.

[0034] In a possible design, the signal period of the first swept optical signal is K times the detection period of the lidar, or the signal period of the second swept optical signal is K times the detection period of the lidar, where K is a positive integer.

[0035] In a possible design, within a target signal period, the sign of the sweep slope of the first swept optical signal in the first time period is opposite to that in the second time period; the sign of the sweep slope of the second swept optical signal in the first time period is opposite to that in the second time period; the sweep slope of the first swept optical signal in the first time period is different from that of the second swept optical signal in the second time period, and the sweep slope of the second swept optical signal in the first time period is different from that of the first swept optical signal in the second time period. Here, the target signal period is the maximum signal period of the signal period of the first swept optical signal and the signal period of the second swept optical signal.

[0036] In a possible design, the minimum frequency difference between the first swept optical signal and the second swept optical signal is related to the receiving bandwidth of the antenna.

[0037] In a possible design, the minimum frequency difference between the first swept optical signal and the second swept optical signal satisfies the following condition:

[0038] min(|f1 - f2|) > |fR1| + |fR2| + fOE;

[0039] Where f1 represents the sweep range of the first swept optical signal, f2 represents the sweep range of the second swept optical signal, fR1 represents the maximum value of the frequency shift amount of the echo signal of the first swept optical signal relative to the local oscillator signal of the first swept optical signal, fR2 represents the maximum value of the frequency shift amount of the echo signal of the second swept optical signal relative to the local oscillator signal of the second swept optical signal, and fOE represents the receiving bandwidth of the antenna.

[0040] In a possible design, the first swept signal and the second swept signal satisfy:

[0041] Or

[0042] Where round() represents the rounding operation, K1 represents the absolute value of the sweep slope of the first swept signal in the first time period, K2 represents the absolute value of the sweep slope of the second swept signal in the first time period, R min represents the minimum detectable distance of the lidar, and c represents the speed of light.

[0043] In a possible design, the waveform of the first swept-frequency optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave; when the sweep slope of the second swept-frequency optical signal is not 0, the waveform of the second swept-frequency optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave.

[0044] In a possible design, the wavelength change ranges of the N swept-frequency optical signals are different, or the polarization directions of the N swept-frequency optical signals are different.

[0045] Based on the implementations provided in the above aspects of this application, further combinations can be made to provide more implementations.

[0046] For the beneficial effects of the above second and third aspects, reference can be made to the relevant descriptions of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] To more clearly illustrate the technical solutions in the embodiments of this application, the following briefly introduces the drawings required for the description of the embodiments.

[0048] Figure 1 It is a schematic diagram of the architecture of a lidar;

[0049] Figure 2 It is a schematic diagram of a local oscillator signal, an echo signal, and a mixed-frequency signal;

[0050] Figure 3 It is a schematic diagram of the frequency spectrum of a mixed-frequency signal;

[0051] Figure 4 It is a schematic diagram of a generated false target;

[0052] Figure 5 It is a schematic diagram of the waveform of a mixed-frequency signal;

[0053] Figure 6 It is a schematic diagram of the detection system architecture of the lidar provided by the embodiments of this application;

[0054] Figure 7 It is a schematic diagram of the waveform of the swept-frequency optical signal provided by the embodiments of this application;

[0055] Figure 8 It is a schematic diagram of the waveforms of the first swept-frequency optical signal and the second swept-frequency optical signal provided by the embodiments of this application;

[0056] Figure 9 It is a schematic diagram of the frequency spectrum of the mixed-frequency signal in the case of two detection targets provided by the embodiments of this application;

[0057] Figure 10 It is a schematic diagram of the distance-velocity resolution principle provided by the embodiments of this application;

[0058] Figure 11 Schematic diagram of the output waveform of the swept optical signal in the polarization multiplexing mode provided by the embodiment of the present application;

[0059] Figure 12 Schematic diagram of the relationship between the detection period and the signal period provided by the embodiment of the present application;

[0060] Figure 13 Schematic diagram of the structure of a receiving device 620 provided by the embodiment of the present application;

[0061] Figure 14 Schematic diagram of the structure of another receiving device 620 provided by the embodiment of the present application;

[0062] Figure 15 Schematic diagram of the architecture of a detection system provided by the embodiment of the present application;

[0063] Figure 16 Schematic diagram of the architecture of a detection system provided by the embodiment of the present application;

[0064] Figure 17 Schematic diagram of the architecture of a detection system provided by the embodiment of the present application;

[0065] Figure 18 Schematic diagram of the architecture of a detection system provided by the embodiment of the present application;

[0066] Figure 19 Schematic diagram of the architecture of a detection system provided by the embodiment of the present application;

[0067] Figure 20 Schematic diagram of the generation method of the swept drive signal source provided by the embodiment of the present application;

[0068] Figure 21 Schematic diagram of the architecture of a detection system provided by the embodiment of the present application;

[0069] Figure 22 Schematic diagram of the generation method of the swept drive signal source provided by the embodiment of the present application;

[0070] Figure 23 Schematic diagram of the architecture of a detection system provided by the embodiment of the present application;

[0071] Figure 24 Schematic diagram of the architecture of a detection system provided by the embodiment of the present application;

[0072] Figure 25 Schematic diagram of the flow of the detection method of a lidar provided by the embodiment of the present application. Detailed implementation manners

[0073] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0074] The following explains some terms in this application. It should be noted that these explanations are for the convenience of those skilled in the art and do not limit the scope of protection required by this application.

[0075] 1) The term "at least one" involved in this application means one or more than one, that is, including one, two, three and more; "a plurality of" means two or more than two, that is, including two, three and more. In addition, it should be understood that in the description of this application, words such as "first" and "second" are only used for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying order. "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone, where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after. "At least one (item)" or its similar expression refers to any combination of these items, including any combination of single item (item) or plural items (items). For example, at least one (item) of a, b, or c can represent: a, b, c, a - b, a - c, b - c, or a - b - c, where a, b, and c can be single or multiple.

[0076] 2) A sweep signal refers to a signal whose frequency changes linearly with time.

[0077] 3) Sweep waveform: The trajectory of the sweep signal during sweeping.

[0078] 4) Sweep slope, which is the frequency change amount of the sweep signal per unit time, with the unit of Hz / s.

[0079] Symbol of the sweep slope: When the symbol of the sweep slope is positive, the frequency increases with time. When the symbol of the sweep slope is negative, the frequency decreases with time. When the symbol of the sweep slope is zero, the frequency does not change with time. Two sweep slopes with opposite symbols mean that the symbol of one sweep slope is positive and the symbol of the other sweep slope is negative.

[0080] 5) Protection bandwidth means that when signals use frequency reuse, there is a certain frequency range between signals, and no signal is loaded in this range to prevent interference between signals of different frequencies.

[0081] 6) A radar transmission signal is generated by one or more sweep signals, and after frequency reuse, it can be transmitted by a transmitting antenna. The radar transmission signal is generally an optical signal.

[0082] 7) Echo signal: The signal that is reflected back after the transmitted signal reaches the detected object. The echo signal is generally an optical signal.

[0083] 8) Minimum detectable distance of lidar: Some lidars have blind spots, and objects that are relatively close to the lidar cannot be detected, such as 1 meter, etc. The minimum distance of this blind spot is the minimum detectable distance of the lidar. Some lidars do not have blind spots, but due to the proximity of some objects to the lidar, due to the limitations of the processor accuracy or algorithm, after the lidar emits a detection signal and the closer object emits an echo signal, the lidar cannot accurately locate the exact position of the object through the echo signal. Therefore, the minimum distance at which accurate positioning can be achieved is the minimum detectable distance of the lidar.

[0084] This application is applied to lidar. The lidar can be installed on vehicles, ships or other machines. See Figure 1 As shown, the lidar emits a swept-frequency optical signal through a swept-frequency signal source. After the swept-frequency optical signal irradiates the detected object, it will be reflected by the object, and the reflected echo signal can be received by the receiving end of the lidar. Thus, the receiving end of the lidar performs beat frequency on the echo signal and the local oscillator signal to generate an intermediate frequency signal that varies with the distance and speed of the detected object. Information such as the distance, speed, and reflectivity of the measured object can be calculated based on the frequency magnitude of the intermediate frequency signal.

[0085] As described in the background art, for objects at a relatively long distance, the light spot of the lidar will diverge, so that the emitted optical signal will generate echo signals of multiple detection targets. For example, see Figure 2 As shown, taking two detection targets as an example, after the two echo signals are coherently detected with the local oscillator signal, multiple mixed-frequency signals are generated. As Figure 2 shown, echo signal 1 is coherently detected with the local oscillator signal to generate mixed-frequency signal 1; echo signal 2 is coherently detected with the local oscillator signal to generate mixed-frequency signal 2. From Figure 2 it can be seen that time can be divided into time period 1 and time period 2. The swept-frequency slopes of the transmitted signal or the echo signal in different time periods are different. Performing Fourier transforms on the signals in time period 1 and time period 2 respectively, a spectrogram as shown in Figure 3 can be obtained. When there is only echo signal 1, Figure 3 in time period 1 of , the signal spectrum only has frequency component 1, and in time period 2 of , the signal spectrum only has frequency component 3.

[0086] Further, based on the frequency component 1 and frequency component 2 in time period 1, and the frequency component 3 and frequency component 4 in time period 2, the distance-related frequency and speed-related frequency of the detection target can be determined. Then, further calculate the distance of the detection target according to the distance-related frequency, and calculate the speed of the detection target according to the speed-related frequency. Since there are 2 frequency components in time period 1 and 2 frequency components in time period 2, 4 detection targets' distances and speeds can be calculated through combination.

[0087] Taking the IQ receiver as an example, the relationship between the frequency components in time period 1 and time period 2 and the distance-related frequency and speed-related frequency satisfies the following formula (1):

[0088] f1 = -f R +f D ; f2 = f R +f D Formula (1)

[0089] Among them, f1 represents the frequency component in time period 1, f2 represents the frequency component in time period 2, f R represents the distance-related frequency, and f D represents the speed-related frequency.

[0090] Further, f R and f D can be calculated through the following formula (2).

[0091]

[0092] The distance of the detection target can be determined through the following formula (3), and the speed of the detection target can be determined through the following formula (4).

[0093]

[0094] Among them, R represents the distance between the detection target and the lidar, and B represents the sweep bandwidth of the emitted optical signal.

[0095] c is the speed of light, and T is the duration of a time period, such as time period 1 or time period 2.

[0096]

[0097] Among them, λ represents the optical wavelength, and V represents the moving speed of the detection target.

[0098] Then, it can be determined through the above formulas (2) - (4) that the relationship between V, R and f1 and f2 can be seen as shown in formula (5).

[0099]

[0100] Combined with the above formula (5), the relationship curve of the speed V with the distance R and f1 and f2 can be determined, as can be seen in Figure 4 shown. From Figure 4 it can be seen that since it is impossible to distinguish which two of the frequency components 1-4 come from the mixing signal 1 and which two come from the mixing signal 2, accurate information about the two detection targets cannot be obtained. It should be understood that when using an I receiver or a Q receiver, the above problem of being unable to distinguish multiple detection targets will also exist.

[0101] In some scenarios, when using an I receiver or a Q receiver, the moving speed of a certain detection target is relatively fast, and there may be a problem of velocity ambiguity in the calculated detection target. For example, Figure 5 Figures (1)-(3) in Figure 5 show schematic diagrams of the frequency changes of the local oscillator signal and the echo signal in three possible cases. In Figure 5 the first possible case shown in (1) in Figure 5 when using an I receiver or a Q receiver for detection, the mixing signals in time period 1 and time period 2 can be seen in

[0102] f1 = f R - f D ; f2 = f R + f D Formula (6)

[0103] In Figure 5 the second possible case shown in (2) in Figure 5 when using an I receiver or a Q receiver for detection, the mixing signals in time period 1 and time period 2 can be seen in Figure 5 shown in (5) in

[0104] f1 = - f R + fD ; f2 = f R + f D Equation (7)

[0105] In Figure 5 in the third possible case shown in (3), when using an I receiver or a Q receiver for detection, the mixed signals in time period 1 and the actual mixed signals in time period 2 can be referred to Figure 5 as shown in (6). The mixed signals in time period 1 and the mixed signals in time period 2 in the case of using an IQ receiver can be referred to Figure 5 as shown in (9). The IQ receiver detection can distinguish between positive and negative frequencies. When using an I receiver or a Q receiver for detection, since the I receiver or the Q receiver cannot distinguish between positive and negative frequencies, the relationship between the frequency components in time period 1 and the frequency components in time period 2 and the distance-related frequency and the speed-related frequency should satisfy the conditions shown in the following Equation (8) in theory.

[0106] f1 = f R - f D ; f2 = - f R - f D Equation (8)

[0107] Based on this, when using an I receiver or a Q receiver for detection, if the frequencies f1 and f2 are calculated in the manner shown in Equation (6), there may be a situation where the calculated results do not match the frequencies of the actual mixed signals, resulting in inaccurate calculated speed and distance. If the frequencies f1 and f2 are calculated respectively in the manners shown in Equations (6), (7) and (8), it is impossible to distinguish which calculated result is accurate.

[0108] Based on this, the present application provides a transmitting device, a measuring device and a detection method for a lidar, which can achieve simultaneous detection of multiple targets, and will not increase the detection duration, and the detection results are relatively accurate. Even when using an I receiver or a Q receiver, there will be no problem of speed ambiguity. In the embodiments of the present application, the detected object is also called a reflector. The detected object can be any object in the antenna scanning direction. For example, it can be a person, a mountain, a vehicle, a tree, a bridge, etc. The antenna involved in the embodiments of the present application includes a transmitting antenna for transmitting an optical signal and a receiving antenna for receiving an optical signal, and can also be called a scanner for transmitting and receiving optical signals.

[0109] Refer to Figure 6The figure shows a schematic structural diagram of a detection system for a lidar. The detection system 600 includes a transmitting device 610 and a receiving device 620. This detection system can be applied to ranging devices or speed measuring devices, such as FMCW lidar, laser speedometers, laser rangefinders, optical coherence tomography (OCT) devices, or optical frequency domain reflectometers (OFDR) devices, etc.

[0110] The transmitting device 610 may include a frequency-swept signal source 611 and a multiplexer / demultiplexer component 612. The frequency-swept signal source 611 emits N frequency-swept optical signals. N is an integer greater than 1. The frequency-swept signal source can be generated by directly modulating a laser (also known as internal modulation), or by externally modulating the optical signal generated by a laser using a modulator. The subsequent structure that the frequency-swept signal source can adopt will be described in detail, and will not be elaborated here.

[0111] At least two of the N frequency-swept signals include frequency-swept optical signals with different frequency-swept waveforms. The frequency ranges of the N frequency-swept optical signals are different. For the sake of easy distinction, these two frequency-swept signals are referred to as the first frequency-swept optical signal and the second frequency-swept optical signal.

[0112] In the first possible implementation, the first frequency-swept optical signal and the second frequency-swept optical signal at least satisfy the following condition 1 and condition 2:

[0113] Condition 1, there is at least a time period with opposite signs of the frequency-swept slopes between the first frequency-swept optical signal and the second frequency-swept optical signal. This time period is referred to as the first time period in this article. It can be understood that within this first time period, the sign of the frequency-swept slope of the first frequency-swept optical signal is opposite to the sign of the frequency-swept slope of the second frequency-swept optical signal.

[0114] Condition 2, within the first time period, the absolute value of the frequency-swept slope of the first frequency-swept optical signal is different from the absolute value of the frequency-swept slope of the second frequency-swept optical signal.

[0115] In the second possible implementation, the first frequency-swept optical signal and the second frequency-swept optical signal satisfy the following condition 3.

[0116] Condition 3, there is a certain time period during which the frequency-swept slope of one of the first frequency-swept optical signal and the second frequency-swept optical signal is 0, and the frequency-swept slope of the other is not 0. For example, within the first time period, the frequency-swept slope of the first frequency-swept optical signal is 0, and the frequency-swept slope of the second frequency-swept optical signal is not 0. Or within the first time period, the frequency-swept slope of the first frequency-swept optical signal is not 0, and the frequency-swept slope of the second frequency-swept optical signal is 0.

[0117] In some possible embodiments, among the N swept optical signals, at least one of the following Conditions 4 to 7 is further satisfied.

[0118] Condition 4: The N swept optical signals are all periodic swept optical signals, or in other words, a certain swept optical signal is a constant-frequency signal, that is, the sweep slope of this swept optical signal is 0. In some embodiments, the signal periods among the N swept optical signals satisfy a multiple relationship, and the multiple can also be 1, that is, the signal periods of the swept optical signals are equal. Taking the first swept optical signal and the second swept optical signal as an example, both the first swept optical signal and the second swept optical signal are periodic swept optical signals. Exemplarily, the signal periods between the first swept optical signal and the second swept optical signal satisfy a multiple relationship. For example, the signal period of the first swept optical signal is M times that of the second swept optical signal, or the signal period of the second swept optical signal is M times that of the first swept optical signal. M can be 1 or an integer greater than 1.

[0119] Condition 5: In one target signal period, there are two time periods in which the sweep slopes of the first swept optical signal and the second swept optical signal have opposite signs. That is to say, in addition to the first time period in which the sweep slopes of the first swept optical signal and the second swept optical signal have opposite signs, there is at least one other time period in which the sweep slopes of the first swept optical signal and the second swept optical signal have opposite signs. For the sake of easy distinction, the time period other than the first time period is called the second time period. The so-called one target signal period refers to the maximum value of the signal periods of the first swept optical signal and the second swept optical signal. Taking the signal period of the first swept optical signal being greater than or equal to the signal period of the second swept optical signal as an example. In the signal period of the first swept optical signal, the sign of the sweep slope of the first swept signal in the first time period is opposite to that in the second time period; the sign of the sweep slope of the second swept signal in the first time period is opposite to that in the second time period; the sweep slope of the first swept signal in the first time period is different from that of the second swept signal in the second time period, and the sweep slope of the second swept signal in the first time period is different from that of the first swept signal in the second time period.

[0120] Condition 6: There is a guard bandwidth between two adjacent swept optical signals in terms of frequency among the N swept optical signals. The setting of the guard bandwidth is related to the receiving bandwidth of the antenna. Taking the first swept optical signal and the second swept optical signal as an example, the first swept optical signal and the second swept optical signal are two swept optical signals with the smallest frequency difference among the N swept optical signals. The minimum frequency difference between the first swept optical signal and the second swept optical signal is related to the receiving bandwidth of the antenna.

[0121] Exemplarily, the minimum frequency difference between the first swept optical signal and the second swept optical signal satisfies the condition shown in the following formula (9).

[0122] min(|f1 - f2|) > |fR1| + |fR2| + fOE Formula (9)

[0123] Wherein, 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 value of the 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 value of the 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.

[0124] Condition 7, the frequency sweep slopes of the first frequency-swept optical signal and the second frequency-swept optical signal satisfy the condition shown in the following formula (10).

[0125] Or

[0126] Wherein, round() represents rounding operation, K1 represents the absolute value of the frequency sweep slope of the first frequency-swept signal in the first time period, K2 represents the absolute value of the frequency sweep slope of the second frequency-swept signal in the first time period, R min represents the minimum detectable distance of the lidar, and c represents the speed of light.

[0127] Exemplarily, the conditions satisfied by the N frequency-swept optical signals in the embodiments of the present application may include various combinations of the above conditions. For example, the N frequency-swept optical signals satisfy Condition 1 + Condition 2 + Condition 6 + Condition 7. Another example is that the N frequency-swept optical signals satisfy Condition 3 + Condition 6 + Condition 7. Another example is that the N frequency-swept optical signals satisfy Condition 1 + Condition 2 + Condition 4 + Condition 5 + Condition 6 + Condition 7. Another example is that the N frequency-swept optical signals satisfy Condition 1 + Condition 2 + Condition 5 + Condition 6 + Condition 7, and so on, which will not be listed one by one here.

[0128] In some embodiments, each periodic signal of the N frequency-swept optical signals involved in the present application may adopt various frequency-swept waveforms such as triangular waves, trapezoidal waves, sawtooth waves, etc. whose frequencies change linearly with time, or any combination of the above waveforms. In other embodiments, some frequency-swept optical signals may adopt a constant frequency waveform, that is, the frequency sweep slope is 0. As an example, see Figure 7 the shown frequency-swept waveform.

[0129] The multiplexer / demultiplexer component 612 multiplexes the N frequency-swept optical signals to obtain a radar transmission signal, and performs beam splitting processing on the radar transmission signal to obtain a local oscillator signal and a detection signal, transmits the detection signal through the antenna, and sends the local oscillator signal to the receiving device 620 of the lidar.

[0130] 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, mixes the echo signal and the local oscillator signal to generate a mixed signal, and then obtains the positioning information of the detected object according to the mixed signal. Exemplarily, the positioning information includes information such as the speed of the detected object, the distance from the lidar, and the reflectivity.

[0131] In some embodiments, when multiplexing N swept-frequency optical signals, frequency multiplexing or polarization multiplexing can be used. It should be noted that when using polarization multiplexing, there is no requirement for the protection bandwidth described in the above condition 6 among the N swept-frequency optical signals.

[0132] As an example, taking the first swept-frequency optical signal and the second swept-frequency optical signal as an example, and the first swept-frequency optical signal and the second swept-frequency optical signal are multiplexed by frequency before transmission. Combining Figure 8 Examples describe several possible swept-frequency waveforms of two swept-frequency optical signals. Figure 8 In (1)-(3) below, taking the swept-frequency bandwidth of the first swept-frequency optical signal as B1 and the swept-frequency bandwidth of the second swept-frequency optical signal as B2 as an example. There is a protection bandwidth between the first swept-frequency optical signal and the second swept-frequency optical signal. There are at least two time periods in which the swept-frequency slopes of the first swept-frequency optical signal and the second swept-frequency optical signal have opposite signs. Figure 8 In (1)-(3) below, in the first time period, the swept-frequency slopes of the first swept-frequency optical signal and the second swept-frequency optical signal have opposite signs and the absolute values of the swept-frequency slopes are not equal. In the second time period, the swept-frequency slopes of the first swept-frequency optical signal and the second swept-frequency optical signal have opposite signs and the absolute values of the swept-frequency slopes are not equal. The swept-frequency slope of the first swept-frequency optical signal in the first time period is different from the swept-frequency slope of the second swept-frequency optical signal in the second time period, and the swept-frequency slope of the second swept-frequency optical signal in the first time period is different from the swept-frequency slope of the first swept-frequency optical signal in the second time period.

[0133] As an example, taking Figure 8 the first swept-frequency optical signal and the second swept-frequency optical signal shown in (1) below as an example, the effect of accurately obtaining the positioning information of multiple targets is described. Refer to Figure 9 As shown, taking two detection targets as an example. The two echo signals corresponding to the local oscillator signal 1 of the first swept-frequency optical signal are echo signal 1-1 and echo signal 1-2 respectively. The two echo signals corresponding to the local oscillator signal 2 of the second swept-frequency optical signal are echo signal 2-1 and echo signal 2-2 respectively. The spectra of the mixed signals generated by beating the local oscillator signal 1 with the echo signal 1-1 and the echo signal 1-2 in time period 1 and the spectra of the mixed signals generated by beating the local oscillator signal 2 with the echo signal 2-1 and the echo signal 2-2 in time period 1 are shown in Figure 9Figure (2) shows the spectrogram of the mixed-frequency signal using an I receiver. Refer to Figure 9 Figure (4) is the spectrogram of the mixed-frequency signal using an IQ receiver. The spectrogram of the mixed-frequency signal generated by the beat frequency of the local oscillator signal 1 with the echo signals 1-1 and 1-2 in time period 2, and the spectrogram of the mixed-frequency signal generated by the beat frequency of the local oscillator signal 2 with the echo signals 2-1 and 2-2 in time period 2. Refer to Figure 9 Figure (3) shows the spectrogram of the mixed-frequency signal using an I receiver. Refer to Figure 9 Figure (5) is the spectrogram of the mixed-frequency signal using an IQ receiver.

[0134] In some embodiments, in the case of using an IQ receiver, the speed and distance of the detection target can be determined based on formulas (2)-(4).

[0135] In other embodiments, in the case of using an I receiver or a Q receiver, the speed and distance of the detection target can be calculated respectively through the following formulas (6)-(8) in combination with formulas (3) and (4). Since multiple swept-frequency optical signals are used for detection in the embodiments of the present application, for each mixed-frequency signal obtained by mixing a swept-frequency optical signal with a local oscillator signal, the speed and distance of the detection target can be calculated through the following formulas (6)-(8) in combination with formulas (3) and (4).

[0136] Due to the introduction of swept-frequency optical signals with different slopes, the real target is coherently detected in two time periods respectively corresponding to different swept-frequency optical signals. Since the distance and speed of the real target calculated by different swept-frequency optical signals do not change, but the distance and speed of the false target will change, so refer to Figure 10 As shown, the speed and distance corresponding to the intersection of the 4 lines are the speed and distance of the real target. In the embodiments of the present application, the transmitted signal formed by frequency multiplexing of swept-frequency signals with different swept-frequency slopes is used to detect M detection objects, which can eliminate false targets and does not increase the detection time.

[0137] When there is a certain guard bandwidth in the frequency domain for different swept-frequency optical signals (i.e., when the condition 6 is satisfied), it is possible to prevent the generation of unwanted beat-frequency signals, thereby preventing calculation errors and reducing the complexity of calculation speed or distance. The embodiment of the present application realizes the discrimination of multiple targets by transmitting the transmitted signal formed by frequency multiplexing, and does not increase the measurement time, maintaining the same point output rate of the lidar. In addition, the embodiment of the present application supports the use of an I receiver or a Q receiver or an IQ receiver. When using an I receiver or a Q receiver, the transmitted signal is formed by frequency multiplexing of multiple swept-frequency optical signals. Since the distance and speed of the real target do not change, the beat-frequency calculation of the local oscillator signal and the echo signal for each swept-frequency optical signal can be performed to obtain the mixed signal, and then the frequency component of the distance and the frequency component of the speed can be determined respectively through the above formulas (6)-(8). That is, three calculation results can be obtained based on each swept-frequency optical signal. Taking two swept-frequency optical signals as an example, the two same results in the calculation results of the two swept-frequency optical signals are the final calculation results, which can solve the problem of speed ambiguity that occurs in the existing detection using an I receiver or a Q receiver. And using an I receiver or a Q receiver can reduce costs compared to using an IQ receiver.

[0138] As another example, taking the first swept-frequency optical signal and the second swept-frequency optical signal as an example, and the first swept-frequency optical signal and the second swept-frequency optical signal are combined by polarization multiplexing before transmission. Figure 11 The following examples describe several possible swept-frequency waveforms of two swept-frequency optical signals. Figure 11 In (1)-(3) below, taking the swept-frequency bandwidth of the first swept-frequency optical signal as B1 and the swept-frequency bandwidth of the second swept-frequency optical signal as B2 as an example. There are at least two time periods in the first swept-frequency optical signal and the second swept-frequency optical signal where the signs of the swept-frequency slopes are opposite. Figure 11 In (1)-(3) below, in the first time period, the swept-frequency slope of the first swept-frequency optical signal and the swept-frequency slope of the second swept-frequency optical signal have opposite signs and unequal absolute values of the swept-frequency slopes. In the second time period, the swept-frequency slope of the first swept-frequency optical signal and the swept-frequency slope of the second swept-frequency optical signal have opposite signs and unequal absolute values of the swept-frequency slopes. The swept-frequency slope of the first swept-frequency optical signal in the first time period is different from the swept-frequency slope of the second swept-frequency optical signal in the second time period, and the swept-frequency slope of the second swept-frequency optical signal in the first time period is different from the swept-frequency slope of the first swept-frequency optical signal in the second time period.

[0139] In the above solution, the swept-frequency optical signals with different swept-frequency slopes form the transmitted signal through polarization multiplexing, and M detected objects are detected, which can eliminate false targets without increasing the measurement time and maintain the same point output rate of the lidar. In addition, it supports the use of an I receiver or a Q receiver or an IQ receiver. When using an I receiver or a Q receiver, the transmitted signal is formed by frequency multiplexing multiple swept-frequency optical signals. Since the distance and speed of the real target do not change, the local oscillator signal and the echo signal of each swept-frequency optical signal can be used for beat frequency calculation to obtain the mixed signal, and then the frequency component of the distance and the frequency component of the speed can be determined respectively through the above formulas (6)-(8). That is to say, three calculation results can be obtained based on each swept-frequency optical signal. Taking two swept-frequency optical signals as an example, the two identical results in the calculation results of the two swept-frequency optical signals are the final calculation results, which can solve the problem of velocity ambiguity that occurs when using an I receiver or a Q receiver for detection. And using an I receiver or a Q receiver can reduce costs compared to using an IQ receiver.

[0140] In some possible implementation manners, in order to improve the detection efficiency and reduce the detection time, the signal period of the swept-frequency optical signal is K times the detection period of the lidar. The signal period of the swept-frequency optical signal mentioned here can be the maximum signal period among the signal periods of N swept-frequency optical signals. K is a positive integer. The detection period refers to the time for obtaining the positioning information of a detected object once.

[0141] As an example, taking the first swept-frequency optical signal and the second swept-frequency optical signal as an example, see Figure 12 As shown, the swept-frequency bandwidths of the first swept-frequency optical signal and the second swept-frequency optical signal are different. Taking the signal periods of the first swept-frequency optical signal and the second swept-frequency optical signal as the same as an example. Figure 12 In [reference] T is used to represent the detection period. Figure 12 In (1) in [reference], both the first swept-frequency optical signal and the second swept-frequency optical signal are triangular waves, and the signal period is equal to the detection period. Figure 12 In (2) in [reference], both the first swept-frequency optical signal and the second swept-frequency optical signal are trapezoidal waves, and the signal period is 2 times the detection period. Figure 12 In (3) in [reference], the first swept-frequency optical signal is a triangular wave and the second swept-frequency optical signal is a trapezoidal wave, and the signal period is 2 times the detection period. Figure 12 In (4) in [reference], the first swept-frequency optical signal is a triangular wave and the second swept-frequency optical signal is a constant-frequency wave, and the signal period is equal to the detection period. Figure 12 It is only used to exemplarily describe the multiple relationship between the signal period and the detection period, and can be configured according to requirements in specific scenarios, and this application embodiment does not make specific limitations on this.

[0142] The following describes the structures of the possible transmitting device 610 and receiving device 620 in the embodiments of the present application with reference to the accompanying drawings, in order to give several exemplary implementation manners.

[0143] In the embodiments of the present application, one or more IQ receivers may be deployed in the receiving device 620, or an I receiver or a Q receiver may be deployed. As an example, refer to Figure 13 As shown, it is a schematic structural diagram of a possible IQ receiver. The IQ receiver includes a 90-degree mixer 6201, a first photodetector 6202 and a second photodetector 6203, a first analog-to-digital converter 6204 and a second analog-to-digital converter 6205, and a signal processor 6206. Exemplarily, the receiving device 620 may further include a receiving antenna, and the receiving antenna may also be located outside the receiving device 620. It should be noted that other devices may also be included in the receiving device 620, and the present application does not make specific limitations thereto. The structures of IQ receivers capable of implementing IQ detection are applicable to the embodiments of the present application.

[0144] The 90-degree mixer 6201 receives the echo signal from the antenna. The received echo signal includes N swept-frequency optical signals corresponding to the echo signal respectively. When there are multiple detected objects, the echo signal corresponding to each swept-frequency optical signal includes multiple. The 90-degree mixer 6201 also receives the local oscillator signal from the transmitting device 610. The received local oscillator signal includes the local oscillator signals corresponding to the N swept-frequency optical signals respectively. The 90-degree mixer 6201 performs mixing processing on the local oscillator signal and the echo signal, and outputs two optical signals, namely the I-component optical signal and the Q-component optical signal. The first photodetector 6202 performs photoelectric 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 photoelectric 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. Further, the signal processor 6206 processes the first digital signal and the second digital signal to obtain the positioning information of the detected object. Exemplarily, the first photodetector 6202 and the second photodetector 6203 may employ single-ended photodetectors or balanced photodetectors (BPD).

[0145] A signal processor 6206, which may include a device with computing capabilities such as a digital signal processor (DSP), a central processing unit (CPU), an accelerated processing unit (APU), a graphics processing unit (GPU), a microprocessor, or a microcontroller. The signal processor 6206 is used to process the sampled digital signal to obtain positioning information such as the speed and distance of the target detection object.

[0146] In the embodiments of the present application, the operation of processing the sampled digital signal to obtain information such as the speed and distance of the target object can be completed by one or more signal processors 6206. For example, it can be completed by one or more DSPs. Of course, it can also be completed by one or more signal processors 6206 in combination with other devices. For example, one DSP can be combined with one or more central processing units CPU to jointly complete it. When the signal processor 6206 processes the sampled digital signal, it can be specifically implemented by calling a computer program stored in a computer-readable storage medium. The computer-readable storage medium includes, 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). It can be configured in the signal processor 6206 or independent of the signal processor 6206.

[0147] As another example, see Figure 14 As shown, it is a schematic structural diagram of a possible I receiver. The I receiver includes a 180-degree mixing device 62011, a photodetector 62012, an analog-to-digital converter (ADC) 62013, and a signal processor 62014. The 180-degree mixing device 62011 performs mixing processing on the local oscillator signal and the 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-to-digital converter 62013 converts the analog electrical signal into a digital signal. Further, the signal processor 62014 processes the digital signal to obtain the positioning information of the detected object. Exemplarily, the receiving device 620 may further include a receiving antenna, and the receiving antenna may also be located outside the receiving device 620. It should be noted that the receiving device 620 may further include other devices, and the present application does not make specific limitations thereon. Any structure of the I receiver that can implement I detection is applicable to the embodiments of the present application.

[0148] See Figure 15 A schematic diagram of a possible detection system structure is shown as follows. Figure 15 Taking the generation of a transmission signal by frequency multiplexing as an example for description. The frequency-sweeping signal source 611 includes N directly modulated frequency-sweeping lasers. Figure 15 Taking N as 2, they are the frequency-sweeping laser 61111 and the frequency-sweeping laser 61112 respectively. The multiplexer / demultiplexer component 612 includes at least one directional waveguide coupler 6121. The receiving device 620 can adopt an IQ receiver, or an I receiver or a Q receiver. Figure 15 Taking the adoption of an IQ receiver as an example, the structure of the IQ receiver is taken as an example of the structure shown as follows. Figure 13 For simplicity of description, each device in the IQ receiver is not further labeled.

[0149] The frequency-sweeping laser 6111, whose wavelength changes with time, so that the frequency of the output frequency-sweeping optical signal changes within a set frequency range. Among the N frequency-sweeping lasers 6111, the wavelength change ranges of different frequency-sweeping lasers 6111 are different.

[0150] The frequency-sweeping laser 61111 outputs a frequency-sweeping optical signal 1, the frequency-sweeping period of the frequency-sweeping optical signal 1 is T1, and the frequency-sweeping bandwidth is B1. The wavelength change range of the frequency-sweeping laser 61111 is [λ1, λ2], and the frequency change range of the output frequency-sweeping optical signal 1 is [f1, f2]. The wavelength change range of the frequency-sweeping laser 61112 is [λ3, λ4], and the frequency change range of the output frequency-sweeping optical signal 2 is [f3, f4]. The frequency-sweeping bandwidths B1 and B2 can be the same or different, and the frequency-sweeping periods T1 and T2 can be the same or different, but T1 / T2 or T2 / T1 is a positive integer. Figure 15 In the shown embodiment, by adjusting the wavelengths of the laser signals emitted by the frequency-sweeping laser 61111 and the frequency-sweeping laser 61112, the output frequency-sweeping optical signal 1 and the frequency-sweeping optical signal 2 are made to satisfy the conditions satisfied by the first frequency-sweeping optical signal and the second frequency-sweeping optical signal as described above. For example, the frequency-sweeping optical signal 1 and the frequency-sweeping optical signal 2 satisfy Condition 1 + Condition 2 + Condition 4 + Condition 5 + Condition 6 + Condition 7.

[0151] The swept-frequency optical signals 1 and 2 output by the swept-frequency lasers 61111 and 61112 are coupled via the directional waveguide coupler 6121, and two optical signals are output, where one optical signal serves as the local oscillator signal and the other optical signal serves as the detection signal. The powers of the two optical signals can be the same or different. In some embodiments, when the powers of the two optical signals are not equal, the optical signal with a relatively small power can be used as the local oscillator signal for coherent reception of the received signal. The optical signal with a relatively large power is emitted as the detection signal via the scanner for detecting the object to be detected. After the detection signal encounters M objects to be detected, M echo signals are reflected. After the M echo signals reach the lidar, they are received via the scanner. The M echo signals and a local oscillator signal enter the 90-degree mixer 6201 for optical mixing to obtain a mixed signal. The two optical signals output after mixing are respectively converted into two analog electrical signals by the first photodetector 6202 and the second photodetector 6203, and then are respectively converted into two digital electrical signals via 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 the distance, speed and other information of the M detected objects are output. In some embodiments, before the detection signal is emitted, it can be amplified first and then emitted. For example, the transmitting device 610 may further include an optical amplifier (not shown in the figure), such as a semiconductor optical amplifier, an optical fiber amplifier, etc. The optical amplifier amplifies the detection signal output by the directional waveguide coupler 3 and then emits it through the scanner.

[0152] In the above solution, different frequency ranges of swept-frequency optical signals are realized by adjusting the wavelength ranges of different swept-frequency lasers, and the implementation is simple. Due to the introduction of swept-frequency optical signals with different slopes, coherent detection of real targets is performed in two time periods of different swept-frequency optical signals, and false targets can be eliminated. When there is a certain guard bandwidth in the frequency domain for different swept-frequency optical signals (that is, when the condition 6 is satisfied), unwanted beat frequency signals can be prevented from being generated, so that calculation errors can be prevented, and the complexity of calculation speed or distance can be reduced. The embodiment of the present application realizes the distinction of multiple targets by emitting the transmitted signal formed by frequency multiplexing, and does not increase the measurement time, maintaining the same output point rate of the lidar.

[0153] See Figure 16 which shows a schematic structural diagram of a possible detection system. Figure 16 Taking the generation of the transmitted signal in the way of frequency multiplexing as an example for description. The swept-frequency signal source 611 includes N directly modulated swept-frequency lasers, Figure 16Taking N as 2 as an example in the present invention, they are a swept-frequency laser 61111 and a swept-frequency laser 61112 respectively. The multiplexer / demultiplexer 612 includes three directional waveguide couplers 6121. For the convenience of distinction, they are respectively called a directional waveguide coupler 6121-1, a directional waveguide coupler 6121-2, and a directional waveguide coupler 6121-3. The receiving device 620 can adopt two IQ receivers. For the sake of simplicity in description, each device in the IQ receiver is not further labeled.

[0154] The swept-frequency laser 61111 outputs a swept-frequency optical signal 1. The swept-frequency laser 61112 outputs a swept-frequency optical signal 2. For the conditions satisfied by the swept-frequency optical signal 1 and the swept-frequency optical signal 2, refer to Figure 15 the description of the corresponding embodiment, which will not be elaborated here. The swept-frequency optical signal 1 is output and divided into two parts through the directional waveguide coupler 6121-1. One part of the optical signal is used as a local oscillator signal and transmitted to one of the receivers, and the other part of the optical signal enters the directional waveguide coupler 6121-3. The swept-frequency optical signal 2 is output and divided into two parts through the directional waveguide coupler 6121-2. One part of the optical signal is used as a local oscillator signal and transmitted to the other receiver, 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 through the scanner to detect the object to be measured. In some embodiments, before the detection signal is transmitted, it can be amplified first and then transmitted. For example, the transmitting device 610 may further include an optical amplifier (not shown in the figure). The optical amplifier amplifies the detection signal output by the directional waveguide coupler 3 and then transmits it through the scanner. In some embodiments, the detection system may further include a wavelength division multiplexer for splitting the echo signal received from the scanner into two optical signals and respectively entering the two receivers. The processing methods of the two receivers are as described above and will not be elaborated here.

[0155] By using the transmission signal formed by frequency multiplexing of two swept-frequency optical signals with different wavelength ranges and different swept-frequency slopes to detect M detected objects, false targets can be eliminated. In addition, by using different IQ receivers at the receiving end to perform coherent detection on different swept-frequency optical signals, the computational complexity of the signal processor can be reduced. The above embodiments can accurately locate multiple detected objects without increasing the measurement time and maintain the same laser radar point output rate.

[0156] In some embodiments, Figure 16 in the detection system shown, the receiving device 620 can also adopt two I receivers or Q receivers, and there will be no problem of velocity ambiguity, and the detection cost can be reduced.

[0157] Refer to Figure 17 shown is a schematic structural diagram of a possible detection system. Figure 17 And Figure 16The difference from the corresponding embodiment is as follows: Figure 17 In Figure 17 , the multiplexing and demultiplexing component includes a wavelength division multiplexer 61211 and a coupler 61212. The swept optical signals 1-N output by N swept lasers are multiplexed by the wavelength division multiplexer 61211. The optical signal output by the wavelength division multiplexer 61211 is divided into two optical signals by the coupler. One of the optical signals is used as the local oscillator signal and input to the receiver, and the other optical signal is used as the detection signal and sent out through the scanner. In some embodiments, before the detection signal is transmitted, it can be amplified first and then transmitted. For example, the transmitting device 610 may further include an optical amplifier (not shown in the figure), and the optical amplifier amplifies the detection signal output by the coupler 61212 and then transmits it through the scanner.

[0158] In the above solution, by loading signals with N different swept waveforms onto laser signals in different wavelength ranges and performing frequency multiplexing to generate the transmitted signal, and using this signal to detect M detection objects simultaneously, false targets can be eliminated. In addition, by using an IQ receiver at the receiving end to perform coherent detection on different swept optical signals, the computational complexity of the signal processor can be reduced. The above embodiments can achieve accurate positioning of multiple target detection objects without increasing the measurement time and maintain the same laser radar point output rate. In some embodiments, Figure 17 In the detection system shown, the receiving device 620 can also adopt an I receiver or a Q receiver, and there will be no problem of velocity ambiguity, and the detection cost can be reduced.

[0159] See Figure 18 Shown is a schematic diagram of a possible structure of the detection system. Figure 18 Different from Figure 15 The difference from the corresponding embodiment is as follows: Figure 15 In Figure 15 , an IQ receiver is adopted in the receiving device 620. Figure 18 In Figure 18 , the receiving device 620 adopts an I receiver or a Q receiver. By adopting the above solution, there will be no problem of velocity ambiguity, and the detection cost can be reduced.

[0160] See Figure 19 Shown is a schematic diagram of a possible structure of the detection system. Figure 19 In Figure 19 , the N swept optical signals are generated by performing IQ modulation on the laser signal emitted by the laser, and the swept waveform can be generated by digital signal processing. The swept signal source 611 includes a laser 1910, a modulator 1920, a swept drive signal source 1930, and two radio frequency amplifiers. For the sake of distinction, the two radio frequency amplifiers are respectively called radio frequency amplifier 1941 and radio frequency amplifier 1942. See Figure 20The figure shows the way for a frequency-swept driving signal source to generate N frequency-swept signals. Frequency-swept signal 1 to frequency-swept signal N are N frequency-swept signals with different frequencies, and are respectively subjected to different up-conversion processes to obtain frequency-swept signals whose frequency ranges meet the aforementioned conditions. Then, through taking the real part and the imaginary part and digital-to-analog conversion processing, the frequency-swept digital signal is converted into a frequency-swept analog signal. Further, after radio frequency amplification, it is modulated onto the laser signal emitted by the laser. After the frequency-swept analog signals with different frequency-swept frequency ranges are modulated onto the laser signal, frequency-swept optical signals with different frequency-swept frequency ranges are obtained. The multiplexer / demultiplexer component 612 includes a coupler 1950. It is used to split a path of optical signal including N frequency-swept optical signals emitted by the modulator 1920 into a local oscillator signal and a detection signal. The coupler 1950 sends the local oscillator signal to the receiving device 620 and emits the detection signal through the scanner. In some embodiments, before the detection signal is emitted, it can be amplified first and then emitted. For example, the transmitting device 610 may further include an optical amplifier (not shown in the figure), and the optical amplifier amplifies the detection signal output by the coupler 1950 and then emits it through the scanner.

[0161] In this solution, by loading frequency-swept analog electrical signals with different frequency-swept slopes and opposite frequency-swept directions onto the laser signal, N frequency-swept optical signals whose frequency-swept frequency ranges meet the requirements are obtained, and M detection objects are detected, and the problem of false targets can be eliminated. The embodiments of the present application can realize the positioning of multiple target detection objects without increasing the measurement time and maintain the point output rate of the lidar unchanged. In some embodiments, Figure 19 In the shown detection system, the receiving device 620 can also adopt an I receiver or a Q receiver, and there will be no problem of velocity ambiguity, and the detection cost can be reduced.

[0162] See Figure 21 The figure shows a schematic diagram of a possible detection system structure. Figure 21 Among them, the N frequency-swept optical signals are generated by performing IQ modulation on the laser signal emitted by the laser, and the frequency-swept waveform can be generated by means of digital signal processing. Figure 21Among them, the swept-frequency signal source 611 includes N swept-frequency signal transmitting components, namely, swept-frequency signal transmitting components 1 to N. Each swept-frequency signal transmitting component includes a swept-frequency drive signal source 2101, a radio frequency amplifier 2102, a radio frequency amplifier 2103, a laser 2104, and a modulator 2105. The swept-frequency drive signal source 2101 generates a swept-frequency signal with a periodically changing frequency, which is amplified by the radio frequency amplifier and then input into the modulator. The laser 2104 emits a laser signal. The modulator 2105 modulates the amplified swept-frequency signal onto the laser signal to obtain a swept-frequency optical signal. Thus, N swept-frequency signal transmitting components generate N swept-frequency optical signals. The multiplexer / demultiplexer component 612 includes a coupler 2106. It is used to combine the swept-frequency optical signals transmitted by the N swept-frequency signal transmitting components, and then split the light to obtain a local oscillator signal and a detection signal. The coupler 2106 sends the local oscillator signal to the receiving device 620 and emits the detection signal through the scanner. In some embodiments, before the detection signal is emitted, it can be amplified first and then emitted. For example, the transmitting device 610 may further include an optical amplifier (not shown in the figure), and the optical amplifier amplifies the detection signal output by the coupler 2106 and then emits it through the scanner.

[0163] Exemplarily, the manner in which the swept-frequency drive signal source 2101 generates a swept-frequency signal with a periodically changing frequency can be referred to Figure 22 as shown. The real part and the imaginary part of the digital swept-frequency signal are taken, and then it is converted into an analog swept-frequency

[0164] In one example, the wavelengths of the laser signals emitted by the lasers included in different swept-frequency signal transmitting components are different. In this example, by emitting laser signals with different wavelengths by the lasers, the frequency ranges of the swept-frequency optical signals emitted by the N swept-frequency signal transmitting components satisfy the conditions shown above.

[0165] In another example, the frequency ranges of the swept-frequency signals generated by the swept-frequency drive signal sources included in different swept-frequency signal transmitting components are different. In this example, by generating swept-frequency analog electrical signals with different frequency ranges by the swept-frequency signal source and modulating them onto the laser signals emitted by the lasers, the frequency ranges of the swept-frequency optical signals emitted by the N swept-frequency signal transmitting components satisfy the conditions shown above.

[0166] In yet another example, the wavelengths of the laser signals emitted by the lasers included in different swept-frequency signal transmitting components are different and the frequency ranges of the swept-frequency signals generated by the swept-frequency drive signal sources included in different swept-frequency signal transmitting components are different. In this example, by generating swept-frequency analog electrical signals with different frequency ranges by the swept-frequency signal source and correspondingly modulating them onto the laser signals with different wavelengths respectively emitted by the N lasers, the frequency ranges of the swept-frequency optical signals emitted by the N swept-frequency signal transmitting components satisfy the conditions shown above.

[0167] The above solution generates N frequency-swept signals that meet the conditions through digital signal processing, and modulates them onto the laser signal to generate N frequency-swept optical signals that meet the conditions for detecting M detected objects, which can eliminate false targets. There is a certain guard bandwidth between adjacent two frequency-swept analog electrical signals in the frequency domain, so that there is a certain guard bandwidth between adjacent two frequency-swept optical signals output in the frequency domain to prevent the generation of unwanted beat frequency signals. The embodiments of the present application can achieve the positioning of multiple target detected objects without increasing the measurement time and maintain the same laser radar point output rate.

[0168] In some embodiments, Figure 21 In the detection system shown, the receiving device 620 can also adopt an I receiver or a Q receiver, without the problem of velocity ambiguity, and the detection cost can be reduced.

[0169] See Figure 23 shown is a schematic structural diagram of a possible detection system. Figure 23 The N frequency-swept optical signals are generated by modulating the laser signal emitted by the laser, and the frequency-swept waveform can be generated by digital signal processing. Figure 23 In, the frequency-swept signal source 611 includes a laser 2301, an optical frequency comb 2302, N micro-ring modulators, and N frequency-swept drive signal sources. The N micro-ring modulators are respectively micro-ring modulator 1 to N, and the N frequency-swept drive signal sources are respectively frequency-swept drive signal source 1 to N. The principle of the frequency-swept drive signal source generating the frequency-swept signal can be seen in Figure 22 shown, which will not be elaborated here.

[0170] The laser 2301 emits a laser signal. The optical frequency comb 2302 processes the laser signal to obtain optical signals of N wavelengths. N swept-frequency drive signal sources are connected to N micro-ring modulators in one-to-one correspondence, and the N micro-ring modulators are arranged in series in the optical paths of the optical signals of N wavelengths. The micro-ring modulator i (i = 1... N) modulates the swept-frequency signal with a periodically changing frequency range output by the swept-frequency drive signal source i onto the optical signal corresponding to the wavelength of the micro-ring modulator i, thereby obtaining N swept-frequency optical signals that meet the conditions described above. The N micro-ring modulators correspond to N wavelengths one by one, and the frequency ranges of the swept-frequency signals output by different swept-frequency drive signal sources are different. The multiplexer / demultiplexer component 612 may include a directional waveguide coupler 2303 for splitting the optical signal output by the micro-ring modulator N into a local oscillator signal and a detection signal. The directional waveguide coupler 2303 sends the local oscillator signal to the receiving device 620 and emits the detection signal through the scanner. In some embodiments, before the detection signal is emitted, it can be amplified first and then emitted. For example, the transmitting device 610 may further include an optical fiber amplifier (not shown in the figure), and the optical fiber amplifier amplifies the detection signal output by the directional waveguide coupler 2303 and then emits it through the scanner.

[0171] In this solution, N swept-frequency analog electrical signals with different frequency ranges are generated by N swept-frequency drive signal sources. The laser signal is converted into light of multiple frequencies by the optical frequency comb, which can also be understood as light of different wavelengths. And N different swept-frequency analog electrical signals with different frequency ranges are respectively modulated onto the optical signals of different wavelengths by N micro-ring modulators, and the frequency ranges of the N generated swept-frequency optical signals meet the conditions shown above. By emitting N swept-frequency optical signals that meet the conditions to detect M detected objects, false targets can be eliminated. There is a certain guard bandwidth between adjacent two swept-frequency analog electrical signals in the frequency domain, so that there is a certain guard bandwidth between adjacent two swept-frequency optical signals in the frequency domain to prevent the generation of unwanted beat frequency signals. The embodiments of the present application can realize the positioning of multiple target detected objects without increasing the measurement time and maintain the same laser radar point output rate.

[0172] In some embodiments, Figure 23 In the detection system shown, the receiving device 620 can also adopt an I receiver or a Q receiver, and there will be no problem of velocity ambiguity, and the detection cost can be reduced.

[0173] See Figure 24 Shown is a schematic structural diagram of a possible detection system. The swept-frequency signal source 611 includes N swept-frequency lasers, namely swept-frequency lasers 1 to N. The polarization directions of the swept-frequency optical signals generated by different swept-frequency lasers are different. The N swept-frequency lasers generate N swept-frequency optical signals, and the N optical signals meet the conditions described above. Figure 24In it, the multiplexer / demultiplexer component 612 includes a polarization beam combiner (PBC) 2401 and a polarization maintaining coupler 2402. The polarization beam combiner 2401 combines N swept-frequency optical signals based on the polarization directions of the N swept-frequency optical signals to obtain a radar transmission signal. Then, the polarization maintaining coupler 2402 splits the radar transmission signal into a local oscillator signal and a detection signal. The polarization maintaining coupler 2402 sends the local oscillator signal to the receiving device 620 and emits the detection signal through a scanner. In some embodiments, before the detection signal is emitted, it can be amplified first and then emitted. For example, the transmitting device 610 may further include a polarization maintaining amplifier (not shown in the figure), and the polarization maintaining amplifier amplifies the detection signal output by the polarization maintaining coupler 2402 and then emits it through the scanner.

[0174] In the above solution, the swept-frequency optical signals with different swept-frequency slopes form a transmission signal through polarization multiplexing. Detecting M detected objects can eliminate false targets without increasing the measurement time and maintain the same point output rate of the lidar. In some embodiments, Figure 24 In the detection system shown, the receiving device 620 can also adopt an I receiver or a Q receiver, without the problem of velocity ambiguity, and the detection cost can be reduced.

[0175] Based on the above content and the same concept, the present application provides a detection method for a lidar. Please refer to Figure 25 for the introduction. This detection method can be applied to the detection system shown in any of the above Figures 15 to 24 embodiments. It can also be understood that the detection method can be implemented based on the detection system shown in any of the above Figures 15 to 24 embodiments.

[0176] As shown in Figure 25 , it is a schematic flowchart of a detection method for a lidar provided by the present application. This detection method includes the following steps:

[0177] 2501. Transmit N swept-frequency optical signals, where N is an integer greater than 1. In the first time period, the sign of the swept-frequency slope of the first swept-frequency optical signal among the N swept-frequency optical signals is opposite to that of the second swept-frequency optical signal, or the swept-frequency slope of the first swept-frequency optical signal is 0 and the swept-frequency slope of the second swept-frequency optical signal is not 0; the frequencies of the N swept-frequency optical signals are different.

[0178] Regarding the conditions that the N swept-frequency optical signals need to meet, reference can be made to the foregoing relevant descriptions, and details will not be elaborated here.

[0179] 2502. Combine the N swept-frequency optical signals to obtain a radar transmission signal, and divide the radar transmission signal into a local oscillator signal and a detection signal.

[0180] 2503, transmit the detection signal through the antenna. The local oscillator signal is used to perform coherent detection with the echo signal of the detection signal to obtain the positioning information of the detected object.

[0181] In a possible design, the detection method may further include:

[0182] 2504, receive the echo signal of the detection signal from the antenna, and perform mixing processing on the echo signal and the local oscillator signal to generate a mixed signal;

[0183] 2505, obtain the positioning information of the detected object according to the mixed signal.

[0184] In a possible implementation manner, the first swept-frequency optical signal and the second swept-frequency optical signal are periodic swept-frequency optical signals.

[0185] In a possible implementation manner, the signal period of the first swept-frequency optical signal is M times the signal period of the second swept-frequency optical signal, or the signal period of the second swept-frequency signal is M times the signal period of the first swept-frequency optical signal, where M is a positive integer.

[0186] In a possible implementation manner, the signal period of the first swept-frequency optical signal is K times the detection period of the lidar, or the signal period of the second swept-frequency optical signal is K times the detection period of the lidar, where K is a positive integer.

[0187] In a possible implementation manner, the signal period of the first swept-frequency optical signal is greater than or equal to the signal period of the second swept-frequency signal; in one signal period of the first swept-frequency optical signal, the sign of the sweep slope of the first swept-frequency signal in the first time period is opposite to the sign of the sweep slope in the second time period; the sign of the sweep slope of the second swept-frequency signal in the first time period is opposite to the sign of the sweep slope in the second time period; the sweep slope of the first swept-frequency signal in the first time period is different from the sweep slope of the second swept-frequency signal in the second time period, and the sweep slope of the second swept-frequency signal in the first time period is different from the sweep slope of the first swept-frequency signal in the second time period.

[0188] In a possible implementation manner, the minimum frequency difference between the first swept-frequency optical signal and the second swept-frequency optical signal is related to the receiving bandwidth of the antenna.

[0189] In a possible implementation manner, the minimum frequency difference between the first swept-frequency optical signal and the second swept-frequency optical signal satisfies the following condition:

[0190] min(|f1 - f2|)>|fR1|+|fR2|+fOE;

[0191] Wherein, 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 value of the 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 value of the 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.

[0192] In a possible implementation, the first frequency-swept signal and the second frequency-swept signal satisfy:

[0193] Or

[0194] Wherein, round() represents the rounding operation, K1 represents the absolute value of the frequency sweep slope of the first frequency-swept signal in the first time period, K2 represents the absolute value of the frequency sweep slope of the second frequency-swept signal in the first time period, R min represents the minimum detectable distance of the lidar, and c represents the speed of light.

[0195] 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; when the frequency sweep slope of the second frequency-swept optical signal is not 0, the waveform of the second frequency-swept optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave.

[0196] In a possible implementation, the wavelength change ranges of the N frequency-swept optical signals are different, or the polarization directions of the N frequency-swept optical signals are different.

[0197] In various embodiments of the present application, if there is no special description and logical conflict, the terms and / or descriptions between different embodiments are consistent and can be cross-referenced. The technical features in different embodiments can be combined to form new embodiments according to their internal logical relationships.

[0198] Those skilled in the art can clearly understand that for the convenience and brevity of description, the above-described method can refer to the corresponding description in the foregoing apparatus or system embodiments, and will not be repeated here.

[0199] Although the present application has been described in combination with specific features and their embodiments, it is obvious that various modifications and combinations can be made without departing from the scope of the present application. Accordingly, the present specification and the drawings are only exemplary illustrations of the solutions defined by the appended claims, and are considered to have covered any and all modifications, variations, combinations, or equivalents within the scope of the present application.

[0200] Obviously, those skilled in the art can make various changes and modifications to this application without departing from the scope of this application. Thus, if these modifications and variations of the embodiments of this application fall within the scope of the claims of this application and their equivalent technologies, this application also intends to include these changes and modifications therein.

Claims

1. A transmitting device for a lidar, characterized in that, It includes a swept-frequency signal source and a multiplexer / demultiplexer component; wherein, the swept-frequency signal source is used to transmit N swept-frequency optical signals, where N is an integer greater than 1. During a first time period, the sign of the sweep slope of the first swept-frequency optical signal among the N swept-frequency optical signals is opposite to the sign of the sweep slope of the second swept-frequency optical signal, and the absolute value of the sweep slope of the first swept-frequency optical signal is different from the absolute value of the sweep slope of the second swept-frequency optical signal; the frequencies of the N swept-frequency optical signals are different; the minimum frequency difference between the first swept-frequency optical signal and the second swept-frequency optical signal satisfies the following condition: min(|f1 - f2|) > |fR1| + |fR2| + fOE; wherein, f1 represents the sweep range of the first swept-frequency optical signal, f2 represents the sweep range of the second swept-frequency optical signal, fR1 represents the maximum value of the frequency shift amount of the echo signal of the first swept-frequency optical signal relative to the local oscillator signal of the first swept-frequency optical signal, fR2 represents the maximum value of the frequency shift amount of the echo signal of the second swept-frequency optical signal relative to the local oscillator signal of the second swept-frequency optical signal, and fOE represents the receiving bandwidth of the antenna; the multiplexer / demultiplexer component is used to process the N swept-frequency optical signals to obtain a local oscillator signal and a detection signal, transmit the detection signal through the antenna, and send the local oscillator signal to the receiving device of the lidar.

2. The transmitting device according to claim 1, characterized in that, The first swept-frequency optical signal and the second swept-frequency optical signal are periodic swept-frequency optical signals.

3. The transmitting device according to claim 2, characterized in that, The signal period of the first swept-frequency optical signal is M times the signal period of the second swept-frequency optical signal, or the signal period of the second swept-frequency optical signal is M times the signal period of the first swept-frequency optical signal, where M is a positive integer.

4. The transmitting device according to claim 2, characterized in that, The signal period of the first swept-frequency optical signal is K times the detection period of the lidar, or the signal period of the second swept-frequency optical signal is K times the detection period of the lidar, where K is a positive integer.

5. The transmitting device according to claim 2, characterized in that: During one target signal period, the sign of the sweep slope of the first swept-frequency optical signal in the first time period is opposite to the sign of the sweep slope in the second time period; the sign of the sweep slope of the second swept-frequency optical signal in the first time period is opposite to the sign of the sweep slope in the second time period; the sweep slope of the first swept-frequency optical signal in the first time period is different from the sweep slope of the second swept-frequency optical signal in the second time period, and the sweep slope of the second swept-frequency optical signal in the first time period is different from the sweep slope of the first swept-frequency optical signal in the second time period; wherein, the target signal period is the maximum signal period among the signal periods of the first swept-frequency optical signal and the second swept-frequency optical signal.

6. The transmitting device according to any one of claims 1-5, characterized in that, The first swept-frequency optical signal and the second swept-frequency optical signal satisfy: Or Among them, round() represents the rounding operation, K1 represents the absolute value of the frequency sweep slope of the first frequency-swept optical signal in the first time period, K2 represents the absolute value of the frequency sweep slope of the second frequency-swept optical signal in the first time period, R min represents the minimum detectable distance of the lidar, and c represents the speed of light.

7. The transmitting device according to any one of claims 1-5, characterized in that, The waveform of the first swept-frequency optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave; When the sweep slope of the second swept-frequency optical signal is not 0, the waveform of the second swept-frequency optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave.

8. The transmitting device according to any one of claims 1-5, characterized in that, The wavelength change ranges of the N swept-frequency optical signals are different, or the polarization directions of the N swept-frequency optical signals are different.

9. A transmitting device for a lidar, characterized in that, It includes a swept-frequency signal source and a multiplexer / demultiplexer component; wherein, the swept-frequency signal source is used to transmit N swept-frequency optical signals, where N is an integer greater than 1. In the first time period, the swept-frequency slope of the first swept-frequency optical signal among the N swept-frequency optical signals is not 0 and the swept-frequency slope of the second swept-frequency optical signal is 0; the frequencies of the N swept-frequency optical signals are different; the first swept-frequency optical signal and the second swept-frequency optical signal are periodic swept-frequency optical signals; the multiplexer / demultiplexer component is used to process the N swept-frequency optical signals to obtain a local oscillator signal and a detection signal, transmit the detection signal through an antenna, and send the local oscillator signal to the receiving device of the lidar.

10. The transmitting device according to claim 9, characterized in that, The signal period of the first swept-frequency optical signal is M times the signal period of the second swept-frequency optical signal, or the signal period of the second swept-frequency optical signal is M times the signal period of the first swept-frequency optical signal, where M is a positive integer.

11. The transmitting device according to claim 9, characterized in that, The signal period of the first swept-frequency optical signal is K times the detection period of the lidar, or the signal period of the second swept-frequency optical signal is K times the detection period of the lidar, where K is a positive integer.

12. The transmitting device according to claim 9, characterized in that: In one target signal period, the signs of the swept-frequency slopes of the first swept-frequency optical signal in the first time period and in the second time period are opposite; the signs of the swept-frequency slopes of the second swept-frequency optical signal in the first time period and in the second time period are opposite; the swept-frequency slope of the first swept-frequency optical signal in the first time period is different from the swept-frequency slope of the second swept-frequency optical signal in the second time period, and the swept-frequency slope of the second swept-frequency optical signal in the first time period is different from the swept-frequency slope of the first swept-frequency optical signal in the second time period; wherein, the target signal period is the maximum signal period among the signal periods of the first swept-frequency optical signal and the second swept-frequency optical signal.

13. The transmitting device according to any one of claims 9-12, characterized in that, The minimum frequency difference between the first swept-frequency optical signal and the second swept-frequency optical signal is related to the receiving bandwidth of the antenna.

14. The transmitting device according to claim 13, characterized in that, The minimum frequency difference between the first swept-frequency optical signal and the second swept-frequency optical signal satisfies the following condition: min(|f1 - f2|) > |fR1| + |fR2| + fOE; wherein, f1 represents the swept-frequency range of the first swept-frequency optical signal, f2 represents the swept-frequency range of the second swept-frequency optical signal, fR1 represents the maximum value of the frequency shift amount of the echo signal of the first swept-frequency optical signal relative to the local oscillator signal of the first swept-frequency optical signal, fR2 represents the maximum value of the frequency shift amount of the echo signal of the second swept-frequency optical signal relative to the local oscillator signal of the second swept-frequency optical signal, and fOE represents the receiving bandwidth of the antenna.

15. The transmitting device according to any one of claims 9-12, characterized in that, The first swept-frequency optical signal and the second swept-frequency optical signal satisfy: Or Among them, round() represents the rounding operation, K1 represents the absolute value of the frequency sweep slope of the first frequency-swept optical signal in the first time period, K2 represents the absolute value of the frequency sweep slope of the second frequency-swept optical signal in the first time period, R min represents the minimum detectable distance of the lidar, and c represents the speed of light.

16. The transmitting device according to any one of claims 9-12, characterized in that, The waveform of the first swept-frequency optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave.

17. The transmitting device according to any one of claims 9-12, characterized in that, The wavelength change ranges of the N swept-frequency optical signals are different, or the polarization directions of the N swept-frequency optical signals are different.

18. A detection system of a lidar, characterized in that, It includes the transmitting device of the lidar and the receiving device of the lidar according to any one of claims 1 - 17; The receiving device is configured to receive the local oscillator signal from the transmitting device and the echo signal of the detection signal transmitted by the transmitting device, and perform mixing processing on the echo signal and the local oscillator signal to generate a mixed signal; and obtain the positioning information of the detected object according to the mixed signal.

19. The system according to claim 18, characterized in that, The receiving device includes a 90-degree 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 mixer is configured to perform mixing processing on the echo signal of the detection signal received from the antenna and the local oscillator signal to generate a mixed signal, divide the mixed signal into a first path signal and a second path signal, and send the first path signal to the first photodetector and send the second path signal to the second photodetector; The first photodetector is configured to perform detection processing on the first path signal and then output it to the first analog-to-digital converter for analog-to-digital conversion; The second photodetector is configured to perform detection processing on the second path signal and then output it 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 the positioning information of the detected object.

20. The system according to claim 18, characterized in that, The receiving device includes a 180-degree mixer, a third photodetector, a third analog-to-digital converter, and a signal processor; The 180-degree mixer is configured to perform mixing processing on the echo signal of the detection signal received from the antenna and the local oscillator signal to generate a mixed signal, and send the mixed signal to the third photodetector; The third photodetector is configured to perform detection processing on the mixed signal and then output it 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 the positioning information of the detected object.

21. A detection method based on a lidar, characterized in that, Including: Transmitting N swept-frequency optical signals, where N is an integer greater than 1. In the first time period, the sign of the sweep slope of the first swept-frequency optical signal among the N swept-frequency optical signals is opposite to the sign of the sweep slope of the second swept-frequency optical signal; the frequencies of the N swept-frequency optical signals are different; the minimum frequency difference between the first swept-frequency optical signal and the second swept-frequency optical signal satisfies the following condition: min(|f1 - f2|) > |fR1| + |fR2| + fOE; where, f1 represents the sweep range of the first swept-frequency optical signal, f2 represents the sweep range of the second swept-frequency optical signal, fR1 represents the maximum value of the frequency shift amount of the echo signal of the first swept-frequency optical signal relative to the local oscillator signal of the first swept-frequency optical signal, fR2 represents the maximum value of the frequency shift amount of the echo signal of the second swept-frequency optical signal relative to the local oscillator signal of the second swept-frequency optical signal, and fOE represents the receiving bandwidth of the antenna; Performing multiplexing on the N swept-frequency optical signals to obtain a radar transmission signal, and dividing the radar transmission signal into a local oscillator signal and a detection signal, and transmitting the detection signal through the antenna; Receive the echo signal of the detection signal from the antenna, and mix the echo signal and the local oscillator signal to generate a mixed signal; Obtain the positioning information of the detected object according to the mixed signal.

22. The method according to claim 21, characterized in that, The first swept-frequency optical signal and the second swept-frequency optical signal are periodic swept-frequency optical signals.

23. The method according to claim 22, characterized in that,The signal period of the first swept-frequency optical signal is M times the signal period of the second swept-frequency optical signal, or the signal period of the second swept-frequency optical signal is M times the signal period of the first swept-frequency optical signal, where M is a positive integer.

24. The method according to claim 22, characterized in that, The signal period of the first swept-frequency optical signal is K times the detection period of the lidar, or the signal period of the second swept-frequency optical signal is K times the detection period of the lidar, where K is a positive integer.

25. The method according to claim 22, characterized in that: In a target signal period, the sign of the sweep slope of the first swept-frequency optical signal in the first time period is opposite to the sign of the sweep slope in the second time period; The sign of the sweep slope of the second swept-frequency optical signal in the first time period is opposite to the sign of the sweep slope in the second time period; The sweep slope of the first swept-frequency optical signal in the first time period is different from the sweep slope of the second swept-frequency optical signal in the second time period, and the sweep slope of the second swept-frequency optical signal in the first time period is different from the sweep slope of the first swept-frequency optical signal in the second time period; Wherein, the target signal period is the maximum signal period of the signal period of the first swept-frequency optical signal and the signal period of the second swept-frequency optical signal.

26. The method according to any one of claims 21-25, characterized in that, The first swept-frequency optical signal and the second swept-frequency optical signal satisfy: or Among them, round() represents the rounding operation, K1 represents the absolute value of the frequency sweep slope of the first frequency sweep optical signal in the first time period, K2 represents the absolute value of the frequency sweep slope of the second frequency sweep optical signal in the first time period, and R min represents the minimum detectable distance of the lidar, and c represents the speed of light.

27. The method according to any one of claims 21-25, characterized in that, The waveform of the first swept-frequency optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave; When the sweep slope of the second swept-frequency optical signal is not 0, the waveform of the second swept-frequency optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave.

28. The method according to any one of claims 21-25, characterized in that, The wavelength change ranges of the N swept-frequency optical signals are different, or the polarization directions of the N swept-frequency optical signals are different.

29. A detection method based on lidar, characterized in that, Comprising: Transmit N swept-frequency optical signals, where N is an integer greater than 1. In the first time period, the sweep slope of the first swept-frequency optical signal among the N swept-frequency optical signals is 0 and the sweep slope of the second swept-frequency optical signal is not 0; the frequencies of the N swept-frequency optical signals are different; The first swept-frequency optical signal and the second swept-frequency optical signal are periodic swept-frequency optical signals; Combine the N swept-frequency optical signals to obtain a radar transmission signal, divide the radar transmission signal into a local oscillator signal and a detection signal, and transmit the detection signal through an antenna; Receive the echo signal of the detection signal from the antenna, and mix the echo signal and the local oscillator signal to generate a mixed signal; Obtain the positioning information of the detected object according to the mixed signal.

30. The method according to claim 29, characterized in that, The signal period of the first swept-frequency optical signal is M times the signal period of the second swept-frequency optical signal, or the signal period of the second swept-frequency optical signal is M times the signal period of the first swept-frequency optical signal, where M is a positive integer.

31. The method according to claim 29, characterized in that, 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.

32. The method according to claim 29, characterized in that: In a target signal period, the sign of the frequency-sweeping slope of the first frequency-swept optical signal in the first time period is opposite to that in the second time period. The sign of the frequency-sweeping slope of the second frequency-swept optical signal in the first time period is opposite to that in the second time period. The frequency-sweeping slope of the first frequency-swept optical signal in the first time period is different from that of the second frequency-swept optical signal in the second time period, and the frequency-sweeping slope of the second frequency-swept optical signal in the first time period is different from that of the first frequency-swept optical signal in the second time period. Wherein, the target signal period is the maximum signal period of the signal period of the first frequency-swept optical signal and the signal period of the second frequency-swept optical signal.

33. The method according to any one of claims 29-32, characterized in that, 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.

34. The method according to claim 33, characterized in that, The minimum frequency difference between the first frequency-swept optical signal and the second frequency-swept optical signal satisfies the following condition: min(|f1 - f2|) > |fR1| + |fR2| + fOE; Wherein, f1 represents the frequency-sweeping range of the first frequency-swept optical signal, f2 represents the frequency-sweeping range of the second frequency-swept optical signal, fR1 represents the maximum value of the 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 value of the 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.

35. The method according to any one of claims 29 - 32, characterized in that, The first frequency-swept optical signal and the second frequency-swept optical signal satisfy: Or Among them, round() represents the rounding operation, K1 represents the absolute value of the frequency sweep slope of the first frequency-swept optical signal in the first time period, K2 represents the absolute value of the frequency sweep slope of the second frequency-swept optical signal in the first time period, and R min represents the minimum detectable distance of the lidar, and c represents the speed of light.

36. The method according to any one of claims 29 - 32, characterized in that, The waveform of the first frequency-swept optical signal includes at least one of a triangular wave, a trapezoidal wave, and a sawtooth wave.

37. The method according to any one of claims 29 - 32, characterized in that, The wavelength change ranges of the N frequency-swept optical signals are different, or the polarization directions of the N frequency-swept optical signals are different.

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