FMCW laser radar device capable of actively suppressing low-frequency interference and frequency modulation method

Abstract

The invention relates to the technical field of laser radars, and discloses an FMCW laser radar device capable of actively suppressing low-frequency interference and a frequency modulation method, and the method comprises the steps: firstly generating a first modulation signal through a signal generator, and carrying out the continuous frequency modulation of an original laser signal generated by a laser; and secondly, in combination with the second modulation signal, the modulated initial laser modulation signal is subjected to power suppression through the optical modulator, so that the power of the target laser modulation signal output by the optical modulator can be actively suppressed. And finally, the suppressed target laser modulation signal is input to the FMCW coherent detection device, and distance detection of the target object is completed. Therefore, according to the invention, the amplitude change of the input power of the laser radar is not caused while the continuous frequency modulation of the laser is realized, so that the introduction of a low-frequency interference signal is avoided, the interference of low-frequency modulation on an actual target signal is suppressed, and the recognition capability of the laser radar on a close-range target is improved.

Description

Technical Field

[0001] The present invention relates to the field of laser radar technology, and in particular to an FMCW laser radar device and a frequency modulation method for actively suppressing low-frequency interference. Background Art

[0002] For FMCW (Frequency Modulated Continuous Wave Radar) laser radar, coherent detection is used to obtain information such as target distance and speed. This type of laser radar requires continuous modulation of the frequency of the laser. Taking the DFB semiconductor laser as an example, the continuous change of the laser output frequency is achieved by continuously changing the driving current of the laser. However, since the output power of the laser is usually related to the driving current, the frequency modulation of the laser is accompanied by the modulation of the laser output power. The frequency of this power modulation signal is generally low, and it will overlap with the reflection signal of the close-range target. After being converted into a frequency domain signal, it will interfere with the judgment and identification of the target signal, affecting the close-range performance of the FMCW laser radar, and is one of the reasons for the close-range "blind spot". Summary of the invention

[0003] In view of this, the present invention provides an FMCW laser radar device and a frequency modulation method for actively suppressing low-frequency interference, so as to solve the problem that the output power of the laser is modulated simultaneously with the frequency modulation of the laser, but the frequency of the power modulation signal is generally low, which will overlap with the reflection signal of the close-range target. After being converted into a frequency domain signal, it will interfere with the judgment and recognition of the target signal, thereby affecting the close-range performance of the FMCW laser radar.

[0004] In a first aspect, the present invention provides an FMCW laser radar device for actively suppressing low-frequency interference, the device comprising a laser modulation device and an FMCW coherent detection device, the laser modulation device comprising a multi-channel signal generator, a laser and an optical modulator, the multi-channel signal generator being connected to the laser and the optical modulator respectively;

[0005] A multi-channel signal generator is used to generate a first modulation signal and a second modulation signal, and output the first modulation signal to a laser, and output the second modulation signal to an optical modulator, wherein the first modulation signal is a periodic triangular wave modulation signal, and the second modulation signal is a periodic triangular wave modulation signal of the same frequency and inverse to the first modulation signal; a laser is used to generate an original laser signal, and continuously frequency modulate the original laser signal based on the first modulation signal to obtain an initial laser modulation signal containing amplitude modulation information, and output the initial laser modulation signal to the optical modulator; the optical modulator is used to suppress the power of the initial laser modulation signal using the second modulation signal under the control of the multi-channel signal generator and output a target laser modulation signal to an FMCW coherent detection device; the FMCW coherent detection device is used to detect a target object based on the target laser modulation signal to obtain a target detection distance.

[0006] The FMCW laser radar device for actively suppressing low-frequency interference provided by the present invention first generates a first modulation signal through a signal generator and continuously frequency modulates the original laser signal generated by the laser. Secondly, the power of the modulated initial laser modulation signal is suppressed by an optical modulator in combination with the second modulation signal, so that the power of the target laser modulation signal output by the optical modulator can be actively suppressed. Finally, the suppressed target laser modulation signal is input to the FMCW coherent detection device to complete the distance detection of the target object. Therefore, by implementing the present invention, while realizing continuous frequency modulation of the laser, it will not cause the amplitude change of the laser radar input power, thereby avoiding the introduction of low-frequency interference signals, suppressing the interference of low-frequency modulation on the actual target signal, and improving the laser radar's ability to recognize close-range targets.

[0007] In an optional implementation, the multi-channel signal generator is further configured to synchronously output a synchronization trigger signal to the FMCW coherent detection device when outputting the first modulation signal and the second modulation signal.

[0008] The FMCW laser radar device that actively suppresses low-frequency interference provided by the present invention, the multi-channel signal generator can also provide support for the subsequent FMCW coherent detection device to detect the target object by synchronously outputting a synchronization trigger signal to the FMCW coherent detection device while outputting a corresponding modulation signal.

[0009] In an optional implementation, the FMCW coherent detection device includes: an FMCW coherent detection module and a signal acquisition and calculation module;

[0010] The FMCW coherent detection module is used to detect the target object based on the target laser modulation signal and generate a mixed signal carrying the target detection distance information; the signal acquisition and calculation module is used to obtain the waveform data of the mixed signal based on the synchronization trigger signal, and calculate the target detection distance based on the waveform data.

[0011] The FMCW laser radar device for actively suppressing low-frequency interference provided by the present invention can generate a mixed signal carrying target detection distance information by detecting the target object using the modulated target modulation signal in the FMCW coherent detection module. At the same time, the signal acquisition and calculation module synchronously obtains the waveform data of the generated mixed signal according to the synchronous trigger signal and calculates the corresponding target detection distance. Therefore, by implementing the present invention, the detection accuracy of close-range targets is improved by detecting through the modulated target modulation signal.

[0012] In an optional embodiment, the optical modulator is a silicon-based MZM type electro-optic modulator.

[0013] In a second aspect, the present invention provides a frequency modulation method for actively suppressing low-frequency interference, which is used in a laser modulation device in an FMCW laser radar device for actively suppressing low-frequency interference according to the first aspect or any corresponding embodiment thereof; the method comprises:

[0014] A multi-channel signal generator is used to generate a first modulation signal and a second modulation signal, wherein the first modulation signal is a periodic triangular wave modulation signal, and the second modulation signal is a periodic triangular wave modulation signal of the same frequency but inversely proportional to the first modulation signal; the first modulation signal is used to perform continuous frequency modulation on an original laser signal of a laser to obtain an initial laser modulation signal containing amplitude modulation information; under the control of the multi-channel signal generator, an optical modulator is used to suppress the power of the initial laser modulation signal based on the second modulation signal to obtain a target laser modulation signal.

[0015] The frequency modulation method for actively suppressing low-frequency interference provided by the present invention suppresses the power of the modulated initial laser modulation signal through the optical modulator, so that the power of the target laser modulation signal output by the optical modulator can be actively suppressed. Furthermore, by implementing the present invention, while realizing continuous frequency modulation of the laser, it will not cause the amplitude change of the laser radar input power, thereby avoiding the introduction of low-frequency interference signals, suppressing the interference of low-frequency modulation on the actual target signal, and improving the laser radar's ability to recognize close-range targets.

[0016] In an optional implementation, under the control of the multi-channel signal generator, based on the second modulation signal, the optical modulator is used to suppress the power of the initial laser modulation signal to obtain the target laser modulation signal, including:

[0017] The output voltage amplitude of the second modulation signal is adjusted; under the control of the multi-channel signal generator, based on the adjusted second modulation signal, the optical modulator is used to suppress the power of the initial laser modulation signal to obtain the target laser modulation signal.

[0018] The frequency modulation method for actively suppressing low-frequency interference provided by the present invention can adjust the output voltage amplitude of the second modulation signal so that the initial laser modulation signal can output a target laser modulation signal with a stable output power amplitude after being processed by the optical modulator, thereby realizing active suppression of the power of the laser signal and providing support for the subsequent improvement of the laser radar's ability to recognize close-range targets.

[0019] In an optional embodiment, the method further includes: outputting the target laser modulation signal to the FMCW coherent detection device, so that the FMCW coherent detection device detects the target object based on the target laser modulation signal.

[0020] The frequency modulation method for actively suppressing low-frequency interference provided by the present invention improves the detection accuracy of close-range targets by inputting the modulated target laser modulation signal into the FMCW coherent detection device and completing the distance detection of the target object.

[0021] In a third aspect, the present invention provides a computer device, comprising: a memory and a processor, the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the frequency modulation method for actively suppressing low-frequency interference of the above-mentioned second aspect or any corresponding embodiment thereof by executing the computer instructions.

[0022] In a fourth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to enable a computer to execute the frequency modulation method for actively suppressing low-frequency interference according to the second aspect or any corresponding embodiment thereof.

[0023] In a fifth aspect, the present invention provides a computer program product, comprising computer instructions for causing a computer to execute the frequency modulation method for actively suppressing low-frequency interference according to the second aspect or any corresponding embodiment thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 is a structural block diagram of an FMCW laser radar device for actively suppressing low-frequency interference according to an embodiment of the present invention;

[0026] Figure 2 is a schematic diagram of the relationship between the driving current and the output power of the laser according to an embodiment of the present invention;

[0027] Figure 3 is a schematic diagram of an FMCW coherent detection module according to an embodiment of the present invention;

[0028] Figure 4 is a flow chart of a frequency modulation method for actively suppressing low-frequency interference according to an embodiment of the present invention;

[0029] Figure 5 is a flow chart of another frequency modulation method for actively suppressing low-frequency interference according to an embodiment of the present invention;

[0030] Figure 6 is a structural block diagram of an FMCW frequency modulated continuous wave laser radar device capable of integrating active low-frequency interference suppression according to an embodiment of the present invention;

[0031] Figure 7 is a schematic diagram of an integration solution based on a silicon photonic chip according to an embodiment of the present invention;

[0032] Figure 8 It is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0034] An embodiment of the present invention provides an FMCW laser radar device that actively suppresses low-frequency interference. The laser signal is actively suppressed by an optical modulator so as to achieve continuous frequency modulation of the laser without causing amplitude changes in the laser radar input power, thereby avoiding the introduction of low-frequency interference signals, suppressing the interference of low-frequency modulation on actual target signals, and improving the laser radar's ability to recognize close-range targets.

[0035] In this embodiment, a FMCW laser radar device that actively suppresses low-frequency interference is provided. Figure 1 As shown, the FMCW laser radar device 1 for actively suppressing low-frequency interference includes: a laser modulation device 11 and a FMCW coherent detection device 12.

[0036] The laser modulation device 11 includes: a multi-channel signal generator 111, a laser 112 and an optical modulator 113. Specifically, the multi-channel signal generator 111 is connected to the laser 112 and the optical modulator 113 respectively.

[0037] Furthermore, the FMCW coherent detection device 12 includes: an FMCW coherent detection module 121 and a signal acquisition and calculation module 122 .

[0038] Optionally, the multi-channel signal generator 111 is used to generate a first modulation signal and output the first modulation signal to a laser and a second modulation signal, and output the first modulation signal to a laser 112 , and output the second modulation signal to an optical modulator 113 .

[0039] The first modulation signal is a periodic triangular wave modulation signal, that is, a continuous signal with a specific periodicity, and its waveform is in a triangular shape.

[0040] Furthermore, the multi-channel signal generator 111 represents an electronic device capable of simultaneously generating multiple independent electrical signal output channels of different types.

[0041] Specifically, the corresponding periodic triangle wave modulation signal, namely the first modulation signal, can be generated through channel 1 in the multi-channel signal generator 111. Further, the periodic triangle wave modulation signal with the same frequency and anti-phase as channel 1, namely the second modulation signal, can be generated through channel 2.

[0042] Further, the multi-channel signal generator 111 outputs the generated first modulation signal and sends it to the laser 112 , and at the same time, outputs the generated second modulation signal and sends it to the optical modulator 113 .

[0043] Optionally, the laser 112 is used to generate an original laser signal, and continuously frequency modulate the original laser signal based on the first modulation signal to obtain an initial laser modulation signal containing amplitude modulation information, and output the initial laser modulation signal to the optical modulator 113 .

[0044] Specifically, the laser 112 requires a stable DC drive (power supply) signal and a relatively small continuous AC signal for frequency modulation, which is provided by a signal generator; Figure 2 As shown, if the laser DC drive current is set at 450mA, the laser output power will be stabilized at 90mW (frequency is f0). At this time, a modulation current of Vpp=100mA (±50mA) is applied, and the total drive current of the laser will continuously change between 400 and 500mA, causing the laser output frequency to continuously change in a certain range (f0±D). At the same time, the output power also fluctuates continuously in a certain range (such as 90±10mW).

[0045] Therefore, the DC driving output of the laser 112 is the original laser signal generated.

[0046] Furthermore, the laser 112 generates continuous frequency modulation under the drive of the modulation signal, that is, after the original laser signal is subjected to continuous frequency modulation, an initial laser modulation signal containing amplitude modulation information can be output. Continuous frequency modulation can include both frequency modulation and amplitude modulation.

[0047] Finally, the laser 112 outputs the modulated initial laser modulation signal containing amplitude modulation information and sends it to the optical modulator 113 .

[0048] Optionally, the optical modulator 113 is used to suppress the power of the initial laser modulation signal using the second modulation signal and output the target laser modulation signal to the FMCW coherent detection device 12 under the control of the multi-channel signal generator 111 .

[0049] The optical modulator 113 represents a device for modulating an optical signal, and can modulate an optical signal by changing certain properties of light, such as light intensity, phase, frequency, polarization, etc. It is usually based on physical principles such as electro-optic effect, acousto-optic effect, magneto-optic effect, etc. For example, in an electro-optic modulator, an electric field is applied to change the refractive index of a material, thereby changing the propagation characteristics of light in the material, thereby modulating the light.

[0050] Specifically, under the drive control of the multi-channel signal generator 111, the optical modulator 113 can combine with the second modulation signal output by the multi-channel signal generator 111 to suppress the power fluctuation of the initial laser modulation signal output by the laser and output the target laser modulation signal with stable power to the FMCW coherent detection device 12. Through the processing of the optical modulator 113, active suppression of the laser signal is achieved.

[0051] In an optional implementation, the optical modulator 113 is a silicon-based MZM electro-optic modulator.

[0052] Specifically, the silicon-based MZM (Mach-Zehnder Modulator) type electro-optical modulator represents an important optoelectronic device based on silicon-based materials, which is mainly composed of a Mach-Zehnder interferometer structure consisting of two arms (usually called the upper arm and the lower arm) and input and output waveguides. Its working principle is: when the input optical signal enters the modulator, it is divided into two parts and enters the upper arm and the lower arm respectively. When no electric field is applied, the optical path difference between the two arms is zero, and the optical signals interfere constructively at the output end, outputting a stronger optical signal; when an electric field is applied through the electrode, due to the electro-optical effect of the silicon-based material, the refractive index of the two arms changes, resulting in a change in the optical path difference. By adjusting the intensity of the electric field, the interference state of the optical signal at the output end can be controlled to achieve modulation of the optical signal.

[0053] Optionally, the FMCW coherent detection device 12 is used to detect the target object based on the target laser modulation signal to obtain the target detection distance.

[0054] Among them, the FMCW (Frequency Modulated Continuous Wave) coherent detection device 12 is an advanced optical detection technology device that can achieve high-precision distance measurement and speed measurement. Furthermore, the distance measurement principle of the FMCW technology is to send and receive continuous laser beams, use mixing detection to measure the frequency difference between the two, and then calculate the distance of the target object.

[0055] First, the target object is detected using the target laser modulation signal in the FMCW coherent detection module 121 and a mixed signal carrying target detection distance information is generated.

[0056] Specifically, after receiving the target laser modulation signal, Figure 3 As shown, the target laser modulation signal is divided into two parts in the FMCW coherent detection module 121, one part is used as the local oscillator light, and the other part is used as the outgoing light. The outgoing light irradiates the object to generate reflected light and returns to the coherent detection module. The returned light and the local oscillator light meet and interfere with each other inside the coherent detection module to generate a mixed signal carrying the target distance information.

[0057] Secondly, in the signal acquisition and calculation module 122, the waveform data of the mixed signal is acquired based on the synchronous trigger signal, and the target detection distance is calculated based on the waveform data.

[0058] The synchronous trigger signal is synchronously output to the signal acquisition and calculation module 122 when the multi-channel signal generator 111 outputs the first modulation signal and the second modulation signal.

[0059] Specifically, when the FMCW coherent detection module 121 generates a mixing signal using a target laser modulation signal, the signal acquisition and calculation module 122 synchronously acquires waveform data of the generated mixing signal under the drive of a synchronous trigger signal.

[0060] Furthermore, in the signal acquisition and calculation module 122, the target frequency is demodulated by a frequency demodulation algorithm such as Fourier transform according to the obtained waveform data of the mixed signal, and the corresponding target detection distance is obtained by conversion.

[0061] The FMCW laser radar device that actively suppresses low-frequency interference provided in this embodiment first generates a first modulation signal through a signal generator and continuously frequency modulates the original laser signal generated by the laser. Secondly, the power of the modulated initial laser modulation signal is suppressed by an optical modulator in combination with the second modulation signal, so that the power of the target laser modulation signal output by the optical modulator can be actively suppressed. Finally, the suppressed target laser modulation signal is input to the FMCW coherent detection device to complete the distance detection of the target object. Therefore, by implementing the present invention, while realizing continuous frequency modulation of the laser, it will not cause the amplitude change of the laser radar input power, thereby avoiding the introduction of low-frequency interference signals, suppressing the interference of low-frequency modulation on the actual target signal, and improving the laser radar's ability to recognize close-range targets.

[0062] According to an embodiment of the present invention, an embodiment of a frequency modulation method for actively suppressing low-frequency interference is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0063] In this embodiment, a frequency modulation method for actively suppressing low-frequency interference is provided, which can be used for the laser modulation device 11 in the FMCW laser radar device 1 for actively suppressing low-frequency interference provided in the above embodiment of the present invention. Figure 4 is a flow chart of a frequency modulation method for actively suppressing low frequency interference according to an embodiment of the present invention. Figure 4 As shown, the process includes the following steps:

[0064] Step S401: Generate a first modulation signal and a second modulation signal using a multi-channel signal generator.

[0065] The first modulation signal is a periodic triangular wave modulation signal, and the second modulation signal is a periodic triangular wave modulation signal of the same frequency and in antiphase with the first modulation signal.

[0066] The specific process may refer to the functional description of the multi-channel signal generator 111 in the laser modulation device 11 in the above embodiment, which will not be repeated here.

[0067] Step S402: Continuously frequency modulate the original laser signal of the laser using the first modulation signal to obtain an initial laser modulation signal containing amplitude modulation information.

[0068] First, the voltage amplitude of the modulation signal and the modulation efficiency of the laser are obtained.

[0069] Specifically, the voltage amplitude of the modulation signal can determine the degree of modulation of the laser 112: when the voltage amplitude of the modulation signal is small, the modulation effect on the laser 112 is relatively weak. This may cause the optical signal output by the laser to change inconspicuously and carry limited information. For example, in optical communication, the data rate of transmission may be reduced, affecting communication efficiency.

[0070] Furthermore, the modulation efficiency of the laser 112 can reflect the responsiveness of the laser 112 to the modulation signal: high modulation efficiency means that the laser 112 can more effectively convert the modulation signal into the change of the optical signal. This can improve the performance of the optical communication system and reduce energy consumption. For example, under the same modulation signal input, a laser with high modulation efficiency can output a stronger modulated optical signal, thereby improving the transmission distance and quality of the signal.

[0071] Furthermore, the modulation efficiency of the laser 112 can be obtained by measuring the relationship between the input electrical signal and the output optical signal, or can be estimated based on the specification parameters of the laser.

[0072] Secondly, generally speaking, a higher voltage amplitude can achieve a wider modulation range. This is because a larger voltage change can cause a greater change in the laser output characteristics, thereby expanding the modulatable frequency range. For example, when the voltage amplitude increases, it may cause more significant changes in the laser output light intensity, frequency or phase parameters, thereby widening the modulation bandwidth.

[0073] Further, according to the description of step S6021, high modulation efficiency means that the laser can respond to the modulation signal more effectively and convert the electrical signal into the change of the optical signal. If the modulation efficiency is high, a wider modulation bandwidth may be achieved even at a lower voltage amplitude. On the contrary, low modulation efficiency may limit the modulation bandwidth, and it is difficult to obtain a larger modulation range even with a higher voltage amplitude.

[0074] Therefore, the modulation bandwidth can be calculated based on the obtained voltage amplitude and modulation efficiency data combined with theoretical models or empirical formulas.

[0075] Finally, based on the obtained modulation bandwidth, the first modulation signal is used to control the change of the laser driving current to generate continuous frequency modulation and output an initial laser modulation signal containing amplitude modulation information. The specific control process can refer to the description of the interaction process between the multi-channel signal generator 111 and the laser 112 in the laser modulation device 11 in the above embodiment, as well as the functional description of the laser 112, which will not be repeated here.

[0076] Step S403: Under the control of the multi-channel signal generator, based on the second modulation signal, the optical modulator is used to suppress the power of the initial laser modulation signal to obtain a target laser modulation signal.

[0077] The specific process can refer to the description of the interaction process between the multi-channel signal generator 111 and the optical modulator 113 in the laser modulation device 11 and the functional description of the optical modulator 113 in the above embodiment, which will not be repeated here.

[0078] The frequency modulation method for actively suppressing low-frequency interference provided in this embodiment suppresses the power of the modulated initial laser modulation signal by the optical modulator, so that the power of the target laser modulation signal output by the optical modulator can be actively suppressed. Furthermore, by implementing the present invention, while realizing continuous frequency modulation of the laser, it will not cause the amplitude change of the laser radar input power, thereby avoiding the introduction of low-frequency interference signals, suppressing the interference of low-frequency modulation on the actual target signal, and improving the laser radar's ability to recognize close-range targets.

[0079] In this embodiment, a frequency modulation method for actively suppressing low-frequency interference is provided, which can be used for the laser modulation device 11 in the FMCW laser radar device 1 for actively suppressing low-frequency interference provided in the above embodiment of the present invention. Figure 5 is a flow chart of a frequency modulation method for actively suppressing low frequency interference according to an embodiment of the present invention. Figure 5 As shown, the process includes the following steps:

[0080] Step S501: Generate a first modulation signal and a second modulation signal using a multi-channel signal generator. Figure 4 Step S401 of the illustrated embodiment will not be described in detail here.

[0081] Step S502: Continuously frequency modulate the original laser signal of the laser using the first modulation signal to obtain an initial laser modulation signal containing amplitude modulation information. Figure 4 Step S402 of the illustrated embodiment will not be described in detail here.

[0082] Step S503: Under the control of the multi-channel signal generator, based on the second modulation signal, the optical modulator is used to suppress the power of the initial laser modulation signal to obtain a target laser modulation signal.

[0083] Specifically, the above step S503 includes:

[0084] Step S5031, adjusting the output voltage amplitude of the second modulation signal.

[0085] Specifically, the output voltage amplitude of the second modulation signal may be adjusted by a knob or button for adjusting the output signal amplitude on a control panel of the multi-channel signal generator 111 , or may be adjusted by computer software or an external circuit.

[0086] Step S5032: Under the control of the multi-channel signal generator, based on the adjusted second modulation signal, the optical modulator is used to suppress the power of the initial laser modulation signal to obtain a target laser modulation signal.

[0087] Specifically, under the control of the multi-channel signal generator 111, the adjusted second modulation signal output by the multi-channel signal generator 111 is used to suppress and adjust the power fluctuation of the initial laser modulation signal in the optical modulator 113 and output a corresponding power-stable target laser modulation signal, thereby achieving active suppression of the laser signal.

[0088] Step S504: output the target laser modulation signal to the FMCW coherent detection device, so that the FMCW coherent detection device detects the target object based on the target laser modulation signal.

[0089] The specific process can refer to the description of the interaction process between the optical modulator 113 in the laser modulation device 11 and the FMCW coherent detection device 12 in the above embodiment, as well as the functional description of the FMCW coherent detection device 12, which will not be repeated here.

[0090] The frequency modulation method for actively suppressing low-frequency interference provided in this embodiment can make the initial laser modulation signal output a target laser modulation signal with a stable output power amplitude after being processed by the optical modulator by adjusting the output voltage amplitude of the second modulation signal, thereby realizing active suppression of the power of the laser signal. Therefore, by implementing the present invention, while realizing continuous frequency modulation of the laser, it will not cause the amplitude change of the laser radar input power, thereby avoiding the introduction of low-frequency interference signals, suppressing the interference of low-frequency modulation on the actual target signal, and improving the laser radar's ability to recognize close-range targets.

[0091] In one embodiment, a FMCW laser radar device capable of integrating active suppression of low-frequency interference is provided, such as Figure 6 As shown, it includes a multi-channel signal generator, a laser, an optical modulator, a FMCW coherent detection module and a signal acquisition and calculation module.

[0092] Specifically, the multi-channel signal generator is used to provide modulation waveforms to the laser and the optical modulator respectively, and to provide a synchronous trigger signal to the signal acquisition and calculation module.

[0093] Furthermore, the laser generates continuous frequency modulation when driven by the modulation signal, and at the same time carries amplitude modulation information to be input into the optical modulator.

[0094] Furthermore, the optical modulator, driven by the signal generator, synchronously suppresses input power fluctuations, so that the optical power emitted from the optical modulator remains stable.

[0095] Furthermore, the laser emitted from the optical modulator is connected to the FMCW coherent detection module, and the signal acquisition and calculation module synchronously collects the signal waveform through the trigger signal, calculates and completes the detection of the target object in real time.

[0096] The FMCW frequency-modulated continuous wave laser radar device for actively suppressing low-frequency interference provided in this example can achieve continuous frequency modulation of the laser without causing amplitude changes in the laser radar input power, thereby avoiding the introduction of low-frequency interference signals, suppressing the interference of low-frequency modulation on the actual target signal, and improving the laser radar's ability to recognize close-range targets.

[0097] In an optional embodiment, an integrated solution based on silicon photonic chips is provided, such as Figure 7 As shown, the semiconductor DFB laser is integrated on a silicon photonic chip, and the light is transmitted to the silicon-based MZM modulator through a silicon optical waveguide. Channel 1 of the multi-channel signal generator provides a periodic triangle wave modulation signal of 100kHz, which controls the change of the laser drive current to produce continuous frequency modulation. The modulation bandwidth is determined by the modulation signal voltage amplitude V1 and the laser modulation efficiency. Frequency modulation also causes the laser output power to produce 100kHz amplitude modulation.

[0098] Furthermore, the bias voltage Vbias of the silicon-based MZM (Mach-Zehnder) intensity modulator is adjusted to operate in the linear working area. Channel 2 of the multi-channel signal generator synchronously outputs a periodic triangle wave modulation signal of the same frequency that is inversely proportional to channel 1, and the output voltage amplitude V2 of the channel 2 signal is adjusted to stabilize the power channel amplitude output by the laser after passing through the MZM optical modulator at a constant value. Subsequently, the laser with stable power is connected to the silicon photonic FMCW coherent detection loop. The signal acquisition and calculation module synchronously collects the time domain waveform of the mixed signal inside the FMCW coherent detection module under the 100kHz square wave trigger signal output by channel 3 of the signal generator, and solves it through FFT calculation to obtain information such as the distance and speed corresponding to the detected target.

[0099] Specifically, ideally, for a general FMCW coherent detection module, its optical path mixing signal is converted into an electrical signal by the detector and contains both DC and AC components, wherein the DC component carries the amplitude information of the laser input light, and the AC component contains information such as the distance of the detection target. In fact, due to the power change caused by frequency modulation, the DC component here often carries a low-frequency AC signal with the same frequency as the frequency modulated signal. Mathematically, the triangular wave can be regarded as the superposition of a series of sine and cosine signals of different frequencies, f(x) = 2A / π*(sin(x)+1 / 3sin(3x)+1 / 5sin(5x)+…).

[0100] Furthermore, after FFT transformation, a series of low-frequency interference signal peaks will be generated in the low-frequency region of the spectrum. For the detection target, its signal frequency is proportional to the distance. For long-distance detection targets, its spectrum signal peak is far away from the low-frequency region, and the signal peak search is almost unaffected; while for close-range detection targets, its spectrum signal peak will overlap with the low-frequency interference peak, making it impossible to accurately judge, and even causing the detection target signal to be lost, thus affecting the close-range performance of the FMCW lidar.

[0101] Therefore, the laser power input to the FMCW coherent detection module is actively adjusted through optical modulation to keep it constant, and the FFT spectrum only contains the reflected signal peak of the detection target, so that the low-frequency interference signal caused by the laser power fluctuation can be actively suppressed.

[0102] The embodiment of the present invention also provides a computer device for executing the above Figures 4 to 5 The laser frequency modulation method for actively suppressing low-frequency interference is shown.

[0103] See also Figure 8 , Figure 8 is a schematic diagram of the structure of a computer device provided by an optional embodiment of the present invention, such as Figure 8 As shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components are connected to each other using different buses for communication, and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 8 A processor 10 is taken as an example.

[0104] The processor 10 may be a central processing unit, a network processor or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be a dedicated integrated circuit, a programmable logic device or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic or any combination thereof.

[0105] The memory 20 stores instructions executable by at least one processor 10, so that at least one processor 10 executes the method shown in the above embodiment.

[0106] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created according to the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely arranged relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0107] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid state drive; the memory 20 may also include a combination of the above types of memory.

[0108] The computer device further comprises a communication interface 30 for the computer device to communicate with other devices or a communication network.

[0109] The embodiment of the present invention also provides a computer-readable storage medium. The method according to the embodiment of the present invention can be implemented in hardware, firmware, or can be implemented as a computer code that can be recorded in a storage medium, or can be implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and will be stored in a local storage medium through a network download, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state hard disk, etc.; further, the storage medium can also include a combination of the above types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor, or hardware, the method shown in the above embodiment is implemented.

[0110] A part of the present invention may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present invention through the operation of the computer. Those skilled in the art should understand that the existence of the computer program instruction in a computer-readable medium includes, but is not limited to, a source file, an executable file, an installation package file, etc., and accordingly, the way in which the computer program instruction is executed by the computer includes, but is not limited to: the computer directly executes the instruction, or the computer compiles the instruction and then executes the corresponding compiled program, or the computer reads and executes the instruction, or the computer reads and installs the instruction and then executes the corresponding installed program. Here, the computer-readable medium may be any available computer-readable storage medium or communication medium accessible to the computer.

[0111] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A FMCW laser radar device that actively suppresses low-frequency interference, characterized in that: The device comprises: a laser modulation device and a FMCW coherent detection device, wherein the laser modulation device comprises a multi-channel signal generator, a laser and an optical modulator, and the multi-channel signal generator is connected to the laser and the optical modulator respectively; The multi-channel signal generator is used to generate a first modulation signal and a second modulation signal, and output the first modulation signal to the laser, and output the second modulation signal to the optical modulator, the first modulation signal is a periodic triangular wave modulation signal, and the second modulation signal is a periodic triangular wave modulation signal of the same frequency and inversely proportional to the first modulation signal; The laser is used to generate an original laser signal, and to continuously frequency modulate the original laser signal based on the first modulation signal to obtain an initial laser modulation signal containing amplitude modulation information, and to output the initial laser modulation signal to the optical modulator; The optical modulator is used to suppress the power of the initial laser modulation signal by using the second modulation signal and output a target laser modulation signal to the FMCW coherent detection device under the control of the multi-channel signal generator; The FMCW coherent detection device is used to detect the target object based on the target laser modulation signal to obtain the target detection distance.

2. The device according to claim 1, characterized in that The multi-channel signal generator is further used to synchronously output a synchronization trigger signal to the FMCW coherent detection device when outputting the first modulation signal and the second modulation signal.

3. The device according to claim 2, characterized in that The FMCW coherent detection device comprises: an FMCW coherent detection module and a signal acquisition and calculation module; The FMCW coherent detection module is used to detect the target object based on the target laser modulation signal and generate a mixed signal carrying target detection distance information; The signal acquisition and calculation module is used to obtain the waveform data of the mixed signal based on the synchronous trigger signal, and calculate the target detection distance based on the waveform data.

4. The device according to claim 1, characterized in that The optical modulator is a silicon-based MZM electro-optical modulator.

5. A frequency modulation method for actively suppressing low-frequency interference, characterized in that: A laser modulation device in a FMCW laser radar device for actively suppressing low-frequency interference as claimed in any one of claims 1 to 4; the method comprising: Generate a first modulation signal and a second modulation signal by using a multi-channel signal generator, wherein the first modulation signal is a periodic triangular wave modulation signal, and the second modulation signal is a periodic triangular wave modulation signal of the same frequency and inversely proportional to the first modulation signal; Continuously frequency modulating an original laser signal of a laser using the first modulation signal to obtain an initial laser modulation signal containing amplitude modulation information; Under the control of the multi-channel signal generator, based on the second modulation signal, the optical modulator is used to suppress the power of the initial laser modulation signal to obtain a target laser modulation signal.

6. The method according to claim 5, characterized in that Under the control of the multi-channel signal generator, based on the second modulation signal, the initial laser modulation signal is power-suppressed by using an optical modulator to obtain a target laser modulation signal, including: adjusting the output voltage amplitude of the second modulation signal; Under the control of the multi-channel signal generator, based on the adjusted second modulation signal, the optical modulator is used to suppress the power of the initial laser modulation signal to obtain the target laser modulation signal.

7. The method according to claim 5, characterized in that The method further comprises: The target laser modulation signal is output to a FMCW coherent detection device, so that the FMCW coherent detection device detects the target object based on the target laser modulation signal.

8. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the frequency modulation method for actively suppressing low-frequency interference as described in any one of claims 5 to 7 by executing the computer instructions.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the frequency modulation method for actively suppressing low-frequency interference according to any one of claims 5 to 7.

10. A computer program product, characterized in that The method comprises computer instructions, wherein the computer instructions are used to cause a computer to execute the frequency modulation method for actively suppressing low-frequency interference according to any one of claims 5 to 7.

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