CN118311588A - Laser detection method and device, terminal equipment and storage medium - Google Patents
Laser detection method and device, terminal equipment and storage medium Download PDFInfo
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Abstract
The application belongs to the technical field of FMCW laser radar, and provides a laser detection method, a device, terminal equipment and a storage medium; the method comprises the following steps: acquiring the signal-to-noise ratio of an ith difference frequency signal at the ith timestamp moment of each modulation period; wherein i=1, 2, …, n, n is a positive integer, and the i-th difference frequency signal is obtained based on coherent mixing of the i-th local oscillation signal and an echo signal reflected by a target object; and if the signal-to-noise ratio of the ith difference frequency signal is smaller than the corresponding ith signal-to-noise ratio threshold, increasing the transmitting power of the laser from the ith transmitting power to the (i+1) th transmitting power. According to the application, the signal-to-noise ratio of the difference frequency signal is obtained at each time stamp moment of each modulation period, and when the signal-to-noise ratio of the difference frequency signal is smaller than the corresponding signal-to-noise ratio threshold, the transmitting power of the laser is increased, so that the transmitting power of the FMCW laser radar can be flexibly adjusted, and the detection performance of the FMCW laser radar is improved.
Description
Technical Field
The application belongs to the technical field of frequency modulation continuous wave (Frequency Modulated Continuous Wave, FMCW) laser radar (LASER RADAR, LIDAR), and particularly relates to a laser detection method, a device, terminal equipment and a storage medium.
Background
The working principle of the FMCW laser radar is that the optical transmitting module generates a detection signal and a local oscillation signal, the detection signal is emitted to a target object and reflected by the target object to form an echo signal, the echo signal is received by the optical receiving module and is interfered and mixed with the local oscillation signal to obtain a difference frequency signal, and the difference frequency signal is processed to obtain the related information such as the speed, the distance, the reflectivity and the like of the target object. The transmitting power of the FMCW laser radar is an important factor affecting the detection performance of the FMCW laser radar, if the transmitting power is too large, the difference frequency signal is easy to saturate in a short-range detection scene, the difference frequency signal is topped off, the center frequency of the difference frequency signal is calculated erroneously, and if the transmitting power is too small, in a long-range detection scene, the detection error is larger due to smaller signal-to-noise ratio.
Disclosure of Invention
The embodiment of the application provides a laser detection method, a device, terminal equipment and a storage medium, which can flexibly adjust the transmitting power of an FMCW laser radar so as to improve the detection performance of the FMCW laser radar.
A first aspect of an embodiment of the present application provides a laser detection method, including:
Acquiring the signal-to-noise ratio of an ith difference frequency signal at the ith timestamp moment of each modulation period; wherein i=1, 2, …, n, n is a positive integer, and the i-th difference frequency signal is obtained based on coherent mixing of the i-th local oscillation signal and an echo signal reflected by a target object;
and if the signal-to-noise ratio of the ith difference frequency signal is smaller than the corresponding ith signal-to-noise ratio threshold, increasing the transmitting power of the laser from the ith transmitting power to the (i+1) th transmitting power.
A second aspect of an embodiment of the present application provides a laser detection apparatus, including:
The signal-to-noise ratio acquisition unit is used for acquiring the signal-to-noise ratio of the ith difference frequency signal at the ith timestamp moment of each modulation period; wherein i=1, 2, …, n, n is a positive integer, and the i-th difference frequency signal is obtained based on coherent mixing of the i-th local oscillation signal and an echo signal reflected by a target object;
And the transmitting power adjusting unit is used for increasing the transmitting power of the laser from the ith transmitting power to the (i+1) th transmitting power if the signal-to-noise ratio of the ith difference frequency signal is smaller than the corresponding ith signal-to-noise ratio threshold.
A third aspect of the embodiments of the present application provides a terminal device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, the processor implementing the steps of the laser detection method provided in the first aspect of the embodiments of the present application when the computer program is executed by the processor.
A fourth aspect of the embodiments of the present application provides a computer readable storage medium storing a computer program which, when executed by a processor, implements the steps of the laser detection method provided in the first aspect of the embodiments of the present application.
According to the laser detection method provided by the first aspect of the embodiment of the application, the signal-to-noise ratio of the difference frequency signal is obtained at each time stamp moment of each modulation period, and when the signal-to-noise ratio of the difference frequency signal is smaller than the corresponding signal-to-noise ratio threshold, the transmitting power of the laser is increased, so that the transmitting power of the FMCW laser radar can be flexibly adjusted, and the detection performance of the FMCW laser radar is improved.
It will be appreciated that the advantages of the second to fourth aspects may be found in the relevant description of the first aspect and are not repeated here.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments or the description of the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of an FMCW lidar according to an embodiment of the present application;
fig. 2 is a schematic flow chart of a first laser detection method according to an embodiment of the present application;
FIG. 3 is a schematic diagram of a second flow chart of a laser detection method according to an embodiment of the present application;
fig. 4 is a schematic diagram of a third flow chart of a laser detection method according to an embodiment of the present application;
fig. 5 is a fourth flowchart of a laser detection method according to an embodiment of the present application;
Fig. 6 is a fifth flowchart of a laser detection method according to an embodiment of the present application;
fig. 7 is a schematic structural diagram of a laser detection device according to an embodiment of the present application.
Detailed Description
In order that those skilled in the art will better understand the present application, a technical solution of an embodiment of the present application will be clearly described below with reference to the accompanying drawings in the embodiment of the present application, and it is apparent that the described embodiment is a part of the embodiment of the present application, but not all the embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, shall fall within the scope of the present application.
The term "comprising" in the description of the application and the claims and in the above figures and any variants thereof is intended to cover a non-exclusive inclusion. For example, a process, method, or system, article, or apparatus that comprises a list of steps or elements is not limited to only those listed but may optionally include additional steps or elements not listed or inherent to such process, method, article, or apparatus. Furthermore, the terms "first," "second," and "third," etc. are used for distinguishing between different objects and not for describing a particular sequential order.
The embodiment of the application provides a laser detection method, which can be executed by a processor of terminal equipment when a computer program with corresponding functions is run, the signal-to-noise ratio of a difference frequency signal is obtained at each time stamp moment of each modulation period, and when the signal-to-noise ratio of the difference frequency signal is smaller than a corresponding signal-to-noise ratio threshold value, the transmitting power of a laser is increased, so that the transmitting power of an FMCW laser radar can be flexibly adjusted, and the detection performance of the FMCW laser radar is improved.
In application, the FMCW laser radar provided by the embodiment of the application has the functions of quick, efficient and accurate ranging, speed measuring, object surface profile, texture, depth detection, object type identification and the like, and can be applied to the fields of intelligent transportation, aerospace, resource exploration, city planning, agricultural development, hydraulic engineering, land utilization, environment monitoring, metallurgical manufacturing, textile manufacturing and the like, for example, unmanned vehicles, unmanned planes, robots, positioning systems, navigation systems, loading and unloading and carrying equipment, metallurgical process control equipment, non-contact measuring equipment and the like.
In application, the terminal device may be an FMCW lidar or a signal processing device in an FMCW lidar. The FMCW laser radar can comprise a laser, a laser emitting component, a laser receiving component and signal processing equipment, and can also comprise an optical amplifier, a power supply module, a communication module and the like; the laser emitting component may include an optical beam splitter (or optical multiplexer, optical circulator), an optical collimator, a scanning system, etc., and the laser receiving component may include an optical beam combiner (or optical circulator), a photoelectric detection module, an interferometer, etc. The FMCW lidar may be a rotary mirror lidar, a galvanometer lidar, an Optical phased array (Optical PHASED ARRAYS, OPA) lidar, a solid-state lidar, etc., and the specific type of the FMCW laser device in the embodiment of the present application is not limited.
In application, the laser may be implemented by any laser capable of emitting a linearly swept optical signal in a linearly frequency modulated mode, such as a semiconductor laser, e.g., a distributed Bragg reflector (Distributed Bragg Reflector, DBR) laser, a distributed feedback (Distributed Feedback Laser, DFB) laser, etc.
In application, the optical beam splitter may be any device capable of splitting light to split signals emitted by the laser into corresponding local oscillation signals and detection signals according to a preset splitting ratio. For example, the optical beam splitter may be an optical coupler, a beam splitter, or the like.
In application, the photoelectric detection module can be any device capable of receiving an echo signal formed by reflecting a local oscillation signal and a detection signal by a target object and outputting an electric signal related to the difference frequency signal obtained by coherence of the local oscillation signal and the detection signal, so that the signal processing equipment can obtain the frequency of the difference frequency signal according to the electric signal. For example, the photo-detection module may comprise a photo-detector; at this time, in the process of receiving the local oscillation signal and the echo signal, the photoelectric detector generates a difference frequency signal in a manner of coherence of the free space optical signal, and the photoelectric detector performs photoelectric conversion on the difference frequency signal, so as to obtain an electrical signal related to the difference frequency signal. For example, the photo-detection module may also include an optical mixer and balanced photo-detector (Balanced Photo Detector, BPD); at this time, the optical mixer is used for receiving the local oscillation signal and the echo signal, so that the local oscillation signal and the echo signal are mixed to generate a difference frequency signal, and the balanced photoelectric detector is used for carrying out balanced detection on the difference frequency signal, so as to obtain an electric signal related to the difference frequency signal.
In an application, the optical amplifier may be a fiber amplifier, such as an erbium doped fiber amplifier (Erbium Doped Fiber Application Amplifier, EDFA); the optical amplifier may be a semiconductor optical amplifier.
In application, the optocoupler may be implemented by an array of optical fibers or an array of planar optical waveguides (PLANAR LIGHTWAVE circuits, PLC).
In an application, the interferometer may be a Mach-Zehnder interferometer.
In applications, the signal processing device may include a gain-adjustable amplifying circuit, a filtering circuit, an Analog-to-Digital Converter (ADC), a transmit power feedback control circuit, a processor, a Time-to-Digital Convertor (TDC), a memory, etc., and the processor may also have a gain-adjustable signal amplifying function, a filtering function, an Analog-to-digital conversion function, a gain feedback control function, an internal memory space, etc. instead of the gain-adjustable amplifying circuit, the filtering circuit, the Analog-to-digital converter, the gain feedback control circuit, the memory, etc.
In application, the gain-adjustable amplification circuit may be an automatic gain control (Automatic Gain Control, AGC) circuit, in which the amplifier may be implemented by a Trans-impedance amplifier (Trans-IMPEDANCE AMPLIFIER, TIA).
In applications, the Processor may be a central processing unit (Central Processing Unit, CPU), but may also be other general purpose processors, digital signal processors (DIGITAL SIGNAL Processor, DSP), application SPECIFIC INTEGRATED Circuit (ASIC), field-Programmable gate array (Field-Programmable GATE ARRAY, FPGA) or other Programmable logic device, discrete gate or transistor logic device, discrete hardware components, or the like. The general purpose processor may be a microprocessor or any conventional processor or the like.
In applications, the memory may in some embodiments be an internal storage unit of the terminal device, such as a hard disk or a memory of the terminal device. The memory may in other embodiments also be an external storage device of the terminal device, for example a plug-in hard disk provided on the terminal device, a smart memory card (SMART MEDIA CARD, SMC), a Secure Digital (SD) card, a flash memory card (FLASH CARD) or the like. Further, the memory may also include both an internal storage unit of the terminal device and an external storage device. The memory is used to store an operating system, application programs, boot Loader (Boot Loader), data, other programs, etc., such as program code for a computer program. The memory may also be used to temporarily store data that has been output or is to be output.
In an application, the power module may include a power management device, a power interface, and the like.
In application, the Communication module may be configured as any device capable of directly or indirectly performing wired or wireless Communication with other devices according to actual needs, for example, the Communication module may provide a solution of Communication including a Communication interface (for example, universal serial bus interface (Universal Serial Bus, USB)), a wired local area network (Local Area Networks, LAN), a wireless local area network (Wireless Local Area Networks, WLAN) (for example, wi-Fi network), bluetooth, zigbee, mobile Communication network, global navigation satellite system (Global Navigation SATELLITE SYSTEM, GNSS), frequency modulation (Frequency Modulation, FM), near field wireless Communication technology (NEAR FIELD Communication, NFC), infrared technology (IR), and so on, which are applied to a network device. The communication module may include an antenna, which may have only one element, or may be an antenna array including a plurality of elements. The communication module can receive electromagnetic waves through the antenna, frequency-modulate and filter the electromagnetic wave signals, and send the processed signals to the processor. The communication module can also receive the signal to be transmitted from the processor, frequency modulate and amplify the signal, and convert the signal into electromagnetic waves through the antenna to radiate.
As shown in fig. 1, a schematic diagram of an FMCW lidar is exemplarily shown, which includes a laser 1, a laser emitting component 2, a laser receiving component 3, and a signal processing device 4, where the signal processing device 4 includes an amplifying and filtering circuit 41, an analog-to-digital converter 42, and a processor 43.
In application, the signal processing apparatus may include, but is not limited to, amplification and filtering circuits, analog-to-digital converters, and processors. It will be appreciated by those skilled in the art that fig. 1 is merely an example of a signal processing device and is not meant to be limiting, and may include more or fewer devices than shown, or may combine some devices, or different devices, e.g., may also include or be external to an input-output device, a network access device, etc. The input output devices may include cameras, audio acquisition/playback devices, display devices, keyboards, keys, etc. The network access device may include a communication module for communicating with other devices, so that a user may send control instructions to the FMCW lidar through the other devices to control (e.g., remotely control) an operation state of the FMCW lidar, so that the FMCW lidar may selectively perform various operations according to the control instructions of the user.
As shown in fig. 2, the laser detection method provided by the embodiment of the application includes the following steps S101 and S102:
step S101, acquiring the signal-to-noise ratio of an ith difference frequency signal at the ith timestamp moment of each modulation period, and entering step S102;
Step S102, if the signal-to-noise ratio of the ith difference frequency signal is greater than or equal to the corresponding ith signal-to-noise ratio threshold, increasing the emission power of the laser from the ith emission power to the (i+1) th emission power.
In the application, in the process of detecting a target object, a laser emits a detection signal to the target object in a detection interval according to a preset modulation period, modulation bandwidth, sampling frequency and 1st emission power, at the 1st timestamp time of the current modulation period, the signal to noise ratio of a 1st difference frequency signal is obtained by coherent mixing based on the local oscillation signal and an echo signal reflected by the target object, then whether the signal to noise ratio of the 1st difference frequency signal is smaller than a corresponding 1st signal to noise ratio threshold value is judged, if the 1st difference frequency signal is smaller than the corresponding 1st signal to noise ratio threshold value, the 1st emission power is too small, the detection performance of the FMCW laser radar is poor, and the 1st emission power needs to be increased to be 2 nd emission power; if the 1st difference frequency signal is larger than or equal to the corresponding 1st signal-to-noise ratio threshold, the 1st transmitting power is moderate, the detection performance of the FMCW laser radar is good, and the transmitting power of the laser is not required to be increased;
After increasing the 1 st transmitting power to the 2 nd transmitting power, the laser continuously transmits a detection signal to the target object with a preset modulation period, a preset modulation bandwidth, a preset sampling frequency and a preset 2 nd transmitting power, at the 2 nd timestamp time of the current modulation period, the signal to noise ratio of a 2 nd difference frequency signal obtained by coherent mixing based on the local oscillation signal and an echo signal reflected by the target object is obtained, then whether the signal to noise ratio of the 2 nd difference frequency signal is smaller than a corresponding 2 nd signal to noise ratio threshold value is judged, if the signal to noise ratio of the 2 nd difference frequency signal is smaller than the corresponding 2 nd signal to noise ratio threshold value, the 2 nd transmitting power is too small, the detection performance of the FMCW laser radar is poor, and the 2 nd transmitting power needs to be increased to the 3 rd transmitting power; if the 2 nd difference frequency signal is larger than or equal to the corresponding 2 nd signal-to-noise ratio threshold, the 2 nd transmitting power is moderate, the detection performance of the FMCW laser radar is good, and the transmitting power of the laser is not required to be increased;
……；
and the like, after the current modulation period is finished, entering the next modulation period, and continuing to detect the target object.
In application, the modulation period, the modulation bandwidth, the sampling frequency, each time stamp time, the detection interval and each transmitting power can be preset according to actual needs, for example, the modulation period can be 10us, the modulation bandwidth can be 2GB, the sampling frequency can be 250MHz, and the detection interval can be 0m-30m. The interval duration between any two adjacent time stamp instants is known and identical and is equal to the interval duration between the start instant of each modulation period and the 1 st time stamp instant. The time counting can be performed according to the sampling frequency to determine whether each time stamp time is reached, the inverse of the sampling frequency is the duration of each time stamp time, and since the interval duration between any two adjacent time stamp times is known, the sampling frequency of the interval between any two adjacent time stamp times is equal to the interval duration divided by the duration of each time stamp time, and whether each time stamp time is reached can be obtained by counting the sampling frequency.
In one embodiment, prior to step S101, comprising:
Dividing the detection interval into n+1 continuous sub-detection intervals;
determining a j-th transmitting power corresponding to a j-th sub-detecting interval; wherein j=1, 2, …, n+1;
Setting n time stamp moments of each modulation period according to the duration of each modulation period;
and determining an ith signal-to-noise ratio threshold corresponding to the upper limit value of the ith sub-detection interval.
In application, when the FMCW laser radar detects target objects at different distances in a detection interval by adopting the same transmission power, if the same transmission power is adopted, the difference frequency signal is saturated due to overlarge transmission power in a short-distance detection scene, the difference frequency signal is topped off, the center frequency of the difference frequency signal is calculated incorrectly, and in a long-distance detection scene, the signal to noise ratio is smaller due to overlarge transmission power, so that the detection error is larger. Therefore, the detection interval may be divided into n+1 consecutive sub-detection intervals, and then different transmission powers are set for each sub-detection interval, where the upper limit value of each sub-detection interval is positively correlated with the corresponding transmission power, that is, the upper limit value of the i+1th sub-detection interval is greater than the upper limit value of the i-th sub-detection interval, and the i+1th transmission power is greater than the i-th transmission power. For example, when the detection interval is set to 0m-30m, the detection interval may be divided into 3 consecutive sub-detection intervals of 0m-10m, 10m-20m and 20m-30m, and the 3 consecutive sub-detection intervals respectively correspond to P1, P2 and P3 and have total transmission power of 3; wherein P1 is less than P2 and less than P3.
In application, after the sub-detection interval is divided and the corresponding transmitting power is determined, each time stamp time can be set according to the duration of each modulation period, the number of time stamp times is equal to the number of sub-detection intervals minus 1, and because the interval duration between any two adjacent time stamp times is known and the same, the 1 st time stamp time of each modulation period=the start time+interval duration of each modulation period, the 2 nd time stamp time of each modulation period=the 1 st time stamp time+interval duration of each modulation period, … …, and so on, the nth time stamp time of each modulation period=the end time of each modulation period.
In application, because of the corresponding transmitting power of each sub-detection interval, when the FMCW laser radar adopts the corresponding transmitting power to detect the target object at the farthest distance of each sub-detection interval, the local oscillation signal and the echo signal reflected by the target object are coherently mixed to obtain the signal-to-noise ratio of the difference frequency signal to meet the requirement, therefore, after the sub-detection interval is divided and the corresponding transmitting power is determined, the signal-to-noise ratio of the difference frequency signal can be obtained based on the coherent mixing of the local oscillation signal and the echo signal reflected by the target object, and the signal-to-noise ratio threshold corresponding to the farthest distance (namely the upper limit value) of each sub-detection interval is determined.
As shown in fig. 3, in one embodiment, determining the j-th transmission power corresponding to the j-th sub-detection section includes the following steps S201 to S204:
step S201, a laser is controlled to emit a j-th test local oscillation signal and a j-th test detection signal to a test object positioned in a j-th sub detection section, and step S202 is entered;
Step S202, obtaining the signal-to-noise ratio of the j-th test difference frequency signal, and entering step S203 or S204;
step S203, if the signal-to-noise ratio of the jth test difference frequency signal is smaller than the corresponding signal-to-noise ratio threshold, increasing the transmitting power of the laser, and returning to the step S201;
And S204, if the signal-to-noise ratio of the j-th test difference frequency signal is greater than or equal to the corresponding signal-to-noise ratio threshold, acquiring the transmitting power of the laser to obtain the j-th transmitting power corresponding to the j-th sub-detection interval.
In application, the method for determining the transmitting power corresponding to each sub-detection interval specifically comprises the following steps:
Controlling a laser to emit a1 st test local oscillator signal and a1 st test detection signal to a test object positioned in a1 st sub detection interval;
Acquiring a signal-to-noise ratio of a1 st test difference frequency signal, wherein the 1 st test difference frequency signal is obtained by coherent mixing based on the 1 st test local oscillation signal and an echo signal reflected by a test object positioned in a1 st sub-detection interval;
If the signal-to-noise ratio of the 1 st test difference frequency signal is smaller than the corresponding signal-to-noise ratio threshold, the signal-to-noise ratio of the 1 st test difference frequency signal indicates that the transmitting power of the laser is smaller and the transmitting power of the laser needs to be increased;
controlling the laser to emit a1 st test local oscillator signal and a1 st test detection signal to a test object positioned in a1 st sub-detection interval with increased emission power;
acquiring the signal-to-noise ratio of the 1 st test difference frequency signal again, and if the signal-to-noise ratio of the 1 st test difference frequency signal is still smaller than the corresponding signal-to-noise ratio threshold, continuing to increase the transmitting power of the laser;
The method comprises the steps of circulating in this way until the signal-to-noise ratio of the 1 st test difference frequency signal is greater than or equal to the corresponding signal-to-noise ratio threshold;
If the signal-to-noise ratio of the 1 st test difference frequency signal is greater than or equal to the corresponding signal-to-noise ratio threshold, acquiring the transmitting power of the laser at the moment as the 1 st transmitting power corresponding to the 1 st sub-detection interval;
The principle of the determining method of the 1 st transmitting power corresponding to the 1 st sub-detection interval is the same as that of the transmitting power corresponding to the other sub-detection interval, and the description is omitted here.
As shown in fig. 4, in one embodiment, determining the ith signal-to-noise ratio threshold corresponding to the upper limit value of the ith sub-detection interval includes the following steps S301 and S302:
Step S301, controlling a laser to emit an ith test local oscillator signal and an ith test detection signal to a test object positioned at the upper limit value position of an ith sub detection interval at an ith emission power, and entering step S302;
step S302, obtaining the signal-to-noise ratio of the ith test difference frequency signal, and obtaining an ith signal-to-noise ratio threshold corresponding to the upper limit value of the ith sub-detection interval.
In application, the method for determining the signal-to-noise ratio threshold corresponding to the upper limit value of each sub-detection interval specifically comprises the following steps:
Controlling the laser to emit a1 st test local oscillation signal and a1 st test detection signal to a test object positioned at the upper limit value position of the 1 st sub-detection interval at the 1 st emission power;
Acquiring a signal-to-noise ratio of a 1 st test difference frequency signal, which is used as a 1 st signal-to-noise ratio threshold corresponding to the upper limit value of a 1 st sub-detection interval, wherein the 1 st test difference frequency signal is obtained by coherent mixing based on the 1 st test local oscillation signal and an echo signal reflected by a test object positioned in the 1 st sub-detection interval;
The principle of the determining method of the signal-to-noise ratio threshold corresponding to the upper limit value of the other sub-detection interval is the same as that of the 1 st signal-to-noise ratio threshold corresponding to the upper limit value of the 1 st sub-detection interval, and the details are not repeated here.
As shown in fig. 5, in one embodiment, step S101 includes the following steps S401 to S403:
Step S401, at the ith time stamp moment of each modulation period, acquiring the energy of an ith effective signal in an ith target frequency interval in an ith difference frequency signal, and entering step S402;
Step S402, obtaining the energy of an ith noise signal outside an ith target frequency interval in an ith difference frequency signal, and entering step S403;
Step S403, according to the energy of the i effective signal and the energy of the i noise signal, obtaining the signal-to-noise ratio of the i difference frequency signal.
In application, the difference frequency signal includes an effective signal and a noise signal, and the noise signal is a part of the difference frequency signal except for the effective signal, that is, the effective signal is subtracted from the difference frequency signal to obtain the noise signal. The frequency of the effective signal is in a preset target frequency interval, the target frequency interval is set according to the center frequency of the difference frequency signal, the target frequency interval comprises the center frequency of the difference frequency signal, the upper limit value of the target frequency interval is larger than or equal to the center frequency of the difference frequency signal, the lower limit value of the target frequency interval is smaller than or equal to the center frequency of the difference frequency signal, and the target frequency interval can only comprise the center frequency of the difference frequency signal.
In application, the difference frequency signal can be represented by using a Fourier series expansion method under the condition that the frequency of the difference frequency signal is known; then, extracting effective signals in a target frequency interval in the difference frequency signal by using a window function (e.g., hanning window); performing Fourier transform (Fourier Transform, FT) on the effective signal, taking the modulus value of the effective signal and squaring the modulus value to obtain the energy of the effective signal; similarly, a window function (e.g., hanning window) may be used to extract an effective signal in a target frequency interval in the difference frequency signal, or the difference frequency signal may be subtracted from the effective signal to obtain a noise signal; then, carrying out Fourier transform on the noise signal, taking the modulus value of the noise signal and squaring the modulus value to obtain the energy of the noise signal; and finally, calculating the energy ratio of the energy of the effective signal to the energy of the noise signal to obtain the signal-to-noise ratio of the difference frequency signal.
In one embodiment, step S401 includes:
performing Fourier transformation on an ith effective signal in an ith target frequency interval in the ith difference frequency signal to obtain a modulus value of the ith effective signal and squaring the modulus value to obtain energy of the ith effective signal;
step S402 includes:
Performing Fourier transform on an ith noise signal outside an ith target frequency interval in the ith difference frequency signal to obtain a modulus value of the ith noise signal and squaring the modulus value to obtain energy of the ith noise signal;
Step S403 includes:
and obtaining the ratio of the energy of the ith effective signal and the energy of the ith noise signal to obtain the signal-to-noise ratio of the ith difference frequency signal.
As shown in fig. 6, in one embodiment, step S101 is preceded by the following steps S001 and S002:
s001, before the ith timestamp moment of each modulation period, controlling a laser to emit an ith local oscillation signal and an ith detection signal at the ith emission power, and entering S002;
S002, carrying out analog-to-digital conversion on the ith difference frequency component in the ith mixed signal to obtain an ith difference frequency signal, and entering step S101.
In application, at the beginning time of each modulation period to the 1 st time stamp time, the laser is controlled to emit the 1 st local oscillation signal and the 1 st detection signal with the 1 st emission power, the laser receiving component carries out coherent mixing on the 1 st local oscillation signal and the echo signal reflected by the target object to obtain the 1 st mixed signal, the 1 st mixed signal is amplified and filtered by the amplifying and filtering circuit, the difference frequency component in the 1 st mixed signal after being amplified and filtered is subjected to analog-to-digital conversion by the analog-to-digital converter to obtain a difference frequency signal in the form of a digital signal, and finally the difference frequency signal is subjected to calculation processing by the processor to obtain the distance of the target object, and related information such as speed, surface profile, texture, depth and object type of the target object can be obtained based on the distance. The difference frequency signal acquisition principle from the 1 st time stamp time to the 2 nd time stamp time, from the 2 nd time stamp time to the 3 rd time stamp time, … … th time stamp time to the n-1 st time stamp time and from the starting time to the 1 st time stamp time of each modulation period is the same, and is not repeated here.
It should be understood that the sequence number of each step in the foregoing embodiment does not mean that the execution sequence of each process should be determined by the function and the internal logic, and should not limit the implementation process of the embodiment of the present application.
The embodiment of the application also provides a laser detection device which is used for executing the steps in the detection method embodiment. The laser detection device may be a virtual device (virtual appliance) in the terminal device, which is executed by a processor of the terminal device, or may be the terminal device itself.
As shown in fig. 7, a laser detection device 100 according to an embodiment of the present application includes:
A signal-to-noise ratio obtaining unit 101, configured to obtain a signal-to-noise ratio of an i-th difference frequency signal at an i-th timestamp time of each modulation period;
And the transmitting power adjusting unit 102 is configured to increase the transmitting power of the laser from the ith transmitting power to the (i+1) th transmitting power if the signal-to-noise ratio of the ith difference frequency signal is smaller than the corresponding ith signal-to-noise ratio threshold.
In one embodiment, the laser detection device further comprises:
the interval dividing unit is used for dividing the detection interval into n+1 continuous sub-detection intervals;
a transmission power determining unit, configured to determine a j-th transmission power corresponding to a j-th sub-detection interval;
A time stamp setting unit, configured to set n time stamp moments of each modulation period according to a duration of each modulation period;
and the signal-to-noise ratio threshold determining unit is used for determining an ith signal-to-noise ratio threshold corresponding to the upper limit value of the ith sub-detection interval.
In one embodiment, the laser detection device further comprises:
The laser transmitting unit is used for controlling the laser to transmit an ith local oscillation signal and an ith detection signal at an ith transmitting power before the ith timestamp moment of each modulation period;
The analog-to-digital conversion unit is used for carrying out analog-to-digital conversion on the ith difference frequency component in the ith mixed signal to obtain an ith difference frequency signal.
In one embodiment, the laser detection device further comprises:
The detection unit is used for acquiring the distance of the target object according to the ith difference frequency signal and acquiring the related information such as the speed, the surface profile, the texture, the depth, the object type and the like of the target object based on the distance of the target object.
It should be noted that, because the content of information interaction and execution process between the above devices/units is based on the same concept as the method embodiment of the present application, specific functions and technical effects thereof may be referred to in the method embodiment section, and will not be described herein.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-described division of the functional units is illustrated, and in practical application, the above-described functional allocation may be performed by different functional units according to needs, i.e. the internal structure of the device is divided into different functional units to perform all or part of the functions described above. The functional units in the embodiment may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit, where the integrated units may be implemented in a form of hardware or a form of a software functional unit. In addition, the specific names of the functional units are also only for distinguishing from each other, and are not used to limit the protection scope of the present application. The specific working process of the units in the above system may refer to the corresponding process in the foregoing method embodiment, which is not described herein again.
The embodiment of the application also provides a computer readable storage medium, wherein the computer readable storage medium stores a computer program, and the computer program realizes the steps of the laser detection method in the embodiment when being executed by a processor.
The embodiment of the application also provides a computer program product, which when run on a terminal device, causes the terminal device to execute the steps of the laser detection method of the above embodiment.
The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the present application may implement all or part of the flow of the method of the above-described embodiments, and may be implemented by a computer program to instruct related hardware, and the computer program may be stored in a computer readable storage medium, where the computer program, when executed by a processor, may implement the steps of each of the method embodiments described above. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, executable files or in some intermediate form, etc. The computer readable medium may include at least: any entity or device capable of carrying computer program code to a terminal device, a recording medium, a computer Memory, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), an electrical carrier signal, a telecommunications signal, and a software distribution medium. Such as a U-disk, removable hard disk, magnetic or optical disk, etc.
In the foregoing embodiments, the descriptions of the embodiments are emphasized, and in part, not described or illustrated in any particular embodiment, reference is made to the related descriptions of other embodiments.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
In the embodiments provided in the present application, it should be understood that the disclosed apparatus, terminal device and method may be implemented by other methods. For example, the above-described device, terminal device embodiments are merely illustrative, e.g., the partitioning of elements is merely a logical function partitioning, and there may be additional partitioning methods in actual implementation, e.g., more than two elements or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection via interfaces, devices or units, which may be in electrical, mechanical or other forms.
The above embodiments are only for illustrating the technical solution of the present application, and are not limiting; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application.
Claims (10)
1. A laser detection method, comprising:
Acquiring the signal-to-noise ratio of an ith difference frequency signal at the ith timestamp moment of each modulation period; wherein i=1, 2, …, n, n is a positive integer, and the i-th difference frequency signal is obtained based on coherent mixing of the i-th local oscillation signal and an echo signal reflected by a target object;
and if the signal-to-noise ratio of the ith difference frequency signal is smaller than the corresponding ith signal-to-noise ratio threshold, increasing the transmitting power of the laser from the ith transmitting power to the (i+1) th transmitting power.
2. The laser detection method as claimed in claim 1, wherein before the signal-to-noise ratio of the i-th difference signal is obtained at the i-th time stamp time of each modulation period, the method comprises:
Dividing the detection interval into n+1 continuous sub-detection intervals;
determining a j-th transmitting power corresponding to a j-th sub-detecting interval; wherein j=1, 2, …, n+1;
Setting n time stamp moments of each modulation period according to the duration of each modulation period;
and determining an ith signal-to-noise ratio threshold corresponding to the upper limit value of the ith sub-detection interval.
3. The laser detection method of claim 2, wherein the determining the j-th transmit power corresponding to the j-th sub-detection interval includes:
Controlling the laser to emit a j-th test local oscillation signal and a j-th test detection signal to a test object positioned in a j-th sub detection interval;
Acquiring the signal-to-noise ratio of a j-th test difference frequency signal; the j test difference frequency signal is obtained by coherent mixing based on the j test local oscillation signal and an echo signal reflected by a test object positioned in a j sub-detection interval;
If the signal-to-noise ratio of the j-th test difference frequency signal is smaller than the corresponding signal-to-noise ratio threshold, increasing the transmitting power of the laser, and returning to the step of controlling the laser to transmit the j-th test local oscillation signal and the j-th test detection signal;
And if the signal-to-noise ratio of the j-th test difference frequency signal is greater than or equal to the corresponding signal-to-noise ratio threshold, acquiring the transmitting power of the laser to obtain the j-th transmitting power corresponding to the j-th sub-detection interval.
4. The laser detection method according to claim 2, wherein determining an ith signal-to-noise ratio threshold corresponding to an upper limit value of an ith sub-detection interval includes:
Controlling the laser to emit an ith test local oscillation signal and an ith test detection signal to a test object positioned at the upper limit value position of an ith sub detection interval at an ith emission power; the ith test difference frequency signal is obtained by coherent mixing based on the ith test local oscillation signal and an echo signal reflected by a test object positioned at the upper limit value position of the ith sub-detection interval;
and acquiring the signal-to-noise ratio of the ith test difference frequency signal, and obtaining an ith signal-to-noise ratio threshold corresponding to the upper limit value of the ith sub-detection interval.
5. The laser detection method as claimed in claim 1, wherein the obtaining the signal-to-noise ratio of the i-th difference signal at the i-th time stamp time of each modulation period includes:
At the time of the ith time stamp of each modulation period, acquiring the energy of an ith effective signal in an ith target frequency interval in an ith difference frequency signal; wherein the ith target frequency interval contains the center frequency of the ith difference frequency signal;
Acquiring energy of an ith noise signal outside an ith target frequency interval in an ith difference frequency signal;
and acquiring the signal-to-noise ratio of the ith difference frequency signal according to the energy of the ith effective signal and the energy of the ith noise signal.
6. The laser detection method as claimed in claim 5, wherein the acquiring the energy of the i effective signal in the i target frequency interval in the i difference frequency signal includes:
Performing Fourier transformation on an ith effective signal in an ith target frequency interval in an ith difference frequency signal, obtaining a modulus value of the ith effective signal, and squaring the modulus value to obtain energy of the ith effective signal;
The obtaining the energy of the ith noise signal outside the ith target frequency interval in the ith difference frequency signal comprises the following steps:
Performing Fourier transformation on an ith noise signal outside an ith target frequency interval in an ith difference frequency signal, obtaining a modulus value of the ith noise signal, and squaring the modulus value to obtain energy of the ith noise signal;
the obtaining the signal-to-noise ratio of the ith difference frequency signal according to the energy of the ith effective signal and the energy of the ith noise signal comprises the following steps:
And obtaining the ratio of the energy of the ith effective signal to the energy of the ith noise signal to obtain the signal-to-noise ratio of the ith difference frequency signal.
7. The laser detection method according to any one of claims 1 to 6, wherein before the signal-to-noise ratio of the i-th difference signal is obtained at the i-th time stamp time of each modulation period, the method comprises:
Before the ith timestamp moment of each modulation period, controlling a laser to transmit an ith local oscillation signal and an ith detection signal at an ith transmission power;
performing analog-to-digital conversion on an ith difference frequency component in the ith mixed signal to obtain an ith difference frequency signal;
the ith mixing signal is obtained based on coherent mixing of the ith local oscillation signal and an echo signal reflected by a target object.
8. A laser detection device, comprising:
The signal-to-noise ratio acquisition unit is used for acquiring the signal-to-noise ratio of the ith difference frequency signal at the ith timestamp moment of each modulation period; wherein i=1, 2, …, n, n is a positive integer, and the i-th difference frequency signal is obtained based on coherent mixing of the i-th local oscillation signal and an echo signal reflected by a target object;
And the transmitting power adjusting unit is used for increasing the transmitting power of the laser from the ith transmitting power to the (i+1) th transmitting power if the signal-to-noise ratio of the ith difference frequency signal is smaller than the corresponding ith signal-to-noise ratio threshold.
9. A terminal device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the laser detection method according to any one of claims 1 to 7 when the computer program is executed by the processor.
10. A computer readable storage medium storing a computer program, characterized in that the computer program when executed by a processor implements the steps of the laser detection method of any one of claims 1 to 7.
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