Multi-channel data synchronous acquisition system and method for hyperspectral laser radar

Abstract

The invention relates to the technical field of surveying and mapping remote sensing, in particular to a multichannel data synchronous acquisition system and method for a hyperspectral laser radar, and the system comprises a photoelectric conversion unit which is used for converting an optical signal of an echo of the hyperspectral laser radar into an electric signal; the clock synchronization unit is used for sending a global trigger signal and a unified clock signal; the plurality of waveform acquisition units are used for controlling the plurality of waveform acquisition units to synchronously acquire echo signals of the hyperspectral laser radar based on the global trigger signal and the unified clock signal, and each waveform acquisition unit comprises a plurality of waveform acquisition channels; the plurality of disk storage units are used for storing echo signals of the hyperspectral laser radar; and the upper computer control unit is used for controlling corresponding target actions of the plurality of units after detecting the laser pulse signal transmitted by the hyperspectral laser radar. Therefore, the problem that the subsequent data quality is affected due to the lack of an effective multi-channel synchronous acquisition mechanism of the hyperspectral laser radar is solved.

Description

Technical Field

[0001] The present application relates to the field of surveying and mapping remote sensing technology, and in particular to a multi-channel data synchronization acquisition system and method for hyperspectral laser radar. Background Art

[0002] Hyperspectral LiDAR is a new type of LiDAR technology that combines the advantages of traditional single-wavelength LiDAR and hyperspectral imaging, that is, it can realize the integrated acquisition of spatial geometric-spectral information of ground objects. The components of hyperspectral LiDAR mainly include supercontinuum laser, scanning mirror, optical receiving unit, photoelectric conversion unit, signal acquisition unit, and host computer control unit. Its working process is that the laser emits supercontinuum laser pulses, which are reflected to the ground object through the scanning mirror. The backscattered echo of the emitted laser and the ground object returns to the optical receiving unit through the scanning mirror. The optical receiving unit divides the continuous spectrum echo into dozens of bands of spectral signals through grating spectroscopy. The dozens of bands of spectral signals are converted into analog voltage signals containing the geometric distance and spectral intensity information of the ground object through the photoelectric conversion unit. The analog voltage signal is collected by the acquisition unit, and the host computer control unit controls the coordinated and orderly operation of all components of the entire system.

[0003] In existing hyperspectral lidar systems, due to the lack of an effective multi-channel synchronization mechanism, data collection in multiple bands often has time deviations. In other words, existing technologies cannot achieve synchronous collection of data from multiple channels, which makes it difficult to match data from different bands, affecting the quality of the final data and the application effect. Summary of the invention

[0004] The present application provides a multi-channel data synchronous acquisition system and method for hyperspectral laser radar, so as to solve the problem that hyperspectral laser radar lacks an effective multi-channel synchronous acquisition mechanism, thereby affecting the subsequent data quality.

[0005] The first aspect of the present application provides a multi-channel data synchronization acquisition system for a hyperspectral laser radar, including: a photoelectric conversion unit, used to convert the optical signal of the echo of the hyperspectral laser radar into an electrical signal; a clock synchronization unit, used to issue a global trigger signal and a unified clock signal; multiple waveform acquisition units, used to control multiple waveform acquisition units to synchronously acquire the echo signal of the hyperspectral laser radar based on the global trigger signal and the unified clock signal, wherein each waveform acquisition unit includes multiple waveform acquisition channels; multiple disk storage units, used to store the echo signal of the hyperspectral laser radar; a host computer control unit, used to control the photoelectric conversion unit, the clock synchronization unit, the multiple waveform acquisition units and the multiple disk storage units to perform corresponding target actions after detecting the laser pulse signal emitted by the hyperspectral laser radar.

[0006] Optionally, the upper computer control unit is also used to: determine a reference waveform acquisition unit from multiple waveform acquisition units; perform signal threshold detection on the echo signal acquired by the reference waveform acquisition unit to obtain reference information of an over-threshold waveform segment; distribute the over-threshold waveform segment reference information to each waveform acquisition unit, and each waveform acquisition unit determines a target over-threshold waveform segment from the acquired echo signal according to the over-threshold waveform segment reference information; and store the target over-threshold waveform segment in multiple disk storage units.

[0007] Optionally, the waveform acquisition unit includes: a core circuit, a signal conditioning circuit, a multi-channel digital-to-analog conversion circuit, a clock management circuit, a cache unit and an interface circuit, wherein the core circuit is used to read and process the echo signal of the hyperspectral laser radar in the multi-channel digital-to-analog conversion circuit, and cache the echo signal of the hyperspectral laser radar in the multi-channel digital-to-analog conversion circuit; the signal conditioning circuit is used to convert the single-ended signal output by the photoelectric conversion unit into a differential signal, and input the signal to the multi-channel analog-to-digital conversion circuit after adjusting the signal amplitude; the multi-channel digital-to-analog conversion circuit is used to sample and digital-to-analog convert the echo signal of the hyperspectral laser radar; the clock management circuit is used to receive the unified clock signal issued by the clock synchronization unit to achieve multi-channel synchronization; the cache unit is used to temporarily cache the echo signal of the hyperspectral laser radar before and after processing by the core circuit; the interface circuit is used to receive the unified clock signal and the global trigger signal issued by the clock synchronization unit, and transmit the echo signal of the hyperspectral laser radar processed by the core circuit to multiple disk storage units.

[0008] The second aspect of the present application provides a multi-channel data synchronous acquisition method for a hyperspectral laser radar, which is acquired using a multi-channel data synchronous acquisition system for a hyperspectral laser radar as in the above embodiment, and includes the following steps: detecting the laser pulse signal emitted by the hyperspectral laser radar; after detecting the laser pulse signal, controlling the clock synchronization unit to send a global trigger signal and a unified clock signal; based on the global trigger signal and the unified clock signal, controlling multiple waveform acquisition units to synchronously acquire the echo signal of the hyperspectral laser radar, wherein each waveform acquisition unit includes multiple waveform acquisition channels; and storing the echo signal of the hyperspectral laser radar in multiple disk storage units.

[0009] Optionally, based on a global trigger signal and a unified clock signal, multiple waveform acquisition units are controlled to synchronously acquire echo signals of a hyperspectral laser radar, including: using a photoelectric conversion unit to convert an optical signal of an echo of the hyperspectral laser radar into an electrical signal; and controlling multiple waveform acquisition channels of multiple waveform acquisition units to synchronously acquire echo signals of the hyperspectral laser radar.

[0010] Optionally, before storing the echo signal of the hyperspectral laser radar in multiple disk storage units, it also includes: determining a reference waveform acquisition unit from multiple waveform acquisition units; performing signal threshold detection on the echo signal acquired by the reference waveform acquisition unit to obtain cross-threshold waveform segment reference information; distributing the cross-threshold waveform segment reference information to each waveform acquisition unit, and each waveform acquisition unit determines a target cross-threshold waveform segment from the acquired echo signal according to the cross-threshold waveform segment reference information; and storing the target cross-threshold waveform segment in multiple disk storage units.

[0011] Optionally, an over-threshold detection is performed on the echo signal collected by the reference waveform acquisition unit to obtain over-threshold waveform segment reference information, including: acquiring the echo signals cached in multiple waveform acquisition channels of the reference waveform acquisition unit; performing a noise threshold evaluation on the cached echo signals; determining a target value of the signal threshold based on a result of the noise threshold evaluation; and performing a signal threshold detection on the echo signal collected by the reference waveform acquisition unit based on the target value to obtain over-threshold waveform segment reference information.

[0012] Optionally, the noise threshold evaluation is calculated as:

[0013] threshold noise =m noise +λ·σ noise ;

[0014] Among them, threshold noise is the noise threshold, m noise is the mean value of the amplitude of multiple sampling points at the beginning and end of the band of the echo signal, σ noise is the standard deviation of multiple sampling points at the beginning or end of the echo signal waveform, and λ is the noise threshold coefficient.

[0015] Optionally, the threshold-crossing waveform segment reference information algorithm is:

[0016] P latency =∪(T cuts (i,j));

[0017] Among them, T cuts are the cross-threshold waveform segments on each reference waveform acquisition channel, i is the channel number, j is the cross-threshold waveform segment number on each reference waveform acquisition channel, and ∪ represents the union of the time position information of the cross-threshold waveform segments.

[0018] The third aspect of the present application provides a host computer, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to execute the multi-channel data synchronous acquisition method for hyperspectral lidar as described in the above embodiment.

[0019] The fourth aspect of the present application provides a computer-readable storage medium having a computer program or instruction stored thereon, and the computer program or instruction is executed by a processor to perform a multi-channel data synchronous acquisition method for a hyperspectral lidar.

[0020] Therefore, this application has at least the following beneficial effects:

[0021] After detecting the laser pulse signal emitted by the hyperspectral laser radar, the embodiment of the present application can send a global trigger signal and a unified clock signal through the clock synchronization unit, and multiple waveform acquisition channels in multiple waveform acquisition units can synchronously acquire the echo signal of the hyperspectral laser radar, thereby realizing high-precision synchronous acquisition of multiple band channel data, thereby improving the subsequent data quality. Therefore, the technical problem that the hyperspectral laser radar lacks an effective multi-channel synchronous acquisition mechanism, which in turn affects the subsequent data quality, is solved.

[0022] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0024] Figure 1 A schematic diagram of a multi-channel data synchronization acquisition system for a hyperspectral laser radar provided according to an embodiment of the present application;

[0025] Figure 2 A schematic diagram of a synchronous acquisition system provided according to a specific embodiment of the present application;

[0026] Figure 3 A schematic diagram of the structure of a clock synchronization unit provided according to an embodiment of the present application;

[0027] Figure 4 A schematic diagram of the structure of a waveform acquisition unit provided according to an embodiment of the present application;

[0028] Figure 5 A flowchart of a multi-channel data synchronous acquisition method for a hyperspectral laser radar provided according to an embodiment of the present application;

[0029] Figure 6 It is a schematic diagram of the structure of a host computer provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0030] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0031] The following describes the multi-channel data synchronization acquisition system and method for hyperspectral laser radar in the embodiment of the present application with reference to the accompanying drawings. In view of the existing hyperspectral laser radar system mentioned in the background technology center, due to the lack of an effective multi-channel synchronization mechanism, there is often a time deviation in the data acquisition of multiple bands, that is, the existing technology cannot achieve the synchronous acquisition of multiple channel data, which leads to the difficulty of matching data between different bands, affecting the quality of the final data and the application effect. The present application provides a multi-channel data synchronization acquisition system for hyperspectral laser radar. In this system, after detecting the laser pulse signal emitted by the hyperspectral laser radar, a global trigger signal and a unified clock signal can be sent through the clock synchronization unit, and multiple waveform acquisition channels in multiple waveform acquisition units synchronously collect the echo signal of the hyperspectral laser radar. In this way, the problem of the lack of an effective multi-channel synchronization acquisition mechanism for the hyperspectral laser radar, which in turn affects the subsequent data quality, is solved.

[0032] Specifically, Figure 1 Schematic diagram of a multi-channel data synchronization acquisition system for hyperspectral lidar provided in an embodiment of the present application.

[0033] like Figure 1 As shown, the multi-channel data synchronization acquisition system 10 for hyperspectral laser radar includes: a photoelectric conversion unit 11, a clock synchronization unit 12, multiple waveform acquisition units 13, multiple disk storage units 14 and a host computer control unit 15.

[0034] Among them, the photoelectric conversion unit 11 is used to convert the optical signal of the echo of the hyperspectral laser radar into an electrical signal; the clock synchronization unit 12 is used to generate a global trigger signal and a unified clock signal after detecting the laser pulse signal emitted by the hyperspectral laser radar; multiple waveform acquisition units 13 are used to control multiple waveform acquisition units to synchronously acquire the echo signal of the hyperspectral laser radar based on the global trigger signal and the unified clock signal, wherein each waveform acquisition unit includes multiple waveform acquisition channels; multiple disk storage units 14 are used to store the echo signal of the hyperspectral laser radar; the host computer control unit 15 is used to control the photoelectric conversion unit, the clock synchronization unit, the multiple waveform acquisition units and the multiple disk storage units to perform corresponding target actions.

[0035] It can be understood that the host computer control unit 15 in the multi-channel data synchronous acquisition system 10 for hyperspectral laser radar in the embodiment of the present application (hereinafter referred to as the acquisition system 10) respectively controls the photoelectric conversion unit 11, the clock synchronization unit 12, multiple waveform acquisition units 13 and multiple disk storage units to perform corresponding target actions, that is, to perform corresponding operations, specifically: the photoelectric conversion unit 10 converts the optical signal of the echo of the hyperspectral laser radar into an electrical signal, and the clock synchronization unit 12 generates a global trigger signal and a unified clock signal after detecting the laser pulse signal emitted by the hyperspectral laser radar. Further, after receiving the global trigger signal and the unified clock signal, the multiple acquisition units 13 control the multiple waveform acquisition units to synchronously acquire the echo signal of the hyperspectral laser radar, and each waveform acquisition unit 13 includes multiple waveform acquisition channels, and multiple disk storage units store the echo signal of the hyperspectral laser radar, thereby realizing high-precision synchronous acquisition of the echo signal of the hyperspectral laser radar through multiple waveform acquisition channels.

[0036] In the embodiment of the present application, the host computer control unit 15 is also used to: determine a reference waveform acquisition unit from multiple waveform acquisition units; perform signal threshold detection on the echo signal acquired by the reference waveform acquisition unit to obtain reference information of an over-threshold waveform segment; distribute the over-threshold waveform segment reference information to each waveform acquisition unit, and each waveform acquisition unit determines a target over-threshold waveform segment from the acquired echo signal according to the over-threshold waveform segment reference information; and store the target over-threshold waveform segment in multiple disk storage units.

[0037] The cross-threshold waveform segment information includes the timing offset of the cross-threshold waveform segment relative to the trigger sampling moment and the length of the cross-threshold waveform segment.

[0038] It can be understood that the upper computer control unit 15 of the embodiment of the present application is also used to determine the reference waveform acquisition unit from multiple waveform acquisition units, perform signal threshold detection on the echo signal collected by the reference waveform acquisition unit, obtain the cross-threshold waveform segment reference information, and distribute the cross-threshold waveform segment reference information to each waveform acquisition unit. Each waveform acquisition unit determines a qualified cross-threshold waveform segment, that is, a target cross-threshold waveform segment, from the collected echo signal according to the cross-threshold waveform segment reference information, and stores the target cross-threshold waveform segment in multiple disk storage units.

[0039] Among them, the embodiment of the present application selects a reference waveform acquisition unit to perform threshold crossing judgment on the acquired signal, and then synchronously transmits the threshold crossing information to the remaining waveform acquisition units, thereby achieving the purpose of removing redundancy of noise components and compressing the data volume for the signals collected by all acquisition channels of the hyperspectral laser radar.

[0040] In the embodiment of the present application, the waveform acquisition unit 13 includes: a core circuit, a signal conditioning circuit, a multi-channel digital-to-analog conversion circuit, a clock management circuit, a cache unit and an interface circuit.

[0041] Among them, the core circuit is used to read and process the echo signal of the hyperspectral laser radar in the multi-channel digital-to-analog conversion circuit, and cache the echo signal of the hyperspectral laser radar in the multi-channel digital-to-analog conversion circuit; the signal conditioning circuit is used to convert the single-ended signal output by the photoelectric conversion unit into a differential signal, and input the signal to the multi-channel analog-to-digital conversion circuit after adjusting the signal amplitude; the multi-channel digital-to-analog conversion circuit is used to sample and digital-to-analog convert the echo signal of the hyperspectral laser radar; the clock management circuit is used to receive the unified clock signal issued by the clock synchronization unit to achieve multi-channel synchronization; the cache unit is used to temporarily cache the echo signal of the hyperspectral laser radar before and after processing by the core circuit; the interface circuit is used to receive the unified clock signal and the global trigger signal issued by the clock synchronization unit, and transmit the echo signal of the hyperspectral laser radar processed by the core circuit to multiple disk storage units.

[0042] It can be understood that the waveform acquisition unit 13 of the embodiment of the present application includes: a core circuit, a signal conditioning circuit, a multi-channel digital-to-analog conversion circuit, a clock management circuit, a cache unit and an interface circuit. The core circuit can be an FPGA (Field-Programmable Gate Array) core circuit, the multi-channel digital-to-analog conversion circuit can be a multi-channel ADC (Analog-to-Digital Converter) circuit, the cache unit can be a DDR4 (Double Data Rate 4 Synchronous Dynamic Random-Access Memory, double data rate fourth generation synchronous dynamic random access memory) unit, and the interface circuit can be a PXIe (PCI Express-based PXI, an instrument bus standard) interface circuit, wherein,

[0043] The core circuit reads, processes and caches the echo signal of the hyperspectral lidar in the digital-to-analog conversion circuit;

[0044] The signal conditioning circuit converts the single-ended signal output by the photoelectric conversion unit into a differential signal, and then adjusts the signal amplitude before inputting it into the digital-to-analog conversion circuit;

[0045] Multi-channel digital-to-analog conversion circuits perform high-speed sampling and digital-to-analog conversion of signal waveforms;

[0046] The clock management circuit receives the unified clock signal sent by the synchronization unit to achieve multi-channel synchronization;

[0047] The cache unit temporarily caches the echo signals before and after the core circuit processing;

[0048] The interface circuit receives the global trigger signal and the unified clock signal sent by the clock synchronization unit and transmits the target threshold-crossing waveform segment processed by the core circuit to the disk storage unit.

[0049] The multi-channel data synchronization acquisition system for hyperspectral laser radar of the present application is explained below through a specific embodiment. The acquisition system comprises a chassis including a PXIe backplane, a clock synchronization unit for receiving laser emission pulse trigger signals and generating a global system clock signal to realize multi-channel synchronous sampling, a waveform acquisition unit for full waveform digital acquisition and processing of echo analog voltage signals, a host computer control unit for human-computer interaction and communication control of other units, and a disk storage unit for storing multi-channel raw waveform data of hyperspectral laser radar.

[0050] Among them, the clock synchronization unit is placed in the system timing slot of the PXIe chassis. On the one hand, it is responsible for receiving the trigger level signal of the external laser emission unit, and on the other hand, it serves as the source of the unified clock signal and waveform sampling trigger signal of the entire acquisition system; the waveform acquisition unit performs full waveform digital synchronous acquisition and online processing of dozens of band echo signals of the hyperspectral laser radar under the control of the control unit and the clock synchronization unit; the disk storage unit is responsible for storing waveforms and additional information data packaged in the defined data frame format; each unit works closely together to realize the synchronous acquisition of dozens of channel data signals of the hyperspectral laser radar.

[0051] like Figure 2 As shown in the figure, based on the PXIe modular instrument bus platform, the entire acquisition system structure is: 1 clock synchronization unit, 14 waveform acquisition units, 1 host computer control unit and 2 disk storage units are deployed on a standard 3U PXIe chassis with 18 PXIe slots. Among them, each waveform acquisition unit contains four waveform acquisition channels, and the entire acquisition system has a total of 56 waveform acquisition channels.

[0052] like Figure 3 As shown in the figure, the clock synchronization unit is composed of functional modules such as FPGA core circuit, external input signal processing circuit, clock management circuit, PXIe interface circuit, etc. The unit distributes global clock signals and trigger signals to each waveform acquisition unit through the dedicated high-performance star bus of the PXIe backplane to realize the synchronous acquisition of multi-channel data of hyperspectral lidar.

[0053] like Figure 4As shown in the figure, the waveform acquisition unit is composed of functional modules such as FPGA core circuit, signal conditioning circuit, ADC circuit, clock management circuit, DDR4 cache unit and PXIe interface circuit. The FPGA circuit is responsible for ADC data reading, ADC data processing, data caching and uploading, peripheral management and other functions. The signal conditioning circuit is responsible for converting the single-ended signal output by the detector into a differential signal and then adjusting the signal amplitude before inputting it into the ADC circuit module. The ADC circuit is responsible for high-speed sampling and digital-to-analog conversion of the signal waveform. The clock management circuit is responsible for receiving the external clock to achieve multi-channel synchronization. The DDR4 storage unit is responsible for temporarily caching the waveform signal before and after FPGA processing; the PXIe interface circuit is responsible for receiving the global clock signal and trigger signal fanned out by the clock synchronization unit and transmitting the waveform data processed by FPGA to the computer disk storage unit.

[0054] The host computer control unit provides a human-computer interaction interface to control the operation of the entire acquisition system; the disk storage unit stores the data stream collected and transmitted from each waveform acquisition unit in real time.

[0055] According to the multi-channel data synchronization acquisition system for hyperspectral laser radar proposed in the embodiment of the present application, after detecting the laser pulse signal emitted by the hyperspectral laser radar, a global trigger signal and a unified clock signal can be sent out through the clock synchronization unit, and multiple waveform acquisition channels in multiple waveform acquisition units can synchronously acquire the echo signal of the hyperspectral laser radar, thereby realizing high-precision synchronous acquisition of multiple band channel data, thereby improving subsequent data quality.

[0056] Next, a multi-channel data synchronous acquisition method for a hyperspectral lidar proposed according to an embodiment of the present application is described with reference to the accompanying drawings.

[0057] Figure 5 It is a flow chart of a multi-channel data synchronous acquisition method for a hyperspectral laser radar according to an embodiment of the present application.

[0058] like Figure 5 As shown, the multi-channel data synchronous acquisition method for hyperspectral laser radar includes the following steps:

[0059] In step S101 , a laser pulse signal emitted by a hyperspectral laser radar is detected.

[0060] It can be understood that the embodiment of the present application can detect the laser pulse signal emitted by the hyperspectral laser radar so as to subsequently execute the acquisition process of the embodiment of the present application.

[0061] In step S102, after the laser pulse signal is detected, the time synchronization unit is controlled to send out a global trigger signal and a unified clock signal.

[0062] It can be understood that, in the embodiment of the present application, after detecting the laser pulse signal, the clock synchronization unit generates a global trigger signal and a unified clock signal.

[0063] In step S103, multiple waveform acquisition units are controlled to synchronously acquire echo signals of the hyperspectral laser radar based on a global trigger signal and a unified clock signal, wherein each waveform acquisition unit includes multiple waveform acquisition channels.

[0064] It can be understood that the embodiments of the present application can control multiple waveform acquisition units to synchronously acquire echo signals of hyperspectral lidar based on a global trigger signal and a unified clock signal, specifically controlling multiple waveform acquisition channels of multiple waveform acquisition units to synchronously acquire.

[0065] In an embodiment of the present application, multiple waveform acquisition units are controlled to synchronously acquire echo signals of a hyperspectral laser radar based on a global trigger signal and a unified clock signal, including: using a photoelectric conversion unit to convert the optical signal of the echo of the hyperspectral laser radar into an electrical signal; controlling multiple waveform acquisition channels of multiple waveform acquisition units to synchronously acquire echo signals of the hyperspectral laser radar.

[0066] It can be understood that the embodiments of the present application can utilize the photoelectric conversion unit to convert the optical signal of the echo of the hyperspectral laser radar into telecommunication, and control multiple waveform acquisition channels of multiple waveform acquisition units to synchronously acquire the echo signal of the hyperspectral laser radar.

[0067] In step S104, the echo signal of the hyperspectral laser radar is stored in a plurality of disk storage units.

[0068] It is understandable that the embodiment of the present application can store the collected echo signals of the hyperspectral laser radar in multiple disk storage units.

[0069] In an embodiment of the present application, before storing the echo signal of the hyperspectral laser radar in multiple disk storage units, it also includes: determining a reference waveform acquisition unit from multiple waveform acquisition units; performing over-threshold detection on the echo signal acquired by the reference waveform acquisition unit to obtain over-threshold waveform segment reference information; distributing the over-threshold waveform segment reference information to each waveform acquisition unit, and each waveform acquisition unit determines a target over-threshold waveform segment from the acquired echo signal according to the over-threshold waveform segment reference information; and storing the target over-threshold waveform segment in multiple disk storage units.

[0070] Among them, the reference waveform acquisition unit is preferably a waveform acquisition unit corresponding to a band with greater signal strength and higher signal-to-noise ratio.

[0071] It can be understood that the embodiments of the present application can determine a reference waveform acquisition unit from multiple waveform acquisition units, and perform signal threshold detection on the echo signal acquired by the reference waveform unit to obtain cross-threshold waveform segment reference information, and distribute the cross-threshold waveform segment reference information to each waveform acquisition unit. Each waveform acquisition unit determines the target cross-threshold waveform segment from the acquired echo signal according to the cross-threshold waveform segment reference information, and stores the target cross-threshold waveform segment in multiple disk storage units. The specific method for performing signal threshold detection is as follows.

[0072] In an embodiment of the present application, a signal threshold detection is performed on the echo signal collected by the reference waveform acquisition unit to obtain reference information of the over-threshold waveform segment, including: acquiring the echo signals cached in multiple waveform acquisition channels of the reference waveform acquisition unit; performing a noise threshold evaluation on the cached echo signals; determining an over-threshold target value based on the result of the noise threshold evaluation; and performing an over-threshold detection on the echo signal collected by the reference waveform acquisition unit based on the target value to obtain reference information of the over-threshold waveform segment.

[0073] Among them, the calculation formula for noise threshold evaluation is:

[0074] threshold noise =m noise +λ·σ noise ;

[0075] Among them, threshold noise is the noise threshold, m noise is the mean value of the amplitude of multiple sampling points at the beginning and end of the band of the echo signal, σ noise is the standard deviation of multiple sampling points at the beginning or end of the echo signal waveform, and λ is the noise threshold coefficient.

[0076] It can be understood that the embodiments of the present application can obtain the echo signals cached in multiple waveform acquisition channels of the reference waveform acquisition unit, and perform noise threshold evaluation on them, and determine the target value of the signal threshold based on the result of the noise threshold evaluation, and perform signal threshold detection on the echo signals collected by the reference waveform acquisition unit based on the target value, thereby obtaining the over-threshold waveform segment information.

[0077] In the embodiment of the present application, the threshold waveform segment reference information algorithm is:

[0078] P latency =∪(T cuts (I,J));

[0079] Among them, T cuts are the cross-threshold waveform segments on each reference waveform acquisition channel, I is the channel number, J is the cross-threshold waveform segment number on each reference waveform acquisition channel, and ∪ represents the union of the time position information of the cross-threshold waveform segments.

[0080] It should be noted that the aforementioned explanation of the embodiment of the multi-channel data synchronous acquisition system for hyperspectral laser radar is also applicable to the multi-channel data synchronous acquisition method for hyperspectral laser radar of this embodiment, and will not be repeated here.

[0081] The following is a specific example of a method for synchronously collecting multi-channel data for a hyperspectral laser radar according to an embodiment of the present application. In combination with the above-mentioned collection system, the method is as follows:

[0082] Step 1: Laser emission pulse trigger signal distribution and unified clock signal distribution.

[0083] Among them, the trigger signal distribution: the laser emission unit of the hyperspectral lidar sends laser pulse light at a high repetition frequency of 130kHz and transmits the trigger level signal to the clock synchronization unit of the acquisition system through a cable; the clock synchronization unit LEMO single-core connector receives the trigger level signal, and the internal external trigger signal processing circuit processes the leading edge timing, generates a system global trigger signal, and then fans it out to each waveform acquisition unit through the chassis backplane PXIe_DSTARB star line;

[0084] Unified clock signal distribution: The 100MHz crystal oscillator in the clock synchronization unit cooperates with the clock management module to generate a high-precision system clock signal, which is transmitted to each waveform acquisition unit via the PXIe_DSTARA star line on the chassis backplane.

[0085] Step 2: Each waveform acquisition unit receives a global trigger signal and a unified clock signal, and multi-channel signals are sampled synchronously.

[0086] Each waveform acquisition unit receives the trigger signal fanned out from the clock synchronization unit through the PXIe_DSTARC star line on the chassis backplane. This global trigger signal serves as an instruction for each acquisition channel of each waveform acquisition unit to start acquiring waveforms.

[0087] The FPGA on each waveform acquisition unit sends a trigger signal to the ADC circuit module on the unit according to the received trigger signal to control the four waveform acquisition channels to achieve synchronous signal sampling;

[0088] The clock management module in each waveform acquisition unit receives the high-precision system clock signal from the PXIe_DSTARA star line on the chassis backplane and eliminates the clock jitter. After optimizing the clock performance, it is sent to each ADC circuit module, thereby ensuring that the clock signal of each waveform acquisition channel of each waveform acquisition unit is synchronized.

[0089] The star-shaped lines on the chassis backplane are strictly of equal length, thereby ensuring that the clocks and triggers received by each waveform acquisition unit are synchronized, thereby ensuring the synchronization of the entire acquisition system.

[0090] Step 3: The reference waveform acquisition unit detects the over-threshold waveform.

[0091] Step 3.1: The waveform acquisition unit corresponding to the band with greater signal strength and higher signal-to-noise ratio is preferably selected as the reference waveform acquisition unit.

[0092] Step 3.2: The reference waveform acquisition unit collects the digitized waveform of the 4-channel buffer and performs a noise threshold evaluation. The noise threshold evaluation is based on the following formula:

[0093]

[0094] m noise =min(m beginning , m ending ); (4)

[0095]

[0096] threshold noise =m noise +λ·σ noise ; (5)

[0097] In the above formula, V i is the amplitude of the i-th sampling point in the waveform segment collected each time the laser is triggered; m beginning and m ending are the mean values ​​of the amplitudes of the 10 sampling points at the beginning and end of the band; σ noise V is the standard deviation of the ten sampling points at the beginning or end of the waveform. noise_i The amplitude of the i-th sampling point at the beginning or end of the collected waveform segment, the beginning or end depends on formula (3), threshold noise is the noise threshold, which is used to remove the noise component. In formula (5), σ noise The noise threshold coefficient λ can be adjusted according to the actual noise situation, and is generally 3 or 4. The reason why the ten points at the beginning or end are not fixedly selected as the noise estimation area is that the peak noise or the echo of the detected object may appear randomly at the beginning or end in the actual detection and acquisition waveform, so the smaller mean of the two is taken as the noise estimation area.

[0098] Step 3-3: Set the over-threshold baseline according to the noise threshold evaluation result to perform over-threshold detection on the acquired waveform, and record the over-threshold waveform segment information, which includes the timing offset of the over-threshold waveform segment relative to the trigger sampling moment and the length of the over-threshold waveform segment.

[0099] Based on the position of the cross-threshold segment on the reference channel, the reference acquisition segment (i.e., the cross-threshold waveform segment) is obtained according to the following formula:

[0100] Tcuts (i, j) = U(t OT (i, j)-δ, t OT (i, j)+2δ);

[0101] Among them, T cuts (i, j) is the reference acquisition segment, t OT (i, j) is the timing offset of the j-th threshold segment of the reference channel with serial number i, δ is the adaptive width parameter that can be set by the host computer, and the value range is between 1 times the actual pulse width and 3 times the actual pulse width. ∪ is the union calculation, which is performed by traversing all the threshold segments on all reference channels and taking the union.

[0102] Step 4: Transmit and distribute reference acquisition segment information (and cross-threshold waveform segment reference information).

[0103] Step 4-1: The reference waveform acquisition unit transmits the reference acquisition segment information to the clock synchronization card through the PXIe_DSTARB star line;.

[0104] Step 4-2: The clock synchronization card receives the reference acquisition segment information from the reference waveform acquisition unit through the PXIe_DSTARC star line, and then distributes it to each waveform digitization module through the PXI_STAR star line transmission. The chassis backplane star line group from the slot where the clock synchronization card is located to the slots where the remaining waveform acquisition units are located is strictly equal in length to ensure that each waveform acquisition unit can synchronously receive the reference acquisition segment information.

[0105] Step 5: Each waveform acquisition unit selects, transmits and stores the acquired segments.

[0106] Step 5-1: Each waveform digitization module extracts a valid waveform segment from the collected waveform data according to the reference collected segment;

[0107] Step 5.2: Pack the selected valid waveform segments according to the defined data frames and transmit them to the disk array unit through the chassis backplane PCIe bus for storage.

[0108] According to the multi-channel data synchronous acquisition method for hyperspectral laser radar proposed in the embodiment of the present application, after detecting the laser pulse signal emitted by the hyperspectral laser radar, the clock synchronization unit is controlled to send a global trigger signal and a unified clock signal, and based on the global trigger signal and the unified clock signal, multiple waveform acquisition channels in multiple waveform acquisition units are controlled to synchronously acquire the echo signal of the hyperspectral laser radar, thereby realizing high-precision synchronous acquisition of multiple band channel data, thereby improving subsequent data quality.

[0109] Figure 6 A schematic diagram of the structure of the host computer provided in the embodiment of the present application. The host computer may include:

[0110] A memory 601 , a processor 602 , and a computer program stored in the memory 601 and executable on the processor 602 .

[0111] When the processor 602 executes the program, the multi-channel data synchronous acquisition method for the hyperspectral laser radar provided in the above embodiment is implemented.

[0112] Furthermore, the host computer also includes:

[0113] The communication interface 603 is used for communication between the memory 601 and the processor 602 .

[0114] The memory 601 is used to store computer programs that can be executed on the processor 602 .

[0115] The memory 601 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0116] If the memory 601, the processor 602 and the communication interface 603 are implemented independently, the communication interface 603, the memory 601 and the processor 602 can be connected to each other through a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 6 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0117] Optionally, in a specific implementation, if the memory 601, the processor 602 and the communication interface 603 are integrated on a chip, the memory 601, the processor 602 and the communication interface 603 can communicate with each other through an internal interface.

[0118] The processor 602 may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0119] An embodiment of the present application also provides a computer-readable storage medium having a computer program or instruction stored thereon. When the computer program or instruction is executed by a processor, the method for synchronously acquiring multi-channel data for a hyperspectral lidar as described above is implemented.

[0120] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0121] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0122] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0123] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one or a combination of multiple of the following technologies known in the art: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0124] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

Claims

1. A multi-channel data synchronous acquisition system for hyperspectral laser radar, characterized in that: include: A photoelectric conversion unit, used for converting the optical signal of the echo of the hyperspectral laser radar into an electrical signal; A clock synchronization unit, used to issue a global trigger signal and a unified clock signal; A plurality of waveform acquisition units, used for synchronously acquiring the echo signal of the hyperspectral laser radar based on the global trigger signal and the unified clock signal, wherein each waveform acquisition unit includes a plurality of waveform acquisition channels; A plurality of disk storage units, used for storing the echo signals of the hyperspectral laser radar; The host computer control unit is used to control the photoelectric conversion unit, the clock synchronization unit, the multiple waveform acquisition units and the multiple disk storage units to perform corresponding target actions after detecting the laser pulse signal emitted by the hyperspectral laser radar.

2. The multi-channel data synchronous acquisition system for hyperspectral laser radar according to claim 1 is characterized in that: The host computer control unit is also used for: determining a reference waveform acquisition unit from the plurality of waveform acquisition units; Performing signal threshold detection on the echo signal collected by the reference waveform collection unit to obtain cross-threshold waveform segment reference information; Distributing the cross-threshold waveform segment reference information to each waveform acquisition unit, each waveform acquisition unit determining a target cross-threshold waveform segment from the acquired echo signal according to the cross-threshold waveform reference segment information; The target threshold-crossing waveform segments are stored in the plurality of disk storage units.

3. The multi-channel data synchronous acquisition system for hyperspectral laser radar according to claim 1 is characterized in that: The waveform acquisition unit includes: a core circuit, a signal conditioning circuit, a multi-channel digital-to-analog conversion circuit, a clock management circuit, a cache unit and an interface circuit, wherein: The core circuit is used to read and process the echo signal of the hyperspectral laser radar in the multi-channel digital-to-analog conversion circuit, and cache the echo signal of the hyperspectral laser radar in the multi-channel digital-to-analog conversion circuit; The signal conditioning circuit is used to convert the single-ended signal output by the photoelectric conversion unit into a differential signal, and adjust the signal amplitude before inputting it into the multi-channel analog-to-digital conversion circuit; The multi-channel digital-to-analog conversion circuit is used to sample and perform digital-to-analog conversion on the echo signal of the hyperspectral laser radar; The clock management circuit is used to receive the unified clock signal sent by the clock synchronization unit to achieve multi-channel synchronization; The cache unit is used to temporarily cache the echo signals of the hyperspectral laser radar before and after being processed by the core circuit; The interface circuit is used to receive the unified clock signal and the global trigger signal sent by the clock synchronization unit, and transmit the echo signal of the hyperspectral laser radar processed by the core circuit to multiple disk storage units.

4. A multi-channel data synchronous acquisition method for hyperspectral laser radar, characterized in that: The method is performed using the multi-channel data synchronous acquisition system for hyperspectral laser radar according to any one of claims 1 to 3, wherein the method comprises the following steps: Detect laser pulse signals emitted by hyperspectral lidar; After detecting the laser pulse signal, controlling the clock synchronization unit to send out a global trigger signal and a unified clock signal; Based on the global trigger signal and the unified clock signal, a plurality of waveform acquisition units are controlled to synchronously acquire the echo signal of the hyperspectral laser radar, wherein each waveform acquisition unit includes a plurality of waveform acquisition channels; The echo signal of the hyperspectral laser radar is stored in a plurality of disk storage units.

5. The method for synchronously collecting multi-channel data for hyperspectral laser radar according to claim 4 is characterized in that: Before controlling a plurality of waveform acquisition units to synchronously acquire the echo signal of the hyperspectral laser radar based on the global trigger signal and the unified clock signal, the method includes: The optical signal of the echo of the hyperspectral laser radar is converted into an electrical signal by using a photoelectric conversion unit; The multiple waveform acquisition channels of the multiple waveform acquisition units are controlled to synchronously acquire the echo signal of the hyperspectral laser radar.

6. The method for synchronously collecting multi-channel data for hyperspectral laser radar according to claim 5, characterized in that: Before storing the echo signal of the hyperspectral laser radar in a plurality of disk storage units, the method further includes: determining a reference waveform acquisition unit from the plurality of waveform acquisition units; Performing signal threshold detection on the echo signal collected by the reference waveform collection unit to obtain cross-threshold waveform segment reference information; Distributing the cross-threshold waveform segment reference information to each waveform acquisition unit, and each waveform acquisition unit determines a target cross-threshold waveform segment from the acquired echo signal according to the cross-threshold waveform segment reference information; The target threshold-crossing waveform segments are stored in the plurality of disk storage units.

7. The method for synchronously collecting multi-channel data for hyperspectral laser radar according to claim 6, characterized in that: The performing signal threshold detection on the echo signal acquired by the reference waveform acquisition unit to obtain the over-threshold waveform segment reference information includes: Acquiring echo signals cached in multiple waveform acquisition channels of the reference waveform acquisition unit; Performing noise threshold evaluation on the buffered echo signal; determining a target value for the signal threshold based on a result of the noise threshold evaluation; Based on the target value, a signal threshold detection is performed on the echo signal collected by the reference waveform collection unit to obtain the over-threshold waveform segment reference information.

8. The method for synchronously collecting multi-channel data for hyperspectral laser radar according to claim 7, characterized in that: The calculation formula for the noise threshold evaluation is: threshold noise =m noise +λ·σ noise ; Among them, threshold noise is the noise threshold, m noise is the mean value of the amplitude of multiple sampling points at the beginning and end of the band of the echo signal, σ noise is the standard deviation of multiple sampling points at the beginning or end of the echo signal waveform, and λ is the noise threshold coefficient.

9. The method for synchronously collecting multi-channel data for hyperspectral laser radar according to claim 7, characterized in that: The threshold-crossing waveform segment reference information algorithm is: P latency =∪(T cuts (i,j)); Among them, T cuts are the cross-threshold waveform segments on each reference waveform acquisition channel, i is the channel number, j is the cross-threshold waveform segment number on each reference waveform acquisition channel, and ∪ represents the union of the time position information of the cross-threshold waveform segments.

10. A host computer, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the multi-channel data synchronous acquisition method for hyperspectral lidar as described in any one of claims 4 to 9.

11. A computer-readable storage medium having a computer program or instruction stored thereon, characterized in that: The computer program or instruction is executed by a processor to implement the multi-channel data synchronous acquisition method for hyperspectral lidar as described in any one of claims 4 to 9.

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