CN112558107B - Direct current baseline adjusting device and method for increasing instantaneous dynamic state of laser radar - Google Patents

Direct current baseline adjusting device and method for increasing instantaneous dynamic state of laser radar Download PDF

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CN112558107B
CN112558107B CN202011260487.9A CN202011260487A CN112558107B CN 112558107 B CN112558107 B CN 112558107B CN 202011260487 A CN202011260487 A CN 202011260487A CN 112558107 B CN112558107 B CN 112558107B
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module
signal
baseline
voltage
analog
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CN112558107A (en
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潘超
时志云
赵一鸣
刘宇哲
赵艳
韩晓爽
于勇
李凉海
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Beijing Research Institute of Telemetry
Aerospace Long March Launch Vehicle Technology Co Ltd
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Beijing Research Institute of Telemetry
Aerospace Long March Launch Vehicle Technology Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G01S17/95—Lidar systems specially adapted for specific applications for meteorological use
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/483—Details of pulse systems
    • G01S7/486—Receivers
    • G01S7/4861—Circuits for detection, sampling, integration or read-out
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/483—Details of pulse systems
    • G01S7/486—Receivers
    • G01S7/487—Extracting wanted echo signals, e.g. pulse detection
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
    • Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Electromagnetism (AREA)
  • Optical Radar Systems And Details Thereof (AREA)

Abstract

The invention provides a direct current baseline adjusting device and a direct current baseline adjusting method for increasing the instantaneous dynamic state of a laser radar, wherein the direct current baseline adjusting device comprises a photoelectric detector, an amplification adjusting unit, a low-pass filtering module and a control processing unit which is electrically connected with the amplification adjusting unit and the low-pass filtering module; the amplification regulating unit comprises a first amplifier, a second amplifier and a regulating module; the control processing unit comprises an analog-digital conversion module, an FPGA module and a digital-analog conversion module in sequence. The invention adopts a digital processing mode to adjust the base line, the base line position can be adjusted randomly according to the use occasion, and the input signal range of the subsequent sampling circuit is not occupied, thereby increasing the receiving loss dynamic state of the laser radar; the analog subtractor structure realized by the operational amplifier is adopted, so that the loss of low-frequency components and the nonlinear distortion of phases of laser radar echo signals are avoided, and the echo signals can be detected with high fidelity and high precision; the baseline level operation is a digital signal real-time processing mode, and the baseline level can be adjusted in real time under short delay.

Description

Direct current baseline adjusting device and method for increasing instantaneous dynamic state of laser radar
Technical Field
The invention relates to the technical field of telecommunication, in particular to a direct current baseline adjusting device and method for increasing the instantaneous dynamic state of a laser radar.
Background
Laser radar is a novel active remote sensing instrument, and in the sixties of the last century, laser radar (Light Detection And Ranging-LIDAR) appears, and is applied to the fields of active distance measurement, wind field measurement, atmospheric remote sensing And the like very soon.
Because the laser radar has long detection distance and large variation range of the scattering coefficient of the target, very high requirements are put forward on the detection sensitivity and the dynamic range of the detector. For example, the detection target of the atmospheric detection laser radar is molecules, aerosol, cloud layer and the like in the atmosphere, not only the weak echo of high-altitude atmosphere rarefied molecules needs to be processed, but also the strong echo of the cloud layer and the low aerosol echo below the cloud layer need to be processed, and the echo energy has 6 orders of magnitude difference according to the detection target characteristics and the height distribution of the detection target. In the process of laser radar development, a large-dynamic and high-sensitivity weak signal detection and processing technology becomes a technical problem which needs to be solved urgently.
In order to realize large-dynamic and high-sensitivity weak signal detection, a high-performance photoelectric detector is a necessary condition, a preposed signal conditioning and amplifying circuit is a core component of the photoelectric detector, and the laser radar photoelectric detector must have the following conditions: high quantum efficiency, high gain, low noise, fast rise time and high time resolution. At present, mature detectors capable of realizing photon magnitude mainly comprise Avalanche Photo Diodes (APDs) and photomultiplier tubes. The output signal of the photoelectric detector is a nA-level weak current signal, and factors such as the noise coefficient of a preposed signal conditioning and amplifying circuit, the circuit layout and the like determine the noise coefficient of the system to a great extent, so that the design of the preposed signal conditioning and amplifying circuit with high gain and high signal-to-noise ratio is a key part for realizing large-dynamic and high-sensitivity weak signal detection. Weak current signals output by the photoelectric detector are converted into hundreds mV magnitude point voltage signals after current-voltage conversion and amplification, and the signals can be collected and subsequently processed by utilizing an analog detection technology.
Due to the influence of background light such as the sun in the detection process of the laser radar and direct current drift of the multistage amplifying circuit along with external conditions such as temperature, a larger direct current component can be superposed on an analog voltage signal after the analog voltage signal is amplified and output by the detector, the part of direct current component does not contain target information detected by the laser radar, and beneficial effects cannot be brought in target characteristic inversion. Meanwhile, the direct current baseline level occupies the input signal range of the subsequent sampling circuit, so that the receiving dynamic of the laser radar is reduced. And the direct current baseline level is adjusted by means of capacitive blocking or high-pass filtering and the like, so that the loss of low-frequency components of laser radar echo signals and nonlinear distortion of phases can be brought, the distortion on an echo waveform time domain is caused, and the measurement inversion accuracy of laser radar target characteristics is influenced.
Therefore, how to more effectively utilize the input dynamics of the subsequent acquisition processing of the laser radar without causing signal distortion and distortion is the current technical difficulty.
Disclosure of Invention
The invention provides a direct current baseline adjusting device and a direct current baseline adjusting method for increasing the instantaneous dynamic state of a laser radar receiver in order to solve the detection problems of high gain and large dynamic state of laser radar echo signals, wherein the baseline adjusting is carried out in a digital processing mode, the baseline position can be adjusted randomly according to the use occasion, the input signal range of a subsequent sampling circuit is not occupied, and the receiving loss dynamic state of the laser radar is increased; the analog subtractor structure realized by the operational amplifier is adopted, so that the loss of low-frequency components and the nonlinear distortion of phases of laser radar echo signals are avoided, and the echo signals can be detected with high fidelity and high precision; the baseline level operation is a digital signal real-time processing mode, and the baseline level can be adjusted in real time under short delay.
The invention provides a direct current baseline adjusting device for increasing the instantaneous dynamic state of a laser radar, which comprises a photoelectric detector, an amplification adjusting unit, a low-pass filtering module and a control processing unit, wherein the photoelectric detector, the amplification adjusting unit, the low-pass filtering module and the control processing unit are electrically connected in sequence;
the photoelectric detector is used for receiving the laser radar echo light signal, completing photoelectric conversion and outputting a current signal; the amplifying and adjusting unit is used for receiving the current signal, performing current-voltage conversion, amplifying and baseline adjustment to output a baseline adjustment voltage signal, the low-pass filtering module is used for receiving the baseline adjustment voltage signal, performing filtering and converting the baseline adjustment voltage signal into an analog voltage signal for output, the control processing unit is used for sampling, processing and calculating the analog voltage signal after receiving the system synchronous trigger signal and generating a baseline adjustment voltage, and the baseline adjustment voltage is negatively fed back to the amplifying and adjusting unit for real-time baseline adjustment.
As a preferred mode, the amplification adjusting unit comprises a first amplifier, a second amplifier and an adjusting module which are sequentially and electrically connected, the first amplifier is electrically connected with the photoelectric detector, and the adjusting module is electrically connected with the low-pass filtering module and the control processing unit;
the first amplifier is used for receiving the current signal, performing current-voltage conversion and amplifying to output a voltage signal, the second amplifier is used for receiving the voltage signal, performing voltage amplification to output an amplified voltage signal, the adjusting module is used for receiving the amplified voltage signal and a baseline adjusting voltage sent by the control processing unit, simulating the subtraction circuit to perform baseline adjustment on the amplified voltage signal, and outputting a baseline adjusting voltage signal, wherein the baseline adjusting voltage is a direct current bias signal.
The invention relates to a direct current baseline adjusting device for increasing the instantaneous dynamic state of a laser radar, which is used as an optimal mode, wherein a control processing unit comprises an analog-to-digital conversion module, an FPGA (field programmable gate array) module and a digital-to-analog conversion module which are electrically connected in sequence, the analog-to-digital conversion module is electrically connected with a low-pass filtering module, and the digital-to-analog conversion module is electrically connected with an adjusting module;
the analog-to-digital conversion module is used for continuously sampling analog voltage signals output by the low-pass filtering module and outputting sampled voltage digital quantity to the FPGA module, the FPGA module is used for being synchronously triggered by a system to control the analog-to-digital conversion module to sample according to time sequence and calculate according to the sampled voltage digital quantity to obtain a current direct-current baseline voltage value, the FPGA module is used for outputting the direct-current baseline voltage value and controlling the digital-to-analog conversion module to generate baseline adjusting voltage, and the digital-to-analog conversion module is used for generating and negatively feeding back the baseline adjusting voltage to the adjusting module.
The invention relates to a direct current baseline adjusting device for increasing the instantaneous dynamics of a laser radar, which is used as an optimal mode, wherein an amplification adjusting unit is formed by cascading a first amplifier, a second amplifier and an adjusting module;
the first amplifier is a transimpedance amplification circuit, the second amplifier is a voltage amplification circuit, and the adjusting module is a unit gain subtracter and is used for subtracting the amplified voltage signal from the baseline adjusting voltage output by the digital-to-analog conversion module and adjusting the baseline position of the analog echo signal.
The invention relates to a direct current baseline adjusting device for increasing the instantaneous dynamic state of a laser radar, which is used as an optimal mode, wherein the sampling rate of an analog-to-digital conversion module is 10-1000 MSPS, and the sampling bit number is more than 12bits; the digital-to-analog conversion digit of the digital-to-analog conversion module is more than 12bits.
The invention relates to a direct current baseline adjusting device for increasing the transient dynamic state of a laser radar.
The direct current baseline adjusting device for increasing the instantaneous dynamics of the laser radar is preferably characterized in that the low-pass filtering module is a passive low-pass Bessel filter, the order of the filter is greater than 5, and the cut-off frequency is 5MHz +/-2.5 MHz.
The invention provides a direct current baseline adjusting method for increasing the instantaneous dynamics of a laser radar, which comprises the following steps:
s1, photoelectric conversion: the photoelectric detector receives the laser radar echo light signal, performs photoelectric conversion on the laser radar echo light signal to obtain a current signal, and outputs the current signal to the amplification regulating unit;
s2, amplification and adjustment: the amplifying and adjusting unit carries out current-voltage conversion and amplification on the current signal to obtain an amplified voltage signal, and the amplifying and adjusting unit carries out difference on the amplified voltage signal and a direct current bias signal output by the control processing unit to obtain a baseline adjusting voltage signal and outputs the baseline adjusting voltage signal to the low-pass filtering module;
s3, filtering: the low-pass filtering module filters the baseline regulation voltage signal and converts the baseline regulation voltage signal into an analog voltage signal to be output.
The invention relates to a direct current baseline adjusting method for increasing the transient dynamic state of a laser radar, which is a preferable mode, the method comprises the following steps of SA, direct current bias signal output before the step S1: the control processing unit samples, processes and calculates the analog voltage signal subjected to photoelectric conversion, amplification regulation and filtering after receiving the system synchronous trigger signal and generates a direct current bias signal, and the control processing unit negatively feeds back the direct current bias signal to the regulation module;
step SA includes:
SA1, photoelectric conversion: the photoelectric detector receives the laser radar echo optical signal for testing, performs photoelectric conversion on the laser radar echo optical signal, and outputs a current signal to the amplification regulating unit;
SA2, amplification regulation: the amplification regulating unit is used for converting current and voltage, amplifying and regulating a base line and then outputting a base line regulating voltage signal to the low-pass filtering module;
SA3, filtering: the low-pass filtering module converts the filtered signals into analog voltage signals and outputs the analog voltage signals; SA4, sampling: under the synchronization of the synchronous trigger input rising edge of the system, the analog-to-digital conversion module is controlled to continuously sample the analog voltage signal output by the low-pass filtering module, the number of sampling points is more than 1000, and the sampled voltage digital quantity is output to the FPGA module;
SA5, obtaining a sampling average value: the FPGA module accumulates, sums and averages the voltage digital quantity to obtain a sampling average value U0;
SA6, judgment: judging whether the sampling average value U0 is greater than an adjusting threshold value UT; if the sampling average value U0 is larger than the adjusting threshold value UT, the sampling average value U0 is a direct-current baseline voltage value, the step SA4 is carried out, and if the sampling average value U0 is smaller than the adjusting threshold value UT, the step SA1 is carried out;
SA7, outputting a direct current bias signal: the FPGA module converts the sampling average value U0 into digital quantity and outputs the digital quantity to the digital-to-analog conversion module, and the digital-to-analog conversion module controls digital-to-analog conversion digits by using the digital quantity and outputs a direct current offset signal to the adjusting input end of the adjusting module.
As an optimal mode, a system synchronous trigger signal is given before the laser radar emits laser pulses, and the advance time is greater than the sum of the sampling time of step SA4, the processing and calculating time of step SA5 and the judgment and output time of step SA6 and step SA 7.
The invention has the following advantages:
(1) The baseline adjustment of the invention adopts a digital processing mode, the baseline position can be adjusted at will according to the use occasion, and the input signal range of the subsequent sampling circuit is not occupied, thereby increasing the receiving loss dynamic of the laser radar.
(2) The direct current baseline adjusting device adopts an analog subtracter structure realized by operational amplifier, avoids the loss of low-frequency components and nonlinear distortion of phases of laser radar echo signals, and can detect the echo signals with high fidelity and high precision.
(3) The baseline level operation of the invention is a digital signal real-time processing mode, and the baseline level can be adjusted in real time under short delay.
Drawings
FIG. 1 is a schematic diagram of an embodiment 1 of a DC baseline adjustment apparatus for increasing transient dynamics of a laser radar;
FIG. 2 is a block diagram of an embodiment 2-3 of a DC baseline adjustment apparatus for increasing the transient dynamics of a lidar;
FIG. 3 is a flow chart of a DC baseline adjustment method for increasing the transient dynamics of a lidar;
fig. 4 is a flow chart of a dc baseline adjustment method step SA for increasing the transient dynamics of a lidar.
Reference numerals:
1. a photodetector; 2. an amplification adjustment unit; 21. a first amplifier; 22. a second amplifier; 23. an adjustment module; 3. a low-pass filtering module; 4. a control processing unit; 41. an analog-to-digital conversion module; 42. an FPGA module; 43. and a digital-to-analog conversion module.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.
Example 1
As shown in fig. 1, a dc baseline adjusting device for increasing transient dynamics of a laser radar includes a photodetector 1, an amplifying and adjusting unit 2, a low-pass filtering module 3, and a control processing unit 4 electrically connected to the amplifying and adjusting unit 2 and the low-pass filtering module 3;
the photoelectric detector 1 is used for receiving the laser radar echo optical signal, completing photoelectric conversion and outputting a current signal; the amplifying and adjusting unit 2 is used for receiving the current signal, performing current-voltage conversion, amplifying and baseline adjustment to output a baseline adjustment voltage signal, the low-pass filtering module 3 is used for receiving the baseline adjustment voltage signal, performing filtering conversion to output an analog voltage signal, the control processing unit 4 is used for receiving the system synchronization trigger signal, sampling, processing and calculating the analog voltage signal, generating a baseline adjustment voltage, and negatively feeding back the baseline adjustment voltage to the amplifying and adjusting unit 2 for real-time baseline adjustment.
Example 2
As shown in fig. 2, a dc baseline adjusting device for increasing the transient dynamics of a laser radar includes a photodetector 1, an amplifying and adjusting unit 2, a low-pass filtering module 3, and a control processing unit 4 electrically connected to the amplifying and adjusting unit 2 and the low-pass filtering module 3;
the photoelectric detector 1 is used for receiving the laser radar echo optical signal, completing photoelectric conversion and outputting a current signal; the amplifying and adjusting unit 2 is used for receiving the current signal, performing current-voltage conversion, amplifying and baseline adjustment to output a baseline adjustment voltage signal, the low-pass filtering module 3 is used for receiving the baseline adjustment voltage signal, performing filtering conversion to output an analog voltage signal, the control processing unit 4 is used for sampling, processing and calculating the analog voltage signal after receiving the system synchronous trigger signal, generating a baseline adjustment voltage, and performing negative feedback to the amplifying and adjusting unit 2 for real-time baseline adjustment;
the photoelectric detector 1 is a photodiode, an avalanche photodiode or a photomultiplier;
the amplification regulating unit 2 comprises a first amplifier 21, a second amplifier 22 and a regulating module 23 which are electrically connected in sequence, the first amplifier 21 is electrically connected with the photoelectric detector 1, and the regulating module 23 is electrically connected with the low-pass filtering module 3 and the control processing unit 4;
the first amplifier 21 is configured to receive a current signal, perform current-voltage conversion and amplify to output a voltage signal, the second amplifier 22 is configured to receive a voltage signal, perform voltage amplification to output an amplified voltage signal, the adjusting module 23 is configured to receive the amplified voltage signal and a baseline adjusting voltage sent by the control processing unit 4, perform baseline adjustment on the amplified voltage signal by using an analog subtraction circuit, and output a baseline adjusting voltage signal, where the baseline adjusting voltage is a dc offset signal;
the amplification regulating unit 2 is formed by cascading a first amplifier 21, a second amplifier 22 and a regulating module 23;
the first amplifier 21 is a transimpedance amplifier circuit, the second amplifier 22 is a voltage amplifier circuit, and the adjusting module 23 is a unity gain subtractor, and is configured to subtract the amplified voltage signal from the baseline adjusting voltage output by the digital-to-analog conversion module 43, and adjust the baseline position of the analog echo signal;
the low-pass filtering module 3 is a passive low-pass Bessel filter, the order of the filter is more than 5, and the cut-off frequency is 5MHz +/-2.5 MHz;
the control processing unit 4 comprises an analog-to-digital conversion module 41, an FPGA module 42 and a digital-to-analog conversion module 43 which are electrically connected in sequence, the analog-to-digital conversion module 41 is electrically connected with the low-pass filtering module 3, and the digital-to-analog conversion module 43 is electrically connected with the adjusting module 23;
the analog-to-digital conversion module 41 is used for continuously sampling the analog voltage signal output by the low-pass filtering module 3 and outputting the sampled voltage digital quantity to the FPGA module 42, the FPGA module 42 is used for being triggered by the system synchronously to control the analog-to-digital conversion module 41 to sample according to a time sequence and calculate according to the sampled voltage digital quantity to obtain a current direct-current baseline voltage value, the FPGA module 42 is used for outputting the direct-current baseline voltage value and controlling the digital-to-analog conversion module 43 to generate a baseline adjustment voltage, and the digital-to-analog conversion module 43 is used for generating and negatively feeding back the baseline adjustment voltage to the adjustment module 23;
the sampling rate of the analog-to-digital conversion module 41 is 10MSPS to 1000MSPS, and the sampling bit number is more than 12bits; the digital-to-analog conversion module 43 has a digital-to-analog conversion bit number larger than 12bits.
The method of use of examples 1-2, as shown in FIGS. 3-4, includes the steps of:
SA, direct current bias signal output: the control processing unit 4 samples, processes and calculates the analog voltage signal subjected to photoelectric conversion, amplification adjustment and filtering after receiving the system synchronous trigger signal, and generates a direct current bias signal, and the control processing unit 4 negatively feeds back the direct current bias signal to the adjusting module 23;
SA1, photoelectric conversion: the photoelectric detector 1 receives the laser radar echo optical signal for testing, performs photoelectric conversion on the received laser radar echo optical signal, and outputs a current signal to the amplification regulating unit 2;
SA2, amplification regulation: the amplification regulating unit 2 performs current-voltage conversion, amplification and baseline regulation and then outputs a baseline regulation voltage signal to the low-pass filtering module 3;
SA3, filtering: the low-pass filtering module 3 converts the filtered signals into analog voltage signals and outputs the analog voltage signals;
SA4, sampling: under the synchronization of the system synchronous trigger input rising edge, the analog-to-digital conversion module 41 is controlled to continuously sample the analog voltage signal output by the low-pass filtering module 3, the number of sampling points is more than 1000, and the sampled voltage digital quantity is output to the FPGA module 42; SA5, obtaining a sampling average value: the FPGA module 42 accumulates, sums and averages the voltage digital quantity to obtain a sampling average value U0;
SA6, judgment: judging whether the sampling average value U0 is greater than an adjusting threshold value UT; if the sampling average value U0 is larger than the adjusting threshold value UT, the sampling average value U0 is a direct-current baseline voltage value, the step SA4 is carried out, and if the sampling average value U0 is smaller than the adjusting threshold value UT, the step SA1 is carried out;
SA7, outputting a direct current bias signal: the FPGA module 42 converts the sampling average value U0 into a digital quantity and outputs the digital quantity to the digital-to-analog conversion module 43, and the digital-to-analog conversion module 43 controls the digital-to-analog conversion digit number by using the digital quantity and outputs a direct current offset signal to the adjustment input end of the adjustment module 23;
s1, photoelectric conversion: the photoelectric detector 1 receives the laser radar echo light signal, performs photoelectric conversion on the laser radar echo light signal to obtain a current signal, and outputs the current signal to the amplification regulating unit 2;
s2, amplification and adjustment: the amplifying and adjusting unit 2 performs current-voltage conversion and amplification on the current signal to obtain an amplified voltage signal, and the amplifying and adjusting unit 2 performs difference between the amplified voltage signal and a direct current bias signal output by the control processing unit 4 to obtain a baseline adjusting voltage signal and outputs the baseline adjusting voltage signal to the low-pass filtering module 3;
s3, filtering: the low-pass filtering module 3 filters the baseline regulation voltage signal and converts the baseline regulation voltage signal into an analog voltage signal to be output;
and a system synchronization trigger signal is given before the laser radar emits the laser pulse, and the advance time is greater than the sum of the sampling time of the step SA4, the processing and calculating time of the step SA5 and the judgment and output time of the step SA6 and the step SA 7.
Example 3
As shown in fig. 2, a dc baseline adjusting device for increasing the transient dynamics of a laser radar includes a photodetector 1, an amplifying and adjusting unit 2, a low-pass filtering module 3, and a control processing unit 4 electrically connected to the amplifying and adjusting unit 2 and the low-pass filtering module 3;
the photoelectric detector 1 is used for receiving the laser radar echo optical signal, completing photoelectric conversion and outputting a current signal; the amplifying and adjusting unit 2 is used for receiving the current signal, performing current-voltage conversion, amplifying and baseline adjustment to output a baseline adjustment voltage signal, the low-pass filtering module 3 is used for receiving the baseline adjustment voltage signal, performing filtering conversion to output an analog voltage signal, the control processing unit 4 is used for sampling, processing and calculating the analog voltage signal after receiving the system synchronous trigger signal, generating a baseline adjustment voltage, and performing negative feedback to the amplifying and adjusting unit 2 for real-time baseline adjustment;
the photoelectric detector 1 is a photodiode, an avalanche photodiode or a photomultiplier tube; the laser emission wavelength of the system is 1064nm, the responsivity of the photoelectric detector 1 is 36A/W, the optical power of an echo signal of the atmospheric laser radar is 0.5 nW-5 uW, and the current output range of the photoelectric detector 1 is 0.18 uA-180 uA;
the amplification regulating unit 2 comprises a first amplifier 21, a second amplifier 22 and a regulating module 23 which are electrically connected in sequence, the first amplifier 21 is electrically connected with the photoelectric detector 1, and the regulating module 23 is electrically connected with the low-pass filtering module 3 and the control processing unit 4;
the first amplifier 21 is configured to receive a current signal, perform current-voltage conversion and amplify to output a voltage signal, the second amplifier 22 is configured to receive a voltage signal, perform voltage amplification to output an amplified voltage signal, the adjusting module 23 is configured to receive the amplified voltage signal and a baseline adjusting voltage sent by the control processing unit 4, perform baseline adjustment on the amplified voltage signal by using an analog subtraction circuit, and output a baseline adjusting voltage signal, where the baseline adjusting voltage is a dc offset signal;
the amplification regulating unit 2 is formed by cascading a first amplifier 21, a second amplifier 22 and a regulating module 23;
the first amplifier 21 is a transimpedance amplifier circuit, the second amplifier 22 is a voltage amplifier circuit, and the adjusting module 23 is a unity gain subtractor, and is configured to perform subtraction between the amplified voltage signal and a baseline adjusting voltage output by the digital-to-analog conversion module 43, so as to adjust the baseline position of the analog echo signal;
the first amplifier 21 is an OPA847 of TI company, the current-voltage conversion gain of the pair is 1000V/A, the output voltage value is 0.18 mV-180 mV, the second amplifier 22 is an OPA847 of TI company, the amplification factor is 10 times, the output voltage value is 1.8 mV-1.8V, and the measured direct current offset voltage is 150mV. The adjusting module 23 is a subtractor with G =1, and is implemented by selecting an AD8041 operational amplifier, the reverse input end is used for inputting the amplified analog echo signal, and the forward input end is connected to the output signal of the digital-to-analog conversion circuit, and is used for subtracting the amplified echo analog echo signal and removing the dc baseline;
the low-pass filtering module 3 is a passive low-pass Bessel filter, the order of the filter is more than 5, and the cut-off frequency is 5MHz +/-2.5 MHz; the low-pass filtering module of the embodiment adopts a passive LC device to design a 5-order Bessel filter, the cut-off frequency is 5MHz, the out-of-band noise suppression is realized, and the signal-to-noise ratio of a channel is improved while the nonlinear distortion is not caused to signals;
the control processing unit 4 comprises an analog-to-digital conversion module 41, an FPGA module 42 and a digital-to-analog conversion module 43 which are electrically connected in sequence, the analog-to-digital conversion module 41 is electrically connected with the low-pass filtering module 3, and the digital-to-analog conversion module 43 is electrically connected with the adjusting module 23;
the analog-to-digital conversion module 41 is used for continuously sampling the analog voltage signal output by the low-pass filtering module 3 and outputting the sampled voltage digital quantity to the FPGA module 42, the FPGA module 42 is used for being synchronously triggered by the system to control the analog-to-digital conversion module 41 to sample according to a time sequence and calculate according to the sampled voltage digital quantity to obtain a current direct-current baseline voltage value, the FPGA module 42 is used for outputting the direct-current baseline voltage value and controlling the digital-to-analog conversion module 43 to generate a baseline adjustment voltage, and the digital-to-analog conversion module 43 is used for generating and negatively feeding back the baseline adjustment voltage to the adjustment module 23;
the sampling rate of the analog-to-digital conversion module 41 is 10MSPS to 1000MSPS, and the sampling bit number is more than 12bits; the digital-to-analog conversion digit of the digital-to-analog conversion module 43 is more than 12bits;
the analog-to-digital conversion module 41 is LTC2201 of LINEAR corporation, the sampling frequency is 20MSPS, and the sampling bit number is 16bits; the FPGA module 42 is A54SX72A of ACTEL company, and the digital-to-analog conversion module 43 is a serial DAC, DAC121S101, conversion frequency 1MSPS and conversion precision 12bits of TI company.
The method of use of example 3, as shown in fig. 3-4, comprises the steps of:
SA, direct current bias signal output: the control processing unit 4 samples, processes and calculates the analog voltage signal after photoelectric conversion, amplification regulation and filtering after receiving the system synchronous trigger signal, and generates a direct current bias signal, and the control processing unit 4 negatively feeds back the direct current bias signal to the regulating module 23;
SA1, photoelectric conversion: the photoelectric detector 1 receives the laser radar echo optical signal for testing, performs photoelectric conversion on the received laser radar echo optical signal, and outputs a current signal to the amplification regulating unit 2;
SA2, amplification regulation: the amplification regulating unit 2 performs current-voltage conversion, amplification and baseline regulation and then outputs a baseline regulation voltage signal to the low-pass filtering module 3;
SA3, filtering: the low-pass filtering module 3 converts the filtered signals into analog voltage signals and outputs the analog voltage signals;
SA4, sampling: under the synchronization of the system synchronous trigger input rising edge, the analog-to-digital conversion module 41 is controlled to continuously sample the analog voltage signal output by the low-pass filtering module 3, the number of sampling points is more than 1000, and the sampled voltage digital quantity is output to the FPGA module 42; SA5, obtaining a sampling average value: the FPGA module 42 accumulates, sums and averages the voltage digital quantity to obtain a sampling average value U0;
SA6, judgment: judging whether the sampling average value U0 is greater than an adjusting threshold value UT; if the sampling average value U0 is larger than the adjusting threshold value UT, the sampling average value U0 is a direct-current baseline voltage value, the step SA4 is carried out, and if the sampling average value U0 is smaller than the adjusting threshold value UT, the step SA1 is returned to; the regulation threshold value UT is set to 50mV;
SA7, outputting a direct current bias signal: the FPGA module 42 converts the sampling average value U0 into a digital quantity and outputs the digital quantity to the digital-to-analog conversion module 43, and the digital-to-analog conversion module 43 controls the digital-to-analog conversion digit number by using the digital quantity and outputs a direct current offset signal to the adjustment input end of the adjustment module 23;
s1, photoelectric conversion: the photoelectric detector 1 receives the laser radar echo light signal, performs photoelectric conversion on the laser radar echo light signal to obtain a current signal, and outputs the current signal to the amplification regulating unit 2;
s2, amplification and adjustment: the amplifying and adjusting unit 2 performs current-voltage conversion and amplification on the current signal to obtain an amplified voltage signal, and the amplifying and adjusting unit 2 performs difference between the amplified voltage signal and a direct current bias signal output by the control processing unit 4 to obtain a baseline adjusting voltage signal and outputs the baseline adjusting voltage signal to the low-pass filtering module 3;
s3, filtering: the low-pass filtering module 3 filters the baseline regulation voltage signal and converts the baseline regulation voltage signal into an analog voltage signal to be output;
in the embodiment, the system synchronization trigger signal is given 100us before the laser radar transmits the laser pulse, the sampling time of 1000 points is 50us, the calculation time of the summation average is about 10us, and the feedback adjustment time is about 30us. The baseline may be zeroed out before the laser useful echo arrives.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims (8)

1. The utility model provides an increase instantaneous dynamic direct current baseline adjusting device of laser radar which characterized in that: the photoelectric detector comprises a photoelectric detector (1), an amplification adjusting unit (2), a low-pass filtering module (3) and a control processing unit (4) which is electrically connected with the amplification adjusting unit (2) and the low-pass filtering module (3) in sequence;
the photoelectric detector (1) is used for receiving the laser radar echo light signal, completing photoelectric conversion and outputting a current signal; the amplifying and adjusting unit (2) is used for receiving the current signal, performing current-voltage conversion, amplifying and baseline adjustment to output a baseline adjustment voltage signal, the low-pass filtering module (3) is used for receiving the baseline adjustment voltage signal, performing filtering and converting the baseline adjustment voltage signal into an analog voltage signal, outputting the analog voltage signal, the control processing unit (4) is used for receiving a system synchronization trigger signal, sampling, processing and calculating the analog voltage signal, generating a baseline adjustment voltage, and negatively feeding back the baseline adjustment voltage to the amplifying and adjusting unit (2) for real-time baseline adjustment;
the direct current baseline adjustment method for increasing the transient dynamic state of the laser radar comprises the following steps:
SA, direct current bias signal output: the control processing unit (4) samples, processes and calculates the analog voltage signal subjected to photoelectric conversion, amplification regulation and filtering after receiving a system synchronous trigger signal, and generates a direct current bias signal, and the control processing unit (4) negatively feeds back the direct current bias signal to the regulation module (23);
SA1, photoelectric conversion: the photoelectric detector (1) receives the laser radar echo light signal for testing, performs photoelectric conversion on the laser radar echo light signal, and outputs a current signal to the amplification regulating unit (2);
SA2, amplification regulation: the amplification regulating unit (2) performs current-voltage conversion, amplification and baseline regulation and then outputs a baseline regulation voltage signal to the low-pass filtering module (3);
SA3, filtering: the low-pass filtering module (3) converts the filtered signal into an analog voltage signal and outputs the analog voltage signal;
SA4, sampling: under the synchronization of a system synchronous trigger input rising edge, controlling an analog-to-digital conversion module (41) to continuously sample the analog voltage signal output by the low-pass filtering module (3), wherein the number of sampling points is more than 1000, and outputting the sampled voltage digital quantity to an FPGA module (42);
SA5, obtaining a sampling average value: the FPGA module (42) accumulates, sums and averages the voltage digital quantity to obtain a sampling average value U0;
SA6, judgment: judging whether the sampling average value U0 is larger than an adjusting threshold value UT; if the sampling average value U0 is larger than the regulation threshold value UT, the sampling average value U0 is a direct-current baseline voltage value, the step SA4 is carried out, and if the sampling average value U0 is smaller than the regulation threshold value UT, the step SA1 is returned;
SA7, outputting a direct current bias signal: the FPGA module (42) converts the sampling average value U0 into a digital quantity and outputs the digital quantity to a digital-to-analog conversion module (43), and the digital-to-analog conversion module (43) controls the digital-to-analog conversion digit number by using the digital quantity and outputs a direct current offset signal to an adjusting input end of an adjusting module (23);
s1, photoelectric conversion: the photoelectric detector (1) receives the laser radar echo optical signal, performs photoelectric conversion on the laser radar echo optical signal to obtain a current signal, and outputs the current signal to the amplification regulating unit (2);
s2, amplification and adjustment: the amplification regulating unit (2) performs current-voltage conversion and amplification on the current signal to obtain an amplified voltage signal, and the amplification regulating unit (2) performs subtraction on the amplified voltage signal and a direct current bias signal output by the control processing unit (4) to obtain a baseline regulation voltage signal and outputs the baseline regulation voltage signal to the low-pass filtering module (3);
s3, filtering: and the low-pass filtering module (3) filters the baseline adjusting voltage signal and converts the baseline adjusting voltage signal into an analog voltage signal to be output.
2. The dc baseline adjustment apparatus for increasing temporal dynamics of lidar according to claim 1, wherein: the amplification adjusting unit (2) comprises a first amplifier (21), a second amplifier (22) and an adjusting module (23) which are electrically connected in sequence, the first amplifier (21) is electrically connected with the photoelectric detector (1), and the adjusting module (23) is electrically connected with the low-pass filtering module (3) and the control processing unit (4);
the first amplifier (21) is configured to receive the current signal, perform current-voltage conversion and amplify the current signal to output a voltage signal, the second amplifier (22) is configured to receive the voltage signal, perform voltage amplification on the voltage signal, and output an amplified voltage signal, the adjusting module (23) is configured to receive the amplified voltage signal and a baseline adjusting voltage sent by the control processing unit (4), perform baseline adjustment on the amplified voltage signal by using an analog subtraction circuit, and output a baseline adjusting voltage signal, where the baseline adjusting voltage is a direct current bias signal.
3. The dc baseline adjustment apparatus for increasing transient dynamics of lidar according to claim 2, wherein: the control processing unit (4) comprises an analog-to-digital conversion module (41), an FPGA module (42) and a digital-to-analog conversion module (43) which are electrically connected in sequence, the analog-to-digital conversion module (41) is electrically connected with the low-pass filtering module (3), and the digital-to-analog conversion module (43) is electrically connected with the adjusting module (23);
the analog-to-digital conversion module (41) is used for continuously sampling the analog voltage signal output by the low-pass filtering module (3) and outputting a sampled voltage digital quantity to the FPGA module (42), the FPGA module (42) is used for being triggered by a system synchronously to control the analog-to-digital conversion module (41) to sample according to a time sequence and calculate according to the sampled voltage digital quantity to obtain a current direct-current baseline voltage value, the FPGA module (42) is used for outputting the direct-current baseline voltage value and controlling the digital-to-analog conversion module (43) to generate the baseline adjustment voltage, and the digital-to-analog conversion module (43) is used for generating and negatively feeding back the baseline adjustment voltage to the adjustment module (23).
4. The dc baseline adjustment apparatus for increasing temporal dynamics of lidar according to claim 3, wherein: the amplification regulating unit (2) is formed by cascading the first amplifier (21), the second amplifier (22) and the regulating module (23);
the first amplifier (21) is a transimpedance amplification circuit, the second amplifier (22) is a voltage amplification circuit, and the adjusting module (23) is a unit gain subtracter and is used for subtracting the amplified voltage signal from the baseline adjusting voltage output by the digital-to-analog conversion module (43) to adjust the baseline position of the analog echo signal.
5. The dc baseline adjustment apparatus for increasing temporal dynamics of lidar according to claim 3, wherein: the sampling rate of the analog-to-digital conversion module (41) is 10-1000 MSPS, and the sampling bit number is more than 12bits; the digital-to-analog conversion digit of the digital-to-analog conversion module (43) is more than 12bits.
6. The dc baseline adjustment apparatus for increasing temporal dynamics of lidar according to claim 1, wherein: the photodetector (1) is a photodiode, an avalanche photodiode or a photomultiplier tube.
7. The dc baseline adjustment apparatus for increasing temporal dynamics of lidar according to claim 1, wherein: the low-pass filtering module (3) is a passive low-pass Bessel filter, the order of the filter is more than 5, and the cut-off frequency is 5MHz +/-2.5 MHz.
8. The dc baseline adjustment apparatus for increasing transient dynamics of lidar according to claim 1, wherein: and the system synchronous trigger signal is given before the laser radar transmits the laser pulse, and the advance time is greater than the sum of the sampling time of the step SA4, the processing and calculating time of the step SA5 and the judgment and output time of the step SA6 and the step SA 7.
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