CN115220055A - Pulse laser coherent ranging method and device based on linear frequency modulation local oscillator - Google Patents

Pulse laser coherent ranging method and device based on linear frequency modulation local oscillator Download PDF

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CN115220055A
CN115220055A CN202210747763.7A CN202210747763A CN115220055A CN 115220055 A CN115220055 A CN 115220055A CN 202210747763 A CN202210747763 A CN 202210747763A CN 115220055 A CN115220055 A CN 115220055A
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frequency
signal
linear
matched filtering
light
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吴姿妍
刘波
赵晓龙
眭晓林
梅博
周寿桓
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CETC 11 Research Institute
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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
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06—Systems determining position data of a target
    • G01S17/46—Indirect determination of position data
    • G01S17/48—Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves

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Abstract

The invention discloses a pulse laser coherent ranging method and a device based on a linear frequency modulation local oscillator, wherein the method comprises the following steps: generating a linear frequency modulation signal in a preset frequency interval under the condition that the first linear modulator is triggered; performing linear frequency modulation on a target signal based on the generated linear frequency modulation signal to form a first signal; modulating the signal light; combining the modulated signal light and the first signal; after the combined optical signal passes through a detector, sampling and matched filtering processing are carried out on the obtained echo signal; and performing distance calculation according to the result of the matched filtering. The embodiment of the application adopts the linear modulation modes that local oscillator light and emergent light receive difference respectively, utilizes the coherent detection principle, carries out matched filtering processing to the linear modulation waveform behind the echo difference frequency, and solves the problems of a plurality of blind spot and distance ambiguity of high repetition frequency integrated pulse laser ranging.

Description

Pulse laser coherent ranging method and device based on linear frequency modulation local oscillator
Technical Field
The invention relates to the technical field of laser ranging, in particular to a pulse laser coherent ranging method and device based on a linear frequency modulation local oscillator.
Background
When a long-distance static target is detected, the traditional receiving and transmitting integrated high-repetition-frequency pulse laser coherent ranging method divides the laser emitted by a seed source into beams, one beam is used as local oscillator light, the other beam is used as signal light, the signal light is subjected to acousto-optic frequency modulation chopping to form pulse signal light with frequency shift information, the pulse signal light is emitted from a lens through a circulator and an optical amplifier, the received signal light and the local oscillator difference frequency are detected, the time information of the difference frequency is detected, and the target distance is calculated.
The high repetition frequency pulse laser coherent ranging has high repetition frequency, so that when the target distance is long, a distance ambiguity phenomenon can be caused, namely in a trigger period, because the target distance is long, the pulse cannot return to a receiving end in the trigger period, and can reach in other periods, so that the distance ambiguity occurs in distance resolution; meanwhile, in the receiving and transmitting integrated laser pulse coherent detection, because the lens end face can reflect strong emergent light at the transmitting moment, in the transmitting pulse period, the echo light at a close distance can not be collected, namely, the echo light is submerged in the reflected light of the lens, so that a close-distance target in the pulse period and a target corresponding to the whole pulse period can not be detected.
In order to solve the problems, the method adopted by the prior art is to utilize multiple frequencies to perform fuzzy solution and utilize a detector to perform turn-off at the pulse transmitting moment, so that the problems of complicated solution and a plurality of blind spots are caused.
Disclosure of Invention
The embodiment of the invention provides a pulse laser coherent ranging method and device based on a linear frequency modulation local oscillator, which are characterized in that local oscillator light and emergent light are subjected to different linear modulation modes respectively, a coherent detection principle is utilized, a combined light signal passes through a band stop or low pass detector and an acquisition system, and then a linear modulation waveform after echo difference frequency is subjected to matched filtering processing, so that the problems of multiple blind spots and range ambiguity of high-repetition-frequency integrated pulse laser ranging are solved.
The embodiment of the invention provides a pulse laser coherent ranging method based on a linear frequency modulation local oscillator, which comprises the following steps:
generating a linear frequency modulation signal in a preset frequency interval under the condition that the first linear modulator is triggered;
performing linear frequency modulation on a target signal based on the generated linear frequency modulation signal, so that the optical frequency emitted by the seed source loads the linear frequency modulation signal on a fundamental frequency to form a first signal;
modulating signal light, and determining the slope and pulse period of the linear frequency modulation signal according to the modulation frequency of the modulated transmitted frequency modulation pulse;
combining the modulated signal light and the first signal;
after the combined optical signal passes through a detector, sampling and matched filtering processing are carried out on the obtained echo signal;
and carrying out distance calculation according to the result of the matched filtering.
Optionally, generating the chirp signal in the preset frequency interval under the condition that the first linear modulator is triggered includes:
in the case of the first linear modulator being triggered, a frequency slave is generated
Figure BDA0003719956880000021
To
Figure BDA0003719956880000022
Trigger period of 0 to Trig local Of a linear frequency modulated signal
Figure BDA0003719956880000023
Wherein the slope of the chirp signal is
Figure BDA0003719956880000024
Wherein the Trig local The farthest detectable distance is determined based on a laser coherent ranging system.
Optionally, the modulation frequency of the nth pulse of the frequency modulation pulse emitted after the signal light is modulated satisfies:
Figure BDA0003719956880000031
wherein, trig sig Denotes the repetition period, k 1 Which represents the chirp rate of the transmitted signal,
Figure BDA0003719956880000032
Figure BDA0003719956880000033
t n the time position of each transmitting signal in a period with the triggering time as 0 meets the following conditions:
(n-1)×Trig sig <t n <(n-1)×Trig sig +T sig
T sig it is shown that the width of the pulse,
Figure BDA0003719956880000034
expressed as the frequency of the termination of the first chirp in the transmitted signal light, based on the optical frequency,
Figure BDA0003719956880000035
indicating the starting frequency of the first chirp on the basis of optical frequency in the transmitted signal light.
Optionally, the performing matched filtering processing on the acquired echo signal includes:
according to a trigger signal for modulating signal light, data acquisition and matched filtering processing are carried out in each repetition period, wherein the matched filtering processing adopts the following steps:
determining the frequency range of the difference frequency characteristics between the local oscillator light and the echo signal:
fitting the frequency of the difference frequency characteristic based on the frequency range, and satisfying the following conditions:
f match (r)＝(k 1 -k 0 )×r+f match_low
wherein r is fitting time, and satisfies the following conditions:
Figure BDA0003719956880000036
f match_high end frequency, f, representing the design match frequency range match_low A start frequency representing a design match frequency range;
a matched filter is determined based on the frequency of the fitted difference frequency signature.
Optionally, after the matched filtering results of each repetition period are obtained, the matched filtering results are accumulated to maximize the matched result value.
Optionally, the performing distance calculation according to the result of the matched filtering includes:
under the condition that only one matching result exists, the distance of the target to be measured meets the following conditions:
Figure BDA0003719956880000041
wherein f is s Representing the sampling rate, N 0 Denotes the abscissa reference of the matching result, N 1 The abscissa value of the actual matching result is represented, and c represents the light speed;
when there are two matching results (N) 1 、N 2 ) In the case of (2), the corresponding abscissa values are each N 1 、N 2 And N is 1 <N 0 <N 2 If N is 2 Corresponding to an amplitude greater than N 1 And (4) processing the corresponding amplitude, wherein the distance of the target to be detected meets the following requirements:
Figure BDA0003719956880000042
if N is present 1 Corresponding to an amplitude greater than N 2 And (3) processing the corresponding amplitude, wherein the distance of the target to be detected meets the following requirements:
Figure BDA0003719956880000043
the embodiment of the present application further provides a laser coherent ranging apparatus, which includes a memory and a processor, where the memory stores a computer program, and the computer program is executed by the processor to implement the steps of the laser coherent ranging method.
An embodiment of the present application further provides a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the steps of the foregoing laser coherent ranging method are implemented.
The embodiment of the application adopts the linear modulation mode that local oscillator light and emergent light receive the difference respectively, utilizes the coherent detection principle, carries out matched filtering to the linear modulation waveform behind the echo difference frequency and handles, solves a plurality of blind spot and the distance fuzzy problem of high repetition frequency integral type pulse laser rangefinder.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
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Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
FIG. 1 is a basic flowchart of a pulse laser coherent ranging method according to an embodiment of the present application;
FIG. 2 is a diagram illustrating an embodiment of a high repetition frequency transmit-receive integrated pulsed laser coherent ranging system based on chirp;
FIG. 3 is a diagram illustrating another embodiment of a high repetition frequency transmit-receive integrated pulsed laser coherent ranging system based on chirp in accordance with an embodiment of the present disclosure;
FIG. 4 is a diagram illustrating another embodiment of a high repetition frequency transmit-receive integrated pulsed laser coherent ranging system based on chirp;
FIG. 5 is an exemplary signal triggering sequence in accordance with an embodiment of the present application;
FIG. 6 is a time frequency diagram of the laser seed source modulated by the modulator 1 according to the embodiment of the present application;
FIG. 7 is a time frequency diagram of a laser seed source modulated by the modulator 2 according to the embodiment of the present application;
FIG. 8 is a graph (τ ') of the difference frequency result of N pulses in the embodiment of the present application'<Trig sig )；
FIG. 9 is a diagram illustrating the difference frequency result of N pulses (T) according to an embodiment of the present invention sig <τ′<Trig sig )；
FIG. 10 is an example of a matched filter design according to an embodiment of the present application;
FIG. 11 is a graph (τ ') of N pulse difference frequency matched filtering results in the embodiment of the present application'<Trig sig )；
FIG. 12 is a diagram illustrating the difference frequency matched filtering results (T) of N pulses according to an embodiment of the present application sig <τ′<Trig sig )。
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The embodiment of the invention provides a pulse laser coherent ranging method based on a linear frequency modulation local oscillator, which comprises the following steps as shown in figure 1:
in step S101, in the case that the first linear modulator is triggered, a chirp signal of a preset frequency interval is generated.
In the present application, a plurality of laser coherent ranging systems may be used to form local oscillator light, and as an example, as shown in fig. 2, a linear modulator 1 and a linear modulator 2 respectively perform frequency modulation operations after receiving a trigger signal shown in fig. 2. The laser seed source enters a beam splitter after being subjected to linear modulation 1, one beam is used as local oscillator light, the other beam is used as signal light, the signal light passes through an optical modulator controlled by a linear modulator 2, then passes through a circulator and an amplifier, high-power pulse laser is emitted out from a lens, an echo signal enters a beam combiner after passing through a circulator 3 end and an optical amplifier, and is combined with the local oscillator light, and data operations such as sampling, matched filtering and the like are carried out after passing through a detector, so that a fixed target distance is obtained.
As another example, as shown in fig. 3, the linear modulator 1 and the linear modulator 2 respectively perform frequency modulation operations after receiving the trigger signal shown in fig. 2. The laser seed source enters the beam splitter, one beam is used as local oscillator light, the other beam is used as signal light, the local oscillator light passes through the optical modulator 1 controlled by the linear modulator 1, and the signal light passes through the optical modulator 2 controlled by the linear modulator 2. The signal light passes through the circulator and the amplifier, high-power pulse laser is emitted out from the lens, echo signals enter the beam combiner after passing through the end 3 of the circulator and the optical amplifier, are combined with a local oscillator beam, and are subjected to data operations such as sampling, matched filtering and the like after passing through the detector, so that the fixed target distance is obtained.
As yet another example, as shown in fig. 4, a laser seed source is internally modulated to generate a linear Chirp signal with a repeating period, and simultaneously generates a trigger electrical signal, which triggers the linear modulator 2 to generate the trigger signal 2. After the optical signal subjected to linear modulation enters the beam splitter, one beam is used as a local oscillator light, the other beam is used as a signal light, the signal light passes through the optical modulator controlled by the linear modulator 2, then the high-power pulse laser is emitted out from the lens through the circulator and the amplifier, the echo signal passes through the end 3 of the circulator and the optical amplifier and then enters the beam combiner to be combined with the local oscillator light, and data operations such as sampling, matched filtering and the like are carried out after the echo signal passes through the detector, so that the fixed target distance is obtained.
In step S102, a target signal is chirped based on the generated chirp signal, so that the optical frequency emitted from the seed source loads the chirp signal on the fundamental frequency to form a first signal. The target signal in this example may be the local oscillator optical signal after passing through the beam splitter, or may be a laser signal of a laser seed source, and after performing linear frequency modulation, the optical frequency emitted by the seed source is at the optical frequencyLoading a linear tuning frequency from a base frequency
Figure BDA0003719956880000071
To
Figure BDA0003719956880000072
In step S103, the signal light is modulated, and the modulation frequency of the modulated and transmitted chirp is determined by the slope and the pulse period of the chirp signal. The signal light referred to in this example is another signal opposite to the local oscillation light.
In step S104, the modulated signal light and the first signal are combined.
In step S105, after the combined optical signal passes through the detector, the acquired echo signal is sampled and matched with a filter. The detector in the example can be a band-stop or low-pass detector, and by selecting a detector with proper frequency response, the problems of multiple blind spots caused by that lens echo light is too strong at the emission moment and the response of the detector needs to be turned off can be solved.
In step S106, distance calculation is performed based on the result of the matched filtering.
The embodiment of the invention adopts different linear modulation modes of local oscillation light and emergent light respectively, utilizes the coherent detection principle, and performs matched filtering processing on the linear modulation waveform after echo difference frequency after a combined light optical signal passes through a band-stop or low-pass detector and an acquisition system, thereby solving the problems of multiple blind spots and distance ambiguity of high-repetition-frequency integrated pulse laser ranging.
In some embodiments, generating the chirp signal of the preset frequency interval in the case where the first linear modulator is triggered comprises:
in the case of the first linear modulator being triggered, a frequency slave is generated
Figure BDA0003719956880000073
To
Figure BDA0003719956880000074
Trigger period of 0 to Trig local Of a linear frequency modulated signal
Figure BDA0003719956880000075
Wherein the slope of the chirp signal is
Figure BDA0003719956880000076
Wherein the Trig local The farthest detectable distance is determined based on a laser coherent ranging system.
Specifically, the process of signal modulation is further described in this example, and the farthest detectable distance of the laser coherent ranging system is set to be L max ，L max Satisfies the following conditions:
Figure BDA0003719956880000077
as shown in fig. 5, when the linear modulator 1 receives the trigger signal, a frequency slave is generated
Figure BDA0003719956880000078
To
Figure BDA0003719956880000079
Time from 0 to Trig local Is shown in fig. 6, assuming that
Figure BDA00037199568800000710
(the frequency modulation scheme is exemplified above, and the frequency down modulation scheme is also applicable to the method of the present application in principle),
Figure BDA0003719956880000081
0<t<Trig local
Figure BDA0003719956880000082
for the laser coherent ranging system shown in fig. 2, the linear modulator 1 can be used to perform linear frequency modulation on the laser seed source to make the seed sourceThe emergent optical frequency loads a linear tuning frequency on the fundamental frequency
Figure BDA0003719956880000083
To
Figure BDA0003719956880000084
One beam of light passes through the beam splitter and serves as a local oscillator. The other beam of light passes through the optical modulator controlled by the linear modulation 2 as signal light and is modulated again.
For the laser coherent ranging system shown in fig. 3, a laser seed source is first split into two beams by a beam splitter, one beam is used as a local oscillator light, and the other beam is used as a signal light. The linear modulator 1 can be used for carrying out linear frequency modulation on the local oscillator light, so that the light frequency emitted by the seed source is loaded with linear tuning frequency on the fundamental frequency
Figure BDA0003719956880000085
To
Figure BDA0003719956880000086
The other beam of light is modulated as signal light by an optical modulator controlled by linear modulation 2.
For the laser coherent ranging system shown in fig. 4, the laser seed source may be internally modulated to generate a linear Chirp signal with a repeating period, and simultaneously generate a trigger electrical signal, which triggers the linear modulator 2 to generate the trigger signal 2.
In some embodiments, as shown in fig. 7, the modulation frequency of the nth pulse of the frequency modulated pulse emitted after modulating the signal light satisfies:
Figure BDA0003719956880000087
wherein, trig sig Denotes the repetition period, k 1 Which represents the chirp rate of the transmitted signal,
Figure BDA0003719956880000088
Figure BDA0003719956880000089
t n the time position of each transmitting signal in a period with the triggering time as 0 meets the following conditions:
(n-1)×Trig sig <t n <(n-1)×Trig sig +T sig
T sig it is shown that the width of the pulse,
Figure BDA00037199568800000810
expressed as the frequency of the termination of the first chirp in the transmitted signal light, based on the optical frequency,
Figure BDA00037199568800000811
indicating the starting frequency of the first chirp on the basis of optical frequency in the transmitted signal light.
In a specific implementation process, taking the above frequency modulation as an example, for the convenience of resolving, it may be specified that:
Figure BDA0003719956880000091
k 1 ＞k 0
for the pulsed laser coherent ranging systems shown in fig. 2 and 4, chopping is performed on the basis of the chirp 1, and the modulation frequency of the chirp 2 in the nth trigger cycle is:
Figure BDA0003719956880000092
for the pulsed laser coherent ranging system shown in fig. 3, the frequency modulated by the linear modulator 2 is:
Figure BDA0003719956880000093
(n-1)×Trig sig <t n <(n-1)×Trig sig +T sig
wherein the repetition period is Trig sig Pulse width of T sig 。
After the pulse passes through the time tau, the pulse is coherent with a local oscillator after passing through a circulator and an amplifier from a lens, and is subjected to sampling and matched filtering processing after passing through a band stop or low-pass detector, and distance calculation is performed according to the matched filtering processing result.
In the laser coherent detection process, signal light passes through the circulator and the optical amplifier and then is combined with local oscillator light, and the combined light enters the detector. Because the photoelectric detector cannot directly detect the optical frequency, according to the basic principle of coherent detection, the sum frequency term generated after the local oscillation optical signals and the local oscillation optical signals are combined cannot be detected, and only the difference frequency term, namely the difference between the optical frequency of the echo signals and the optical frequency of the local oscillation signals, can be detected. In some examples, sampling, matched filtering the acquired echo signals includes:
in some embodiments, the target is at a distance S, passing
Figure BDA0003719956880000094
After time, the echo and the local oscillator light are combined into a beam, and at this time, the local oscillator light frequency is:
Figure BDA0003719956880000095
the optical frequency of the echo signal is as follows:
Figure BDA0003719956880000096
its difference frequency f c (τ', n) is:
Figure BDA0003719956880000097
wherein the content of the first and second substances,
(n-1)×Trig sig <t n <(n-1)×Trig sig +T sig
0<t n -(n-1)×Trig sig <T sig
Figure BDA0003719956880000101
to fix the frequency difference, (k) 1 -k 0 )×(t n -(n-1)Trig sig ) The part is a fixed chirp signal with a modulation frequency of 0 to (k) 1 -k 0 )×T sig Modulation time of 0 to T sig . I.e. f c (τ ', n) is independent of n, and the difference frequency result is only dependent on τ'. When the target distance is closer, i.e. τ'<T sig The result of the difference frequency of N pulses is shown in FIG. 8, and a fixed frequency difference chirp is obtained when the target distance is far, i.e. T sig <τ′<Trig sig The frequency difference results of N pulses are shown in fig. 9, and two kinds of fixed frequency differences chirp are obtained.
From the above analysis, the difference frequency result is independent of N, and the bandwidth of the obtained frequency difference chirp signal is (k) 1 -k 0 )×T sig I.e. the slope is constant, the center frequency is related to the echo time tau'. Further in this example, the Trig is repeated every repetition period according to a trigger signal for modulating the signal light sig Data acquisition and matched filtering processing are carried out, wherein the matched filtering processing adopts the following steps:
determining the difference frequency f between the local oscillator light and the echo signal match Is characterized by a slope of (k) 1 -k 0 ) The frequency range satisfies:
f match_low <f match <f match_high
f match_low ＝f sig (1)-f local2
f match_high ＝f sig (N-1)+k 1 ×T sig -f local1
fitting the frequency of the difference frequency characteristic based on the frequency range, and satisfying the following conditions:
f match (r)＝(k 1 -k 0 )×r+f match_low
wherein r is fitting time and satisfies the following relation:
Figure BDA0003719956880000102
f match_high end frequency, f, representing the design match frequency range match_low A start frequency representing a design match frequency range;
as shown in fig. 10, a matched filter is determined based on the frequency of the fitted difference frequency feature. In the case of a constant slope, f match_low Can be lowered properly, f match_high Can be suitably increased.
In some embodiments, after obtaining the matched filtering results of each repetition period, the matched filtering results are accumulated to maximize the matched result value. Obtaining each Trig sig After the matched filtering result, M (M is more than or equal to N) trigs are used sig The results are accumulated, and the accumulated results are shown in fig. 11 and 12. When τ' =0, according to the designed matched filter (the matched filter can be obtained based on the matched template), the matched filtering result is obtained with the abscissa of N 0 And when the matched filtering result value is maximum. When the target test is carried out, the output result is obtained on the abscissa N 1 (or abscissa N) 1 、N 2 ) A match is achieved (i.e. the output value is maximum and exceeds the detection threshold).
In some embodiments, performing the distance solution according to the result of the matched filtering comprises:
under the condition that only one matching result exists, the distance of the target to be measured meets the following conditions:
Figure BDA0003719956880000111
wherein, f s Representing the sampling rate, N 0 Denotes the abscissa reference of the matching result, N 1 The abscissa value of the actual matching result is represented, and c represents the light speed;
when there are two matching results (N) 1 、N 2 ) In the case of (2), the corresponding abscissa values are each N 1 、N 2 And N is 1 <N 0 <N 2 If N is 2 Corresponding to an amplitude greater than N 1 And (4) processing the corresponding amplitude, wherein the distance of the target to be detected meets the following requirements:
Figure BDA0003719956880000112
if N is present 1 Corresponding to an amplitude greater than N 2 And (4) processing the corresponding amplitude, wherein the distance of the target to be detected meets the following requirements:
Figure BDA0003719956880000113
when adopting integrative pulse laser range finding of receiving and dispatching, at the transmission moment, there is some signal light to directly return from the camera lens face, and this part signal light power is stronger, takes the mode that the detector was shut off at the transmission moment, can cause each transmission moment of transmission to all can't survey the echo signal, in longer distance, has a plurality of blind spot. The method of the application utilizes a high repetition frequency receiving and transmitting integrated pulse laser coherent ranging method based on linear frequency modulation local oscillator to reach a specified short time (such as
Figure BDA0003719956880000121
Num is a positive integer), the frequency of the echo light from the lens is within
Figure BDA0003719956880000122
Figure BDA0003719956880000123
Within the range, by selecting a band-stop or low-pass detector which does not respond in the frequency band, long-distance detection with shorter blind distance can be realized. The phenomenon that the distance cannot be measured due to a plurality of blind spot under the condition of high repetition frequency is avoided. When the distance is measured, the multiple frequency is not needed to be changed by controlling the trigger time, and the multiple frequency ambiguity resolution calculation is carried out; the remote measurement can be realized only by the design of the local oscillator light repetition frequency.
The embodiment of the present application further provides a laser coherent ranging apparatus, which includes a memory and a processor, where the memory stores a computer program, and the computer program is executed by the processor to implement the steps of the laser coherent ranging method.
An embodiment of the present application further provides a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the steps of the foregoing laser coherent ranging method are implemented.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising a component of' 8230; \8230;" does not exclude the presence of another like element in a process, method, article, or apparatus that comprises the element.
The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.
Through the description of the foregoing embodiments, it is clear to those skilled in the art that the method of the foregoing embodiments may be implemented by software plus a necessary general hardware platform, and certainly may also be implemented by hardware, but in many cases, the former is a better implementation. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which is stored in a storage medium (such as ROM/RAM, magnetic disk, optical disk) and includes instructions for enabling a terminal (such as a mobile phone, a computer, a server, an air conditioner, or a network device) to execute the method according to the embodiments of the present invention.
While the present invention has been described with reference to the particular illustrative embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various modifications, equivalent arrangements, and equivalents thereof, which may be made by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (8)

1. A pulse laser coherent ranging method based on a linear frequency modulation local oscillator is characterized by comprising the following steps:
generating a linear frequency modulation signal in a preset frequency interval under the condition that the first linear modulator is triggered;
performing linear frequency modulation on a target signal based on the generated linear frequency modulation signal, so that the optical frequency emitted by the seed source loads the linear frequency modulation signal on a fundamental frequency to form a first signal;
modulating signal light, and determining the slope and pulse period of the linear frequency modulation signal according to the modulation frequency of the modulated transmitted frequency modulation pulse;
combining the modulated signal light and the first signal;
after the combined optical signal passes through a detector, sampling and matched filtering processing are carried out on the obtained echo signal;
and carrying out distance calculation according to the result of the matched filtering.
2. The laser coherent ranging method of claim 1, wherein the generating of the chirp signal of the preset frequency interval in case that the first linear modulator is triggered comprises:
in the case of the first linear modulator being triggered, a frequency slave is generated
Figure FDA0003719956870000011
To
Figure FDA0003719956870000012
Trigger period is 0 to Trig local Of a linear frequency modulated signal
Figure FDA0003719956870000013
Wherein the slope of the chirp signal is
Figure FDA0003719956870000014
Wherein the Trig local The farthest detectable distance is determined based on a laser coherent ranging system.
3. The laser coherent ranging method according to claim 2, wherein a modulation frequency of an nth pulse of the frequency modulated pulses emitted after modulating the signal light satisfies:
Figure FDA0003719956870000015
wherein, trig sig Denotes the repetition period, k 1 Which represents the chirp rate of the transmitted signal,
Figure FDA0003719956870000016
Figure FDA0003719956870000017
t n the time position of each transmitting signal is represented by taking the triggering time as 0 time in a period, and the following conditions are satisfied:
(n-1)×Trig sig ＜t n ＜(n-1)×Trig sig +T sig
T sig it is shown that the width of the pulse,
Figure FDA0003719956870000021
expressed as the frequency of the termination of the first chirp in the transmitted signal light, based on the optical frequency,
Figure FDA0003719956870000022
indicating the starting frequency of the first chirp on the basis of optical frequency in the transmitted signal light.
4. The laser coherent ranging method of claim 3, wherein the matched filtering process of the acquired echo signals comprises:
according to a trigger signal for modulating signal light, data acquisition and matched filtering processing are carried out in each repetition period, wherein the matched filtering processing adopts the following steps:
determining the frequency range of the difference frequency characteristics between the local oscillator light and the echo signal:
fitting the frequency of the difference frequency characteristic based on the frequency range, and satisfying the following conditions:
f match (r)＝(k 1 -k 0 )×r+f match_low
wherein r is fitting time, and satisfies the following conditions:
Figure FDA0003719956870000023
f match_high end frequency, f, representing the design match frequency range match_low A start frequency representing a design match frequency range;
a matched filter is determined based on the frequency of the fitted difference frequency signature.
5. The laser coherent ranging method of claim 4, wherein after the matched filtering results for each repetition period are obtained, the matched filtering results are accumulated so that a matched result value is maximized.
6. The laser coherent ranging method of claim 5, wherein the distance solution according to the result of the matched filtering comprises:
under the condition that only one matching result exists, the distance of the target to be measured meets the following conditions:
Figure FDA0003719956870000024
wherein, f s Representing the sampling rate, N 0 Denotes the abscissa reference of the matching result, N 1 The abscissa value of the actual matching result is represented, and c represents the light speed;
when there are two matching results (N) 1 、N 2 ) In the case of (2), the corresponding abscissa values are each N 1 、N 2 And N is 1 ＜N 0 ＜N 2 If N is 2 Where the corresponding amplitude is greater than N 1 And (3) processing the corresponding amplitude, wherein the distance of the target to be detected meets the following requirements:
Figure FDA0003719956870000031
if N is present 1 Corresponding to an amplitude greater than N 2 And (3) processing the corresponding amplitude, wherein the distance of the target to be detected meets the following requirements:
Figure FDA0003719956870000032
7. a laser coherent ranging device comprising a memory and a processor, the memory storing a computer program which when executed by the processor implements the steps of the laser coherent ranging method of any one of claims 1 to 6.
8. A computer-readable storage medium, characterized in that a computer program is stored thereon, which computer program, when being executed by a processor, carries out the steps of the laser coherent ranging method according to one of the claims 1 to 6.
CN202210747763.7A 2022-06-29 2022-06-29 Pulse laser coherent ranging method and device based on linear frequency modulation local oscillator Pending CN115220055A (en)

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