CN110266398B - Underwater submarine communication method for air-based system - Google Patents

Underwater submarine communication method for air-based system Download PDF

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CN110266398B
CN110266398B CN201910451768.3A CN201910451768A CN110266398B CN 110266398 B CN110266398 B CN 110266398B CN 201910451768 A CN201910451768 A CN 201910451768A CN 110266398 B CN110266398 B CN 110266398B
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CN110266398A (en
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柯熙政
杨尚君
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Xian University of Technology
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/60—Receivers
    • H04B10/61—Coherent receivers
    • H04B10/63—Homodyne, i.e. coherent receivers where the local oscillator is locked in frequency and phase to the carrier signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/80—Optical aspects relating to the use of optical transmission for specific applications, not provided for in groups H04B10/03 - H04B10/70, e.g. optical power feeding or optical transmission through water
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0056—Systems characterized by the type of code used
    • H04L1/0059—Convolutional codes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/14—Two-way operation using the same type of signal, i.e. duplex

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Abstract

The invention discloses an air-based system underwater submersible communication device and a communication method, wherein the air-based system underwater submersible communication device is utilized, and the transmission method comprises the following steps: splitting a light source to obtain a first light source and a second light source, and splitting the second light source into a first horizontal polarized light signal and a first vertical polarized light signal; encoding a source of a downlink; modulating the coded information source to a first horizontal polarized light signal, combining and separating the first horizontal polarized light signal and a first vertical polarized light signal, delaying the separated vertical polarized light signal, and then performing coherent detection, decoding and decoding on the horizontal polarized light signal and the vertical polarized light signal to complete transmission of downlink information; encoding a source of an uplink; carrying out secondary modulation on the second vertical polarized light signal by using the coded signal source; and carrying out coherent detection, decoding and decoding on the modulated signal and the first light source to finish the transmission of uplink information.

Description

Underwater submarine communication method for air-based system
Technical Field
The invention belongs to the technical field of communication methods, relates to an underwater submersible communication device of an air-based system, and further relates to a communication method of the underwater submersible communication device of the air-based system.
Background
One of the common submarine communication modes is ultra-low frequency and very-low frequency electromagnetic waves, and for the communication modes of the ultra-low frequency and very-low frequency electromagnetic waves, the antenna has large size requirement and the available frequency band range is limited; another way of communicating underwater acoustically, the attenuation of sound waves in water is proportional to the square of the frequency, which results in underwater acoustic channels that are bandwidth limited. The submarine communication mode adopting optical communication has low detection sensitivity on a receiving end due to the attenuation of an atmospheric channel and a seawater channel to optical signals, and meanwhile, few mention is made on the communication of an air-based system uplink.
Disclosure of Invention
The invention aims to provide an underwater submersible communication device of a space-based system, which can improve the detection sensitivity of a receiving end of a duplex link.
The underwater submarine alignment communication device of the air-based system comprises a downlink device and an uplink device, wherein the downlink device comprises a laser, the laser is connected with a beam splitter, one output end of the beam splitter is connected with a first polarization beam splitter, the first output end of the first polarization beam splitter is connected with a modulator, the input end of the modulator is connected with a first encoder, the output end of the modulator is connected with a polarization beam combiner, and the second output end of the first polarization beam splitter is connected with the polarization beam combiner; the output end of the polarization beam combiner is connected with a second polarization beam splitter through an optical antenna, the first output end of the second polarization beam splitter is connected with a first coherent receiver, the second output end of the second polarization beam splitter is connected with a delayer, and the delayer is connected with the first coherent receiver;
the uplink device comprises a reverse modulator, the input end of the reverse modulator is connected with the second output end of the second polarization beam splitter, the input end of the reverse modulator is further connected with a second encoder, the output end of the reverse modulator is connected with a second coherent receiver through an optical antenna, and the input end of the second coherent receiver is connected with the other output end of the beam splitter.
The invention is also characterized in that:
the first coherent receiver comprises a coherent detector, a decoder and a decoder connected in sequence.
The invention further aims to provide an underwater submersible communication method for the air-based system, which can realize two-way communication of an uplink and a downlink.
The invention adopts another technical scheme that an air-based system underwater submersible communication method is adopted, the air-based system underwater submersible communication device is utilized, and the transmission method comprises the following steps:
step 1, splitting a light source to obtain a first light source and a second light source, and splitting the second light source into a first horizontal polarized light signal and a first vertical polarized light signal;
step 2, coding the information source of the downlink;
step 3, modulating the coded information source to a first horizontal polarized light signal to obtain a second horizontal polarized light signal;
step 4, combining the second horizontal polarized light signal and the first vertical polarized light signal;
step 5, separating the combined optical signals to obtain a third horizontal polarized optical signal and a second vertical polarized optical signal;
step 6, delaying the second vertical polarized light signal, then performing coherent detection on the third horizontal polarized light signal and the delayed second vertical polarized light signal, and decoding the output baseband signal to complete the transmission of downlink information;
step 7, coding the information source of the uplink;
step 8, performing secondary modulation on the second vertical polarized light signal by using the coded information source to obtain a third vertical polarized light signal;
and 9, performing coherent detection, decoding and decoding on the third vertical polarized light signal and the first light source to finish the transmission of uplink information.
The present invention is also characterized in that,
step 1, firstly splitting a light source to obtain a first light source and a second light source E, and then splitting the second light source E into a first horizontal polarized light signal ExAnd a first vertically polarized optical signal Ey；
Ex＝Exmcos(ωt-kz+φx) (1)；
Ey＝Eymcos(ωt-kz+φy) (2)；
Wherein Exm、EymIs the amplitude of the optical signal in the x and y polarization directions, omega is the angular frequency of the light wave, k is the wave vector, phixAnd phiyInitial phase of x and y polarization directions, t and z are time variable and space variable, respectively, and electric field E of the synthesized wave optical signal is equal to ExEx+eyEy；
Step 2, coding the information source of the downlink by adopting a Turbo code coding mode to obtain a baseband sequence { ck}；
Step 3, adopting a 16QAM modulation mode to carry out alignment on the baseband sequence { ckModulate with corresponding amplitude and phase after every 4 code words are mapped to obtain the second code wordOptical field E of two-level polarized light signal16QAM：
Figure BDA0002075366400000031
m＝(ckck+1)2，n＝(ck+2ck+3)2 (4)；
Step 4, combining the second horizontal polarized light signal and the first vertical polarized light signal by using a polarization beam combiner;
step 5, separating the combined optical signals to obtain a third horizontal polarized optical signal EsAnd a second vertically polarized optical signal ELo；
Figure BDA0002075366400000041
Step 6, firstly, delaying the time T of the second vertical polarized light signal, then carrying out self-homodyne coherent detection on the third horizontal polarized light signal and the delayed second vertical polarized light signal, and outputting two paths of baseband signals Ii(t) and Iq(t); applying baseband signal processing algorithm to baseband signal Ii(t) and Iq(t) decoding to obtain a recovered baseband sequence { c'k}; for recovered baseband sequence { c'kDecoding is carried out, and the transmission of downlink information is completed;
step 7, Turbo code coding is carried out on the information source of the uplink to obtain a coded sequence sk；
Step 8, changing the defocusing amount of the second vertical polarized light signal passing through the lens by using the cat eye structure of the reverse modulator, and passing through a sequence skChanging the second vertical polarized light signal according to the corresponding relation with the defocusing amount to obtain a third vertical polarized light signal;
and 9, performing coherent detection on the third vertical polarized light signal and the first light source by adopting a homodyne coherent detection mode, and then decoding and decoding the baseband signal output by the coherent detection to obtain a second vertical polarized light signal so as to finish the transmission of uplink information.
The step 6 specifically comprises the following steps:
step 6.1, firstly, a time delayer is adopted to firstly delay the time T of the second vertical polarized light signal, then the self-homodyne coherent detection is carried out on the third horizontal polarized light signal and the delayed second vertical polarized light signal, and two paths of baseband signals I are outputi(t) and Iq(t)：
Figure BDA0002075366400000042
Figure BDA0002075366400000043
Wherein beta is a photoelectric conversion coefficient of the balance detector, and j is an imaginary number dimension;
step 6.2, base band signal Ii(t) and Iq(t) filtering the baseband signal Ii(t) and Iq(t) extracting and sampling the bit timing pulse, and sampling and judging the filtered output waveform at a specified time to obtain a recovered baseband sequence { c'k}；
Step 6.3, utilizing a Turbo code iterative decoder to recover the baseband sequence { c'kDecoding, initializing the input information symbol probability log-likelihood ratio Λ (u; I) of a component decoder A in the Turbo code iterative decoder to 0 when performing iterative decoding for the first time, and taking the decoded output information symbol probability log-likelihood ratio Λ (u; O) as the input information symbol probability log-likelihood ratio after interleaving:
Figure BDA0002075366400000051
after a component decoder B in the Turbo code iterative decoder decodes and outputs, the first iterative decoding is finished, then an information symbol probability log-likelihood ratio generated by a component decoder B decoding module in the Turbo code iterative decoder is interleaved and fed back to a component decoder A decoding module to be used as prior information of the next decoding:
Figure BDA0002075366400000052
in the above formula, the superscript indicates that the different component decoding modules are corresponded, the subscript indicates that the interleaving process is performed, I-1Indicating de-interleaving;
repeating the above process until reaching a certain number of iterations or satisfying a certain iteration condition; and finally, carrying out hard decision according to the output information symbol probability log-likelihood ratio value lambda (u; O) of a component decoder B in the Turbo code iterative decoder to obtain decoding output and finish the transmission of downlink information.
The step 8 specifically comprises the following steps:
the second coherent receiver receives the reflected echo power p of the cat eye target of the inverse modulatorrComprises the following steps:
Figure BDA0002075366400000053
in the above formula, ptFor laser emission power, τaIs the atmospheric transmittance, taurFor receiving the optical system transmittance, psIs the reflection coefficient, D is the aperture of the focusing lens, f is the focal length of the lens, theta0Is the beam divergence angle, d is the defocus, r is the distance between the inverse modulator and the second coherent receiver;
echo power p is carried out by controlling defocusing amount d of cat eye structurerModulated, modulated second vertically polarized light signal light field E4ASKComprises the following steps:
Figure BDA0002075366400000061
by(s)ksk+1)2Changing the value of d to complete the light field E4ASKAnd obtaining a third vertically polarized optical signal.
The invention has the beneficial effects that:
according to the underwater submarine communication device of the air-based system, the down link device adopts the self-homodyne coherent detector, the up link adopts the homodyne coherent detector, and the receiving ends of the duplex links improve the detection sensitivity, so that the communication in the air-based system is more reliable; the uplink communication adopts a reverse modulator, and utilizes the characteristic of reverse modulation return light, so that a capture tracking system and a receiving light source of a passive end (seawater end) are omitted, and the two-way communication of the submarine and the airplane is realized.
According to the underwater pair-submersible communication method of the air-based system, Turbo coding is carried out on the transmitted information source, so that the anti-interference capacity of the signal can be improved; because the same laser light source is used for the uplink and the downlink, the frequencies of the signal light and the local oscillator light are completely the same, a homodyne coherent detection mode with high sensitivity (the homodyne detection has a gain of 23dB relative to the direct detection) is used, and the cat eye reverse modulation mode is adopted to realize the communication of the uplink.
Drawings
FIG. 1 is a schematic structural diagram of an underwater submersible communication device of an air-based system of the invention;
FIG. 2 is a schematic structural diagram of a coherent receiver of an underwater submersible communication device of an air-based system according to the present invention;
FIG. 3 is a schematic structural diagram of an encoder in the underwater submersible communication method of the air-based system of the invention;
FIG. 4 is a second horizontal polarized light signal 16QAM signal constellation diagram in the underwater submarine-pair communication method of the air-based system of the present invention;
FIG. 5 is a demodulation flowchart of a decoder in the underwater submersible pair communication method of the air-based system according to the invention;
FIG. 6 is a schematic structural diagram of a decoder in the underwater submersible communication method of the air-based system according to the invention;
FIG. 7 is a schematic diagram of a cat eye structure of a reverse modulator in the underwater submersible communication method of the air-based system of the present invention;
fig. 8 is a constellation diagram of a third vertically polarized light signal after 4ASK modulation in the underwater submarine-pair communication method of the air-based system of the present invention.
In the figure, 1, a laser, 2, a beam splitter, 3, a modulator, 4, a first encoder, 5, a polarization beam combiner, 6, a second coherent receiver, 7, a second polarization beam splitter, 8, a first coherent receiver, 8-1, a coherent detector, 8-2, a decoder, 8-3, a decoder, 9, a reverse modulator, 10, a second encoder, 11, a time delay device, 12, a beam splitter.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
An underwater vehicle communication device of a space-based system comprises a downlink (from atmosphere to seawater) device and an uplink (from seawater to atmosphere) device, wherein the downlink device comprises a laser 1, the laser 1 is connected with a beam splitter 12, one output end of the beam splitter 12 is connected with a first polarization beam splitter 2, the first output end of the first polarization beam splitter 2 is connected with a modulator 3, the input end of the modulator 3 is connected with a first encoder 4, the output end of the modulator 3 is connected with a polarization beam combiner 5, the second output end of the first polarization beam splitter 2 is connected with the polarization beam combiner 5, the first output end of the first polarization beam splitter 2 outputs a first horizontal polarization light signal, and the second output end of the first polarization beam splitter 2 outputs a first vertical polarization light signal; the light source emitted by the laser 1 is single light source blue-green light.
The output end of the polarization beam combiner 5 is connected with a second polarization beam splitter 7 through an optical antenna, the first output end of the second polarization beam splitter 7 is connected with a first coherent receiver 8, the second output end of the second polarization beam splitter 7 is connected with a time delayer 11, the first output end of the second polarization beam splitter 7 outputs a third horizontal polarized light signal, the second output end of the second polarization beam splitter 7 outputs a second vertical polarized light signal, and the time delayer 11 is connected with the first coherent receiver 8.
The first polarization beam splitter 2, the modulator 3, the first encoder 4 and the polarization beam combiner 5 are the transmitting end of the downlink device and are located in the atmosphere, and the second polarization beam splitter 7, the delayer 11 and the first coherent receiver 8 are the receiving end of the downlink device and are located in the seawater.
The uplink device comprises a reverse modulator 9, the input end of the reverse modulator 9 is connected with the second output end of the second polarization beam splitter 7, the input end of the reverse modulator 9 is further connected with a second encoder 10, the output end of the reverse modulator 9 is connected with a second coherent receiver 6 through an optical antenna, and the input end of the second coherent receiver 6 is connected with the other output end of the beam splitter 12. The inverse modulator 9 and the second encoder 10 are the transmitting end of the uplink and are located in the seawater, and the second coherent receiver 6 is the receiving end of the uplink and is located in the atmosphere.
The first coherent receiver 8 comprises a coherent detector 8-1, a decoder 8-2 and a decoder 8-3 connected in series.
Preferably, the coherent detector 8-1 is a self-homodyne coherent detector, the decoder 8-2 is a baseband signal decoder, and the decoder 8-3 is a Turbo code iterative decoder.
The second coherent receiver 6 has the same structure as the first coherent receiver 8, and its coherent detector is a homodyne coherent detector.
An underwater submersible communication method for an air-based system specifically comprises the following steps:
step 1, splitting a light source to obtain a first light source and a second light source E, and splitting the second light source E into a first horizontal polarized light signal and a first vertical polarized light signal;
specifically, first, a single-light-source blue-green light emitted by the laser 1 is split by the beam splitter 12 to obtain a first light source and a second light source E, the first light source is used for coherent detection with an uplink, and then the second light source E is split into a first horizontal polarized light signal ExAnd a first vertically polarized optical signal Ey；
Ex＝Exmcos(ωt-kz+φx) (1)；
Ey＝Eymcos(ωt-kz+φy) (2)；
Wherein Exm、EymIs the amplitude of the optical signal in the x and y polarization directions, omega is the angular frequency of the light wave, k is the wave vector, phixAnd phiyInitial phase of x and y polarization directions, t and z are time variable and space variable, respectively, and electric field E of the synthesized wave optical signal is equal to ExEx+eyEy。
Step 2, adopting a first encoder 4 to encode the information source of the downlink to obtain a baseband sequence { c }k}；
Specifically, as shown in fig. 2, in the Turbo code encoding process, the input information sequences of the two component codes are the same, and the information sequence with the length N { u }kThe system output is used as the coding of the component coder A at the same time
Figure BDA0002075366400000091
Directly to the multiplexer while { u }kInterlace sequence after interleaver I { u }nIt is sent to component encoder B. The output check sequences of the two component encoders are respectively
Figure BDA0002075366400000092
And
Figure BDA0002075366400000093
in order to improve the code rate and the system spectrum efficiency, two check sequences can be obtained after deleting the matrix and deleting
Figure BDA0002075366400000094
And then output with the system
Figure BDA0002075366400000095
Are multiplexed together to form a codeword sequence ck}。
Step 3, adopting a 16QAM modulation mode and utilizing a modulator 3 to carry out pair of baseband sequences { ckModulating the mapped 4 code words with corresponding amplitude and phase to obtain a second horizontal polarized light signal light field E16QAM：
Figure BDA0002075366400000096
m＝(ckck+1)2，n＝(ck+2ck+3)2 (4)；
Wherein (c)kck+1)2And (c)k+2ck+3)2Representing the conversion of binary values into decimal values;
in particular, for the baseband sequence ckAfter mapping every 4 code words, modulating the code words with corresponding amplitudes A,2A,3A,4A and phases 0, pi/2, pi, 3 pi/2 to obtain a modulation signal light field expression E16QAMTable 1 shows coding rules corresponding to 16 QAM.
Table 116 QAM modulation source correspondence table
ck,ck+1,ck+2,ck+3 S16QAM
0 0 0 0 E16QAM＝A·Exmcos(ωt-kz+φx+0)
0 0 0 1 E16QAM＝A·Exmcos(ωt-kz+φx+π/2)
0 0 1 0 E16QAM＝A·Exmcos(ωt-kz+φx+π)
0 0 1 1 E16QAM＝A·Exmcos(ωt-kz+φx+3π/2)
0 1 0 0 E16QAM＝2A·Exmcos(ωt-kz+φx+0)
0 1 0 1 E16QAM＝2A·Exmcos(ωt-kz+φx+π/2)
0 1 1 0 E16QAM＝2A·Exmcos(ωt-kz+φx+π)
0 1 1 1 E16QAM＝2A·Exmcos(ωt-kz+φx+3π/2)
1 0 0 0 E16QAM＝3A·Exmcos(ωt-kz+φx+0)
1 0 0 1 E16QAM＝3A·Exmcos(ωt-kz+φx+π/2)
1 0 1 0 E16QAM＝3A·Exmcos(ωt-kz+φx+π)
1 0 1 1 E16QAM＝3A·Exmcos(ωt-kz+φx+3π/2)
1 1 0 0 E16QAM＝4A·Exmcos(ωt-kz+φx+0)
1 1 0 1 E16QAM＝4A·Exmcos(ωt-kz+φx+π/2)
1 1 1 0 E16QAM＝4A·Exmcos(ωt-kz+φx+π)
1 1 1 1 E16QAM＝4A·Exmcos(ωt-kz+φx+3π/2)
The constellation diagram of the modulated transmitted second horizontal polarized optical signal 16QAM is shown in fig. 3.
And 4, combining the second horizontal polarized light signal and the first vertical polarized light signal by using a polarization beam combiner 5.
Step 5, separating the combined optical signal by using a second polarization beam splitter 7 to obtain a third horizontal polarized optical signal (i.e. signal light) and a second vertical polarized optical signal (as local oscillator light);
Figure BDA0002075366400000111
and 6, delaying the local oscillator light, then performing coherent detection on the signal light and the delayed local oscillator light, and decoding the output baseband signal to complete the transmission of downlink information.
Step 6.1, the local oscillator light is delayed for time T by adopting the delayer 11 to improve coherence, then self-homodyne coherent detection is carried out on the third horizontal polarized light signal and the delayed second vertical polarized light signal by utilizing the coherent detector 8-1, and two paths of baseband signals I are outputi(t) and Iq(t)：
Figure BDA0002075366400000112
Figure BDA0002075366400000113
Wherein beta is a photoelectric conversion coefficient of the balance detector, and j is an imaginary number dimension;
step 6.2, the baseband signal I is decoded by the decoder 8-2i(t) and Iq(t) performing a filtering process, the synchronous extraction circuit extracting the baseband signal I from the baseband signali(t) and Iq(t) extracting and sampling the bit timing pulse, and sampling and judging the filtered output waveform at a specified time to obtain a baseband sequence { c'k}；
Because the carrier frequency of the signal light is the same as that of the local oscillator light, the output analog signal is directly a baseband signal. As shown in fig. 4, the self-zero-difference coherent detection digital signal processing algorithm firstly performs filtering processing on a received signal by using a receiving filter to filter out channel noise and other interferences, a sampling decision device performs sampling decision on an output waveform of the receiving filter at a specified time to recover a baseband signal, a bit timing pulse for sampling is extracted from the received signal by a synchronous extraction circuit, the accuracy or non-accuracy of the bit timing directly affects the decision effect, and amplitude judgment is used for recovering an actually transmitted baseband sequence { c'k}; recovered baseband sequence { c 'at zero bit error'kIs the baseband sequence { c }k}。
Step 6.3, utilizing decoder 8-3 to pair recovered baseband sequence { c'kAnd decoding to obtain decoded output and finish the transmission of downlink information.
Specifically, as shown in fig. 5, in the first iterative decoding, the input information symbol probability log-likelihood ratio Λ (u; I) of the component decoder a is initialized to 0, and the decoded output information symbol probability log-likelihood ratio Λ (u; O) is used as the input information symbol probability log-likelihood ratio after interleaving
Figure BDA0002075366400000121
After the component decoder B decodes and outputs, the first iterative decoding is finished, then the information symbol probability log-likelihood ratio generated by the component decoder B decoding module is interleaved and fed back to the component decoder A decoding module to be used as prior information of the next decoding
Figure BDA0002075366400000122
Repeating the above process until reaching a certain number of iterations or satisfying a certain iteration condition; and finally, carrying out hard decision according to the output information symbol probability log-likelihood ratio value Λ (u; O) of the component decoder B to obtain decoding output.
Step 7, encoding the uplink information source by using a second encoder 10;
coding the information source of the uplink to obtain a coded sequence sk；
Step 8, changing the defocusing amount of the second vertical polarized light signal passing through the lens by adopting the cat eye structure of the reverse modulator 9, and passing through a sequence ckChanging the corresponding relation with the defocusing amount to change the optical field E of the second vertical polarized light signal4ASKAnd obtaining a third vertical polarized light signal.
Table 24 ASK modulation source correspondence table
Figure BDA0002075366400000123
Figure BDA0002075366400000131
Specifically, as shown in fig. 6, when the reflector is located at the defocused surface, the incident light beam will return exactly as it is, and when the reflector is defocused, the incident light beam diverges, and the power of the retroreflected light is modulated by controlling the defocusing amount of the "cat eye" structure. The second coherent receiver 6 receives the reflected echo power p of the cat eye targetrIs composed of
Figure BDA0002075366400000132
Wherein p istFor laser emission power, τaIs the atmospheric transmittance, taurFor receiving the optical system transmittance, psIs the reflection coefficient, D is the aperture of the focusing lens, f is the focal length of the lens, theta0The beam divergence angle, d the defocus and r the distance of the inverse modulator to the second coherent receiver 6. Therefore, the second vertical polarized light signal light field E after modulation by the cat eye4ASKIs expressed as
Figure BDA0002075366400000133
By(s)ksk+1)2Changing the value of d to complete the light field E4ASKFig. 7 is a constellation diagram of the third vertically polarized light signal after 4ASK modulation.
And 9, performing coherent detection on the third vertical polarized light signal and the first light source by using a second coherent receiver 6 in a homodyne coherent detection mode, and then decoding and decoding a baseband signal output by the coherent detection to obtain a second vertical polarized light signal so as to complete transmission of uplink information. The method of decoding and decoding the baseband signal is the same as that of the downlink.
Through the mode, the underwater pair-diving communication device and the communication method of the air-based system, disclosed by the invention, have the advantages that the downlink device adopts a self-homodyne coherent detection mode, the uplink adopts a homodyne coherent detection mode, and the receiving ends of the duplex links improve the detection sensitivity, so that the communication in the air-based system is more reliable; the uplink communication adopts a reverse modulation mode, and utilizes the characteristic of reverse modulation return light, so that a capture tracking system and a receiving light source of a passive end (seawater end) are omitted, and the two-way communication of a submarine (seawater) and an airplane (atmosphere) is realized. The full-duplex communication system of the airplane and the submarine is realized by utilizing the characteristic that the attenuation of blue-green light in the atmosphere and the sea water is small, adopting a self-homodyne coherent detection mode in a downlink and adopting a reverse modulation and homodyne coherent detection mode in an uplink.

Claims (2)

1. An underwater pair submersible communication method of an air-based system utilizes the underwater pair submersible communication device of the air-based system to transmit, the underwater pair submersible communication device of the air-based system comprises a downlink device and an uplink device, the downlink device comprises a laser (1), the laser (1) is connected with a beam splitter (12), one output end of the beam splitter (12) is connected with a first polarization beam splitter (2), the first output end of the first polarization beam splitter (2) is connected with a modulator (3), the input end of the modulator (3) is connected with a first encoder (4), the output end of the modulator (3) is connected with a polarization beam combiner (5), and the second output end of the first polarization beam splitter (2) is connected with the polarization beam combiner (5); the output end of the polarization beam combiner (5) is connected with a second polarization beam splitter (7) through an optical antenna, the first output end of the second polarization beam splitter (7) is connected with a first coherent receiver (8), the second output end of the second polarization beam splitter (7) is connected with a time delay device (11), and the time delay device (11) is connected with the first coherent receiver (8); the uplink device comprises a reverse modulator (9), wherein the input end of the reverse modulator (9) is connected with the second output end of the second polarization beam splitter (7), the input end of the reverse modulator (9) is further connected with a second encoder (10), the output end of the reverse modulator (9) is connected with a second coherent receiver (6) through an optical antenna, the input end of the second coherent receiver (6) is connected with the other output end of the beam splitter (12), and the transmission method comprises the following steps:
step 1, firstly splitting a light source to obtain a first light source and a second light source E, and then splitting the second light source E into a first horizontal polarized light signal ExAnd a first vertically polarized optical signal Ey；
Ex＝Exmcos(ωt-kz+φx) (1)；
Ey＝Eymcos(ωt-kz+φy) (2)；
Wherein Exm、EymIs the amplitude of the optical signal in the x and y polarization directions, omega is the angular frequency of the light wave, k is the wave vector, phixAnd phiyInitial phase of x and y polarization directions, t and z are time variable and space variable, respectively, and electric field E of the synthesized wave optical signal is equal to ExEx+eyEy；
Step 2, coding the information source of the downlink by adopting a Turbo code coding mode to obtain a baseband sequence { ck}；
Step 3, adopting a 16QAM modulation mode to carry out alignment on the baseband sequence { ckModulating every 4 code words after mapping with corresponding amplitude and phase to obtain a second horizontal polarized light signal light field E16QAM：
Figure FDA0002664651080000021
m＝(ckck+1)2，n＝(ck+2ck+3)2 (4)；
Step 4, combining the second horizontal polarized light signal and the first vertical polarized light signal by using a polarization beam combiner;
step 5, separating the combined optical signals to obtain a third horizontal polarized optical signal EsAnd a second vertically polarized optical signal ELo；
Figure FDA0002664651080000022
Step 6, firstly, delaying the time T of the second vertical polarized light signal, then carrying out self-homodyne coherent detection on the third horizontal polarized light signal and the delayed second vertical polarized light signal, and outputting two paths of baseband signals Ii(t) and Iq(t); applying a baseband signal processing algorithm to the baseband signal Ii(t) and Iq(t) decoding to obtain a recovered baseband sequence { c'k}; to the recovered baseband sequence { c'kDecoding is carried out, and the transmission of downlink information is completed;
step 7, Turbo code coding is carried out on the information source of the uplink to obtain a coded sequence sk；
Step 8, changing the distance of the second vertical polarized light signal passing through the lens by using the cat eye structure of the reverse modulatorAmount of coke by the sequence skChanging the second vertical polarized light signal according to the corresponding relation with the defocusing amount to obtain a third vertical polarized light signal;
the second coherent receiver (6) receives the reflected echo power p of the target cat eye of the inverse modulatorrComprises the following steps:
Figure FDA0002664651080000031
in the above formula, ptFor laser emission power, τaIs the atmospheric transmittance, taurFor receiving the optical system transmittance, psIs the reflection coefficient, D is the aperture of the focusing lens, f is the focal length of the lens, theta0Is the beam divergence angle, d is the defocus, r is the distance between the inverse modulator (9) and the second coherent receiver (6);
echo power p is carried out by controlling defocusing amount d of cat eye structurerModulated, modulated second vertically polarized light signal light field E4ASKComprises the following steps:
Figure FDA0002664651080000032
by(s)ksk+1)2Changing the value of d to complete the light field E4ASKObtaining a third vertical polarized light signal;
and 9, performing coherent detection on the third vertical polarized light signal and the first light source by adopting a homodyne coherent detection mode, and then decoding and decoding the baseband signal output by the coherent detection to obtain a second vertical polarized light signal so as to finish the transmission of uplink information.
2. The underwater submersible communication method for the air-based system according to claim 1, wherein the step 6 specifically comprises the following steps:
step 6.1, firstly, a time delayer (11) is adopted to firstly carry out time T delay on the second vertical polarized light signal, and then the second vertical polarized light signal is delayedThe third horizontal polarized light signal and the delayed second vertical polarized light signal are subjected to self-homodyne coherent detection, and two paths of baseband signals I are outputi(t) and Iq(t)：
Figure FDA0002664651080000033
Figure FDA0002664651080000034
Wherein beta is a photoelectric conversion coefficient of the balance detector, and j is an imaginary number dimension;
step 6.2, base band signal Ii(t) and Iq(t) filtering the baseband signal Ii(t) and Iq(t) extracting and sampling the bit timing pulse, and sampling and judging the filtered output waveform at a specified time to obtain a recovered baseband sequence { c'k}；
Step 6.3, utilizing a Turbo code iterative decoder to carry out iterative decoding on the recovered baseband sequence { c'kDecoding, initializing the input information symbol probability log-likelihood ratio Λ (u; I) of a component decoder A in the Turbo code iterative decoder to 0 when performing iterative decoding for the first time, and taking the decoded output information symbol probability log-likelihood ratio Λ (u; O) as the input information symbol probability log-likelihood ratio after interleaving:
Figure FDA0002664651080000041
after a component decoder B in the Turbo code iterative decoder decodes and outputs, the first iterative decoding is finished, then an information symbol probability log-likelihood ratio generated by a component decoder B decoding module in the Turbo code iterative decoder is interleaved and fed back to a component decoder A decoding module to be used as prior information of the next decoding:
Figure FDA0002664651080000042
in the above formula, the superscript indicates that the different component decoding modules are corresponded, the subscript indicates that the interleaving process is performed, I-1Indicating de-interleaving;
repeating the above process until reaching a certain number of iterations or satisfying a certain iteration condition; and finally, carrying out hard decision according to the output information symbol probability log-likelihood ratio value lambda (u; O) of the component decoder B in the Turbo code iterative decoder to obtain decoding output and finish the transmission of downlink information.
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CN110912617B (en) * 2019-11-05 2020-10-02 中南大学 Increase and decrease photon system for improving underwater continuous variable quantum key distribution and implementation method thereof
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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013116208A1 (en) * 2012-01-30 2013-08-08 Unipixel Displays, Inc. Method and system for free space optical communication utilizing a modulated electro-optical polymer retro-reflector
CN204906403U (en) * 2015-09-06 2015-12-23 中国计量学院 Two modem devices of free space optical communications
CN105871464A (en) * 2016-05-19 2016-08-17 北京大学 Wireless optical communication system and modulation-demodulation method
CN108306680A (en) * 2017-12-19 2018-07-20 中国人民解放军战略支援部队航天工程大学 A kind of reverse modulation laser netting communication system based on chatoyancy
CN108667516A (en) * 2018-04-09 2018-10-16 北京大学 Polarization based on self adaptive control is concerned with radio optical communication system
CN109217924A (en) * 2018-08-03 2019-01-15 中国人民解放军陆军工程大学 Two-dimensional signal modulation and demodulation device and method for inverse modulation space optical communication

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
HU0700132D0 (en) * 2007-02-06 2007-05-02 Bayer Innovation Gmbh Phase modulator system comprising a beam splitter and a linear polarisation mode phase modulator and method for separating a light beam travelling toward and reflected back from such a phase modulator
US9203211B2 (en) * 2010-12-22 2015-12-01 Xieon Networks S.A.R.L. Optical network component and method for processing data in an optical network

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013116208A1 (en) * 2012-01-30 2013-08-08 Unipixel Displays, Inc. Method and system for free space optical communication utilizing a modulated electro-optical polymer retro-reflector
CN204906403U (en) * 2015-09-06 2015-12-23 中国计量学院 Two modem devices of free space optical communications
CN105871464A (en) * 2016-05-19 2016-08-17 北京大学 Wireless optical communication system and modulation-demodulation method
CN108306680A (en) * 2017-12-19 2018-07-20 中国人民解放军战略支援部队航天工程大学 A kind of reverse modulation laser netting communication system based on chatoyancy
CN108667516A (en) * 2018-04-09 2018-10-16 北京大学 Polarization based on self adaptive control is concerned with radio optical communication system
CN109217924A (en) * 2018-08-03 2019-01-15 中国人民解放军陆军工程大学 Two-dimensional signal modulation and demodulation device and method for inverse modulation space optical communication

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Experimental Study of Free Space Coherent Optical Communication on 1km;Xizheng Ke，et al;《2018 10th International Conference on Advanced Infocomm Technology (ICAIT)》;20180815;61-65 *

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