CN115333645B - Multi-path diversity method and system for communication sonar - Google Patents
Multi-path diversity method and system for communication sonar Download PDFInfo
- Publication number
- CN115333645B CN115333645B CN202210970250.2A CN202210970250A CN115333645B CN 115333645 B CN115333645 B CN 115333645B CN 202210970250 A CN202210970250 A CN 202210970250A CN 115333645 B CN115333645 B CN 115333645B
- Authority
- CN
- China
- Prior art keywords
- frequency
- communication
- frequency code
- path
- optimal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000004891 communication Methods 0.000 title claims abstract description 106
- 238000000034 method Methods 0.000 title claims abstract description 38
- 238000001514 detection method Methods 0.000 claims abstract description 32
- 238000005070 sampling Methods 0.000 claims abstract description 25
- 238000001208 nuclear magnetic resonance pulse sequence Methods 0.000 claims description 36
- 238000010276 construction Methods 0.000 claims description 12
- 238000004590 computer program Methods 0.000 claims description 6
- 239000000969 carrier Substances 0.000 claims description 5
- 238000001914 filtration Methods 0.000 claims description 2
- 230000001902 propagating effect Effects 0.000 claims 1
- 238000005516 engineering process Methods 0.000 abstract description 17
- 238000012545 processing Methods 0.000 abstract description 7
- 230000005540 biological transmission Effects 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- 238000010586 diagram Methods 0.000 description 6
- 238000009825 accumulation Methods 0.000 description 4
- 230000003044 adaptive effect Effects 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 230000009977 dual effect Effects 0.000 description 3
- 238000007906 compression Methods 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000013144 data compression Methods 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 238000005562 fading Methods 0.000 description 1
- 230000010363 phase shift Effects 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 239000013535 sea water Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B13/00—Transmission systems characterised by the medium used for transmission, not provided for in groups H04B3/00 - H04B11/00
- H04B13/02—Transmission systems in which the medium consists of the earth or a large mass of water thereon, e.g. earth telegraphy
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/713—Spread spectrum techniques using frequency hopping
- H04B1/715—Interference-related aspects
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/10—Frequency-modulated carrier systems, i.e. using frequency-shift keying
- H04L27/106—M-ary FSK
-
- 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
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
Abstract
The invention provides a multi-path diversity method and a system for communication sonar, which are the technology for innovating the self-adaptive pseudo-random frequency modulation underwater acoustic communication signal processing mode. Firstly, the full-time sampling method is used for replacing the time accurate synchronization of all layers which are difficult to realize, and the optimal incoherent detection of the maximum value of each of the complex and changeable multi-order multi-path pulse information is realized. On the basis, optimal Rake receiving is carried out on multi-order multi-path pulses formed by each frequency code, so that the output signal-to-noise ratio and stability of the communication sonar are improved, and the communication in an acoustic shadow area where sound waves cannot directly reach frequently occurs is particularly facilitated to be normally carried out. Under the support of the full-time sampling method technology, the underwater acoustic communication signal processing mode taking Rake receiving as a core can construct communication sonar with different communication distances and communication rates according to actual demands, and particularly, the military communication sonar with lower rate and longer communication distance of a blind equalization working mode is developed, so that actual sea warfare service is provided.
Description
Technical Field
The invention relates to the technical field of underwater acoustic communication, in particular to a multi-path diversity method and system for communication sonar.
Background
Underwater acoustic communication is a primary means of underwater information acquisition, transmission and control. Therefore, the research and development and the application of the communication sonar with the universality, the compatibility, the confidentiality and the stability relate to the bureau of establishing world first-class navy, and must be carefully treated and practically solved.
The construction of the underwater acoustic data communication network is an important development direction of the modern underwater acoustic communication technology, and is a core technology of modern informationized local sea warfare. The battlefield information in the network-distribution sea area is transparent to the my, which lays a foundation for winning underwater network war.
However, the underwater acoustic channel is the most difficult recognized wireless channel. The current construction of point-to-point communication sonar and underwater acoustic networks has a series of substantial defects, which limit the application of the network in the military and civil fields, such as: the effective bandwidth of the underwater acoustic channel is very narrow, the communication rate is low, and the distance is short; the strong and rapid random time-space-frequency variation characteristics exist, and the stability and reliability of the underwater acoustic communication and the network are poor; under the dual actions of multi-path expansion with long time delay and large Doppler frequency shift, the signal processing is difficult; easy self-exposure, etc. Inter-symbol interference, which is generated by complex and variable multi-path effects in an underwater acoustic communication channel, is a fundamental obstacle for the correct detection of underwater acoustic communication signals, and must be carefully overcome.
For this reason, from the root cause of the problems in the underwater acoustic communication, in order to explore possible technical approaches for solving or adapting to the problems and key technologies that need to be mainly solved, the inventor of the present invention constructs an autonomous innovative underwater acoustic communication signal processing mode: adaptive pseudo-random frequency modulation. The method comprises four key technologies related to each other: a pseudorandom frequency modulation sequence full time sampling technique, an optimal multi-path diversity technique, a channel parameter self-adaptive technique and a frequency code compression technique. The military communication sonar constructed in the mode can be well adapted to complex and changeable underwater sound communication channels, and universal, compatible, stable and secret underwater sound communication can be carried out.
The propagation of sound waves in water is carried out in the sea at a certain depth. Due to the successive reflections at the sea surface and the sea bottom, when a pulse signal is transmitted, the acoustic signal arriving at the receiving point will consist of a series of pulses, called a multi-path structure. Multi-path propagation is an essential feature of underwater acoustic information transmission. The first problem is how to overcome the difficulty of intersymbol interference generated by multiple paths and realize the correct detection of communication information. Further, how to separate the multipath pulses with different time delays, thereby providing multiple-order independent fading channel paths, and then combining the paths after detection in a proper way, it is possible to obtain the optimal accumulation effect of multiple paths, and improve the output signal to noise ratio of the whole machine. In radio communication, a processing gain of 10dB or more can be brought about. However, in an underwater acoustic communication channel, the multi-path structure is not only time-delayed (up to several hundred ms), but also dependent on the operating frequency, communication distance, etc., from time to time, from place to place (including different transmit-receive transducer depths). In particular, due to the slow propagation speed of the underwater acoustic wave, when the two-way transmission is transmitted and received, a non-negligible Doppler frequency shift is generated, and each-order multi-way pulse has different incidence angles to the same receiving point, so that different frequency shifts are generated. Similarly, each order multipass pulse is reflected from a different nature of interface at a different angle of incidence, and also has a different relative displacement. It is much more difficult to overcome the inter-symbol interference generated by the multipath effect under the dual action of the time domain and the frequency domain, so as to realize the optimal Rake reception. The method is a fundamental obstacle for constructing high-performance communication sonar, and particularly in an acoustic shadow area where acoustic signals cannot directly reach, communication interruption can be caused, so that the problem is not solved effectively at present.
The invention discloses a pseudo-random frequency modulation sequence multi-path diversity technology with mutually known sender and receiver, which is applied to underwater acoustic communication sonar and aims to solve a series of problems caused by underwater acoustic communication multi-path propagation. The military communication sonar constructed by the self-adaptive pseudo-random frequency modulation signal processing mode taking the invention as the core technology can better adapt to the substantial defects of intersymbol interference and the like generated by strong time-space-frequency variation characteristics and multi-path effects in a submarine and acoustic communication channel, realizes the remote and stable point-to-point multimedia communication between submarines and surface vessels (including aircraft carriers), submarines and submarines, underwater unmanned submarines and the like, and provides a basic premise for the construction of an informationized and intelligent submarine local war core combat system.
Disclosure of Invention
The invention provides a multi-path diversity method and a system for communication sonar, which are used for solving the substantial defects in the multi-path transmission channel.
In one aspect, the invention provides a multi-path diversity method for communication sonar, the method comprising the steps of:
S1: designing a pseudo-random frequency modulation sequence according to a specific index of a communication sonar, enabling a sender and a receiver to know the pseudo-random frequency modulation sequence, modulating the pseudo-random frequency modulation sequence by adopting multi-element frequency shift keying (MFSK) to obtain a modulation signal, and transmitting the modulation signal by utilizing a power amplifier and an underwater acoustic transducer;
s2: the modulation frequency codes of single pulses of the pseudorandom frequency modulation sequences in the modulation signals are transmitted through an underwater acoustic channel to obtain a multi-order multi-path pulse sequence, full-time sampling is respectively carried out on the multi-order multi-path pulse sequences corresponding to the frequency codes, and the maximum value of optimal incoherent detection of the multi-order multi-path pulse sequences corresponding to the frequency codes is obtained;
S3: rake receiving is carried out on the maximum value of the optimal incoherent detection of the multi-order multi-path pulse sequence corresponding to each frequency code, so that the optimal output corresponding to each frequency code is obtained, and the output signal to noise ratio of each frequency code is improved;
S4: and comparing the optimal output corresponding to each frequency code with a preset threshold level respectively, and judging the frequency code reached at the current moment of the multi-order multi-path pulse sequence so as to achieve the aim of demodulation.
In a specific embodiment, the designing the pseudo-random frequency modulation sequence according to the specific index of the communication sonar includes: and designing parameters of the frequency code number, the working frequency band, the frequency code pulse width and the transmitting sound power of the pseudo-random frequency modulation sequence according to specific indexes of the communication distance, the communication speed and the error rate of the communication sonar.
In a specific embodiment, the frequency code pulse width is set to the inverse of the communication rate.
In a specific embodiment, the number of complete carriers contained in one of the frequency code pulse widths is preferably greater than 30. Based on this, a suitable carrier frequency is selected in order to increase the energy contained in the pulse signal.
In a specific embodiment, the specific step of S2 is: and performing full-time sampling by adopting optimal incoherent detection of frequency domain based on FFT matched filtering or time domain matched filtering-envelope detection, and performing maximum value detection of full-contained pulse width on the multi-order multi-path pulse sequence corresponding to each frequency code.
In a specific embodiment, the full time sampling method includes:
And setting the pulse width of the frequency code of the pseudo-random frequency modulation sequence as b, and carrying out optimal incoherent detection on the multi-order multi-path pulse sequence corresponding to each frequency code by utilizing a mutually nested double time window with the length of 2b and the mutual time delay of b, wherein the maximum value of the width of b is fully contained.
In a specific embodiment, the specific step of S3 is: and accumulating the energy of the maximum value of the optimal incoherent detection of the multi-order multi-path pulse sequence corresponding to each frequency code. In order to adapt to the detection of weak signals in underwater acoustic communication, the energy of the maximum value of the optimal incoherent detection of the multi-order multi-path pulse sequence corresponding to each frequency code obtained by full-time sampling is respectively accumulated, thereby realizing the Rake receiving effect, effectively improving the signal-to-noise ratio under the condition of weak signals, and particularly realizing the normal communication in the frequent sound-shadow area.
In a specific embodiment, the specific step of S4 is:
And for the MFSK modulation mode, M definite frequency codes form a group, the optimal output corresponding to each frequency code is respectively compared with a preset threshold level, and the frequency code with the optimal output amplitude reaching the threshold level in the group is used as the frequency code reaching the current moment in the multi-order multi-path pulse sequence, so that the decoding purpose is achieved. Since the magnitude of the background noise accumulation will be pre-limited by a preset adaptive threshold level, no interference will occur.
According to a second aspect of the present invention, a computer-readable storage medium is presented, on which a computer program is stored, which computer program, when being executed by a computer processor, carries out the above-mentioned method.
According to a third aspect of the invention, there is provided a multi-path diversity system for communication sonar, the system comprising:
A pseudo-random frequency modulation sequence construction unit: the method comprises the steps of configuring a pseudo-random frequency modulation sequence according to a specific index of a communication sonar, enabling a sender and a receiver to know the pseudo-random frequency modulation sequence, modulating the pseudo-random frequency modulation sequence by adopting multi-element frequency shift keying (MFSK) to obtain a modulation signal, and transmitting the modulation signal by utilizing a power amplifier and an underwater sound transducer;
Full time sampling unit: configuring a modulation frequency code of a single pulse of each pseudorandom frequency modulation sequence in the modulation signal, obtaining a multi-order multi-path pulse sequence through underwater sound channel propagation, and respectively performing full-time sampling on the multi-order multi-path pulse sequence corresponding to each frequency code to obtain the maximum value of optimal incoherent detection of the multi-order multi-path pulse sequence corresponding to each frequency code;
Optimal Rake receiving unit: the method comprises the steps of configuring the maximum value of optimal incoherent detection of the multi-order multi-path pulse sequence corresponding to each frequency code for Rake receiving, and obtaining the optimal output corresponding to each frequency code;
and (3) comparing the judgment demodulation unit: and the optimal output corresponding to each frequency code is respectively compared with a preset threshold level, and the frequency code which is reached at the current moment of the multi-order multi-path pulse sequence is determined.
The military communication sonar constructed by the pseudo-random frequency modulation signal processing method taking the application as the core technology can adapt to the substantial defects of strong time-space variation characteristic, multi-path interference, easiness in self exposure and the like in a submarine and acoustic communication channel, realize the remote and stable point-to-point multimedia communication between submarines and surface vessels (including aircraft carriers), submarines and submarines, underwater unmanned submarines and the like, and provide the basic premise of stable multimedia information transmission for constructing the modern marine local war core combat system of an informatization and intelligent submarine network.
Drawings
The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and together with the description serve to explain the principles of the application. Many of the intended advantages of other embodiments and embodiments will be readily appreciated as they become better understood by reference to the following detailed description. Other features, objects and advantages of the present application will become more apparent upon reading of the detailed description of non-limiting embodiments, made with reference to the accompanying drawings in which:
FIG. 1 is a flow chart of a multi-path diversity method for communication sonar according to an embodiment of the present invention;
fig. 2 is a schematic block diagram of Rake reception in accordance with a specific embodiment of the present invention;
Fig. 3 is a schematic diagram of Rake reception of a measured fourth order multi-path pulse in accordance with an embodiment of the present invention;
FIG. 4 is a block diagram of a multi-path diversity system for communication sonar according to an embodiment of the present invention.
Detailed Description
The application is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the application and are not limiting of the application. It should be noted that, for convenience of description, only the portions related to the present application are shown in the drawings.
It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The application will be described in detail below with reference to the drawings in connection with embodiments.
FIG. 1 shows a flowchart of a multi-path diversity method for communication sonar according to an embodiment of the invention. As shown in fig. 1, the method comprises the steps of:
s101: and designing a pseudo-random frequency modulation sequence according to the specific index of the communication sonar and the underwater sound communication channel condition, and transmitting the frequency code of the pseudo-random frequency modulation sequence which is mutually known by the sender and the receiver after the frequency code is modulated by the MFSK into the underwater sound channel.
In a specific embodiment, designing the pseudo-random frequency modulation sequence according to the specific index of the communication sonar comprises: and designing parameters of the frequency code number, the working frequency band, the frequency code pulse width and the transmitting sound power of the pseudo-random frequency modulation sequence according to specific indexes of the communication distance, the communication speed and the error rate of the communication sonar.
S102: the frequency code of the transmitted pseudo-random frequency modulation single pulse becomes a multi-step multi-path pulse of random time-space-frequency variation after being transmitted through an underwater acoustic communication channel, and the full-time sampling method is adopted to replace the common accurate multi-level time synchronization so as to obtain the maximum value of the optimal incoherent detection of the multi-step multi-path pulse of the randomly arrived modulation frequency code.
S103: and carrying out Rake receiving on the maximum value obtained by multi-order multi-path pulse full-time sampling of each frequency code to obtain the optimal accumulation output effect of each frequency code.
S104: the output of the optimal Rake receiving of each frequency code is compared with a preset threshold level respectively, so that which frequency code in the MFSK modulation arrives in real time is judged, and the aim of demodulation is achieved.
Fig. 2 is a Rake reception schematic block diagram of a specific embodiment of the present invention, and the Rake reception principle of this embodiment is described below with reference to fig. 2.
The multi-order multi-path pulse distribution in the underwater acoustic communication channel has random time-space-frequency variation characteristics, particularly different Doppler frequency shift and phase shift of different multi-path pulses, a full-time sampling method (201) is adopted, and optimal incoherent detection of the maximum frequency domain or time domain is carried out on the multi-order multi-path pulses formed by the modulation frequency code S (f i) of the randomly input pseudo-random frequency modulation sequence, so that the problem of multi-level synchronization of the common accurate time is fundamentally solved.
And summing the maximum values of the multi-order multi-path pulses formed by a certain known modulation frequency code S (f i) of the full-time sampling to obtain the optimal Rake receiving (202) effect of the frequency code, and greatly improving the signal-to-noise ratio of the communication sonar.
And comparing (203) the output of Rake reception with a preset threshold level, if the output is greater than the threshold level, the S (f i) is the frequency code reached by the pseudo-random frequency modulation sequence determined at the moment, and the purpose of decoding is achieved.
The threshold level is related to real-time noise, and needs to be adaptively adjusted, so that noise interference is avoided, correct detection of signals is affected, and the false alarm probability tends to 0. For higher working frequency bands, the noise levels of marine environment noise and ship self-noise are lower, the time correlation is also weaker, the threshold level can be set lower, and the characteristic that higher frequency bands have larger transmission attenuation is compensated to a certain extent, so that the communication distance of communication sonar is improved.
Fig. 3 is a schematic diagram of Rake reception of an actual measured fourth-order multi-path pulse, S (f i) showing a multi-path pulse profile (301) with pulse width b measured in shallow yellow-sea water, including fourth-order accumulated significant pulses, according to an embodiment of the present invention.
Full time sampling (302) the input fourth-order multi-path pulse with full time sampled double time windows a and B of 2B width, each delayed by B, as can be seen from the figure, the first-order multi-path pulse is best incoherent detected with maximum value of B width all comprised by the (2-4) time window (303) of the a path; the second, third and fourth-order multi-path pulses are detected by the (3-5), (5-7) and (7-9) time windows of the B path respectively.
The four-order multi-path pulse formed by certain modulation frequency code S (f i) is subjected to the full accumulation of Rake reception to obtain the maximum value (304) output. And comparing the threshold level to judge whether the S (f i) information arrives in real time, thereby achieving the aim of demodulation.
It is particularly pointed out that the multichannel distribution of the underwater acoustic communication channel has relative stability. In the yellow sea experiment, 5 explosion sound sources are emitted for 5 times at intervals of 5 seconds, the working frequency band of (900-1100) hertz is taken, and the correlation coefficient of the corresponding envelopes of the multi-order multi-way received at different moments reaches 0.92-0.98, so that the method is very beneficial to the realization of the stability of Rake reception; and the full time sampling allows the signal time domain to fluctuate by the order of the pulse width.
FIG. 4 shows a block diagram of a multi-path diversity system for communication sonar, according to an embodiment of the invention. The system comprises a pseudo-random frequency modulation sequence construction unit 401, a full time sampling unit 402, an optimal Rake receiving unit 403 and a contrast decision demodulation unit 404.
In a specific embodiment, the pseudo-random frequency modulation sequence construction unit 401 is configured to design a pseudo-random frequency modulation sequence according to a specific index of the communication sonar, and enable a sender and a receiver to know the pseudo-random frequency modulation sequence, modulate the pseudo-random frequency modulation sequence by using Multiple Frequency Shift Keying (MFSK) to obtain a modulation signal, and then transmit the modulation signal by using a power amplifier and an underwater sound transducer;
The full-time sampling unit 402 is configured to obtain a multi-order multi-path pulse sequence by using a modulation frequency code of a single pulse of each pseudorandom frequency modulation sequence in the modulation signal through underwater acoustic channel propagation, and respectively perform full-time sampling on the multi-order multi-path pulse sequence corresponding to each frequency code to obtain the maximum value of optimal incoherent detection of the multi-order multi-path pulse sequence corresponding to each frequency code;
The best Rake receiving unit 403 is configured to perform Rake reception on a maximum value of best incoherent detection of the multi-order multi-path pulse sequence corresponding to each frequency code, so as to obtain a best output corresponding to each frequency code;
The comparing and demodulating unit 404 is configured to compare the optimal output corresponding to each frequency code with a preset threshold level, and determine the frequency code reached at the current moment of the multi-order multi-path pulse sequence.
As can be seen from the above discussion, on the premise of constructing a communication signal by using pseudo-random frequency modulation sequences which are mutually known by both transmitting and receiving parties, an adaptive pseudo-random frequency modulation system which is organically matched with an all-time sampling technology and uses the best Rake reception as a core technology can be adopted to construct military communication sonar, and the sonar has the following advantages:
1. The key problem of accurate time synchronization signal detection of all layers is replaced by a full-time sampling technology which can adapt to strong time domain and other fluctuation of the underwater acoustic channel, so that the structure is simplified, and the stability is improved;
2. under the support of the full-time sampling technology, the Rake receiving of complex and changeable multi-order multi-path pulses of the underwater sound channel is realized, the difficult problem of intersymbol interference formed by the multi-path effect is overcome, the energy of the multi-order multi-path is accumulated in a Rake mode, the output signal to noise ratio of the sonar is greatly improved, particularly, an acoustic film area is often formed due to refraction of negative sound velocity gradient and blocking of a submerged reef, sound waves cannot directly reach the acoustic film area, and Rake receiving is an effective means for solving weak sound field information detection in the acoustic film area, so that interruption of communication is avoided;
3. the communication sonar of the pseudo-random frequency modulation system emits a pseudo-random frequency modulation sequence, is pseudo-random (i.e. definite) to the my, is truly random to the adversary, and has the excellent performance of secret communication;
4. The communication sonar of the pseudo-random frequency modulation system has the performance of Code Division Multiple Access (CDMA) and can be conveniently adapted to the multiple access communication of the underwater acoustic network;
5. Because of the long-range underwater acoustic communication, a lower operating frequency band is used, so is the communication rate, and vice versa. The communication sonar of the self-adaptive pseudo-random frequency modulation system using the Rake receiver as the core technology can be used for constructing practical communication sonar with different communication distances and rates with the advantages through careful design of pseudo-random frequency modulation sequences, in particular to military communication sonar with lower communication rate (multimedia capable of transmitting data, texts, compressed voice and the like) and longer communication distance (comprising communication with more than 200 km of adaptation nuclear submarines and aircraft carriers). Therefore, blind equalization working modes in channel equalization are carefully designed, the construction of communication sonar is much simpler, and the stability is improved. The sonar can be used for remote point-to-point underwater acoustic communication, provides basic conditions for stable information transmission for the construction of large underwater acoustic networks including fixed underwater acoustic networks for the shore, and is expected to serve modern construction of naval forces in China.
It should be noted that, the communication sonar of the adaptive pseudo-random frequency modulation system is similar to the frequency hopping communication system, the frequency band utilization rate is lower, and the communication rate is also lower. Therefore, on the basis of development and construction of lower-rate communication sonar, the two latter technical keys in the self-adaptive pseudo-random frequency modulation signal processing mode are needed to be adopted: the channel parameter self-adaptive technology and the frequency code compression technology can adapt to the underwater acoustic communication channel to a certain extent, strictly limit the characteristics of the working frequency band, obtain the improvement of the communication rate to a certain extent, comprise realizing the image communication of larger data compression, can adapt to Doppler frequency shift under high-speed navigation, realize the general, compatible, stable and secret point-to-point underwater acoustic communication under the dual functions of time domain and frequency domain and the reliable transmission of underwater acoustic information in the underwater acoustic network, and are expected to serve the construction of a first-class navy.
Embodiments of the present application also relate to a computer readable storage medium having stored thereon a computer program which, when executed by a computer processor, implements the method as described above. The computer program contains program code for performing the method shown in the flow chart. The computer readable medium of the present application may be a computer readable signal medium or a computer readable medium, or any combination of the two.
The above description is only illustrative of the preferred embodiments of the present application and of the principles of the technology employed. It will be appreciated by persons skilled in the art that the scope of the application referred to in the present application is not limited to the specific combinations of the technical features described above, but also covers other technical features formed by any combination of the technical features described above or their equivalents without departing from the inventive concept described above. Such as the above-mentioned features and the technical features disclosed in the present application (but not limited to) having similar functions are replaced with each other.
Claims (9)
1. A multi-path diversity method for communication sonar, comprising the steps of:
S1: designing a pseudo-random frequency modulation sequence according to a specific index of a communication sonar, enabling a sender and a receiver to know the pseudo-random frequency modulation sequence, modulating the pseudo-random frequency modulation sequence by adopting multi-element frequency shift keying (MFSK) to obtain a modulation signal, and transmitting the modulation signal by utilizing a power amplifier and an underwater sound transducer;
s2: the method comprises the steps that modulation frequency codes of single pulses of each pseudorandom frequency modulation sequence in a modulation signal are transmitted through an underwater acoustic channel to obtain a multi-order multi-path pulse sequence, full-time sampling is respectively carried out on the multi-order multi-path pulse sequences corresponding to each frequency code, the frequency code pulse width of the pseudorandom frequency modulation sequence is set to be b, the best incoherent detection which fully comprises the maximum value of the b width is carried out on the multi-order multi-path pulse sequences corresponding to each frequency code by utilizing a mutually telescopic double time window with the length of 2b and the mutual delay of b, and the maximum value of the best incoherent detection of the multi-order multi-path pulse sequences corresponding to each frequency code is obtained;
S3: rake receiving is carried out on the maximum value of the optimal incoherent detection of the multi-order multi-path pulse sequence corresponding to each frequency code, and the optimal output corresponding to each frequency code is obtained;
S4: and comparing the optimal output corresponding to each frequency code with a preset threshold level respectively, and judging the frequency code reached at the current moment of the multi-order multi-path pulse sequence.
2. The method of claim 1, wherein said designing a pseudo-random frequency modulation sequence according to a specific indicator of communication sonar comprises: and designing parameters of the frequency code number, the working frequency band, the frequency code pulse width and the transmitting sound power of the pseudo-random frequency modulation sequence according to specific indexes of the communication distance, the communication speed and the error rate of the communication sonar.
3. The method of claim 2, wherein the frequency code pulse width is set to the inverse of the communication rate.
4. The method of claim 2 wherein one of said frequency code pulse widths comprises a number of complete carriers greater than 30.
5. The method according to claim 1, wherein the specific step of S2 is: and performing full-time sampling by adopting optimal incoherent detection of frequency domain based on FFT matched filtering or time domain matched filtering-envelope detection, and performing maximum value detection of full-contained pulse width on the multi-order multi-path pulse sequence corresponding to each frequency code.
6. The method according to claim 1, wherein the specific step of S3 is: and accumulating the energy of the maximum value of the optimal incoherent detection of the multi-order multi-path pulse sequence corresponding to each frequency code.
7. The method according to claim 1, wherein the specific step of S4 is:
And for the MFSK modulation mode, M definite frequency codes form a group, the optimal output corresponding to each frequency code is respectively compared with a preset threshold level, and the frequency code with the optimal output amplitude reaching the threshold level in the group is used as the frequency code reaching the current moment in the multi-order multi-path pulse sequence, so that the decoding purpose is achieved.
8. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a computer processor, implements the method of any of claims 1 to 7.
9. A multi-path diversity system for communication sonar, comprising:
a pseudo-random frequency modulation sequence construction unit: the method comprises the steps of configuring a pseudorandom frequency modulation sequence according to a specific index of a communication sonar, enabling a sender and a receiver to know the pseudorandom frequency modulation sequence, modulating the pseudorandom frequency modulation sequence by using a multi-element frequency shift keying (MFSK) to obtain a modulation signal, and transmitting the modulation signal by using a power amplifier and an underwater sound transducer;
Full time sampling unit: configuring a modulation frequency code of a single pulse of each pseudorandom frequency modulation sequence in the modulation signal, propagating through an underwater acoustic channel to obtain a multi-order multi-path pulse sequence, respectively performing full-time sampling on the multi-order multi-path pulse sequence corresponding to each frequency code, setting the frequency code pulse width of the pseudorandom frequency modulation sequence as b, and performing optimal incoherent detection on the multi-order multi-path pulse sequence corresponding to each frequency code by utilizing a mutually nested double time window with the length of 2b and the mutual delay as b, wherein the maximum value of the full-included b width is the maximum value of the multi-order multi-path pulse sequence corresponding to each frequency code, so as to obtain the maximum value of the optimal incoherent detection of the multi-order multi-path pulse sequence corresponding to each frequency code;
Optimal Rake receiving unit: the method comprises the steps of configuring the maximum value of optimal incoherent detection of the multi-order multi-path pulse sequence corresponding to each frequency code for Rake receiving, and obtaining the optimal output corresponding to each frequency code;
and (3) comparing the judgment demodulation unit: and the optimal output corresponding to each frequency code is respectively compared with a preset threshold level, and the frequency code which is reached at the current moment of the multi-order multi-path pulse sequence is determined.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210970250.2A CN115333645B (en) | 2022-08-12 | 2022-08-12 | Multi-path diversity method and system for communication sonar |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210970250.2A CN115333645B (en) | 2022-08-12 | 2022-08-12 | Multi-path diversity method and system for communication sonar |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN115333645A CN115333645A (en) | 2022-11-11 |
| CN115333645B true CN115333645B (en) | 2024-10-15 |
Family
ID=83923974
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210970250.2A Active CN115333645B (en) | 2022-08-12 | 2022-08-12 | Multi-path diversity method and system for communication sonar |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115333645B (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109031311A (en) * | 2018-05-28 | 2018-12-18 | 西北工业大学 | It is a kind of that angle active probe method is split greatly based on the bistatic of time sliding window processing |
| CN110535537A (en) * | 2019-09-25 | 2019-12-03 | 哈尔滨工程大学 | A kind of subsurface communication detection integral method |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU2018452060B2 (en) * | 2018-12-05 | 2022-08-11 | Beijing Institute Of Control And Electronic Technology | Chaotic sequence-based 5G multi-carrier spread spectrum underwater acoustic communication method |
| CN113179235B (en) * | 2021-04-08 | 2022-09-30 | 中国人民解放军战略支援部队信息工程大学 | MFSK signal demodulation method and system under shallow sea impulse noise and multi-path channel |
-
2022
- 2022-08-12 CN CN202210970250.2A patent/CN115333645B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109031311A (en) * | 2018-05-28 | 2018-12-18 | 西北工业大学 | It is a kind of that angle active probe method is split greatly based on the bistatic of time sliding window processing |
| CN110535537A (en) * | 2019-09-25 | 2019-12-03 | 哈尔滨工程大学 | A kind of subsurface communication detection integral method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN115333645A (en) | 2022-11-11 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Diamant et al. | Low probability of detection for underwater acoustic communication: A review | |
| Edelmann et al. | Underwater acoustic communications using time reversal | |
| Song et al. | Multiple-input-multiple-output coherent time reversal communications in a shallow-water acoustic channel | |
| Rouseff et al. | Underwater acoustic communication by passive-phase conjugation: Theory and experimental results | |
| CN106936514B (en) | Detection method of underwater acoustic preamble signal based on energy concentration in sparse channel | |
| Jiang et al. | A sonar-embedded disguised communication strategy by combining sonar waveforms and whale call pulses for underwater sensor platforms | |
| Aparicio et al. | Asynchronous detection and identification of multiple users by multi-carrier modulated complementary set of sequences | |
| Lei et al. | Implementation of a high reliable chirp underwater acoustic modem | |
| CN115333645B (en) | Multi-path diversity method and system for communication sonar | |
| CN119210965B (en) | A dual-mode demodulation method and system for underwater acoustic communication based on minimum frequency shift keying | |
| Sklivanitis et al. | Distributed mimo underwater systems: Receiver design and software-defined testbed implementation | |
| KR101554286B1 (en) | Method for implementing underwater acoustic communication using channel transfer characteristic estimation based on superimposed pilot scheme | |
| CN115333644B (en) | Full-time sampling method and system for communication sonar | |
| Kim et al. | Chirp-based Frequency Shift Keying for Underwater Acoustic Communications | |
| KR100894144B1 (en) | Multimodulation Underwater Communication Device and Its Operation Method | |
| Petroni et al. | Adaptive ppm acoustic detection in very shallow water reservoir | |
| He et al. | Underwater acoustic communications using M-ary chirp-DPSK modulation | |
| Green | Acoustic modems, navigation aids, and networks for undersea operations | |
| Zappa et al. | Doppler compensation for JANUS applied to data collected in the baltic sea | |
| Ishikawa et al. | RAKE Reception of OFDM Signals in Non-Line-of-Sight Underwater Acoustic Communication | |
| Du et al. | Experimental demonstration of underwater acoustic communication over deep-sea channel | |
| Ye | Traitement statistique de l’information et du signal pour l’internet des objets sous-marins | |
| Balaji | Emerging underwater communication technology | |
| Park et al. | Underwater Communication with Spatio-Temporal Diversity in a Deep-Water Environment | |
| Shimura et al. | Results of basic at-sea experiments on time-reversal communication in the deep ocean |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |