CN111245546A - Link type one-transmitting multi-receiving submarine node high-precision time service system - Google Patents
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- CN111245546A CN111245546A CN202010019411.0A CN202010019411A CN111245546A CN 111245546 A CN111245546 A CN 111245546A CN 202010019411 A CN202010019411 A CN 202010019411A CN 111245546 A CN111245546 A CN 111245546A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J3/00—Time-division multiplex systems
- H04J3/02—Details
- H04J3/06—Synchronising arrangements
- H04J3/0635—Clock or time synchronisation in a network
- H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
- H04J3/0644—External master-clock
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
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- 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
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Abstract
The invention provides a link type one-transmitting multi-receiving submarine node high-precision time service system, which comprises a signal transmitting base station and a signal transmission link; the signal transmitting base station comprises an atomic clock and a transmitter; the signal transmission link includes: the system comprises a plurality of submarine receiving arrangement links, a signal transmission module and a signal receiving module, wherein each submarine receiving arrangement link comprises a plurality of submarine nodes, and the submarine nodes on each submarine receiving arrangement link are connected through the signal transmission module; one end of each seabed node array is provided with an atomic clock, clock information of the atomic clock is sent to the first seabed node on each link through a transmitter, and then synchronous time service is carried out on each node of the same cascade link in an inductive coupling type wireless transmission mode, so that the clock consistency of each node under water is realized. The invention can realize the purpose of carrying out high-precision synchronous time service on a large number of submarine nodes by using a small number of atomic clocks under water without equipping each submarine node with an atomic clock.
Description
Technical Field
The invention relates to the technical field of exploration of ocean oil gas and seabed natural gas hydrates, in particular to a link type one-transmitting multi-receiving seabed node high-precision time service system.
Background
Ocean OBN (Ocean Bottom Nodal-OBN) is a strictly "stand-alone" task. The underwater time signal transmission device works under the water all the time, can only establish communication with a GPS or other time beacons in a wireless transmission mode, and if the underwater time signal transmission device relies on underwater sound communication, the underwater time signal transmission device is bound to be influenced by transmission speed and cannot synchronously time. Long term deviations of its internal clock, as counted by the 30-45 day on-time of the OBN device, should be on the order of ppb (parts per billion) higher than the ppm (parts per million) deviation of a typical precision clock source.
US6002339 discloses a time synchronization method for seismic acquisition by a seismic exploration system, which is suitable for land exploration and adopts a wireless communication mode, and the time synchronization process is complicated.
CN102508197A discloses a method and a device for accurately measuring and correcting multi-node synchronous acquisition time errors. This patent is used in ocean bottom streamer seismic exploration systems, but requires a high precision clock built into each node. And the accurate clock is arranged in each node, so that the cost of a single OBN is high, and the acquisition cost of the ocean bottom seismic data is increased.
Disclosure of Invention
The invention aims to solve the defects of the prior art and provide a link type one-transmitting multi-receiving subsea node high-precision time service system which realizes high-precision synchronous time service on a large number of subsea nodes by using a small number of atomic clocks under water on the premise of not needing each subsea node to be provided with an atomic clock.
A link type one-transmitting multi-receiving submarine node high-precision time service system comprises a signal transmitting base station and a signal transmission link;
the signal transmitting base station comprises an atomic clock and a transmitter;
the signal transmission link includes: each seabed receiving and arranging link comprises a plurality of seabed nodes, and the signal output end of the previous seabed node 4 takes a plastic-coated steel cable as a transmission medium of an inductive coupling signal and is connected with the signal input end of the next seabed node 4;
one end of each seabed node array is provided with an atomic clock, clock information of the atomic clock is sent to the first seabed node on each link through a transmitter, and then synchronous time service is carried out on each node of the same cascade link in an inductive coupling type wireless transmission mode, so that the clock consistency of each node under water is realized.
Further, the link-type one-transmitting-multiple-receiving subsea node high-precision time service system as described above, the transmitter includes: the device comprises a frequency divider, a pseudo code generator, a frequency synthesizer, an IGIR-B coding module, a spread spectrum modulation module, a DPSK modulation module, a digital-to-analog converter and a power amplifier;
the frequency divider divides a high-frequency clock signal provided by the atomic clock into clock signals with different frequencies for a pseudo-code generator and a frequency synthesizer in the transmitter to use;
the pseudo-code generator generates pseudo-random codes required by spread spectrum modulation;
the frequency synthesizer generates a sine wave with variable frequency as a carrier wave modulated by the DPSK;
the IGIR-B coding module is used for coding local time generated by an atomic clock into absolute time information including pulse per second information, year, day, hour, minute, second and binary second counting days after IRIG-B coding;
the spread spectrum modulation module multiplies the code stream output by IRIG-B by the generated pseudo-random sequence to complete spread spectrum modulation;
the DPSK modulation module is used for moving a signal spectrum to a sending frequency;
the digital-to-analog converter is used for converting the signal output by the DPSK modulation module;
and the power amplifier is used for amplifying the signal converted by the digital-to-analog converter and then sending out the amplified signal.
Further, in the link-type one-transmitting-multiple-receiving subsea node high-precision time service system, the magnetic coupling communication module includes a first amplifying circuit, a band-pass filter circuit, a second amplifying circuit, an analog-to-digital conversion circuit, a signal processing circuit, and a communication control circuit, which are connected in sequence;
the signal on the ferrimagnetic ring is amplified and filtered, and then is converted into a digital signal which can be identified by a CPLD in a signal processing circuit.
Has the advantages that:
according to the invention, a base station is arranged at one end of each link node to carry a clock signal wireless transmitter, time signals are coded, a magnetic coupling communication device and a plastic-coated steel cable are carried on the seabed nodes in an inductive coupling type wireless transmission mode, and time service calibration is carried out on a clock source crystal oscillator in an intelligent node, so that the purpose of carrying out high-precision synchronous time service on a large number of seabed nodes by using a small number of atomic clocks under water can be realized without equipping each seabed node with an atomic clock.
Drawings
FIG. 1 is a schematic diagram of a submarine receiving arrangement link of a bottom node time service system according to the present invention;
FIG. 2 is a schematic diagram of a connection between two subsea nodes in a subsea receiving array link according to the present invention;
FIG. 3 is a block diagram of a transmitter according to the present invention;
FIG. 4 is a block diagram of a magnetic coupling communication module according to the present invention;
1-a signaling base station; 2-a signal transmission link; 3-a magnetic coupling communication module; 4-subsea nodes; 5-plastic-coated steel cable.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention are described below clearly and completely, and it is obvious that the described embodiments are some, not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The inductive coupling type wireless transmission mode mainly comprises four parts, namely an underwater sensor, a signal coupling magnetic ring, an above-water terminal device and a signal transmission plastic-coated steel cable. The inductive coupling type wireless data transmission system utilizes the characteristic that coil inductance can be converted into electric signals and magnetic signals, the coil is used as a transmitting and receiving carrier, a transmitting end converts the modulated and changed electric signals into changed magnetic field signals through the coil, the coil of a receiving end induces the changed magnetic field signals to form corresponding electric signals, and data transmission can be realized by analyzing the relation. The wireless data transmission system has the characteristics of low cost, small volume, simple and reliable circuit, no need of cables and the like, and is suitable for underwater short-distance non-contact data transmission.
The invention provides a link type one-transmitting multi-receiving submarine node high-precision time service system, which comprises a base station carrying clock signal wireless transmitter arranged at one end of each link node and used for coding a time signal; and carrying a magnetic coupling communication device and a plastic-coated steel cable on the submarine node by adopting an inductive coupling type wireless transmission mode, and carrying out time service calibration on a clock source crystal oscillator inside the intelligent node. Specifically, as shown in fig. 1 and fig. 2, the link-type one-transmission multi-reception subsea node high-precision time service system provided in the embodiment of the present invention includes: a signal transmitting base station 1 and a signal transmission link 2;
the signal transmission base station 1 comprises an atomic clock and a transmitter;
the signal transmission link 2 comprises: each of the plurality of submarine receiving array links comprises a plurality of submarine nodes 4, and the signal output end of the former submarine node 4 is connected with the signal input end of the next submarine node 4 by taking a plastic-coated steel cable as a transmission medium of an inductive coupling signal.
One end of each seabed node array is provided with an atomic clock, clock information of the atomic clock is sent to the first seabed node on each link through a transmitter, and then synchronous time service is carried out on each node of the same cascade link in an inductive coupling type wireless transmission mode, so that the clock consistency of each node under water is realized.
Specifically, the signal transmitting base station 1 transmits an electric signal, the signal transmission link 2 converts the electric signal into a magnetic signal through a plastic-coated steel cable, converts the magnetic signal into an electric signal, transmits the electric signal to the signal coupling ring, and performs calibration time service on a crystal oscillator in the submarine node through decoding and processing of the communication control circuit.
The transmitting process and the receiving process of the submarine receiving arrangement link are as follows:
after a signal passes through a signal coupling ring which is mounted on the plastic-coated cable and used for sending, a variable magnetic field is formed in the annular ferrite; the plastic-coated cable penetrating through the annular ferrite and the external seawater form a loop, in the loop, a magnetic field in the ferrite changes along with modulated waveform data, so that correspondingly changed current can be formed in the plastic-coated cable, further changed induced electromotive force is formed in a signal coupling ring used for receiving, and data transmission can be realized by analyzing the changed induced voltage, namely the transmitting process. The communication module mounted on the coupling communication chain is integrated with a transceiver, and can be used as a transmitting module or a receiving module. The same as the sending process, through the inverse process, along with the current changing in the plastic-coated cable, the correspondingly changed induced electromotive force can be generated in the signal coupling ring of the coupling chain communication module as the receiving node, and through analyzing the change relationship, the sent data information can be obtained, namely the receiving process.
As shown in fig. 3, the transmitter includes: the device comprises a frequency divider, a pseudo code generator, a frequency synthesizer, an IGIR-B coding module, a spread spectrum modulation module, a DPSK modulation module, a digital-to-analog converter and a power amplifier;
the frequency divider divides a high-frequency clock signal provided by the atomic clock into clock signals with different frequencies for a pseudo-code generator and a frequency synthesizer in the transmitter to use;
the pseudo-code generator generates pseudo-random codes required by spread spectrum modulation;
the frequency synthesizer generates a sine wave with variable frequency as a carrier wave modulated by the DPSK;
the IGIR-B coding module is used for coding local time generated by an atomic clock into absolute time information including pulse per second information, year, day, hour, minute, second and binary second counting days after IRIG-B coding;
the spread spectrum modulation module multiplies the code stream output by IRIG-B by the generated pseudo-random sequence to complete spread spectrum modulation;
the DPSK modulation module is used for moving a signal spectrum to a sending frequency;
the digital-to-analog converter is used for converting the signal output by the DPSK modulation module;
and the power amplifier is used for amplifying the signal converted by the digital-to-analog converter and then sending out the amplified signal.
Specifically, the clock signal wireless transmitter has the following principle: firstly, local time is changed into absolute time information including pulse per second information, year, day, time, minute, second, binary second counting day and the like after IRIG-B coding by using a synchronous atomic clock, then the code stream is input into a wireless transmitter, the wireless transmitter firstly carries out spread spectrum modulation on the code stream, then carries out DPSK modulation on the code stream to shift a signal frequency spectrum to a transmission frequency, and finally carries out D/A conversion and power amplification and then transmits the signal through an antenna. The clock signal wireless transmitter adopts IRIG-B decoding for the clock decoding module, and the wireless receiver adopts a direct spread spectrum system and a DPSK (differential phase Shift Keying) demodulation mode. Principle of terminal equipment: the method comprises the steps of receiving signals from a base station at a fixed time, firstly demodulating radio frequency signals through a wireless receiver, restoring the demodulated signals into baseband signals after despreading, and then obtaining time information of the base station through a decoding module for time service. The time signal transmitter loaded on the base station comprises an atomic clock, a digital part of the transmitter, a D/A converter and a power amplifier, wherein the digital part is integrated on a chip, and the whole transmitting and receiving system adopts a direct spread communication mode. The digital part comprises a frequency divider, a coding module, a spread spectrum modulation module, a pseudo code generator, a modulation module and a frequency synthesizer. The frequency divider divides the high frequency clock provided by the atomic clock into clock signals of different frequencies for use by other modules in the transmitter. And the coding module codes the current standard time into a bit stream and outputs the bit stream. The pseudo code generator generates pseudo random codes required by spread spectrum modulation, GOLD codes and pseudo random sequences can be used according to different conditions, and meanwhile, the length of the pseudo random codes can be adjusted according to different conditions. And the spread spectrum modulation module multiplies the code stream output by the IRIG-B by the generated pseudo-random sequence to complete spread spectrum modulation. The DPSK modulated carrier with variable frequency generated by the frequency synthesizer is modulated to the frequency for wireless transmission by the modulation module, the carrier frequency is adjusted according to different conditions, and the D/A converter and the power amplifier can select products according to different bit widths and rates.
As shown in fig. 4, the magnetic coupling communication module includes a first amplifying circuit, a band-pass filter circuit, a second amplifying circuit, an analog-to-digital conversion circuit, a signal processing circuit, and a communication control circuit, which are connected in sequence;
the signal on the ferrimagnetic ring is amplified and filtered, and then is converted into a digital signal which can be identified by a CPLD in a signal processing circuit.
Specifically, the receiving of the magnetic coupling communication module adopts an LC resonance circuit mode. The function of the receiving circuit is to extract the signal of the signal coupling loop, firstly amplify and filter the signal, and then convert the signal into a digital signal which can be identified by the CPLD in the signal processing circuit. The receiving preprocessing comprises an amplifying circuit, a band-pass filter circuit, an amplifying circuit and an analog-to-digital conversion circuit. Most of the work of the CPLD is completed on a computer, and the design flow of a chip is as follows: opening integrated development software, writing hardware description language, compiling, giving an input excitation signal of a logic circuit, simulating, checking whether a logic output result is correct, carrying out pin input, output locking, generating a code, transmitting the code through a download cable and storing the code in a CPLD chip. And finally, carrying out time service on the internal crystal oscillator of the submarine node by the decoded signal.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (3)
1. A link type one-transmitting multi-receiving submarine node high-precision time service system is characterized by comprising: a signal transmitting base station (1) and a signal transmission link (2);
the signal transmission base station (1) comprises an atomic clock and a transmitter;
the signal transmission link (2) comprises: each seabed receiving and arranging link comprises a plurality of seabed nodes (4), and the signal output end of the previous seabed node (4) uses a plastic-coated steel cable as a transmission medium of an inductive coupling signal and is connected with the signal input end of the next seabed node (4);
one end of each seabed node array is provided with an atomic clock, clock information of the atomic clock is sent to the first seabed node on each link through a transmitter, and then synchronous time service is carried out on each node of the same cascade link in an inductive coupling type wireless transmission mode, so that the clock consistency of each node under water is realized.
2. The link-type one-transmission-multiple-reception subsea node high-precision time service system according to claim 1, wherein said transmitter comprises: the device comprises a frequency divider, a pseudo code generator, a frequency synthesizer, an IGIR-B coding module, a spread spectrum modulation module, a DPSK modulation module, a digital-to-analog converter and a power amplifier;
the frequency divider divides a high-frequency clock signal provided by the atomic clock into clock signals with different frequencies for a pseudo-code generator and a frequency synthesizer in the transmitter to use;
the pseudo-code generator generates pseudo-random codes required by spread spectrum modulation;
the frequency synthesizer generates a sine wave with variable frequency as a carrier wave modulated by the DPSK;
the IGIR-B coding module is used for coding local time generated by an atomic clock into absolute time information including pulse per second information, year, day, hour, minute, second and binary second counting days after IRIG-B coding;
the spread spectrum modulation module multiplies the code stream output by IRIG-B by the generated pseudo-random sequence to complete spread spectrum modulation;
the DPSK modulation module is used for moving a signal spectrum to a sending frequency;
the digital-to-analog converter is used for converting the signal output by the DPSK modulation module;
and the power amplifier is used for amplifying the signal converted by the digital-to-analog converter and then sending out the amplified signal.
3. The link type one-transmitting-multi-receiving subsea node high-precision time service system according to claim 1, wherein the magnetic coupling communication module comprises a first amplifying circuit, a band-pass filter circuit, a second amplifying circuit, an analog-to-digital conversion circuit, a signal processing circuit, and a communication control circuit, which are connected in sequence;
the signal on the ferrimagnetic ring is amplified and filtered, and then is converted into a digital signal which can be identified by a CPLD in a signal processing circuit.
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| CN111891294A (en) * | 2020-07-31 | 2020-11-06 | 中国海洋大学 | Ocean intelligent node three-dimensional observation system |
| CN112332929A (en) * | 2020-10-23 | 2021-02-05 | 中国科学院声学研究所东海研究站 | Underwater PNT system with wide area coverage and autonomous monitoring |
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