CN108917910B - Hydrophone synchronous sampling system - Google Patents
Hydrophone synchronous sampling system Download PDFInfo
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- CN108917910B CN108917910B CN201810894426.4A CN201810894426A CN108917910B CN 108917910 B CN108917910 B CN 108917910B CN 201810894426 A CN201810894426 A CN 201810894426A CN 108917910 B CN108917910 B CN 108917910B
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- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
Abstract
The invention discloses a synchronous sampling system of hydrophones, which comprises a synchronous control module, a clock recovery module and a plurality of hydrophones, wherein the plurality of hydrophones are connected in series through optical fibers, the synchronous control module is respectively connected with head and tail hydrophones through the optical fibers, and the synchronous control module comprises a high-precision clock reference, a signal modulation unit, a signal detection unit and a logic control unit, wherein the high-precision clock reference is connected with the signal modulation unit. The clock recovery module comprises a first photoelectric conversion unit, the first photoelectric conversion unit receives an optical fiber input signal, the first photoelectric conversion unit, the synchronous extraction unit, the reset extraction unit and the clock relay unit are connected together, the clock relay unit is respectively connected with a local clock, a sampling clock and a second photoelectric conversion unit, and the second photoelectric conversion unit outputs a signal through an optical fiber. The invention has the advantages of realizing the long-time continuous synchronous acquisition of the hydrophones in all the arrays, along with good synchronous effect and high reliability.
Description
Technical Field
The invention belongs to the technical field of underwater sound, and relates to a synchronous sampling system of a hydrophone.
Background
In marine acoustic signal propagation measurements, it is often necessary to arrange vertical receiving hydrophone arrays from the sea surface to the seafloor to meet full-field arraying, or within the vocal tract axis depth range. In deep sea applications, receiving arrays of hundreds of meters or even kilometers are usually implemented, and since analog signals cannot be transmitted over long distances, self-contained hydrophones with independent acquisition and independent storage are available in recent years. The self-contained hydrophones work independently and are connected with each other without cables, and can form a large-aperture vertical receiving array in deep sea application, as shown in figure 1. However, because hydrophones are independent from each other, the application in deep sea cannot acquire GPS or Beidou signals, and the realization of synchronous sampling among array elements becomes a difficult point. At present, the following methods are available for realizing synchronous sampling:
1. a chip-level atomic clock is used as an accurate sampling clock, and the synchronization requirement of short-time work can be met. However, atomic clocks have problems of high cost, large power consumption, long clock time, and the like.
2. The cable is used for transmitting the synchronous signal, but the submarine transmission distance is long, so that the method has the problems of large delay, strong interference, serious signal attenuation and the like, and the conditions of signal interruption, distortion and the like are easy to occur in practical application, so that the method is difficult to adopt.
Disclosure of Invention
The invention aims to provide a hydrophone synchronous sampling system, which has the beneficial effects of realizing long-time continuous synchronous acquisition of hydrophones in all arrays, good synchronization effect and high reliability.
The technical scheme adopted by the invention is that the device comprises a synchronous control module, a clock recovery module and a plurality of hydrophones, wherein the hydrophones are connected in series through optical fibers, the synchronous control module is respectively connected with the hydrophones at the head and the tail through the optical fibers, and optical signals of the optical fibers are transmitted in a single direction.
Further, the synchronous control module comprises a high-precision clock reference, a signal modulation unit, a signal detection unit and a logic control unit, the high-precision clock reference is connected with the signal modulation unit, the signal modulation unit is respectively connected with the logic control unit and an optical fiber output end, the signal detection unit is respectively connected with the logic control unit and the optical fiber input end, and the following signals are provided for the hydrophone through optical fiber transmission:
a reset signal for resetting the hydrophone array element;
the synchronous signal is used for carrying out sampling synchronous starting control on the hydrophone array element;
the clock signal is used for providing a sampling clock of the hydrophone array element;
the high-precision clock reference is used for providing synchronous acquisition clock signals; the signal modulation unit sends a responding clock signal according to the requirement, and different signals can be distinguished on duty ratio and frequency; the signal detection unit receives a return signal of the tail hydrophone and is used for judging the integrity of the communication link.
Further, the logic control unit firstly sends a reset signal, the hydrophones automatically reset after receiving the reset signal and ensure that the reset signal is transmitted to the next hydrophone until the signal is transmitted back to the synchronous control module, the logic control unit judges whether a communication link is complete and whether the reset operation is completed according to a return signal provided by the signal detection unit, all the hydrophones enter a standby dormant state after the reset is completed, the logic control unit judges whether sampling needs to be started according to preset logic, if so, a synchronous signal is sent through the signal modulation unit firstly, and the success of sending the synchronous signal is ensured according to the return signal provided by the signal detection unit; then, the logic control unit ensures that the signal modulation unit continuously sends the clock signal provided by the high-precision clock reference through logic control, and provides synchronous sampling clocks for all the hydrophones until the sampling is finished; if signal interruption caused by hydrophone abnormity occurs in the whole working process, the logic control unit sends a reset signal to reset the hydrophone at any time according to the requirement.
Furthermore, each hydrophone comprises a clock recovery module, the clock recovery module acquires a sampling clock for internal data sampling, and outputs the sampling clock to the next stage hydrophone through an optical fiber;
the electric pulse signals after photoelectric conversion carry reset, synchronization and clock information by changing pulse frequency and duty ratio parameters, the reset extraction unit is responsible for extracting reset signals, once the reset signals are detected, reset levels are output to carry out global reset on the local hydrophones, the synchronization extraction unit is responsible for extracting synchronization signals, and once the synchronization signals are detected, local data acquisition is started.
Further, the working clock of the clock relay unit is from the local clock, the frequency of the local clock is N times of the sampling clock, and in the standby state, the clock relay unit conducts transparent transmission processing on the input signal and directly transmits the input signal to the next stage; during collection, if an external clock signal is normally input, the clock relay unit conducts transparent transmission processing on the input signal, meanwhile, the signal is used as a sampling clock of a local AD, once the input clock signal is detected to be lost, the clock relay unit outputs the clock signal of the local clock after N frequency division, the clock signal is used as the sampling clock of the local AD and a next stage of hydrophone, if the input clock is recovered, the input clock is switched back to work, the whole switching process is seamless, and clock beats cannot be increased or lost.
Drawings
FIG. 1 is a hydrophone array structure;
FIG. 2 is a synchronization system topology for an optical fiber;
FIG. 3 is a schematic diagram of a synchronization control module;
fig. 4 is a schematic diagram of a clock recovery module structure.
In the figure, 1, a synchronous control module, 2, a clock recovery module, 3, a hydrophone, 101, a high-precision clock reference, 102, a signal modulation unit, 103, a signal detection unit, 104, a logic control unit, 201, a first photoelectric conversion unit, 202, a synchronous extraction unit, 203, a reset extraction unit, 204, a clock relay unit, 205, a local clock, 206, a sampling clock, 207 and a second photoelectric conversion unit are arranged.
Detailed Description
The present invention will be described in detail with reference to the following embodiments.
The system of the invention is shown in figure 2 and comprises a synchronous control module 1, a clock recovery module 2 and a plurality of hydrophones 3, wherein the plurality of hydrophones 3 are connected in series through optical fibers, and the synchronous control module 1 is respectively connected with the head hydrophone 3 and the tail hydrophone 3 through the optical fibers. The optical signal of the optical fiber is transmitted in a single direction.
As shown in fig. 3, the synchronous control module 1 includes a high-precision clock reference 101, a signal modulation unit 102, a signal detection unit 103, and a logic control unit 104, where the high-precision clock reference 101 is connected to the signal modulation unit 102, the signal modulation unit 102 is respectively connected to the logic control unit 104 and an optical fiber output end, the signal detection unit 103 is respectively connected to the logic control unit 104 and the optical fiber input end, and provides the following signals for the hydrophone 3 through optical fiber transmission:
a reset signal for resetting the hydrophone array element;
the synchronous signal is used for carrying out sampling synchronous starting control on the hydrophone array element;
and the clock signal is used for providing a sampling clock of the hydrophone array element.
The high-precision clock reference 101 is used for providing synchronous acquisition clock signals; the signal modulation unit 102 sends a clock signal according to the requirement, and different signals can be distinguished in duty ratio and frequency; the signal detection unit 103 receives the return signal of the bottom hydrophone, and is used for judging the integrity of the communication link.
After the system is started, the logic control unit 104 first sends a reset signal, the hydrophone 3 automatically resets itself globally after receiving the reset signal and ensures that the reset signal is transmitted to the next hydrophone 3 until the signal is transmitted back to the synchronous control module 1, and the logic control unit 104 judges whether the communication link is complete and the reset operation is completed according to the return signal provided by the signal detection unit 103. After the resetting is completed, all the hydrophones 3 enter a standby dormant state, the logic control unit 104 judges whether sampling needs to be started according to preset logic, if so, a synchronous signal is sent through the signal modulation unit 102, and the successful sending of the synchronous signal is ensured according to a return signal provided by the signal detection unit 103. Subsequently, the logic control unit 104 ensures, by means of logic control, that the signal modulation unit 102 continues to transmit the clock signal provided by the high-precision clock reference 101, providing a synchronized sampling clock for all hydrophones 3 until the end of the sampling. If signal interruption caused by abnormality of the hydrophone 3 occurs in the whole working process, the logic control unit 104 sends a reset signal to reset the hydrophone 3 at any time according to the requirement.
Each hydrophone 3 internally comprises a clock recovery module 2, the clock recovery module 2 acquires a sampling clock for internal data sampling, and the sampling clock is output to the next-stage hydrophone 3 through an optical fiber. In the sampling process, if the optical fiber communication is interrupted due to external force, the local clock 205 of the clock recovery module 2 can output the same-frequency clock in time to be supplied to the hydrophone 3 and the subsequent hydrophone 3 as the sampling clock, and after the communication is recovered, the sampling clock is switched back to the optical fiber clock, so that seamless switching can be realized in the whole process. As shown in fig. 4, the clock recovery module 2 includes a first photoelectric conversion unit 201, the first photoelectric conversion unit 201 receives an optical fiber input signal, the first photoelectric conversion unit 201, the synchronization extraction unit 202, the reset extraction unit 203, and the clock relay unit 204 are connected together, the clock relay unit 204 is connected to a local clock 205, a sampling clock 206, and a second photoelectric conversion unit 207, respectively, and the second photoelectric conversion unit 207 outputs a signal through an optical fiber.
The photoelectrically converted electrical pulse signal carries reset, synchronization and clock information by changing parameters such as pulse frequency and duty ratio, the reset extraction unit 203 is responsible for extracting the reset signal, and once the reset signal is detected, a reset level is output to perform global reset on the local hydrophone 3. The synchronization extraction unit 202 is responsible for extracting the synchronization signal, which, upon detection, initiates local data acquisition.
The operating clock of the clock relay unit 204 is from the local clock 205, and the clock frequency of the local clock 205 is N times of the sampling clock. In the standby state, the clock relay unit 204 performs transparent transmission processing on the input signal and directly transmits the input signal to the next stage. During the collection operation, if the external clock signal is normally input, the clock relay unit 204 performs transparent transmission processing on the input signal, and meanwhile, the signal is used as a sampling clock of the local AD. Upon detecting that the input clock signal is lost, the clock relay unit 204 divides the clock signal N of the local clock 205 and outputs the divided clock signal as the sampling clock of the local AD and the next stage hydrophone 3. If the input clock is recovered, the operation of the input clock is switched back. The whole switching process is seamless, and clock beats cannot be increased or lost.
The invention also has the advantages that:
1. the method realizes complete synchronous sampling, and all array elements of the system adopt the same sampling clock and the starting signal, thereby realizing the synchronous sampling in the true sense. And the traditional atomic clock scheme can only meet the requirement of short-time synchronization.
2. The power consumption is low, each hydrophone array element in the system integrates a pair of optical fiber transceivers, and the power consumption is less than 50mW and far lower than that of an atomic clock.
3. The cost is low, and compared with the cost of an atomic clock, the cost of the underwater optical fiber is much lower.
4. High reliability, compare with traditional cable scheme, the transmission reliability of optic fibre is about far more than the former, because the system possesses clock recovery circuit, even communication interruption appears, can not influence data sampling yet.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not intended to limit the present invention in any way, and all simple modifications, equivalent variations and modifications made to the above embodiments according to the technical spirit of the present invention are within the scope of the present invention.
Claims (1)
1. A hydrophone synchronous sampling system, comprising: the system comprises a synchronous control module, a clock recovery module and a plurality of hydrophones, wherein the plurality of hydrophones are connected in series through optical fibers, the synchronous control module is respectively connected with head and tail hydrophones through the optical fibers, and optical signals of the optical fibers are transmitted in a single direction; the synchronous control module comprises a high-precision clock reference, a signal modulation unit, a signal detection unit and a logic control unit, wherein the high-precision clock reference is connected with the signal modulation unit and provides a synchronous acquisition clock signal for the system; the signal modulation unit is respectively connected with the logic control unit and the optical fiber output end, and provides the following signals for the hydrophone through optical fiber transmission:
the reset signal is used for resetting the hydrophone;
the synchronous signal is used for carrying out sampling synchronous starting control on the hydrophone;
a clock signal for providing a sampling clock of the hydrophone;
different signals may be distinguished in duty cycle and frequency;
the signal detection unit is respectively connected with the logic control unit and the optical fiber input end and is used for judging the integrity of the communication link by receiving a return signal of the tail hydrophone;
after the system is started, the logic control unit firstly sends a reset signal, the hydrophones automatically reset the whole body after receiving the reset signal and ensure that the reset signal is transmitted to the next hydrophone until the signal is transmitted back to the synchronous control module, the logic control unit judges whether a communication link is complete and whether the reset operation is finished according to a return signal provided by the signal detection unit, all the hydrophones enter a standby dormant state after the reset is finished, the logic control unit judges whether sampling needs to be started according to preset logic, if so, a synchronous signal is sent through the signal modulation unit firstly, the synchronous signal is ensured to be successfully sent according to the return signal provided by the signal detection unit, and then the logic control unit ensures that the signal modulation unit continuously sends a clock signal provided by a high-precision clock reference through logic control to provide a synchronous sampling clock for all the hydrophones, until sampling is finished, if signal interruption caused by hydrophone abnormity occurs in the whole working process, the logic control unit sends a reset signal to reset the hydrophone at any time according to requirements; each hydrophone comprises a clock recovery module, the clock recovery module acquires a sampling clock for sampling internal data and outputs the sampling clock to the next stage hydrophone through an optical fiber, the clock recovery module comprises a first photoelectric conversion unit, the first photoelectric conversion unit receives an optical fiber input signal, the first photoelectric conversion unit, a synchronous extraction unit, a reset extraction unit and a clock relay unit are connected together, the clock relay unit is respectively connected with a local clock, the sampling clock and a second photoelectric conversion unit, and the second photoelectric conversion unit outputs a signal through the optical fiber;
the photoelectric-converted electric pulse signals carry reset, synchronization and clock information by changing pulse frequency and duty ratio parameters, the reset extraction unit is responsible for extracting reset signals, once the reset signals are detected, reset levels are output to carry out global reset on the local hydrophones, the synchronous extraction unit is responsible for extracting synchronous signals, and once the synchronous signals are detected, local data acquisition is started;
the working clock of the clock relay unit is from the local clock, the local clock frequency is N times of the sampling clock, in the standby state, the clock relay unit conducts the transparent transmission processing on the input signal and directly transmits the input signal to the next stage, when the clock relay unit conducts the transparent transmission processing on the input signal if the external clock signal is normally input during collection work, meanwhile, the signal is used as the sampling clock of the local AD, once the input clock signal is detected to be lost, the clock relay unit outputs the clock signal of the local clock after N frequency division and uses the clock signal as the sampling clocks of the local AD and the next stage hydrophone, if the input clock is recovered, the clock relay unit can switch back to the input clock to work, the whole switching process is seamless, and the clock beat cannot be increased or lost.
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