70 results about "Very low frequency" patented technology

The invention relates to the technical field of thunder and lightning signal sampling, and discloses a GAN-based thunder and lightning very-low-frequency electromagnetic wave signal up-sampling method, a terminal and a medium. The method comprises the following steps: preprocessing a lightning very-low-frequency low-sampling signal and a real high-sampling signal; constructing a generative adversarial network; the generator is used for extracting initial features from the low-sampling signals and performing residual enhancement, then mapping low-sampling features after residual enhancement to a high-sampling dimension through a feature-guided dynamic interpolation mechanism, and performing correction and signal mapping on intermediate features after interpolation to obtain reconstructed signals matched with a target high-sampling rate; the discriminator is used for reconstructing the authenticity probability of the signal; after a generator and a discriminator are jointly trained by adopting an alternative updating mode of discriminator loss and generator loss, a newly input low sampling signal is preprocessed, and a corresponding reconstruction signal is output through the generator. According to the invention, accurate reconstruction from a lightning very-low-frequency low-sampling signal to a high-sampling signal is realized.

The invention discloses a self-adaptive multi-unit very-low-frequency phased-array antenna system and a control method thereof, and the system comprises an antenna unit which comprises a vertical radiator and a top loading capacitor network erected on the vertical radiator; the central signal processing and distributing unit comprises parallel signal channels with the same number as the antenna units, and the signal channels are integrated with signal adjusting devices; the input end of the feed network is connected to the central signal processing and distributing unit, and the output end is connected to the vertical radiator to transmit a radio frequency excitation signal; the plurality of feedback sensors are arranged in the feed network and are used for monitoring electrical state parameters of signals flowing to the antenna units; the central control unit is connected with the feedback sensor and the central signal processing and distributing unit, monitors electrical state parameters based on the feedback sensor, and controls the signal adjusting device to adjust the amplitude and phase of the excitation signal. According to the invention, the beam forming and directional communication capabilities of the very-low-frequency antenna are realized, and the flexibility of an antenna system is expanded.

The invention belongs to the field of geophysical exploration, and particularly relates to a very-low-frequency three-component coil calibration method based on frequency sweep excitation, which comprises the following steps: acquiring an alternating-current excitation current and a time domain signal of a three-component coil, and performing frequency domain transformation on the time domain signal to obtain a plurality of frequency domain response vectors covering a frequency sweep range; constructing a linear equation set for describing a coil system error based on a plurality of frequency domain response vectors measured under each attitude and the calculated excitation magnetic field reference vector, and solving the linear equation set by using a least square method to obtain a calibration matrix for correcting measurement data; and the calibration matrix is adopted to correct the measurement data of the three-component coil in the use state, so that systematic errors of the very-low-frequency three-component coil can be accurately calibrated and calibrated, and the measurement precision and data reliability of a very-low-frequency electromagnetic method are effectively improved.

The present application belongs to the technical field of very low frequency fluctuation detection, and discloses a very low frequency station signal information extraction method and system based on a phase-locked loop. The present application amplifies and samples a wide frequency signal containing a very low frequency station transmitting signal, sets local MSK demodulation parameters, uses phase-locked loop technology to respectively perform carrier synchronization on the upper and lower frequencies of the MSK modulated signal transmitted by the target monitoring very low frequency station, extracts a baseband synchronization signal and a carrier synchronization signal from the phase-locked loops of the upper and lower frequencies, respectively, calculates the amplitude information of the upper and lower frequencies using the baseband synchronization signal, and further obtains the amplitude information of the target monitoring very low frequency station. The carrier synchronization signals of the upper and lower frequencies are used to extract the frequency of the carrier synchronization signal of the MSK modulated signal transmitted by the target monitoring very low frequency station, and further extract the phase offset information of the target monitoring very low frequency station. The present application can improve the accuracy of very low frequency station signal information extraction.

The application discloses a dynamic non-cooperative very low frequency signal carrier frequency and phase measurement system, comprising a high-precision analog-to-digital converter, a high-precision digital-to-analog converter connected with an FPGA module, and a labview host computer connected with the FPGA module, and discloses a dynamic non-cooperative very low frequency signal carrier frequency and phase measurement method. The FPGA module is used for performing carrier frequency estimation and carrier phase rotation correction on MSK signals collected by the high-precision digital-to-analog converter, and the carrier frequency and phase with high precision are transmitted to the labview host computer to be displayed. The application can realize fast and high-precision carrier frequency estimation, has strong noise resistance and a wide estimation range.

The embodiment of the invention provides a very low frequency signal monitoring method and device, and the device consists of a signal receiving unit (1), a signal measurement unit (2), a parameter regulation and control unit (3), and a main control unit (4). And the parameter regulation and control unit (3) can respectively set parameters of each working component in the signal receiving unit (1) and the signal measuring unit (2) according to the center frequency and bandwidth list of the main control unit (4), and can control a turntable (5) of an antenna coil (13) to align to the strongest direction of a synchronous measurement signal, so that measurement and data storage of a specific very low frequency signal in the bandwidth are realized. The method is characterized in that collection of monitoring signals and measurement of signal parameters are realized based on synchronization characteristics of known signals, interference signals can be well distinguished, and the accuracy of monitoring data is guaranteed.

The invention provides an ionosphere parameter inversion method and device, and belongs to the technical field of short-wave communication, and the method comprises the steps: enabling the actually-measured amplitude and phase difference to be mapped into a low-order wave mode excitation amplitude and a complex feature value through the synchronous receiving of the same very-low-frequency transmitting station signal at different transmitting and receiving distances on the ground; and then fast convergence solution is carried out by using a Newton-Raphson method, and ionosphere electron concentration parameters are circularly corrected by using a gradient descent method, so that the residual error of a theoretical calculation result and a measured value is stabilized within a preset threshold, thereby getting rid of excessive dependence on a traditional ionosphere mode, remarkably improving the inversion precision of low ionosphere parameters, and improving the reliability of the low ionosphere. The method has the advantages of simple operation, low cost and long-term operation.

The application provides a piezoelectric driving self-biased very low frequency mechanical transmitting antenna and a preparation method thereof. The preparation method comprises the following steps: step one, preparing piezoelectric ceramic material; step two, cutting and slotting; step three, pouring resin; step four, cutting layer sheet; step five, packaging; step six, polarization treatment; step seven, preparing adhesive layer; and step eight, hot-pressing compounding. Compared with the existing magnetoelectric antenna, the self-biased very low frequency mechanical transmitting antenna has the characteristics of self-bias, high piezoelectricity, miniaturization, no additional noise source and electromagnetic interference, and the like, has the advantages of high stress transmission efficiency and small ohmic loss, can realize the miniaturization requirement of the magnetoelectric mechanical antenna, is easy to form a large-scale array, improves the magnetic transmitting performance under zero bias, and achieves the low frequency communication effect.

The invention discloses a very-low-frequency narrow-band antenna pre-distortion broadband transmitting method. The core of the very-low-frequency narrow-band antenna pre-distortion broadband transmitting method is composed of double-tuning network parameter calculation and pre-distortion waveform design. The method comprises the following steps: with a constraint condition that transmitter port equivalent impedance is equal to transmitter characteristic impedance under an antenna center frequency, adjusting a load current gain peak frequency to a working frequency by calculating an undetermined parameter so as to realize working frequency point tuning; changing parameters of the double-tuned network to design a low-Q-value target group, acquiring primary and secondary side currents under constant-amplitude excitation, importing the primary and secondary side currents into an actual network of an experimental group, and deducing corresponding excitation voltage; according to the method, tuning and resistance changing are achieved through the double-tuning network, transient current fluctuation suppression is achieved through the pre-distortion design, and the active power utilization rate and the very-low-frequency communication rate of the power amplifier are effectively improved.

This invention discloses a lightweight monopole transmitting antenna for an aerostat. From the inside out, it comprises a central reinforcing filler made of multi-strand twisted lightweight reinforcing fibers, a binding layer made of polytetrafluoroethylene film, a non-metallic reinforcing layer woven from non-metallic reinforcing fibers, an inner sheath made of extruded polyethylene, a radiator layer woven from metal wires, and an outer sheath comprising a semi-conductive outer sheath and a metal-woven outer sheath. The semi-conductive and metal-woven outer sheaths have the same outer diameter and alternately cover the outside of the radiator layer. This invention offers advantages such as miniaturization, lightweight, corona resistance, high current resistance, and fatigue resistance, resulting in high reliability and practicality, meeting the requirements for rapid deployment of long-range very low frequency (VLF) communication systems using aerostats.

The application belongs to the technical field of preparation and determination of aviation equipment absorbing material, and discloses a wide low-frequency sound absorption and vibration reduction covering layer structure and a design method. The design method comprises the following steps: by changing the geometric parameters of a single unit composed of an embedded neck hole diameter d, an embedded neck length l and a cavity wall plate height L, the strong non-local coupling between a plurality of embedded rubber Helmholtz resonators is changed, the impedance of the embedded rubber Helmholtz resonator is changed, and the overall structure of the wide low-frequency sound absorption and vibration reduction covering layer structure of the sound absorption metasurface array is obtained by the weak coupling resonance sound absorption mechanism; the embedded rubber Helmholtz resonator is composed of an embedded neck, a damping rubber coating layer and a sound absorption cavity. The non-local coupling between the plurality of embedded rubber Helmholtz resonators in the multi-element metasurface array is adjusted, effective broadband impedance modulation is realized, and strong dissipation of broadband sound energy is realized at very low frequency.

The application provides a very low frequency atomic magnetometer environment interference suppression method based on polarization selection reception, wherein a precession main magnetic field B e and -B e are respectively applied by a main magnetic field coil in z direction and -z direction in front and back two regions of a gas chamber e and -B e regions are detected by using detection laser in x direction; external very low frequency signals are detected by interaction with atoms polarized in z direction to make the atoms produce precession signals in xOy plane, so that the signals are detected by light detection; when the external signals are linear polarization, according to the selection rule of angular momentum conservation, the precession signals of atoms in B e and -B e regions are offset, so that the system does not respond to linear polarization signals; for circular polarization signals, only atoms in B e or -B e region have precession signals, so that the detection of circular polarization signals is realized. The technical scheme of the application is applied to solve the technical problem of environmental magnetic noise interference of a very low frequency atomic magnetometer in an actual application scene in the prior art.

The invention belongs to the technical field of wireless detonators. The invention discloses a low-frequency through-the-earth communication transmitting antenna for a wireless detonator, and the antenna comprises a transmitter which is used for generating a low-frequency / very-low-frequency radio-frequency power signal with a specific frequency, wherein the power signal carries a detonation instruction; the tuner is connected with the transmitter and is used for enabling the output impedance of the transmitter to be matched with the input impedance of the low-frequency through-the-earth communication antenna, so that the power of the transmitter is most effectively transmitted to the low-frequency through-the-earth communication antenna; the low-frequency through-the-earth communication antenna is connected with the tuner and is used for receiving a signal transmitted to the low-frequency through-the-earth communication antenna by the tuner and generating an alternating electromagnetic field signal; wherein the transmitter, the tuner and the low-frequency through-the-earth communication antenna are respectively provided with a cable plug, and the cable plugs are in quick release connection through connecting cables; the tuner and the low-frequency through-the-earth communication antenna form a group of low-frequency through-the-earth communication mechanisms, the transmitter is connected with the multiple groups of low-frequency through-the-earth communication mechanisms, and an antenna array is formed among the multiple groups of low-frequency through-the-earth communication mechanisms.

The invention provides a multi-unit very-low-frequency transmitting antenna system and a tuning method thereof, and belongs to the technical field of very-low-frequency transmitting antennae, and the multi-unit very-low-frequency transmitting antenna system comprises a plurality of antenna units, a plurality of tuning pavilions, a plurality of low-voltage feeder lines, a transmitter and a plurality of ground nets, the plurality of tuning pavilions are respectively positioned near the central position of each group of antenna units, each tuning pavilion consists of a plurality of tunable coils with the same structure, and the tuning pavilions are connected with the root parts of the antenna units; the plurality of low-voltage feeders are respectively connected with the transmitter and the plurality of tuning booths, the transmitter is located at the geometric center of the antenna array formed by the plurality of antenna units, and the transmitter is connected with the low-voltage feeders through the shunt device and the high-voltage isolation switch; the plurality of ground nets are respectively laid by taking the plurality of antenna units as the center, each ground net is composed of a plurality of local ground nets which are laid in a radial shape, and the plurality of ground nets are connected through metal ground net wires or are kept independent and not connected. According to the invention, the complexity and difficulty of antenna design and construction are obviously reduced, and the dependence on the terrain of an antenna array is reduced.

An adaptable low frequency (LF) or very low frequency (VLF) receive antenna is configured to provide an amplified analog signal and / or a digital signal to a receiver. Such an adaptable LF / VLF receive antenna may be used with older generations of analog and digital receivers as well as newer generations of digital receivers that use a digital feed. Thus, an LF / VLF receive antenna in accordance with the present disclosure may be used to replace an existing antenna connected to an analog receiver and will continue to work when the analog receiver is upgraded in the future so as to ease the transition to newer digital receivers. In one or more embodiments, the digital signal may be further processed within the LF / VLF receive antenna so as to reduce its bandwidth and permit transmission of the processed digital signal over a data network.

The invention relates to a very-low-frequency sinusoidal vibration mechanism and a water sound pressure calibration device, and the mechanism comprises a servo motor which is used for providing rotation power; the harmonic reducer is connected with an output shaft of the servo motor and is used for reducing the rotating speed and improving the output torque; the driving shaft is connected with the output end of the harmonic reducer, and a sine curve guide groove is formed in the driving shaft; and the guide crank is provided with a tip part matched with the sine curve guide groove in the driving shaft, and the tip part is matched with the sine curve guide groove to enable the rotary motion of the driving shaft to be converted into the linear motion of the guide crank. According to the sine vibration mechanism, lower vibration frequency and higher stability can be generated, the harmonic reducer and the servo motor are introduced into the sine vibration mechanism for driving for the first time, lower frequency can be generated, and the influence of waveform distortion degree introduced by the sine vibration mechanism is reduced.

The invention relates to the field of vector hydrophone calibration, and discloses a very low frequency sensitivity calibration device, system and method of a vector hydrophone, the device comprises a base and a co-vibration unit which can be horizontally or vertically installed on the base, the co-vibration unit comprises a square frame, and a vibration exciter and a co-vibration slide block which are installed in the square frame, the co-vibration sliding block is connected with the vibration exciter, the vibration excitation direction of the vibration exciter is the horizontal axial direction of the co-vibration unit, and the co-vibration sliding block can move in the square frame under the action of the vibration exciter; the co-vibration slide block is provided with a horizontal fixing groove and a vertical fixing groove which are used for fixing the vector hydrophone. According to the invention, the sensitivity calibration of the vector hydrophone in the horizontal and vertical directions can be realized through one set of device, the use flexibility of the device is greatly enhanced, and the calibration of the vector hydrophone under a very low frequency condition can be realized; the problem that in an existing calibration method, a liquid column tube is poor in planar standing wave uniformity and parallelism under excitation of lower than 20 Hz is effectively solved.

The invention discloses a receiving and releasing device for a very-low-frequency transmitting antenna, and belongs to the technical field of very-low-frequency transmitting antennas. The winding and unwinding device comprises a rack, a winding displacement assembly and a winding drum assembly. The rack is of a U-shaped structure; the wire arranging assembly comprises a driving unit and a connecting block, and the driving unit is located on the rack; the winding drum assembly comprises a first motor, a winding drum, a swing arm and a fixed pulley, the first motor is located on one side plate of the rack and is in transmission connection with the winding drum, the swing arm is rotatably arranged on the connecting block, a rotating shaft of the swing arm is arranged in the first direction, and the fixed pulley is rotatably inserted into the swing arm; and the outer peripheral wall of the fixed pulley is provided with a wire slot for accommodating a very-low-frequency transmitting antenna. The winding and unwinding device for the very-low-frequency transmitting antenna is simple in structure, the occupied space is small after the very-low-frequency transmitting antenna is wound, and the problem that the very-low-frequency transmitting antenna is broken due to friction damage can be avoided.

The present disclosure provides systems and methods of analyzing a sleep session as a REM sleep session or a wake session. According to aspects of the present disclosure, a computer- implemented method includes accessing cardiopulmonary coupling data throughout a sleep session of a person, identifying a period in the sleep session corresponding to very low frequency coupling in the cardiopulmonary coupling data, accessing high frequency coupling data and / or low frequency coupling data in the cardiopulmonary coupling data corresponding to the period, and designating the period as a REM sleep session or a wake session based on the high frequency coupling data and / or the low frequency coupling data corresponding to the period, wherein the period is designated based on the cardiopulmonary coupling data without using non-cardiopulmonary coupling physiological data.

The invention relates to the technical field of lightning position indicators, and discloses an automatic calibration device and method for a very low frequency-low frequency lightning position indicator. The device comprises a shielding cabin, an electric field radiation antenna, a magnetic field radiation antenna, a lightning signal simulation board and a test instrument. The interior of the shielding cabin is divided into two independent areas, the two radiating antennas are arranged in the shielding cabin, and a taking and placing window is arranged on the outer side of the shielding cabin. The electric field radiation antenna is of a parallel metal plate structure, and the magnetic field radiation antenna is of a Helmholtz coil structure; the lightning signal analog board is connected with the two radiation antennas through shielding cables, and the test instrument is respectively communicated with the lightning signal analog board and the lightning locator to be calibrated. An electric field antenna and a magnetic field antenna of a position indicator to be calibrated can be correspondingly placed in the two radiating antennas through the taking and placing windows. The device can realize the automatic calibration of the positioning instrument, guarantee the accuracy and reliability of calibration, improve the calibration efficiency, and adapt to the respective calibration requirements of the double antennas of the positioning instrument.

The present Invention relates to methods and devices for sending and receiving electrical signals through "dissipative" media such as soil, mud, or sea / fresh water to distances extending to several tens of meters. Present methods for sending through such media use very high-power levels ranging to Mega-Watts and employ large equipment. Very Low Frequency (VLF) and Extremely Low Frequency (ELF) communication systems used to communicate with submarines are an example. In contrast, methods and devices disclosed here are powered by general purpose batteries (such as Lithium-Ion batteries) and can be used with consumable items as small as a mobile phone. The invention achieves this functionality by combining near field resonant magnetic coupling with symbol stretching at the transmitting end and matched filtering at the receiving end. While the range of near field magnetic coupling is limited to approximately 1' (30 cm), the combination disclosed in the invention enables to send / receive signals extending to several tens of meters. This new technology (the combination) opens several new applications. At present, there is no systematic methodology to detect victims of natural or man-made disasters such as landslides, earthquakes, and disasters where the victims are buried in media such as soil or mud. The invention can be used to add functionality to consumer devices such as mobile phones or similar so that they can be easily located. Alternatively, a novel device one can easily carry (smaller that the size of a mobile phone) can be introduced, which would be very useful for communities living in countries prone to natural disasters. Scanning for victims can be done fast by mounting the search device on a drone. The methods and devices disclosed can also be used for underwater communication between diver to diver and diver to vessel and the technology is especially suitable for freshwater applications. In addition, this technology can also be used for communication in mines in emergency situations. It is suggested to use in emergency situations due to low data rates.

Embodiments described herein relate to a VLF data communication system and method that allows a VLF transmitter or receiver to operate underground and be powered by a co-located power source for a long period of time. Data to be transmitted is encapsulated in a single data packet for transmission, minimizing the on time of the transmitter and receiver. One or more receivers process the data packet to synchronize with the transmitter symbol timing clock and then demodulate the encapsulated data. Timing information can also be used by the receiver to control external devices. The method used can be implemented on a low power microcontroller unit (MCU) to further reduce power consumption.

The invention discloses a low-crosstalk long-distance sensing integrated device and a very-low-frequency sensing method, and relates to the technical field of fusion of optical fiber sensing and optical fiber communication. The device comprises a laser, a coupler, a communication modulation device, a sensing modulation device, an optical fiber transmission and relay link, a communication receiving device, a sensing receiving device and a signal processing device. The communication modulation device adopts digital subcarrier multiplexing and reserves a guard interval in a frequency spectrum center, and residual carrier filtering is combined to reduce the inductance crosstalk; the sensing modulation device realizes high-extinction-ratio pulses through a cascade light modulator, and the signal-to-noise ratio is improved. The optical fiber link adopts a bidirectional amplification relay module to synchronously amplify forward and backward signals so as to realize ultra-long distance transmission. The signal processing device carries out high-density sampling and space-time dimension fusion on the sensing beat frequency signals, and very low frequency vibration information is effectively extracted. According to the invention, common-light-source, low-crosstalk, long-distance, very-low-frequency and high-sensitivity integrated transmission and detection of communication and sensing signals are realized.

The present application belongs to the field of radio wave propagation theory and electromagnetic field numerical calculation technology, and discloses a low-dispersion very low frequency radio wave propagation characteristic prediction method.The present application method aims at the defects of large numerical dispersion, low calculation efficiency and high resource occupation of the existing FDTD method in long-distance, complex layered medium scene, and realizes high-precision and high-efficiency prediction of the very low frequency radio wave propagation characteristic in seawater-air-ionosphere medium by combining HIE-FDTD method and M(2,4)FDTD method through three-layer processing of the whole calculation area.The present application method solves the contradiction between reducing numerical dispersion error and reducing computer consumption of the traditional FDTD method, can greatly reduce computer memory resource occupation and improve calculation speed while ensuring prediction accuracy, is suitable for electromagnetic propagation simulation of large-size, complex medium and terrain, and has obvious advantages in phase delay prediction of very low frequency ground wave propagation.

The application provides a method and system for improving the receiving bandwidth of a very low frequency atomic magnetometer, which polarizes alkali metal atoms in an atomic cell along the direction of a driving laser by using the driving laser; an external magnetic field at the cell is compensated by a three-axis magnetic coil and a three-axis magnetic sensor to provide a zero-field environment, and a main magnetic field B is applied to the coil in the direction of the driving light; the precession of the spin projection signal of the polarized atoms in the x direction is detected by using a detection laser in the x direction; an external very low frequency signal interacts with the atoms polarized in the z direction to make the atoms produce a precession signal in the xOy plane, so that the detection light is detected. After the detection light signal is collected, the control system feeds back a damping magnetic field to the atomic ensemble through the coil, and the bandwidth of the system is expanded by adjusting the feedback parameters while keeping the sensitivity unchanged. The technical scheme of the application solves the technical problem that high sensitivity and high bandwidth cannot be achieved simultaneously in the prior art.

The utility model relates to a kind of micro mechanical antenna, belong to antenna technical field.It includes pulsed terahertz laser source, beam expanding system, phase modulation array, double-layer hexagonal boron nitride array and substrate;The pulsed terahertz laser of pulsed terahertz laser source is expanded after beam expanding system and is incident to phase modulation array, and is irradiated to double-layer hexagonal boron nitride array after phase modulation by phase modulation array;The double-layer hexagonal boron nitride array is set on the substrate, and under the action of pulsed terahertz laser, based on displacement type ferroelectric effect, ferroelectric polarization flips, to cause the periodic inversion of surface charge, form time-varying electric dipole and produce electromagnetic radiation output.Solve the existing low frequency and very low frequency antenna rely on wire current oscillation to cause size huge, difficult to integrate, and existing mechanical antenna medium surface charge density is low, radiation efficiency is low, lack effective phase control ability, difficult to realize directional radiation and other problems.Widely used in low frequency communication and special environment communication scene.

The invention relates to the technical field of radio direction finding, in particular to a ship-borne very-low-frequency emission source positioning method and device based on data fusion, and the method comprises the steps: carrying out the positioning of a ship-borne very-low-frequency emission source when a ship-borne platform is located at a first target position and drives to a second target position; acquiring a first magnetic field and a second magnetic field generated by the very-low-frequency emission source at the first target position and the second target position to calculate a first possible deviation, a second possible deviation, a third possible deviation and a fourth possible deviation of the very-low-frequency emission source; and determining the direction of the very-low-frequency emission source based on the directions with intersection between the deviations, and positioning the actual position of the very-low-frequency emission source in combination with the distance of the very-low-frequency emission source relative to the second target position. According to the invention, based on the actual navigation condition of the ship, the receiving device of the ship is effectively utilized to receive the magnetic field information generated by the electromagnetic waves emitted by the very-low-frequency emission source, and the single-point direction finding and double-point positioning functions of the fixed very-low-frequency emission source are simply and efficiently realized in combination with the three-dimensional coordinate system.

This invention discloses a convolutional neural network model and its training method for evaluating the amplitude distribution of very low frequency (VLF) signals, addressing the problems of long computation time and low efficiency in traditional physical models. The model includes: an input layer configured to receive data on the effective reflection height and electron density variation rate at the bottom of the ionosphere; a convolutional layer configured to extract feature information by performing a convolution operation on the data; a pooling layer configured to compress and extract the feature information extracted by the convolutional layer; a fully connected layer configured to map the extracted feature information to VLF signal amplitude; and an output layer configured to output the VLF signal amplitude. This invention significantly reduces computation time while ensuring the accuracy of the calculation results, and has significant value in the engineering application field of VLF detection.

The invention provides a frequency hopping signal parameter blind detection method and system based on deep learning, and the method comprises the steps: carrying out the S transformation time-frequency analysis of a received mixed signal, and generating a time-frequency graph for suppressing a very low frequency interference signal and Gaussian white noise; a hybrid encoder architecture is constructed based on an RMT backbone network, and multi-scale time-frequency features are extracted; inputting the time-frequency diagram into a hybrid encoder architecture, extracting multi-level features through an RMT backbone network, generating a target query through a hybrid encoder, and outputting bounding box coordinates of a frequency hopping signal by a decoder; and according to the physical parameters of the bounding box coordinate mapping frequency hopping signal, calculating the frequency hopping frequency and the hopping time, and completing robust estimation of the frequency hopping frequency and the hopping time. According to the invention, direct estimation of frequency hopping frequency and time is realized by using a reverse mapping mechanism of the TF graph.

The application discloses a kind of deep sea direct sound zone near seabed very low frequency line spectrum target ranging method, belong to deep sea signal processing and underwater target positioning field.The method steps include: based on target sea area environmental parameter establishment sound propagation model, through near seabed vertical direct receiving array obtains depth-intensity interference fringe;Copy sound field calculation model is constructed using virtual source method, and three main propagation paths are retained to generate copy interference fringe;To measured and copy stripe are standardized, with cross-correlation coefficient as matching index, realize target distance estimation by peak search.The application realizes the estimation of target sound source distance by matching the depth-intensity interference fringe formed by the near seabed vertical array at a single frequency, with the depth-intensity one-dimensional interference fringe as the matching object, the array aperture is small, the feature dimension is lower, the calculation amount of copy field generated by virtual source method is smaller, and due to the equivalent assumption of virtual source method, the method is not sensitive to environmental mismatch, and has good robustness.