34 results about "Free space propagation" patented technology

The invention belongs to the technical field of short-wave communication, and particularly relates to a short-wave sky wave channel propagation parameter optimization method based on antenna directivity, which comprises the following steps: acquiring directivity diagrams of a transmitting antenna and a receiving antenna; determining a propagation path of sky wave rays from a transmitting antenna to a receiving antenna by adopting a numerical ray tracing algorithm; according to the propagation path, calculating free space propagation loss, ionosphere loss and ground reflection loss; performing directional gain correction on the signal intensity on the propagation path according to the directional diagrams of the transmitting antenna and the receiving antenna; calculating the total propagation loss according to the free space loss, the ionosphere loss, the ground reflection loss and the antenna directivity correction value; outputting propagation parameters including the total propagation loss, the propagation path, the antenna directivity correction value and the time delay; according to the method, antenna directivity parameters and propagation path loss are dynamically coupled, and the defect that a traditional model ignores the influence of antenna radiation directivity on signal strength is overcome.

An optical system is presented for use in a near-eye mixed reality system. The system comprises a relay system defining an eyebox of the optical system, said relay system being configured and operable to relay a virtual image light field from a light-engine onto an eye pupil plane while combining said virtual image with real-world light field. The relay system is configured as a free space relay system configured for free space propagation of said virtual image light field being relayed, said free space relay system comprising at least one off-axis 4f-system. Each of said at least one off-axis 4f-system comprises at least one lens formed from at least one resonance-domain surface relief diffractive optical element (SRDOE) operable for combining said virtual image light field with the real-world light field, said at least one SRDOE being configured with a predetermined global surface relief pattern characterized by global variation of at least some of pattern parameters across said SRDOE.

The invention discloses a multi-terrain adaptive wireless communication path loss prediction method and equipment, and relates to the technical field of wireless communication. The objective of the invention is to solve the problems of discontinuous prediction and precision reduction in a terrain transition region when a separated model is adopted to predict cross-terrain path loss in related technologies. The method comprises the steps of firstly obtaining terrain environment information and communication parameters; a numerical parameter terrain factor for uniformly quantifying different terrain types is introduced, and the features of a transition region can be quantified by performing numerical interpolation on the terrain factors of adjacent terrains; then, decomposing the total path loss into free space propagation loss, terrain correction loss and atmosphere correction loss; and finally, superposing the three types of loss to obtain a path loss predicted value. According to the method, the unified terrain quantification framework and the loss calculation model are constructed, so that continuous and accurate path loss prediction in a complex multi-terrain environment is realized, and the universality and the reliability of prediction are improved.

The invention relates to the technical field of communication anti-interference testing, in particular to an unmanned aerial vehicle interference testing method based on dynamic attenuation and power division. According to the method, multi-dimensional environment feature vectors including power spectral density, modulation features and signal time delay are extracted; a dynamic attenuation matrix is constructed based on the vector, and a composite path loss model is established on the basis of correcting a free space propagation model, so that interference characteristics in a real wireless propagation scene can be effectively simulated, a test channel is enabled to be more fit with an actual deployment environment, and the credibility and adaptability of interference test are improved; according to the invention, based on the optimal power proportion, three types of signals, namely, an environment noise signal, a deceptive interference signal and an impressive interference signal, are generated respectively, and three indexes, namely communication response time delay, positioning deviation and a communication interruption rate, are combined to form an accurate anti-interference evaluation system; and the robustness, the stability and the fault-tolerant capability test precision of the unmanned aerial vehicle communication system in different interference environments are effectively improved.

The present application relates to the field of wireless communication and positioning technology, in particular to a three-dimensional space positioning method based on wireless mesh network and a server; the method comprises determining path loss factor and reference signal strength of free space propagation model by using known distance and signal strength between N reference nodes; selecting M reference nodes with strongest signal received by target node, obtaining coordinates of the M reference nodes and calculating distance from the target node based on the determined free space propagation model; calculating initial coordinate value of the target node by using genetic algorithm based on coordinates of the M reference nodes and measured distance from the target node; calculating final coordinate value of the target node by using improved Gauss-Newton algorithm based on the initial coordinate value of the target node. The present application can effectively reduce the influence of multipath interference and shadow fading on RSSI positioning, and significantly improve the accuracy and stability of three-dimensional positioning.

An ultraprecision frequency-domain Light Detection and Ranging (LiDAR) system for remote micro-movement sensing includes a laser diode with a bandpass filter configured to modulate power using RF signals to generate intensity-modulated optical signals. The LiDAR system includes a Michelson interferometer to split generated optical signals via a 50 / 50 directional coupler into two optical paths. A first optical path includes a fiber-optic delay line with a silver-coated end reflecting phase-shifted optical signals towards a photodetector. A second optical path features a semiconductor optical amplifier amplifying the generated optical signals, with an optical collimator and a target beyond a free-space propagation region. A photodetector is connected to the 50 / 50 directional coupler that receives both the phase-shifted and amplified optical signals, converting them to electrical signals. A feedback loop, including a bandpass filter and a frequency-domain analyzer detects frequency shifts caused by micro-movements of the target.

Select a transmission wavelength suitable for light propagation in free space. [Solution] The optical communication device comprises an optical transmitting unit that transmits a main signal, which is an optical signal, into free space, and a control unit that controls the wavelength of the main signal transmitted by the optical transmitting unit.

The invention belongs to the technical field of Bluetooth positioning, and particularly relates to a Bluetooth indoor propagation model correction method of a support vector regression machine, comprising the following steps: S1, determining a Bluetooth indoor initial propagation model to be corrected, the initial propagation model being an indoor propagation model improved based on a free space propagation model or a logarithmic distance path loss model, input parameters of the initial propagation model at least comprise a linear distance between a Bluetooth transmitting end and a Bluetooth receiving end and the number of walls on a propagation path, and output parameters are propagation loss values of Bluetooth signals; according to the support vector regression (SVR) Bluetooth indoor propagation model correction method provided by the invention, the problems of single feature dimension, unquantized time sequence fluctuation, poor regional adaptability and the like in the prior art are effectively solved by innovatively fusing multi-modal data collaborative acquisition, time sequence statistical feature modeling and partition adaptive correction strategies.

Systems and methods are provided for implementing a free space light backplane structure including a body and a plurality of mirrors. The body includes a chamber, a front plate, and a plurality of apertures disposed in the front plate, the plurality of apertures including a first set of apertures and a second set of apertures. The plurality of mirrors includes first and second mirror arrays mounted at first and second sets of heights, respectively, within the chamber and aligned with first and second sets of holes located in the front plate. The first and second mirror arrays are arranged to guide a laser signal propagating through a free space, the laser signal is transmitted from the first device through the first set of apertures, between the first and second mirror arrays, and through the second set of apertures to the respective second device or from the respective second device through the first set of apertures, between the first and second mirror arrays, and through the second set of apertures to the first device.

The invention relates to the technical field of optical imaging, in particular to a multi-layer phase screen synthesis method for atmospheric turbulence simulation, which comprises the following steps of: distributing a memory in a computer, and setting an initial light field in the memory; inputting set turbulence parameters into a parameter configuration module of the computer, generating a random phase screen sequence, and loading the turbulence parameters and the phase screen sequence into a memory; the simulation initial light field sequentially passes through each layer of phase screen and then is subjected to free space propagation, and a target light field is generated; taking the target light field as an initial value of reverse propagation, performing reverse calculation through the modulation effect of each layer of phase screen and the diffraction effect of the propagation path, and synthesizing an equivalent phase diagram; performing phase extraction on the phase diagram, adding a fill factor to compensate amplitude attenuation, and mapping to a single spatial light modulator; the multi-layer phase screen synthesis method for atmosphere turbulence simulation is realized. According to the invention, propagation of light waves in a turbulent medium can be simulated more accurately, and simulation requirements of different scenes can be met flexibly.

Systems and methods for contactless identification of an optical fiber under test (FUT) are disclosed. System embodiments include an optical power meter and an optical accessory. The power meter can include a casing, a detection port extending through the casing, and a photodetector optically coupled to the detection port within the casing. The accessory can include a housing and a focusing lens. The housing extends between an attachment end and a testing end, and encloses an interior region defining an optical pathway. The attachment end is releasably connected to the detection port, while the testing end is configured to be positioned at a testing distance from the FUT and allow fiber light emanating from the FUT to enter the optical pathway via free-space propagation. The focusing lens is positioned within the housing along the optical pathway and configured to direct the fiber light onto the photodetector through the detection port.

The present invention relates to the field of optical imaging technology, and in particular to a multi-layer phase screen synthesis method for atmospheric turbulence simulation, comprising: allocating memory in a computer and setting an initial light field in the memory; inputting set turbulence parameters into a parameter configuration module of the computer, generating a random phase screen sequence at the same time, and loading the turbulence parameters and the phase screen sequence into the memory; simulating the initial light field to propagate through each layer of phase screen in turn in free space to generate a target light field; using the target light field as the initial value for reverse propagation, reversely calculating and synthesizing an equivalent phase diagram through the modulation effect of each layer of phase screen and the diffraction effect of the propagation path; performing phase extraction on the phase diagram, adding a fill factor to compensate for amplitude attenuation, and mapping it to a single spatial light modulator; and realizing a multi-layer phase screen synthesis method for atmospheric turbulence simulation. The present invention can more accurately simulate the propagation of light waves in turbulent media and flexibly adapt to the simulation requirements of different scenarios.

The invention relates to an optical processing device (DR) for optically processing an incident light beam (I0) which has propagated through a free space and whose phase front is susceptible to distortion. The optical processing device (DR) comprises: mode conversion means (M) configured to break down at least a portion of the incident light beam (I0) into at least two elementary light beams (to); and an integrated photonic device (C) configured to coherently recombine the at least two elementary beams (to) and to produce at least one recombined beam () on the output optical port (P2). The basic light beam (arrival) propagates between the input optical port (P1) and the output optical port (P2) along at least two separate optical paths, respectively. The optical processing device (DR) is characterized in that at least one of the optical paths comprises at least one static delay element (D1, D2, D3) configured to equalize the propagation time of the elementary optical radiation along the optical path.

The invention discloses a partial discharge detection method and device based on a Rydberg atomic electric field sensor, belongs to the technical field of partial discharge detection, and solves the problem that the sensor is easily damaged by electrical breakdown in a strong electric field environment in an existing partial discharge detection technology. A ground state cesium atom is excited to a Rydberg state, based on a free space coupling configuration mode, a to-be-measured radio frequency signal is directly propagated into an atomic gas chamber through a free space to be coupled with the Rydberg atom, an atomic energy level is displaced, the transmissivity of an electromagnetically-induced transparent spectrum is changed, electric field information is encoded into an optical signal, and the optical signal is transmitted to the ground state cesium atom. And then the photoelectric detector is used for converting the modulated optical signal into an electric signal, the electric signal is input into the oscilloscope for time domain waveform analysis, and based on an electrical-optical-electric signal conversion mechanism, the common electric breakdown risk in the traditional ultrahigh frequency detection technology is effectively avoided.

A module accommodates multiple superluminescent light emitting diodes, SLEDs, 12r, 12g and 12b. The SLEDs are arranged in an enclosure and output respective light beams to propagate into free space within the enclosure. The individual light beams from the SLED sources are combined into a single beam path within the enclosure using beam combiners 40r-g, 40rg-b. Each beam combiner is realized as a planar optical element, the back side of which is arranged to receive a SLED beam and route it through the optical element to the front side where it is combined with another SLED beam that is incident on and reflected by the front side. The free-space propagating combined beam is output from the module via an optical fiber 42 (or through a window).

The invention discloses a telemetering wireless communication operating distance calculation method. Comprises: obtaining a free space propagation model; model parameters are corrected; and calculating a telemetering wireless communication operating distance. A telemetering wireless communication operating distance calculation method is a key link of design, operation and optimization of a measurement and control large system, and is related to and determines system design and planning, performance evaluation and optimization, safety and reliability guarantee, cost control and resource optimization, and fault diagnosis and maintenance. And the method plays a crucial role in ensuring the reliability, effectiveness and economy of the system.

The invention relates to the technical field of data transmission, in particular to an offshore wind plant data transmission method based on data security. The method comprises the following steps: acquiring a radio signal attenuation value monitored by a monitoring station, and determining a current transmission environment according to a comparison result of the radio signal attenuation value and an electric signal attenuation threshold value; calculating a standard loss value based on the free space propagation model and the marine environment correction term, and comparing the propagation loss value with the standard loss value; performing crisis detection according to the interruption detection and the data identification to determine whether transmission interruption exists or not; and analyzing the influence of the blocking effect and the multipath effect on the transmission of the alarm signal so as to execute a dynamic security strategy or adjust transmission parameters. According to the method, the security of data transmission is judged by monitoring attenuation of radio signals, and the influence of a wind power plant structure on radio signal transmission is considered by combining equipment life prediction, data identification, potential risk early warning and introduction of blocking analysis and multipath effect analysis, so that more accurate identification is realized.

The invention discloses a non-ground network differential measurement reporting method, device and equipment and a medium, and relates to the technical field of communication, a terminal device obtains satellite ephemeris and geographic position information of the terminal device, calculates a satellite end real-time geometric distance and predicts path loss based on a free space propagation model, and reports a non-ground network differential measurement report result. Calculating theoretical reference signal receiving power by combining network side radio frequency configuration parameters; the method comprises the steps of obtaining actual receiving power through physical layer radio frequency measurement, calculating a difference value between the actual receiving power and the actual receiving power, carrying out quantization coding to generate a short-bit difference measurement report, reporting the short-bit difference measurement report to a network side for recovering the actual power, designing a difference rollback and environment calibration mechanism, selecting a reporting channel according to an uplink channel state, effectively compressing the reporting data volume, and improving the transmission efficiency. The uplink signaling overhead is reduced, the slow fading characteristic of a satellite channel is adapted, the uplink resource utilization efficiency of a non-ground network is improved, and the accuracy and reliability of measurement reporting are guaranteed.

A method and system for testing automotive radar using a simulated radar data cube simulator are disclosed. A simulated radar transmission waveform is defined based on expected radar performance. A virtual real-world scenario including one or more virtual target objects is constructed. The virtual target objects simulate the reflection and scattering characteristics of real-world objects to incident radar waves. The simulation includes the operation of radar transmit and receive channels including an antenna array and free-space propagation to obtain simulated raw radar data. The simulated raw radar data is processed to establish a simulated radar data cube. The simulated radar data cube is utilized to test radar perception algorithms.

The invention provides an AIS (Automatic Identification System) base station receiving distance evaluation method and system, relates to the technical field of communication, and is used for accurately eliminating abnormal data and retaining an effective navigation state by fusing ship maneuvering characteristics and time continuity constraints through a dynamic threshold cleaning mechanism. Local polynomial fitting is carried out on trajectory parameters, and the authenticity of dynamic changes of the navigational speed and the navigational direction is maintained while noise is suppressed. A space-time coupling model of rainfall attenuation and a ship geographical distance is established, a rainfall attenuation coefficient is dynamically calculated based on an ITU standard, free space propagation loss is corrected, static modeling limitation of a traditional method on meteorological interference is broken through, and high-precision evaluation of a base station receiving distance in a complex environment is realized.

The invention discloses an MIMO through-the-wall radar imaging method based on propagation compensation and coherence factors. Aiming at the problems of target signal attenuation weakening, grating lobe and side lobe accompanied by imaging and low imaging efficiency, the method comprises the following steps: firstly, deducing obtained data reconstruction based on a coherence factor, deforming echo data, and carrying out parallel calculation on obtained reconstruction data and original echo data to obtain a non-coherence superposition part of the coherence factor; then reducing the dimension of the MIMO array echo data into single static array echo data based on the equivalent phase center; a specific propagation compensation value is obtained through quantitative derivation based on the scalar diffraction theory, fixed free space propagation attenuation is compensated under the condition that non-fixed wall attenuation is difficult to obtain, and wave number domain processing is completed; wall compensation factors of a wave number domain are designed, and extra time delay introduced by through-wall refraction is directly corrected in the wave number domain; and finally, the non-coherence superposition component and the coherence superposition component which are obtained through parallel calculation are utilized to complete weighted imaging to obtain a final imaging result.

A free space optical oscillator system for sensing perturbations in optical signals transmitted through a free space propagation region includes a laser diode which generates intensity-modulated optical signals. A first 50 / 50 directional coupler connected to the laser diode injects the intensity-modulated optical signals into an optical sensing path. A free space propagation region located between a first and second collimating lens generates phase shifts in the intensity-modulated optical signals upon detecting changes in a substance located within a sensing zone of the free space propagation region. A semiconductor optical amplifier (SOA) amplifies the phase shifted intensity-modulated optical signals. A phase shift loop, connected between a second 50 / 50 directional coupler and the first 50 / 50 directional coupler, inserts a fixed phase shift into the amplified phase shifted intensity-modulated optical signals through a piezoelectric (PZT) fiber stretcher. A measurement loop converts the phase-shifted amplified intensity-modulated optical signals to electrical signals using a photodetector.

The application discloses a kind of super-resolution optical imaging method and system based on diffraction neural network, it is related to optical imaging and information processing field, comprising: S1, by diffraction neural network construction includes multiple phase modulation layers of diffraction modulation component;S2, utilize electronic convolutional neural network to carry out phase compression coding to high-resolution image, obtain corresponding low-resolution phase encoding graph;S3, under the irradiation of light source module, load low-resolution phase encoding graph to spatial light modulator to obtain the input light field of optical system;S4, input light field sequentially through each phase layer of diffraction modulation component, and it is transmitted according to free space propagation law between each layer, again through the superposition interference and diffraction effect in transmission, complete the information processing of neural network-like, obtain corresponding output light field;S5, by setting detector at the end of diffraction neural network, to construct the detection surface of capture output light field, to complete super-resolution optical imaging.

An interface device for performing off-chip coupling in optical waveguides includes an optical waveguide core for propagating light of a particular wavelength or a plurality of wavelengths and an array of radiative elements configured to change the propagation direction of the light. The optical waveguide core is configured to control the effective refractive index of the propagation mode of the light. The device can thus serve as an optical antenna for coupling between a waveguide mode and a free-space propagating beam or a plurality of free-space propagating beams in an arrayed configuration.

This invention relates to a channel estimation and user localization method based on a spherical array intelligent metasurface. Specifically, it includes: designing a spherical array intelligent metasurface (RIS) by arranging reconfigurable reflective elements in an ordered manner according to a three-dimensional spherical topology; constructing a beam training signal model based on standard multivariate decomposition according to the multipath propagation characteristics of cascaded channels, and recovering the path angle parameters on the base station side using a tensor signal processing algorithm; designing a RIS training reflection coefficient beamforming method based on the spherical phase mode excitation principle, and recovering the equivalent path angle parameters on the RIS side using a spatial spectrum estimation algorithm; and achieving unique decoupling of user path angle and time delay parameters based on the free-space propagation characteristics of broadband multicarrier signals, thus completing user localization. This invention can achieve unambiguous channel estimation, which is unsupported by traditional planar array RIS, with lower hardware costs and training overhead, thereby enabling high-precision user localization applications.

The invention discloses a super-resolution optical imaging method and system based on a diffraction neural network, and relates to the field of optical imaging and information processing, and the method comprises the steps: S1, constructing a diffraction modulation assembly comprising a plurality of phase modulation layers through the diffraction neural network; s2, performing phase compression coding on the high-resolution image by using an electronic convolutional neural network to obtain a corresponding low-resolution phase coding graph; s3, under the irradiation of a light source module, loading the low-resolution phase coding diagram to a spatial light modulator to obtain an input light field of the optical system; s4, the input light field sequentially passes through each phase layer of the diffraction modulation assembly and is transmitted among the layers according to a free space propagation rule, information processing of the neural network is completed through superposition interference and diffraction effect in transmission, and a corresponding output light field is obtained; and S5, arranging a detector at the tail end of the diffraction neural network to construct a detection surface for capturing an output light field so as to complete super-resolution optical imaging.

This invention discloses a small airborne laser communication terminal based on single-mode transmission and multi-mode reception, including a signal transmission and beacon transmission module and a signal reception and beacon reception module. The beacon light in the signal transmission and beacon transmission module is emitted at a specific half-divergence angle, and the signal light is also emitted at a specific half-divergence angle. After propagating a certain distance in free space, the signal light and beacon light are received by the receiving telescope, which focuses the beacon light onto the camera target surface. The pointing angle of the three-axis gimbal is driven based on the position error signal of the beacon light spot, completing the bidirectional alignment of the telescope. This invention employs a small and lightweight laser communication system, which improves fiber coupling efficiency, reduces signal light link loss, and has better robustness to atmospheric turbulence and platform vibration, making it suitable for use on UAVs for free-space optical communication experiments.

This invention discloses a method for active interference signal-to-interference ratio (SIR) analysis of aircraft radio communications. The method includes: acquiring aircraft track data, ground station coordinate data, and interference source coordinate data, and mapping them uniformly to a three-dimensional coordinate system; obtaining the interference limit of the interference source at a reference distance and obtaining the reference interference field strength at the reference distance through correction processing; constructing a free-space propagation model of the active interference source, calculating the minimum distance between the aircraft's track point and the interference source, and obtaining the interference signal strength at the track point from the free-space propagation model; calculating the signal strength between the ground station and the aircraft at the track point, and calculating the SIR in decibels at the aircraft's airborne receiver at the track point. This invention can quickly generate SIR curves for interference assessment analysis of different interference sources on aircraft at different flight segments or different locations, significantly improving the accuracy and comprehensiveness of active interference analysis for airborne equipment.

The present invention discloses a diffraction phased array antenna based on space feeding. The diffraction phased array antenna includes a space feed source and a radiation panel. The space feed source and the radiation panel are arranged in parallel and spaced apart. The geometric centers of the space feed source and the radiation panel are at the same height, and the space feed source and the radiation panel are arranged in close proximity. The radiation panel is a planar aperture formed by a periodic uniform or non-uniform arrangement of multiple reconfigurable artificial surface units. The electromagnetic waves radiated by the space feed source propagate through free space and are incident on the radiation panel. The multiple reconfigurable artificial surface units independently perform phase compensation on the electromagnetic waves incident on themselves in the incident field, thereby obtaining a target diffraction phased array. The present invention adopts a space feed source, and an aspheric wave field is incident on the radiation panel. With the help of the phase reconfigurability of the artificial surface, the incident electromagnetic wave is phase compensated. While improving the aperture efficiency, the fluctuation of the gain of different directional beams is reduced, thereby achieving a larger angular scanning range.

This invention relates to the field of waveguide laser technology, comprising a pair of parallel, oppositely arranged electrode plates, spaced apart to form a waveguide gap; resonant cavities are provided at both ends of the two electrode plates along their length; an insulating coating is provided on the inner surface of at least one electrode plate corresponding to the beam waist region of the resonant cavity; the insulating coating is used to locally weaken the constraint of the electric field on this region by utilizing the difference in conductivity between itself and the electrode plates, forming a free-space-like propagation region with an electric field strength lower than the surrounding region, thereby preferentially selecting the lowest-order waveguide mode for propagation. This invention significantly improves the suppression capability of higher-order modes, avoids the processing difficulty and loss problems caused by excessively small gaps, significantly improves the long-term operational stability of the device, increases the laser damage resistance threshold by approximately 40%, and improves surface thermal conductivity by approximately 25%, thereby effectively extending the device's lifespan.