66 results about "Free space propagation" patented technology

A method and a system for free space optical tomography provides one or more light source and one or more light sensors spaced, which in one embodiment are spaced apart from and object to be imaged. A surface capture system coupled to a variety of optical models provides the method and system with the ability to render accurate tomographic images though the light has propagated both through a diffuse medium and, in on embodiment, also through free space to the one or more light sensors.

A self managed ad hoc communications network nodes and node mobility management. Nodes include an Artificial Neural Network (ANN) that determines connection to other network nodes. The ANN may use free space propagation link life estimation, inverse modeling for partition prediction, Stochastic Approximation, and / or coarse estimation. The node includes storage storing network tables and matrices indicating network connectivity and connection to other nodes. Also, a wireless communications unit provides for wireless communicating with other nodes.

The invention discloses an indoor visible light positioning system. The indoor positioning technology is completed jointly by combination of an LED lamp, a hand-held receiving terminal, and a positioning algorithm. Position information is modulated on a carrier wave distributed to the LED lamp and reverse fast Fourier transform is carried out; a signal is sent into a drive circuit and then the signal is transmitted to an air channel in a visible light mode by free space. A receiving terminal carries out light convergence by an optical lens; the signal is converted into an electric signal; fast Fourier transform is carried out and digital demodulation is carried out; and according to information of three detected strongest powers, a distance between the receiving terminal and the LED lamp is estimated by a lambertian model. According to position coordinate information of a carried transmitting terminal and estimated distance information, a receiving coordinate is calculated finally and positioning is carried out. According to the invention, communication reliability is enhanced; the positioning precision is improved; and the interference of communication between LED cells is effectively resisted.

The invention relates to a rainfall distribution and dynamic measurement method based on a big-data mobile communication network. The method comprises the following steps: (1) constructing a central server which is connected with a mobile terminal base station and establishing a data communication link among mobile terminals, base stations and the central server; (2) collecting transmitting power of the base stations and power, received by the base stations, of corresponding mobile terminals in real time; (3) establishing one-to-one correspondence relationships between the mobile terminals and some base stations and calculating the path attenuation of the communication link between each mobile terminal and the base station; (4) by taking the transmitting power of the base stations as a reference, calculating attenuation of signals of the mobile terminals caused by non-meteorological factors such as free space propagation loss, buildings, vegetation, unset obstacles and the like; obtaining rain-induced attenuation values of mobile terminal signals in unit distance; establishing correlative relationships between the signal attenuation characteristic of the mobile terminals and rainfall intensity distribution; carrying out fusion analysis with professional meteorological data such as a rain gauge, weather radar and the like to obtain areal distribution of rainfall and dynamic changes of rainfall.

The present invention relates to radio frequency (RF) distribution systems for mobile communications. In particular, the present invention relates to a radio frequency network facilitating radio communication where the usual free space propagation of electromagnetic waves is hampered, undesired or impossible, for example in tunnels, mines, and buildings and in large complexes like exhibition grounds, shopping malls, and airports. The radio frequency network (1) comprises a distributed antenna system (2) having radiating elements, a wired distribution system (3) feeding the distributed antenna system (2), at least one antenna amplifier (5) between one end of the wired distribution system (3) and the distributed antenna system (2), at least one line amplifier (4) at the other end of the wired distribution system (3), and automatic self-leveling units included in the antenna and line amplifiers (4, 5).

The invention provides a high gain bidirectional end-fire antenna array applied to a mine and a tunnel, belonging to the antenna design field in wireless communication. A folded dipole with a bending line as a dipole arm is employed as an antenna unit which has a compact structure. An antenna unit medium plate employs an I shape structure, introduced discontinuity is reduced when a feed transmission line steps across the antenna unit, and reflection is reduced. A series connection feed form with combination of horizontal parallel double-line and vertical parallel double-line structures is used, reverse excitation and impedance match of adjacent units are realized, and high gain bidirectional end-fire radiation is obtained. The antenna array is suitable for realization of wireless communication in a typical non-free space transmission channel with limited space such as the mine and the tunnel, and the antenna array has the advantages of the compact antenna unit, a small windward area, low cost and a high gain.

Multiplexing of information from a plurality of information flows into fixed-length packets such as, but not limited to, MPEG packets allows efficient utilization of bandwidth and also can be used to reduce transmission latency. In addition, utilizing MPEG packets and transport streams for octet multiplexing allows the packets carrying octet-multiplexed data to easily be integrated with other MPEG packets for other services that are commonly found in cable transmission networks of all coax, hybrid fiber coax, and / or all fiber. Moreover, the multiplexing techniques described herein will work in both wired (or constrained media) and wireless (or free-space propagation) environments. The multiplexing / demultiplexing of octets using MPEG packets generally is described by mappings that specify the use of octets in MPEG packets. Changes to allocations in a map generally should be propagated in a way that reliably ensures that both the transmitter and receiver have a consistent view of the octet mappings.

This spectrometer comprises at least one elementary spectrometer that comprises an optical phase array comprising a microguide assembly (12) and formed on a cleaved planar optical guide (14), reflecting means (24, 30, 32, 34) capable of successively reflecting radiation sent from the microguide assembly, for propagating this radiation in the folded form and in free space, means (26) for photodetecting the radiation so reflected and means (28) for focusing radiation on said photodetection means.

The invention discloses a simulative division method and a simulative division system for cell coverage. The method comprises the following steps that: after performing discretization on a target area, and then acquiring the coverage diagram of the cell through a free space of a single cell, the system acquires a combined coverage diagram of a plurality of cells; and the system performs vector processing on the acquired combined coverage diagram of the plurality of cells by means of boundary following and key point fitting to acquire the simulative division of the coverage corresponding to each cell. By using the invention, the problems that the conventional cell coverage simulative division algorithm based on Voroni diagram is low in accuracy, and a large amount of data is generated in the cell coverage simulative division based on field intensity are solved.

Improvements to atom interferometers. An improved atom interferometer has a single polarization-preserving fiber, coupled for propagation of beams of two Raman frequencies, and a parallel displacement beamsplitter for separating the laser beams into respective free-space-propagating parallel beams traversing at least one ensemble of atoms. A reflector generates one or more beams counterpropagating through the ensemble of atoms. Other improvements include interposing a beam-splitting surface common to a plurality of parallel pairs of beams counterpropagating through the ensemble of atoms, generating interference fringes between reflections of the beams to generate a detector signal; and processing the detector signal to derive at least one of relative phase and relative alignment between respective pairs of the counterpropagating beams.

The present invention belongs to the technical field of wireless communication, and relates to a digital-to-analog hybrid beamforming method based on uplink training. The method of the invention mainly comprises the following steps: sending by a user terminal a training sequence of a certain length, and receiving by a base station a training signal which travels via free space and is subjected to noise interference; and forming an optimal estimation of the training sequence; through the assumption that the BS knows the training sequence, establishing an objective function wherein the solution of the function is the optimal beamforming matrix; using the reciprocity of the uplink and downlink free-space travel channels to regard the optimal beamforming matrix obtained from the uplink training as the optimal beamforming matrix for the downlink transmission; and then through matrix decomposition, obtaining the beamforming matrixes of the analog domain and the digital domain. The technical schemes of the invention are to eliminate some interference in the analog domain, utilize and improve the idea of orthogonal matching and tracking, search the analog domain beamforming matrix in the codebook set, and finally solve the digital domain beamforming matrix by the least squares method.

A method for predicting the coverage of a 4G LTE (Long-Term Evolution) network based on 3G path measurement data comprises a process for measuring the key coverage indexes of base stations in the existing 3G network and a process for calculating measuring results, wherein the key coverage indexes of each related base station in the existing 3G network are acquired by a test tool, the wireless signal propagation loss of each related base station is calculated, the extra wireless propagation loss, which is caused by frequency variation, of each related base station is measured and calculated according to a freedom space propagation model, the key indexes for evaluating the quality of the 4G LTE network are obtained, a predicting result is obtained, and the predicting result is finally presented by a secondary development tool of a geographic information system. The coverage of the 4G network deployed by the existing 3G network can be predicted, and the deviation degree between the predicting result and a test result after the deployment of an actual test network is within 6dB.

The invention discloses a terahertz space external phase modulator based on a high electron mobility transistor. The phase modulator combines the quick response type high electron mobility transistor with a novel artificial electromagnetic medium resonant structure, so as to be able to conduct quick phase modulation on terahertz waves transmitted in free space. The phase modulator is composed of a semiconductor material substrate, an HEMT epitaxial layer, a periodical artificial metal electromagnetic resonant structure and a muff-coupling circuit. The concentration of two-dimensional electron gas in the HEMT epitaxial layer is controlled through loaded voltage signals, so that the electromagnetic resonance mode of the artificial electromagnetic medium resonant structure is changed, and then phase modulation of terahertz waves is achieved. Over-90-degree phase modulation depth can be realized within a large bandwidth, and the maximum phase modulation depth can be about 140 degrees. Furthermore, the phase modulator is simple in structure, easy to machine, high in modulation speed, convenient to use and easy to package.

The invention provides a method for positioning a pseudo base station. The method comprises the following steps that (I) a signaling collection system acquires and filters location updating signaling of a user; (II) a location area of the pseudo base station is determined and is divided into location blocks; (III) a high-risk location block is determined; (IV) the pseudo base station is positioned by applying rayleigh distribution based on signal attenuation and a cooperative positioning technology based on an electromagnetic wave free space propagation model. According to the method, the area where the pseudo base station appears can be obtained in real time, and accurate positioning can be performed in the area; the problems that a traditional positioning method is slow in response and low in accuracy are solved, resources of law enforcement are saved, the pseudo base station can be effectively fought against, and normal network communication is protected.

A mode selection laser comprises a recess which is formed in the surface of an electrode in a waveguide in the laser. The recess provides a region of free space propagation within the waveguide which preferentially selects the lowest order mode. A mode selective RF excited CO2slab laser may be constructed, having a stable resonator in the waveguide dimension and a negative branch unstable resonator in the non-waveguide dimension. The position and size of the recess is considered to provide low order mode selection.

Described is a space-time digital power amplifier that can be used to generate an arbitrary waveform for a carrier signal. The space-time digital power amplifier employs temporal modulation of transmit signals generated by an array of transmitter modules. The RF signals transmitted from the array are spatially combined through free space propagation to generate the desired waveform. Advantageously, no digital-to-analog conversion is required and upconversion is unnecessary. The digital power amplifiers for the transmitter modules can be combined in a single chip package. The space-time digital power amplifier enables high power efficiency to be realized using pulse-shaped waveforms thus eliminating any need for the power amplifiers to operate over a wider bandwidth with a spectrally unconfined waveform.

A mode selection technique in a laser is described wherein a recess is formed in a surface of a waveguide in the laser. The recess provides a region of free space propagation within the waveguide which preferentially selects the lowest order mode. A mode selective RF excited CO2 slab laser, having a stable resonator in the waveguide dimension and a negative branch unstable resonator in the non-waveguide dimension, is constructed and the position and size of the recess is considered to provide low order mode selection.

A sensor system for detection of a gaseous chemical substance is provided, which comprises an optical sampling cell holding a sampling chamber of a volume of at most 20mm 3, a light emitter and a light receiver. The sampling cell is adapted for free-space propagation of the light beam. With the sensor system, high sensitivity is obtained by elimination of interferometric noise.

The invention relates to the technical field of space-air-ground-sea integrated communication, in particular to a space-air-ground integrated terahertz communication channel modeling method. The modeling method comprises a free space propagation loss module, a cloud attenuation module, a molecular absorption loss module, a rainfall attenuation module, a channel transmission time delay module, a Doppler frequency shift module, a Doppler frequency shift change rate module, a random phase module and a signal impact function generation module. The modeling method provided by the invention covers main factors of the terahertz space-air-ground channel; a space-air-ground terahertz communication channel modeling process is constructed, a step-by-step channel parameter generation method is provided, response data of a dynamic terahertz channel composite attenuation effect under different transmission conditions can be provided, and corresponding transmission technology design suggestions are provided for realizing reliable communication of future space-air-ground integrated terahertz.

The invention provides a building wall imaging method and device using coupling mode dictionary learning suitable for the field of building wall imaging. The method comprises that an echo signal, collected by a radar system of an antenna pulse system, of a target building wall is received; a random measurement matrix is used to compress and sample the echo signal of the target building wall to obtain an observation value vector; an imaging dictionary is designed according to propagation characteristic of the free space, and a compressed sensing model is established on the basis of the observation value vector and imaging dictionary; and according to the compressed sensing model, a sparse signal vector of a behind-wall image is reconstructed via a coupling mode Bayesian dictionary learningalgorithm, and an image of the building wall is obtained. Compared with a present method, a reconstruction performance of a wall extended target reflection coefficient in SOI is improved wholly, the problems including defocusing and position offset of the wall image due to the facts that the quantity, position and wall parameters are unknown and a measurement noise causes mismatching between the dictionary and the imaging scene can be solved effectively, and the data number needed by imaging is reduced effectively.

The invention discloses a bidirectional radiating antenna used in mine shafts and tunnels, belonging to the field of antenna design in wireless communication. The bidirectional radiating antenna is characterized in that a rectangular metal frame is stimulated by a short metal post, wherein the metal frame works in a one-wavelength mode, two narrow sides of the metal frame are radiating main bodies, the distance between the two narrow sides is a little bit smaller than half wavelength, the radiating main bodies form an array and realize the bidirectional radiating with higher gain, the bidirectional radiating antenna can be matched better at a feed port by regulating the height and the diameter of the short metal bars, the long side length and the narrow side length of the metal frame and the width of the metal frame, and the bidirectional radiating property with higher gain is realized. The bidirectional radiating antenna has the advantages of being small in volume, small in windward area, low in cost, easy to process, high in gain and the like, is suitable for realizing wireless communication in the classical space-limited non-free space propagation channels, such as the mine shafts and the tunnels.

The invention discloses a dual-frequency common-caliber VICTS phased-array antenna. The antenna comprises a radiation layer, a parallel plate waveguide layer and a feed network layer which are sequentially arranged from top to bottom, the feed network layer is used for accessing external TE mode electromagnetic waves, converting the accessed TE mode electromagnetic waves into TEM mode electromagnetic waves and outputting the electromagnetic waves to the parallel plate waveguide layer, the parallel plate waveguide layer is used for transmitting the TEM mode electromagnetic waves input into the parallel plate waveguide layer to the radiation layer in an air medium conduction mode, and the radiation layer is used for transmitting the TEM mode electromagnetic waves transmitted to the radiation layer to a free space. The antenna has the advantages that: two frequency bands of a mobile satellite communication system can be covered at the same time, and the area, cost and power consumption of the mobile satellite communication system can be reduced when the antenna is used for the mobile satellite communication system.

The invention discloses a micro-nano satellite cluster relative positioning method based on a position fingerprint. The method comprises the following steps: S1, setting N dynamic proper stars in a micro-nano cluster as AP of cluster relative positioning, and according to cluster need, establishing a dynamic coordinate system; S2, based on real sampling data and a free-space propagation model, establishing a dynamic fingerprint database; S3, periodically broadcasting by the proper stars; S4, receiving a field strength signal by member stars, and downloading the fingerprint database, thus completing position fingerprint identification; and S5, informing the proper stars of a measuring result of relative positioning by each member star through inter-star directional communication, filteringby the proper stars according to relative motion, thereby acquiring continuous cluster relative positioning information. According to the method provided by the invention, in a process of micro-nano satellite close range cluster formation, a simple omnidirectional antenna is erected, through an existing inter-star communication link device, a relative position relation between the clusters can easily acquired, realizing rapid relative positioning between members in the tight cluster, and space environment is pure, and the device is simple and reliable.

A method and a system for free space optical tomography provides one or more light source and one or more light sensors spaced, which in one embodiment are spaced apart from and object to be imaged. A surface capture system coupled to a variety of optical models provides the method and system with the ability to render accurate tomographic images though the light has propagated both through a diffuse medium and, in on embodiment, also through free space to the one or more light sensors.

The invention relates to an optical switch, in particular to an ultra-silent mechanical free-space switching optical switch device, which aims to solve the rebound jitter and noise problems easily generated in the use of the existing electromagnetic relay mechanical optical switch. The ultra-silent mechanical free-space switching optical switch device comprises a base, wherein an iron core is vertically arranged on the upper surface of the base, and a stationary contact is arranged on the upper end surface of the iron core; a first spring is vertically arranged on the upper end surface of the stationary contact, and a movable contact is vertically arranged at the upper end of the first spring; and a connecting rod part is arranged on the upper surface of the base and comprises a first connecting rod, a second connecting rod, a third connecting rod and a fourth connecting rod, and a small-hole shading film is fixedly arranged at the other end of the first connecting rod. In the ultra-silent mechanical free-space switching optical switch device, the rebound jitter and noise problems easily generated in the use of the existing electromagnetic relay mechanical optical switch are effectively solved, and the optical switch device is suitable for quickly turning on or off laser propagated in a free space in various precision optical experiments.