9 results about "Free space propagation" patented technology

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.

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 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 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.

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 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.

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.

The present application relates to the technical field of communication anti-jamming test, in particular to a kind of unmanned aerial vehicle interference test method based on dynamic attenuation and power division;The present application extracts multidimensional environmental characteristic vector including power spectral density, modulation feature and signal time delay.Based on the vector, a dynamic attenuation matrix is constructed, and a composite path loss model is established based on the correction of free space propagation model, which can effectively simulate the interference characteristics in the real wireless propagation scene, make the test channel more close to the actual deployment environment, and thus improve the credibility and adaptability of the interference test;The present application generates three types of signals, including environmental noise signal, deceptive jamming signal and suppressive jamming signal, based on the optimal power ratio, and forms a precise anti-interference evaluation system by combining three indicators, including communication response time delay, positioning deviation and communication interruption rate, to effectively improve the test accuracy of the robustness, stability and fault-tolerant capability of the unmanned aerial vehicle communication system in different interference environments.