Signal beam

About: Signal beam is a research topic. Over the lifetime, 1881 publications have been published within this topic receiving 20717 citations.

Low-probability-of-intercept transmitted signal design method based on FDA-OFDM

Abstract: The invention discloses a low-probability-of-intercept transmitted signal waveform design method based on FDA-OFDM. The invention solves the technical problem that a frequency diversity array transmitted signal is easy to intercept and interfere. The low-probability-of-intercept transmitted signal waveform design method comprises an implementation method of: constructing an array model of a frequency diversity array; designing an orthogonal transmitted signal; constructing an array oriented matrix A; defining a weighting moderate matrix W; and by the array oriented matrix A and the weighting moderate matrix W together, obtaining a frequency diversity array beam energy diagram so as to complete low-probability-of-intercept transmitted signal waveform design based on FDA-OFDM. According to the invention, the transmitted signal adopts orthogonal waveform design; each array element uses two orthogonal subcarriers; a transmitted signal beam pattern is changed from conventionality, complexity is improved, and the transmitted signal beam pattern is a result of overlaying two transmitted signals at an assumed target position. According to the invention, the probability of intercepting andidentifying the transmitted signals is reduced, interference resistance is promoted, and the low-probability-of-intercept transmitted signal waveform design method is beneficial for implementing low-probability-of-intercept performance of the signals. The low-probability-of-intercept transmitted signal waveform design method can be applied to a frequency diversity array MIMO radar, inhibition on distance correlation interference and spuriousness and low-probability-of-intercept electronic detection.

Wavelength detecting device

Abstract: A wavelength detecting device is used for a wavelength multiplexing optical communication system, is simple and inexpensive, and can strictly control the wavelengths of signal beams that are close to one another. The device has a path splitter and a wavelength selector. The path splitter splits a beam into at least three beams having different path angles. The wavelength selector filters the split beams into beams having predetermined wavelengths. One of the filtered beams is provided as a signal beam and the other beams are provided as monitor beams used to detect the wavelength of the signal beam.

Optical interferometer, information acquisition apparatus, and information acquisition method

Abstract: An optical interferometer includes: a light source that emits a coherent first beam and a second beam that has a frequency difference corresponding to the natural frequency of a target molecule; amplitude modulating means that modulates the amplitude of the second beam; splitting means that splits the first beam into a reference beam and a first applied beam; optical path length adjusting means that adjusts the optical path length of the reference beam; and detecting means that detects an interference pattern between the reference beam and the first beam (a signal beam) that has experienced a stimulated Raman loss or gain in accordance with the amplitude modulation as a result of the frequency difference resonating with the target molecule when the first applied beam and a second applied beam (the amplitude modulated second beam) have been applied to a measurement position of an object.

Method and apparatus for recording and/or reproducing data into and/or from optical disk

Abstract: Provided are a method and apparatus for recording and/or reproducing data into and/or from an optical disk. The apparatus includes a reference beam optical system to form a focus of a reference beam in an optical data storage layer of the optical disk and including an objective lens; a signal beam optical system to form a focus of a signal beam in the optical data storage layer and also including the objective lens; and a servo optical system to project a servo beam onto the optical disk, receiving a reflection servo beam which is reflected on the optical disk, and performing focusing and tracking control on the objective lens. The reference beam optical system includes a first focus mover to move the focus of the reference beam, and the signal beam optical system includes a second focus mover to move the focus of the signal beam. The data is recorded into a plurality of recording layers in the optical data storage layer by moving a first focus position, at which the foci of the reference beam and the signal beam are located, in a thickness direction of the optical data storage layer, which is a focusing direction.

Picosecond four-wave mixing reflectivity of GaAs at 1.06 μm

Abstract: The picosecond degenerate four-wave mixing reflectivity of semi-insulating gallium arsenide at 1.06 μm is calculated in this paper. The dependence of the reflectivity on the pump and signal fluences is measured. Reflectivities of more than one are possible. The Fourier components of the excited-carrier densities are calculated as a function of the pump fluence. The wavefront-correction property of this reflectivity is demonstrated with a lens group in the signal beam.