A system for reducing co-channel interference includes a power spectrum analyzer which provides a spectral signal representative of an intermediate frequency signal from the receiver of a direction finding system. The system further includes threshold/window logic that, responsive to the comparison of threshold levels and spectral windows to the interfering signals, will provide stop and continue signals to an integrator. The integrator receives signals from the direction finding system and stops and starts integration of the output signal responsive to the threshold logic. In so doing, co-channel interference is substantially reduced.
A radio communication system for mobile communications, or more specifically, a radio receiver for a base station which receives signals transmitted from a plurality of mobile stations is provided wherein the propagation characteristics of channels with respect to a frequency domain can be instanteously measured at all times even while the channels are in use. A frequency converter collectively receives signals transmitted from the mobile stations and converts the signals to IF-band signals, respectively. The IF-band signals output from the frequency converter are set apart from one another by corresponding ones of frequency differences of the signals transmitted from the mobile stations. Complex Fourier transform deriving means collectively derives the complex Fourier transforms of these IF-band signals, and outputs the resulting frequency spectra to analyzing means. The analyzing means simultaneously analyzes the propagation characteristics of the individual received waves, based on the frequency spectra supplied thereto. In accordance with the results of the analysis, a wave having excellent propagation characteristics is received.
The invention refers to array antennas consisting of a set of individual sources set out over the surface of the antenna and whose mechanical positioning is determined in such a way as to obtain the desired radiation pattern. The process according to the invention is designed to compensate for the positioning errors of radiating elements occurring when such an antenna is constructed. These positioning errors follow a law that is in theory random and whose result is known by determining the imperfection vector I whose components of real positioning errors measured for each feed of the antenna obtained comprising components forming values of an error function .delta.(n) where n represents the index attributed to the radiating element in question. The process according to the invention consists in first measuring the positioning errors. It then consists in determining the spatial spectral components making up error function .delta.(n). It finally consists in applying to each component an amplitude or phase modulation correction in order to compensate for the degradation of the error function .delta.(n) on the obtained antenna radiation pattern F(.theta.). The process according to the invention applies more particularly to antennas comprising radiating beams.
A broadband partial fan cone direction finding antenna and array disclosed. The antenna includes a radiator having a partial cone shape. The radiator substantially occupies a spatial area defined by a portion of a cone and the cone is defined by a cone axis, a cone height, and a cone angle. The cone has a base and an apex, and the portion of the cone is defined by a cone sweep angle. The cone sweep angle is determined as the angle subtended by a projection of the portion of the cone projected onto a plane that is perpendicular to the cone axis. The cone sweep angle is less than 360.degree. so that the portion of the cone is bounded on its sides by edges which extend radially from the apex of the cone outward to the base of the cone.
A broadband partial fan cone direction finding antenna and array disclosed. The antenna includes a radiator having a partial cone shape. The radiator substantially occupies a spatial area defined by a portion of a cone and the cone is defined by a cone axis, a cone height, and a cone angle. The cone has a base and an apex, and the portion of the cone is defined by a cone sweep angle. The cone sweep angle is determined as the angle subtended by a projection of the portion of the cone projected onto a plane that is perpendicular to the cone axis. The cone sweep angle is less than 360.degree. so that the portion of the cone is bounded on its sides by edges which extend radially from the apex of the cone outward to the base of the cone.
A broadband partial fan cone direction finding antenna and array disclosed. The antenna includes a radiator having a partial cone shape. The radiator substantially occupies a spatial area defined by a portion of a cone and the cone is defined by a cone axis, a cone height, and a cone angle. The cone has a base and an apex, and the portion of the cone is defined by a cone sweep angle. The cone sweep angle is determined as the angle subtended by a projection of the portion of the cone projected onto a plane that is perpendicular to the cone axis. The cone sweep angle is less than 360.degree. so that the portion of the cone is bounded on its sides by edges which extend radially from the apex of the cone outward to the base of the cone.
