Abstract: A method and apparatus for generating digitally modulated signals in which a serial data stream of digital signals to be modulated (70) is provided, the serial data stream being converted into real and imaginary components (74) which are then converted into a complex polar signal (80) representing the serial data stream. A carrier of appropriate frequency is generated by an infinite impulse response filter (84,86) and the polar signal is mixed with the output of the infinite impulse response filter to provide a representation of the complex polar signal modulated at the frequency generated by the infinite impulse response filter (88). Subsequently the imaginary component of the resulting representation is stripped from the signal (90) and the real component of the resulting representation is applied to a digital to analog converter (92) to produce an analog version of the serial data stream.

Abstract: A method and apparatus for generating digitally modulated signals in which a serial data stream of digital signals to be modulated (70) is provided, the serial data stream being converted into real and imaginary components (74) which are then converted into a complex polar signal (80) representing the serial data stream. A carrier of appropriate frequency is generated by an infinite impulse response filter (84,86) and the polar signal is mixed with the output of the infinite impulse response filter to provide a representation of the complex polar signal modulated at the frequency generated by the infinite impulse response filter (88). Subsequently the imaginary component of the resulting representation is stripped from the signal (90) and the real component of the resulting representation is applied to a digital to analog converter (92) to produce an analog version of the serial data stream.

Abstract: A mechanical scanning and digital beamforming antenna (20, FIG. 2) uses a receive and transmit digital beamforming network (FIG. 3, 410, 320) to provide communications beam scanning in a first plane. In a second plane, a reflective surface (FIG. 2, 240) is used to focus and scan the communications beam. Through proper orientation of the reflective surface (240), a communications satellite (FIG. 1, 10) can be tracked by way of electronic scanning by way of the transmit or receive digital beamforming network (FIG. 3, 320, 410). Thus, the complexity of the digital beamforming network is reduced as is the wear on the mechanical components of the antenna. The mechanical scanning and digital beamforming antenna (20, FIG. 20) makes use of a second digital beamforming network (FIG. 3, 415, 325) and reflective surface (FIG. 3, 250) to ensure that two communications satellites can be simultaneously tracked.

Abstract: A direction of arrival (DOA)-aided digital beamforming (DBF) subsystem (300 FIG. 3) is provided for mitigating interference and increasing the frequency reuse factor in communication systems. The DOA-aided DBF subsystem is used to accurately position beams and nulls in at least one antenna beam pattern. By accurately directing beams at desired locations and nulls at undesired locations, the DOA-aided DBF subsystem provides a more efficient processing of antenna beam patterns in communication systems. The DOA-aided DBF subsystem is used in geostationary satellites, non-geostationary satellites, and terrestrial communication devices. The DOA-aided DBF subsystem uses a unique algorithm to determine DOA information that allows more efficient beam management and allows more subscribers to be served, while saving spectrum and power.