Abstract: System and method for signal modulation. In one embodiment, a circuit includes a channel for carrying an analog RF signal, a phase offset circuit on the channel, and configured to receive a phase code for modifying the analog RF signal to produce a modified RF signal, and a feedforward cancellation path coupled in parallel to the phase offset circuit for canceling a portion of the modified analog signal.

Abstract: System and method for signal modulation. In one embodiment, a circuit includes a channel for carrying an analog RF signal, a phase offset circuit on the channel, and configured to receive a phase code for modifying the analog RF signal to produce a modified RF signal, and a feedforward cancellation path coupled in parallel to the phase offset circuit for canceling a portion of the modified analog signal.

Abstract: The present disclosure is directed towards an analog beamformer multiple beam feed (MBF). The analog beamformer MBF comprises a plurality of encoder elements to receive radiofrequency (RF) signals and generate coded analog signals. The RF signals may be coded using code division multiple access (CDMA) codes. The analog beamformer MBF further comprises a combiner to combine the coded analog signals received from the plurality of encoder elements and a divider to receive the combined coded analog signals and generate a plurality of coded analog outputs. The analog beamformer MBF further comprises a plurality of decoder elements to receive the plurality of coded analog outputs and generate decoded analog signals. In some embodiments, the RF signals may be decoded using CDMA codes. The analog beamformer MBF further comprises a plurality of beamformer elements configured to generate beam outputs corresponding to the decoded analog signals.

Abstract: The present disclosure is directed towards an analog beamformer multiple beam feed (MBF). The analog beamformer MBF comprises a plurality of encoder elements to receive radiofrequency (RF) signals and generate coded analog signals. The RF signals may be coded using code division multiple access (CDMA) codes. The analog beamformer MBF further comprises a combiner to combine the coded analog signals received from the plurality of encoder elements and a divider to receive the combined coded analog signals and generate a plurality of coded analog outputs. The analog beamformer MBF further comprises a plurality of decoder elements to receive the plurality of coded analog outputs and generate decoded analog signals. In some embodiments, the RF signals may be decoded using CDMA codes. The analog beamformer MBF further comprises a plurality of beamformer elements configured to generate beam outputs corresponding to the decoded analog signals.

Abstract: Methods and apparatus to cancel an interfering signal using an analog cancellation stage followed by a digital cancellation stage. In an exemplary embodiment, the interfering signal is processed to determine modulation type for removal in the analog domain. The digital stage provides further interference reduction in the digital domain.

Abstract: Methods and apparatus to cancel an interfering signal using an analog cancellation stage followed by a digital cancellation stage. In an exemplary embodiment, the interfering signal is processed to determine modulation type for removal in the analog domain. The digital stage provides further interference reduction in the digital domain.

Abstract: A system and method for processing antenna signals are provided. For example, the method includes, in a receive mode, weighting and combining signals from at least one low-band antenna radiator element operable over a first bandwidth, at least one high-band antenna radiator element operable over a second bandwidth at least partially overlapping the first bandwidth, and, in some examples, at least one antenna radiator element operable over one or more intermediate bandwidths. The method also includes, in a transmit mode, separating and weighting a full-band input port signal into at least one low-band sub-system output port signal, at least one high-band sub-system port output signal, and, in some examples, at least one intermediate sub-system output port signal operable over one or more overlapping intermediate bandwidths. The weighted combination and weighted separation cover an uninterrupted continuous full-band frequency whose extent covers the full frequency range of all subbands.

Abstract: A system and method for processing antenna signals are provided. For example, the method includes, in a receive mode, weighting and combining signals from at least one low-band antenna radiator element operable over a first bandwidth, at least one high-band antenna radiator element operable over a second bandwidth at least partially overlapping the first bandwidth, and, in some examples, at least one antenna radiator element operable over one or more intermediate bandwidths. The method also includes, in a transmit mode, separating and weighting a full-band input port signal into at least one low-band sub-system output port signal, at least one high-band sub-system port output signal, and, in some examples, at least one intermediate sub-system output port signal operable over one or more overlapping intermediate bandwidths. The weighted combination and weighted separation cover an uninterrupted continuous full-band frequency whose extent covers the full frequency range of all subbands.

Abstract: A frequency and temperature dependent pre-distortion device. The novel pre-distortion device includes a plurality of pre-distortion generators, each pre-distortion generator adapted to receive an input signal and output a pre-distorted signal, and a pre-distortion selector for selecting one of the pre-distortion generators in accordance with a frequency of the input signal and/or a temperature. Each pre-distortion generator is adapted to compensate for distortions produced in a particular frequency range and/or temperature range. In an illustrative embodiment, the pre-distortion generators are implemented using digital look-up tables.

Abstract: An apparatus for reducing the amount of circuitry required to process satellite communication signals uses a beamformer to reduce the number of signals coupled to the communications circuitry, thereby reducing the amount of communication circuitry required to process received signals.

Abstract: A multi-resonator filter, including a housing, at least one resonating element, at least one high dielectric constant element, at least one fine tuning screw located above the at least one resonating element and secured in a housing cover by a locking nut, housing screws to secure the housing cover to the housing. Where at least two resonating elements and at least two high dielectric constant elements are present, at least two slots are located in the at least two high dielectric constant elements to allow the easy installation and removal of at least one high dielectric coupling bridge used to increase the coupling between resonator sections, and at least one coupling probe.

Abstract: An apparatus for limiting intermediate frequency variation in a multiple conversion phase locked loop includes a reference oscillator and a voltage controlled oscillator (VCO). The reference oscillator generates a first reference frequency, while the VCO generates an output frequency. The output frequency is divided by a first VCO divider and mixed with the first reference frequency to generate a first intermediate frequency. A second VCO divider also divides the output frequency and mixes it with the first intermediate frequency to generate a second intermediate frequency, which is filtered and used to control the VCO. An algorithm processor generates the division constants of the first and second VCO dividers as a function of the reference frequency and the output frequency to limit intermediate frequency variation.

Abstract: Methods and systems for calibrating an array antenna are described. The array antenna has a plurality of antenna elements each having a signal with a phase and an amplitude forming an array antenna signal. For calibration, the phase of each element signal is sequentially switched one at a time through four orthogonal phase states. At each orthogonal phase state, the power of the array antenna signal is measured. A phase and an amplitude error for each of the element signals is determined based on the power of the array antenna signal at each of the four orthogonal phase states. The phase and amplitude of each of the element signals is then adjusted by the corresponding phase and amplitude errors.

Abstract: A frequency synthesizer having two atomic frequency standard inputs that is adapted to provide seamless switching or transition between the atomic frequency standard inputs with no change in the synthesizer output phase and frequency. The synthesizer includes a multichannel phase comparison system, each channel adapted for handling an atomic frequency standard input, a digital phase lock loop, a digital to analog converter, and a voltage controlled crystal oscillator which provides the synthesizer output. The phase comparison system is adapted to continually monitor the integrity of the atomic frequency standard inputs and to continually estimate the phase differences between the two atomic frequency standard inputs. The phase difference is used to estimate the proper phase and frequency offset between the primary and secondary inputs.

Abstract: A plurality of biphase modulators (42) each modulate a sinusoidal radio frequency signal based upon a corresponding one of a plurality of bits contained in a time-dependent data word. The biphase modulators (42) form a plurality of biphase modulated signals which are communicated to a summing network (40). The summing network (40) contains a plurality of attenuators (44) which attenuate the modulated signals to form a plurality of attenuated signals. The summing network (40) combines the attenuated signals to form a radio frequency signal.

Abstract: A system (36, 98) for determining the linearity of an RF detector (46, 106). A first technique involves combining two RF signals from two stable local oscillators (38, 40) to form a modulated RF signal having a beat frequency, and applying the modulated RF signal to a detector (46) being tested. The output of the detector (46) is applied to a low frequency spectrum analyzer (48) such that a relationship between the power levels of the first and second harmonics generated by the detector (46) of the beat frequency of the modulated RF signal are measured by the spectrum analyzer (48) to determine the linearity of the detector (46). In a second technique, an RF signal from a local oscillator (100) is applied to a detector (106) being tested through a first attenuator (102) and a second attenuator (104).

Abstract: A satellite-based communication system providing high rate transfer of data between linked terminals. The system comprises a plurality of user terminals (VSAT's) that are linked by and that communicate with each other by way of a satellite-based relay system. A network control center provides configuration signals that control the satellite relay system and coordinate linking of terminals to each other. Frequency division multiplexing uplinks are used from the terminals and the network control center to the satellite relay system. Time division multiplexing are used on downlinks from the satellite relay system to the terminals and the network control center. Each user terminal comprises a data compression and decompression circuit, a transceiver, and an antenna for transmitting and receiving data to and from the satellite relay system. The satellite relay system comprises a satellite, a wide area antenna, a plurality of receive antennas, a plurality of transmit antennas, and a signal processor.

Abstract: A system and method for polar digital beamforming of at least one independent transmit beam is disclosed. A computer generates a digital signal representing both pointing and modulation information which is communicated to a plurality of subarray controllers which generate the polar weighting signals corresponding to the appropriate antenna element for transmitting. The complex weighting signals may be generated by summing a sequence of complex multiplications or by simply inverting the real and imaginary components of the weighting signal for particular modulation schemes. A phasor may be used in conjunction with an attenuator to modulate a local carrier signal. Alternatively, phasors are utilized without attenuators to increase the efficiency of the power amplifiers. The antenna architecture disclosed permits a single set of phasors and attenuators to be utilized per antenna element regardless of the number of beams to be generated.

Abstract: A phased array antenna (10A, 10B, 10C) is constructed of an array of radiators (24), each of which has a radiating aperture, a first port (26) and a second port (26). The first port introduces a first radiation with a first polarization, and the second port introduces a second radiation with a second polarization which is orthogonal to the first polarization. Individual transmitting amplifiers, in the case of a transmitting array, or individual receiving amplifiers (16A), in the case of a receiving array, are connected to the ports of each of the radiators. The amplifiers associated with the first ports of the respective radiators are connected, in turn, to phase shifters (18A) and attenuators (20A) which constitute a first beamformer for forming a set of one or more beams of radiation.

Abstract: Frequency reuse and data coding methods for use in a high data rate satellite communication system. The frequency reuse method provides for dual polarization and spatial reuse of transmit and receive beams to provide for a twelve-fold increase in the effective bandwidth and number of users that may be supported by the system. Transmit and receive antennas provide multiple, interleaved transmit and receive antenna beams. Digital input data at a source user terminal is coded and transmitted from a source user terminal on one of the plurality of receive antenna beams. The received data is demodulated and is routed so that it may be transmitted to a destination user terminal. The data is then remodulated, multiplexed, and transmitted to the destination user terminal on one of the plurality of transmit beams. The transmitted data is decoded at the destination user terminal to produce the output data.