Abstract: An amplifier subsystem has a modulator to generate a pair of constant amplitude phase-modulated components which are in response to an input signal, a pair of channels that include a pair of power amplifiers to amplify the components, and a combiner to combine the amplified components. A number of variable gain elements are coupled into some of a number of signal paths of the amplifier subsystem. A controller is to receive feedback from the amplifier subsystem and in response maintains signal levels of some of the signal paths within predefined ranges and controls a net gain of the linear amplifier, by adjusting the variable gain elements.

Abstract: An amplifier subsystem has a modulator to generate a pair of constant amplitude phase-modulated components which are in response to an input signal, a pair of channels that include a pair of power amplifiers to amplify the components, and a combiner to combine the amplified components. A number of variable gain elements are coupled into some of a number of signal paths of the amplifier subsystem. A controller is to receive feedback from the amplifier subsystem and in response maintains signal levels of some of the signal paths within predefined ranges and controls a net gain of the linear amplifier, by adjusting the variable gain elements.

Abstract: A plant output signal is divided into a number of output frequency subband signals. Each subband signal may be digitized at a sampling rate that need only be sufficiently high to capture the bandwidth of that subband signal. The digitized output subband signals are time-aligned with an estimated output signal that has been derived from a plant input signal. An adaptive equalization process is performed using the time aligned output subband and estimated output signals. This technique may be applied to adaptively equalize the channels of a linear amplification with nonlinear components (LINC) style radio frequency (RF) amplifier.

Abstract: A calibration method and apparatus for calibrating and linearizing an amplifier in which an input signal is decomposed into N channels. Then the amplifier is modeled to generate an estimated amplifier transfer function for each channel. Using the estimated amplifier transfer function for each channel, equalizer values are computed for equalizers that are applied to each channel prior to amplification, thus enabling the amplification of amplitude and/or phase modulated signals via the non-linear amplifiers.

Abstract: The invention is embodied in a parameter encoder for identifying selected parameters of a digitally sampled incoming signal lying within a receiver bandwidth, wherein the receiver bandwidth is divided into plural contiguous frequency channels, each channel having a channel bandwidth, whereby the incoming signal is divided into plural channelized signals lying in respective ones of the plural frequency channels, the parameter encoder includes plural channel processors connected to receive respective ones of the channelized signals, each of the channel processors including Fourier transform apparatus for producing a frequency value and an amplitude value for each sample of the respective channelized signal.

Abstract: The invention is embodied in a digital direction finding receiver having N frequency channels spanning a frequency band of the receiver and capable of receiving signals simultaneously from a plurality of antennas spaced from one another, one of the antennas including a reference location antenna.