The invention relates to a control method and a control arrangement which comprises a feedforward power amplifier (10), which receives and amplifies a signal and which on amplifying the signal causes non-linearities to the signal. The control arrangement also comprises adjusting members (50, 80) and adaptation means (110, 130), which form an adaptation factor and control the operation of the adjusting means (50, 80) by means of the adaptation factor by adapting the amplitudes and phases of signal propagating along different signal paths to one another. The control arrangement further comprises control means (120), which produce information of the gain required by the power amplifier (10), said control means (120) ordering the adaptation means (110, 130) to adjust the adaptation factor in advance on the basis of the received information to correspond to the gain of the power amplifier (10), which enables adaptation of the signal also when the input power level changes rapidly.
The present invention is a telecommunication system, comprising of at least one base station connected to a telecommunication network, a plurality of subscriber stations each cooperating with the base station to establish a connection between a user device operably connected to the subscriber station and the telecommunication network. The base station is also connected with a subscriber database to maintain the subscriber records that contain provisioning information for services, features and account information, and an interactive response system operable to create and modify a subscriber record in the subscriber database in response to input received over the connection from a subscriber using the user device to select services, features and account information for the subscriber station.
Methods and apparatus are provided for substantially reducing and/or canceling nonlinearities of any order in circuits, devices, and systems such as amplifiers and mixers. In particular, methods and apparatus are provided for substantially reducing and/or canceling third order nonlinearities in circuits, devices, and systems such as amplifiers and mixers. A first coupler is used to split an input signal into two equal-amplitude in-phase components, each component is processed by two nonlinear devices with different nonlinearities, and a final combiner, such as a 180-degree hybrid, recombines the processed signals 180 degrees out of phase and substantially reduces and/or cancels the undesired nonlinear distortion components arising due to nonlinearities in the nonlinear devices.
