 Loudspeaker unit adapted to environment |
| An object of the present invention is to provide a loudspeaker unit adapted to the environment and ... |
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| Subband coded digital transmission system using some composite signals |
| What is claimed is: 1. A digital transmission system, for producing a replica of a digital signal ... |
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| Low bit-rate high-resolution spectral envelope coding for audio encoder and decoder |
| I claim: 1. An encoder of one or more channels of input signals comprising signal samples, said ... |
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| Montgomery reduction apparatus |
| OF THE INVENTION A Montgomery reduction apparatus and method of the present invention aim at more ... |
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| Audio system for vehicular application |
| Systems and methods in accordance with the invention enable virtually infinite segmentation and ... |
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| Medium having photographically recorded digital audio bits |
| The invention is a medium (such as motion picture film) having digital audio signals ... |
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| Digital hearing aid |
| Therefore, it is an object of the present invention to provide a digital hearing aid which can ... |
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| Apparatus for creating 3D audio imaging over headphones using binaural synthesis |
| Accordingly, it is an object of the present invention to provide an apparatus for creating three-... |
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| System, apparatus, and method for improving speech quality in multi-party devices |
| A method, system, and apparatus are provided, such that cross talk terms may be removed from speech ... |
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| Speaker excursion control system |
| OF THE PREFERRED EMBODIMENT Referring initially to FIG. 1, there is shown a sound system which may ... |
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Method of and apparatus for modulation dependent signal amplification
| Details |
Inventors: Klomsdorf, Armin; Winkelmann, Luke; Schwent, Dale Gerard; Greene, Matthew;
Assignee: Motorola, Inc. (Schaumburg, IL)
Primary Examiner: Pascal; Robert
Assistant Examiner: Choe; Henry
Attorney, Agent or Firm: Bartusiak; Paul J.
A modulation format switch in signal communication with an amplifier, which produces a plurality of modulation format signals, and a load is described. The modulation format switch includes at least one matching network in signal communication with the amplifier and the load, where the at least one matching network capable of having a plurality of impedance values corresponding to the plurality of modulation format signals. The modulation format switch also includes a controllable element in the matching network, the controllable element capable of having more than one impedance value. |
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DETAILED DESCRIPTION Referring to FIG.
1, an example transmitter 10 is shown.
The transmitter 10 may preferably be a cellular telephone transmitter or any other wireless type transmitter capable of transmitting information in a wireless environment.
It is obvious to those skilled in the art that transmitter 10 comprises other components such as filters mixers, but these elements are not shown in order to not unduly complicate the drawing figure.
The transmitter 10 includes a linear power amplifier 15, a modulation format switch (MFS) 20 (also referred to as a variable impedance network), load 25, a control unit 30, a microprocessor 42, and a supply and bias control unit 52.
The linear power amplifier 15 and the control unit 30 are connected to the MFS 20 via signal connections 35 and 40 respectively.
The MFS 20 is connected to the load 25 via signal connection 45.
The linear power amplifier 15 is a general solid state amplifier circuit biased for linear operation as is known in the art.
The load 25 is the element for which power is delivered, and the load 25 comprises, among other things, an antenna.
The MFS 20 switches the impedance values seen by the output stage of the linear power amplifier 15.
It is appreciated by those skilled in the art that the different impedance values are adjusted to optimize performance of the output stage of the linear power amplifier 15 for the different modulation types such as Code Division Multiple Access (CDMA) and linear Time Division Multiple Access (TDMA).
For example, the load presented to the output of an amplifier effects its operating point along a load line as is known in the art.
The load impedance can thus be adjusted to increase the efficiency and/or linearity of the linear power amplifier 15.
The necessary load impedance for a particular modulation format signal is predetermined experimentally.
The microprocessor 42 provides various control functions for the transmitter, such as providing control to the supply and bias control unit 52 and the control unit 30 as will be described further below
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Audio Signal Processing 
