Harris Corporation

Imagine Communications Corp.

David Christopher Danielsons

Zhiqun Hu

Jeffrey M Malec

Ed Twitchell

Bob Davis

Geoffrey Norman Mendenhall

Paul Henry Mizwicki

Dave Nickell

Bob Plonkn

Bruce Russell Meredith

Bob Plonka

A data acquisition system can include a central controller to provide a data acquisition signal. The data acquisition system can also include a cabinet to receive the data acquisition signal. The cabinet can have an array of modules installed therein. The cabinet can include a backplane connected to each module of the array of modules. The backplane can provide a status request signal to a given module in the array of modules if the given module is assigned a module address identified by the data acquisition signal. The given module can provide status data characterizing an operational status of the given module in response to the status request.

Data acquisition

A data acquisition system can include a central controller to provide a data acquisition system signal. The data acquisition system can also include a cabinet to receive the data acquisition system signal. The cabinet can have an array of modules installed therein. The cabinet can include a backplane connected to each module of the array of modules. The backplane can provide a status request signal to a given module in the array of modules if the given module is assigned a module address identified by the data acquisition system signal. The given module can provide status data characterizing an operational status of the given module in response to the status request.

An RF amplifier system having closed cavity containing an amplifying device that includes at least a cathode, an anode and a grid and wherein the amplifying device exhibits an internal grid-to-anode capacitance. Apparatus is presented for use in neutralizing the internal capacitance. This includes a feedback circuit including an external capacitor of fixed value and a phase inverting transformer having a transformer primary winding connected in series with the capacitor to the cathode. The transformer has a secondary winding connected between the cathode and the grid for supplying a phase inverted negative feedback voltage to the grid for neutralizing the cavity by the feedback voltage. The transformer coupling is adjustable to vary the magnitude of the feedback voltage.

RF amplifier system for neutralizing internal capacitance in a cavity

A phase lock control system is presented for controlling a voltage controlled oscillator. The system includes a voltage controlled oscillator that produces a frequency signal exhibiting an output frequency that varies dependent upon the value of a control voltage applied thereto. A frequency deviation determining system employs a counter intermittently triggered ON for a fixed time by successive timing pulses received from a reference source and a comparator that determines any frequency deviation of the output frequency relative to a preset frequency. An error filter monitors the comparator for any frequency deviation for a plurality of samples of the frequency deviation determinations. A controller varies the control voltage to vary the output frequency in a direction to eliminate any frequency deviation.

Phase lock control system for a voltage controlled oscillator

A radio frequency (RF) transmitter system is presented having an input circuit for receiving an RF signal to be amplified and transmitted. A series circuit is provided which includes first and second cascaded amplifier networks located downstream from the input circuit and wherein the first amplifier network is located upstream from the second amplifier network and wherein the first and second networks respectively include first and second non-linear amplifiers that exhibit non-linear response characteristics to the RF signal and that introduce non-linear distortions into the RF signal and that the second network includes a filter that introduces linear distortions into the RF signal. The first correction circuit is located upstream from the series circuit for pre-correcting the RF signal in a manner to compensate for the linear and non-linear distortions introduced by the second amplifier network. A second pre-correction circuit is interposed between the first correction circuit and the first amplifier network for pre-correcting the RF signal to compensate for the non-linear distortions introduced by the first amplifier network. The second pre-correction circuit includes a third non-linear amplifier selected so as to exhibit a non-linear response characteristic to an applied RF signal similar to that of the first amplifier.

RF transmitter employing linear and non-linear pre-correctors

A digital radio frequency transmitter system having an input circuit for receiving digital signals to be amplified and transmitted. A digital-to-analog converter converts the digital signals into analog signals. A series circuit is provided including a radio frequency filter and a radio frequency amplifier located downstream from the converter and wherein the filter and the amplifier respectively introduce linear and non-linear distortions into the analog signals for transmission by the transmitter. A digital pre-correction circuit is located upstream from the digital-to-analog converter for pre-correcting the digital signals in a manner to compensate for at least some of the distortions. An analog pre-correction circuit is interposed between the digital-to-analog converter and the series circuit for pre-correcting the analog signals to additionally compensate for at least some of the distortions prior to application to the series circuit.

Digital RF transmitter system employing both digital pre-correction and analog pre-correction

A system and method for predistorting a signal which is to be amplified by a non-linear amplifier. The system and method uses additional predistortion circuits to eliminate the predistortion caused by amplifier input circuits and amplifier output circuits. In one aspect of the invention, the system and method uses a frequency response and phase corrector circuit to modify the amplitude versus frequency of the signal independent of phase.

System and method for predistorting signals to be amplified

A system and method for transmitting advanced television signals such as digital television signals. The system and method controls the frequency of the RF signal by compensating for errors in the signal received from a transport system. The system and method also reduces the complexity of the transmission system by inserting a pilot frequency signal after the television signal has been filtered and shaped.

System and method for transmitting advanced television signals

A system and method for controlling the frequency of a signal being transmitted wherein the frequency of the signal received at the transmitter site is error corrected before being broadcast. The error in the frequency may be developed and applied to the intermediate frequency upconversion and/or the channel upconversion to reduce or eliminate the effects of the error. In the system and method, a pilot frequency signal can be added to the signal to be broadcast after the signal to be broadcast has been shaped and filtered.

System and method for controlling a transmitter frequency

Apparatus and method are provided for linearizing a first amplifier having a non-linear signal response characteristic to an applied input signal wherein the amplifier is located between a signal source and a load. This is accomplished by selecting a second amplifier that exhibits a non-linear signal response characteristic to an applied input signal similar to that of the first amplifier. A portion of the input signal obtained from the signal source is then applied to the second amplifier to generate an output signal. A determination is made as to whether there is any difference between the input signal and the output signal and a difference signal is provided in accordance therewith. The difference signal is phase inverted to obtain an inverted difference signal. This inverted difference signal is combined with the input signal to provide a corrected input signal. The corrected input signal is applied to the first amplifier to obtain a corrected output signal therefrom.

Method and apparatus for linearizing an amplifier

An inductive output tube (IOT) amplifier system is presented for receiving an RF input signal and providing therefrom an amplified RF output signal. The system includes a high tension DC voltage supply and an IOT tube. The IOT tube includes a cathode coupled to the voltage supply for emitting electrons, an anode coupled to the supply for accelerating the electrons, a collector located downstream from the anode that collects the electrons, and a grid located between the cathode and the anode for controlling electron emission from the cathode. The tube has an input for receiving a modulated RF input signal between the grid and the cathode. An output resonant cavity is interposed between the anode and the collector. An output is coupled to the cavity for providing amplified RF output signal. The tube exhibits an inherent interelectrode capacitance which may cause distortions in the output signal. An inductor is interposed between the high tension supply and the cathode such that the inductor and the inherent capacitance form a low pass filter that reduces any distortions in the output signal.

Inductive output tube (IOT) amplifier system

In an amplifier circuit having an amplifier path, a new pre-distortion arrangement is provided. The amplifier circuit includes a signal source, an intermediate amplifier stage, and a power amplifier stage connected sequentially, in series along the amplifier path. The power amplifier stage includes one or more amplifiers operationally connected in parallel, and one or more pre-correction circuits. Each of the amplifiers subjecting an inputted signal to shifts away from their intended values. Each of the pre-correction circuits is associated with one of the amplifiers and connected between an output of the intermediate amplifier stage and the associated amplifier. Each of the pre-correction circuits pre-distorts the signal input to the associated amplifier to compensate for the distortion caused by the associated amplifier. Also, preferably, pre-correction circuits are associated with, and in series with, each of the amplifier stages for pre-distorting the signal input to the associated amplifier stage to compensate for the distortion shifts of the associated amplifier stage.

Apparatus and method for pre-distortion correction of a power amplifier

An output amplifier having a non-linear signal response characteristic is linearized by selecting a preceding amplifier in a multistage amplifier network and providing feedforward overcorrection to the preceding amplifier to compensate for the non-linear signal response characteristics of the output amplifier.

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Maineville, OH, United States of America

David Christopher Danielsons