Rca Inc.

Lockheed Martin Corporation

General Electric Company

Martin Marietta Corporation

Herbert J Wolkstein

Arye Rosen

Jitendra Goel

Daniel D Mawhinney

Allen Katz

Douglas Vernon McKinnon

Zygmond Turski

Novellone Rozario

Thaddeus Arthur Hawkes

Theodore John Staub

James J Meighan, Iii

Marvin R Freeling

Brian R Dornan

A method for tuning phase relationships for a multi-port amplifier. The method includes providing a plurality of amplifiers arranged in a multi-port configuration, which has more than two amplifiers. The method includes selecting one of a plurality of test patterns to be input into one or more of the plurality of amplifiers to detect phase information of one or more of the amplifiers and detecting an output signal at a designated output coupled to the plurality of amplifiers. The method also includes adjusting a phase relation of the one or more amplifiers based upon the output signal.

Adjustable multiport power/phase method and system with minimum phase error

A traveling wave tube (TWT) amplifier includes a beam forming electrode (BFE) and a BFE modulator having a bias-based keyer so that the TWT amplifier signals are keyed off during periods when RF power is not to be amplified. Biasing the beam forming electrode voltage off relative to cathode voltage effectively shuts down the electron beam without shutting down the power supply minimizes power supply stress and significantly improves reliability, so that low-level RF signal input is not amplified, and no significant RF power is output. Likewise, given that no amplification has taken place, no power associated with the TWT amplification function is consumed. Thus, the only power consumed by the TWT amplifier is that associated with the cathode heater and the electronic power conditioner (EPC) used as the electron beam source.

Power regulator for intermittent use of traveling wave tube amplifiers in communications satellites

A method and apparatus to individually detect the cathode to helix current of multiple TWTs sharing a common cathode to helix voltage supplied by a single HV EPC, which provides the capability to determine which tube has exceeded the limit and to adequately protect each helix structure from destruction due to excessive current. An apparatus for detecting travelling wave tube helix current comprises a capacitor having an input electrically connected to a radio frequency signal, an inductor having an input electrically connected to an output of the capacitor and to an input to a helix of a travelling wave tube, the helix of the traveling wave tube electrically connected to a chassis of the traveling wave tube by an impedance, a resistor having an input electrically connected to an output of the inductor and an output electrically connected to the chassis of the travelling wave tube; and wherein a cathode to helix current of the travelling wave tube may be sensed across the resistor.

Method and apparatus for detecting individual TWT helix current for multiple TWT loads

A spacecraft includes a plurality of paralleled RF amplifiers. Each paralleled power amplifier (206) includes a signal splitter (222) which produces two nominally equal-amplitude signals, and a signal combiner (242) which combines appropriately phased signals to produce a sum signal at a sum port (250). The signal combiner also includes a null output port (248). A pair of elemental amplifiers (236, 238) is coupled between the splitter outputs and the combiner inputs. In order to allow for phase drift of the elemental amplifiers, at least one phase shifter (258) is associated with one of the elemental amplifiers. A phase control loop is coupled from the null output of the combiner, around the paralleled amplifier arrangement, and controls the phase shifter to maintain the phase within bounds, to maximize the signal at the sum port of the combiner. In order to provide for redundancy, at least one channel (271; 272) of the paralleled amplifier includes the cascade of a phase shifter (258; 259) and a switching arrangement (281) which allows a failed elemental amplifier to be replaced by a redundant unit. No additional phase shifters are required, since the loop phase shifters compensate for differences between failed and redundant amplifiers.

Spacecraft with paralleled amplifiers and redundancy

A travelling-wave tube (TWT) for a satellite communication system includes a cathode current regulator which compares a sensed I.sub.K signal with a cathode current reference to form an cathode current error signal, and controls the cathode current in response to the cathode current error signal. Helix arc protection is provided by a helix current shut-down, which compares the helix current with a particular reference, and shuts the TWT supply down when helix current flows. Desirable high efficiency TWTs have a small input drive range between maximum TWT output and a defocussed condition, in which beam current flows in the helix. Sudden changes in path attenuation may result in an RF overdrive condition, and cause helix current flow, and undesirably shut down the TWT. A helix current limiter senses the helix current, and compares it with a reference which represents less helix current than that which causes shutdown, to produce a helix current error signal. The helix current error signal adjusts the cathode current reference, to thereby reduce the cathode current in a feedback manner, to thereby tend to maintain the helix current constant at a value below the shut-down helix current.

Travelling-wave tube protection arrangement

A multichannel communication system carries signals having a different frequency range in each channel. In order to achieve a particular output power level from each channel, an amplifier is associated with each channel to boost the signal level. For reliability, a switching arrangement switches amplifiers among the channels in accordance with a priority, or substitutes a redundant amplifier for a degraded or failed unit in a channel. The amplifier is subject to distortion at the desired output level, and is cascaded with a distortion equalizer or linearizer for reducing the total distortion. In accordance with the invention, each distortion equalizer is fixedly connected in one channel, and is optimized for the relatively narrow frequency range of that channel, rather than being switched together with the amplifier and being optimized over the total or cumulative bandwidth of all the channels.

Multichannel communication system with an amplifier in each channel

A power amplifier arrangement includes a power divider for dividing the signal to be amplified into equal-amplitude components. Each component is amplified by a signal amplifying path. The amplified signals are applied to a phase-sensitive power combiner. The combined signal appears at the sum port and a phase-related difference signal appears at a difference port of the combiner. The difference signal is processed to produce a control signal for controlling the relative phases of the signals passing through the signal amplifying paths.

Parallel amplifiers with combining phase controlled from combiner

A laser is modulated in accordance with an input signal of time varying value. The modulated beam is intercepted by a Bragg cell acoustically modulated in accordance with one or more preselected control frequencies from a selectable source of such frequencies. The beam is deflected by an amount or amounts dependent on the acoustically modulated frequency or frequencies. A plurality of photodetectors are positioned to intercept the deflected beam at its respective possible deflection angles and to convert optical signals so recieved into electrical output signals. Thus by choice of control frequency, a signal corresponding to the input signal can be caused to appear at the output of one or more photodiodes.

Optoelectronic multiposition RF signal switch

A device comprising a microstrip including a narrow conductor connected in series between a circuit input terminal and the power amplifier, a film of ferrimagnetic material positioned adjacent the conductor and magnetic biasing means. The biasing means normally biases the ferrimagnetic material to operate at frequencies about a selected center frequency for nonlinearly enhancing RF input signals as a function of input amplitude. The device normally, undesirably provides nonlinear phase shifts to the input signal as a function of input power at frequencies removed from the center frequency. By choice of the amount of the bias, for a particular input signal frequency, the device can be adjusted to produce phase shift which changes as a function of input power to offset the nonlinear phase shift of the RF amplifier.

Method and apparatus for compensating non-linear phase shift through an

A serrodyne includes a phase shifting circuit adapted to receive a sawtooth modulating signal for providing frequency translation of a radio frequency signal which can be at any of a range of input frequencies. The serrodyne also includes a discriminator which produces in response to the input RF signal a voltage of amplitude proportional thereto. The serrodyne further includes a circuit producing a sawtooth voltage waveform of period 1.div.m, where m is the amount of frequency shift desired in the serrodyne. The sawtooth waveform is applied to the phase shifting circuit. The sawtooth waveform is amplified by an amplifier to which is applied the sawtooth voltage waveform and the signal from the frequency discriminator. The amplification is such that the peak-to-peak magnitude of the amplified waveform is dependent on the amplitude value of the voltage from the frequency discriminator and causes the serrodyne frequency to be shifted by 360.degree. at any of the range of input frequencies.

Optimization circuit for a serrodyne frequency translator

An injection laser modulator comprises a self-biased field-effect transistor (FET) and an injection laser to provide a quiescent state during which lasing of the injection laser occurs in response to a high repetition rate signal of pulse coded modulation (PCM). The modulator is d.c. coupled to an input pulse source of PCM rendering it compatible with an input pulse referenced to ground and not being subject to voltage level shifting of the input pulse. The modulator circuit in its preferred and alternate embodiments provides various arrangements for high impedance input and low impedance output matching. In addition, means are provided for adjusting the bias of the FET as well as the bias of the injection laser.

High repetition rate driver circuit for modulation of injection lasers

A microwave power limiter for generating an output RF signal of substantially constant power level in response to an input RF signal of varying power level comprises a dual gate field effect transistor (FET). The FET is biased such that the RF power output variation is small compared to the input power variation in the saturation region. A number of FET cascaded stages may be utilized to reduce this power output variation. A small signal amplifier including a number of FET cascaded stages may be employed in the limiter to increase the power level to that gain or drive level compatible with the saturated FET stages.

Microwave power limiter comprising a dual-gate FET

A microwave power limiter for generating an output RF signal of substantially constant power level in response to an input RF signal of varying power level comprises a single gate field effect transistor (FET). The FET is biased such that the RF power output variation is small compared to the input power variation in the saturation region. A number of FET cascaded stages may be utilized to reduce this power output variation. A small signal amplifier including a number of FET cascaded stages may be employed in the limiter to increase the power level to that gain or drive level compatible with the saturated FET stages.

Microwave power limiter comprising a single-gate FET

A radio frequency burst signal memory system is described which includes a feedback loop for recirculation of the received RF burst signal when a proper burst signal is detected. The output from an RF amplifier is split into separate frequency bands by a diplexer. When one of these bands is sensed at the input, only signals of the sensed frequency band are recirculated.

RF Burst signal recirculation memory system having a diplexed feedback

A frequency synthesizer capable of rapidly changing to a different desired output frequency includes a voltage-controlled oscillator and a variable frequency divider arranged in a phase-locked loop. A first frequency-control voltage is initially applied to the voltage-controlled oscillator to cause a rapid change in its output frequency toward a desired value. Then, the divisor of the variable frequency divider is changed to produce a second frequency-control voltage which precisely sets and maintains the oscillator output frequency at the desired value.

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Livingston, NJ, United States of America

Herbert J Wolkstein