Abstract: An apparatus and method for performing spatial nulling in antenna electronics that provides an integrated solution of signal attenuation and bi-phase modulation. One implementation is comprised of load resistors and field-effect-transistors in a gallium arsenide component configured in such fashion as to provide attenuation and bi-phase capability in response to coupled control signals.

Abstract: A system for customizing the ramp voltage pulses used to drive an active matrix liquid crystal display. The customized ramp voltage compensates for brightness problems associated with any number of parameters. The V (ramp) also can allow for customized dimming of portions of the display. The standard V (ramp) is replaced with a variable wave form correlated to the timing of the driving of the LCD. The wave form can compensate for changes in brightness caused by off axis viewing angle or can compensate for brightness changes caused by temperature. Also, the system is directed to spatially modulating brightness of pixels for an active matrix LCD to correct color or brightness problems. A driving voltage wave form, which is varied as a function of location on LCD and grey scale is generated to cause selected sets of pixels to be adjusted from an instructed grey scale.

Abstract: An improved autopilot system of the type which uses pitch commands to control airspeed with an improvement of including a temporary pitch hold command being issued if thrust changes would oppose the autopilot pitch command. The temporary pitch hold command would end when the airspeed reaches a calculated airspeed capture point.

Abstract: An apparatus and method of accomplishing over-voltage protection for variable power levels and frequency applications including the microwave range. Clamping means are provided that instantaneously absorb over-voltage conditions for a brief period while simultaneously providing feedback control of a driver signal to reduce the source of the over-voltage condition.

Abstract: An arrangement for generating a digital, downconverted complex baseband signal from a bandpass signal comprises a signal source for providing first and second clock signals at first and second clocking rates, respectively. The first clocking rate is at four times the expected center frequency of the bandpass signal, and the second clocking rate is at an exact subharmonic frequency of the bandpass frequency. The bandpass signal is sampled by a composite sampling event of two sampling pulses which occur once during each period of the second clocking signals and which are time-spaced from each other by the inverse of the first clocking rate. The complex baseband samples are ready as an A/D converter output, with no requirement for DSP processing to complete the downconversion to zero-IF.

Abstract: An apparatus and method for improving the performance of a satellite communications modem is disclosed. The invention is particularly applicable to mobile satellite receivers, and includes a variable-gain automatic frequency controlled (AFC) loop, the gain of which is controlled adaptively, based on the AFC lock status and the lock status of the modem's inner loop, in addition to other parameters determined by the invention.

Abstract: A magnetically variable inductor for high power, high frequency applications which includes a solenoid with a magnetic core therein, disposed coaxially around a conductor for carrying the high power, high frequency signal and a variable current source coupled with the solenoid so that a manipulation of the current through the solenoid results in a variable inductance for said conductor. Also disclosed are additional features of ferrite rings disposed around each end of the magnetic core, a shield disposed between the core and the solenoid, and a sheath disposed around the solenoid.

Abstract: A regulated and constrained current source is used to drive the cathodes of a hot cathode gas discharge lamp to provide heating during lamp operation. In one embodiment, the regulated current source is time shared between the lamp cathodes and the lamp arc.

Abstract: A composite signal recognizer separator, and PSK, AM, FM demodulator apparatus for processing received communication signals. The receiver utilizes N demodulators cascadely-coupled, where N is equal to or greater than the number of co-channel signals or perceived interference. Detailed in both dual and single stages cascaded fashion, the receiver first tracks to a predominant (stronger) signal, and regeneratively improves track on other (weaker) signals by subtracting predominant noise portion from the input of further demodulation stages. A unified approach to PSK carrier phase tracking, character data tracking, and recovery clock tracking is utilized.

Abstract: A bipolar modulator and its associated control devices for use with a high-efficiency amplifier in an RF transmitter. The modulator receives an inverted reference signal that has passed through at least two comparators. The modulator output is filtered and then rectified and coupled to a high-efficiency power amplifier.

Abstract: An adjustable digital synthesizer has frequency increments of a selected step size. The adjustable digital synthesizer includes a digital accumulator having N stages. The digital accumulator counts at a predetermined clock frequency such that, in response to each clock, the accumulator increments the step size determined by the digital input. The accumulator counts to 2.sup.Nth state and wraps around in response to an overflow. An adder, responsive to the overflow, adds an offset to the accumulator, the offset being a function of the difference between 2.sup.Nth times the minimum step size and the desired clock frequency.

Abstract: In a radio transmitter, a PM input signal is provided directly to a frequency synthesizer. The synthesizer includes a PLL having a reference frequency input signal and a controlled frequency output signal. The PLL includes a frequency divider which is directly connected in a feedback circuit path between the controlled frequency output signal and the PLL's phase-detector. The frequency divider has a frequency control input signal for setting a division ratio N for the divider, and a PM circuit has as input signal the PM input signal and the frequency control input signal. The PM circuit provides an offset signal to the phase detector output, so that the PLL creates a correcting phase signal resulting from the offset signal. The magnitude of the offset signal changes as a function of the change in the value of N.

Abstract: A transceiver which operates in separate transmit and receive bands has a first conversion stage for generating a first IF signal translation of a receive signal, which first conversion stage also functions as a first and final, hence, single conversion stage for generating a transmit signal at its transmission frequency. A modulated transmit signal component used in the single conversion to the transmission frequency of the transmission signal has harmonics which lie outside the transmission band and is of a frequency which permits a substantial overlap of transmit and receive injection frequencies generated by a first numerically controlled signal generator which are applied to a first mixer of the first conversion stage during respective transmit and receive mode operations.

Abstract: An RF voltage/current sensor apparatus comprising a plurality of transmission lines coupled through resistive means to voltage sense circuitry. The voltage sense circuitry utilizes transistor technology thereby reducing the use of switching relays, transformers and diodes thereby providing an apparatus operational over a frequency range from approximately two megahertz to two gigahertz.

Abstract: An apparatus and method of controlling the light intensity in a light source of variable emission affected by a drive signal. Spatial optical integration based upon light summation is incorporated into the accompanying encasement device at a backlight source by means of a light source support structure that allows light not directed toward a viewed surface, such as an LCD, to serve as a control input to the light drive signal.

Abstract: A railroad in-cab signaling system which includes transceivers disposed at signals where various transceivers are operating on different frequencies and addresses so as to provide for easy identification and highly secure communication to the signal transceiver and a tunable transceiver disposed on the locomotive, the locomotive transceiver being coupled to an interrogator which interrogates transponders disposed in the tracks, the transponders providing a message containing the predetermined frequency and address of the signal transceiver thereby allowing the locomotive transceiver to tune to the appropriate frequency and established a connection for the signal which it is approaching. The locomotive transceiver and the signal transceiver are then capable of exchanging information along the entire distance from the transponder to the signal.

Abstract: An active ring laser gyroscope having two optical amplifier diodes therein which are switched in such a fashion that the two counter propagating light pulses in the ring are never in an activated optical amplifier diode at the same time.

Abstract: An apparatus and method for accomplishing DC-to-AC power conversion that combine the AC outputs of n interleaved, time division multiplexed inverters and steer the secondary pulses positively or negatively, as commanded by the time varying reference signal, such that the effective switching, or sampled-data, frequency of any of the inverter or pulse-steering transistors. The n interleaved inverter system can, in turn, be paralleled such that, relative to a single inverter supplying all the power, the losses for any inverter transistor are 1/np, n due to time multiplexing and p due to paralleling.

Abstract: An electronic library system cabinet having a ring bus architecture with a high reliability backplane wherein the electronic library system includes a plurality of slots for receiving a plurality of modules therein. The modules capability of determining whether the adjacent slot is occupied by a module and alternately directing output information from the module onto a return bus if the adjacent slot is unoccupied or onto an intermodule connection line if the adjacent slot is occupied by a module.

Abstract: An RF transmitter protection circuit for providing protection to a power amplifier includes circuitry for sensing the presence of an input excitation signal applied to the input of the power amplifier. Circuitry is provided for monitoring an output signal generated by the power amplifier at the output of the power amplifier and for generating a signal proportional to the output signal. Circuitry is further provided for applying the signal generated by the monitoring circuit to the input of the power amplifier in response to a loss of input signal detected by the sensor.