Abstract: A ferroelectric phase shifter in the form of a coplanar waveguide and a method of fabrication thereof in which a ferroelectric film and a high temperature superconductor film are deposited onto a substrate in of a number of configurations. The high temperature superconductor material is biased in order to vary the dielectric constant of the ferroelectric material. Changing the dielectric constant enables varying the amount of phase shift of a wave applied to the phase shifter.

Abstract: A method for fabricating a monolithic micro-optical component. The construction of the micro-optical components is accomplished by using standard semiconductor fabrication techniques. The method comprises the steps of depositing an etch stop layer (44) onto a semiconductor substrate (42); depositing an optical component layer (46) onto the etch stop layer (44); coating the entire surface of the optical component layer with a photoresist material; applying a photoresist mask (50) to the photoresist material on the optical component layer (46); selectively etching away the optical component layer (46) to form at least one optical column (52); forming a pedestal (54) for each of the optical columns (52) by selectively etching away the etch stop layer (44); and finally polishing each of the optical columns (52), thereby forming monolithic optical components (56).

Abstract: A method of controlling communication satellite system capacity in a satellite-based cellular telecommunication system where two or more communication satellites provide coverage of a service region. Communication satellites are assigned to mobile cellular stations in a manner designed to minimize the maximum single-satellite power that is required for the communication satellites collectively to supply a specified number of transmissions to the service region. The service region may be divided into grids, where each grid is characterized by a number which is proportional to the average number of active mobile cellular stations. This information, in conjunction with a power utilization factor associated with each satellite/grid pair, is used to determine the assignments of the communication satellites to the mobile cellular stations.

Abstract: A quenchable VCO that is adapted to be used in switched band synthesizer applications. The VCO may be formed from a heterojunction bipolar transistor (HBT) in a common collector configuration. A quenching circuit which includes a p-i-n diode, is electrically coupled in series with the collector of the HBT. The p-i-n diode is adapted to be monolithically integrated with the HBT. Since the p-i-n diode is electrically connected to the collector of the HBT, as opposed to the base and emitter terminals of the HBT, which forms the main oscillator feedback loop, the Q-factor of the p-i-n diode will have relatively less loading on the phase noise of the HBT oscillator. Moreover, since the p-i-n diode is isolated from the base-emitter junction, the configuration will result in reduced frequency pulling and generation of spurious oscillation and transient effects due to the switching of the p-i-n diode quenched circuit.

Abstract: A system and method for monitoring the mode of an input beam to a phase conjugated master oscillator power amplifier (PC MOPA). In order to prevent catastrophic optical damage to the MOPA components, the method and system shuts down the master oscillator when a multi-mode input beam is detected.

Abstract: A balanced photoreceiver which includes one or more photodiodes coupled to an amplifier that includes a common base configured input stage which operates over a frequency band from DC to millimeter wave frequencies. In one embodiment of the invention, the amplifier is formed as a three-stage direct coupled amplifier which includes a direct coupled complementary common base configured input stage, a complementary common emitter configured Darlington pair intermediate stage and a complementary common collector configured output stage. The common collector configured output stage is used to recombine the complementary current outputs from the input and intermediate stages. The photoreceiver in accordance with the present invention provides relatively superior output waveform symmetry over an increasing power input.

Abstract: An RF switch formed as a micro electro-mechanical switch (MEMS) which can be configured in an array forming a micro electro-mechanical switch array (MEMSA). The MEMS is formed on a substrate. A pin, pivotally carried by the substrate defines a pivot point. A rigid beam or transmission line is generally centrally disposed on the pin forming a teeter-totter configuration. The use of a rigid beam and the configuration eliminates the torsional and bending forces of the beam which can reduce reliability. The switch is adapted to be monolithically integrated with other monolithic microwave integrated circuits (MMIC) for example from HBTs and HEMTs, by separating such MMICs from the switch by way of a suitable polymer layer, such as polyimide, enabling the switch to be monolithically integrated with other circuitry. In order to reduce insertion losses, the beam is formed from all metal, which improves the sensitivity of the switch and also allows the switch to be used in RF switching applications.

Abstract: A method for enhancing the performance of a communications system is disclosed. The system generally includes an originating ground station (300) which produces error-control coded uplink signals and transmits the coded uplink signals to a satellite (310). The system also includes a destination ground station (326) which receives a downlink beam from the satellite (310). The method includes the steps of receiving uplink signals transmitted by an originating ground station (300) at a destination ground station (326) and determining a downlink channel signal quality indication (504) at the destination ground station (326). The method also includes the steps of measuring an error rate associated with at least a portion of a downlink beam at said destination ground station (326) and determining an operating point (506) relative to a desired performance curve (502) based on the signal quality indication (504) and the error rate.

Abstract: A high temperature superconductor junction and a method of forming the junction are disclosed. The junction 40 comprises a first high-T.sub.c superconductive layer (first base electrode layer) 46 on a substrate 42 and a dielectric layer 48 on the first high-T.sub.c superconductive layer. The dielectric layer and the first high-T.sub.c superconductive layer define a ramp edge 50. A trilayer SNS structure 52 is disposed on the ramp edge to form an SSNS junction. The SNS structure comprises a second high-T.sub.c superconductive layer (second base electrode layer) 54 directly on the first high-T.sub.c superconductive layer, a normal barrier layer 56 on the second high-T.sub.c superconductive layer, and a third high-T.sub.c superconductive layer 58 (counterelectrode) on the barrier layer. The ramp edge is typically formed by photoresist masking and ion-milling. A plasma etch step can be performed in-situ to remove the photoresist layer 62 following formation of the ramp edge.

Abstract: There is provided a heat pipe assembly 10 formed of dissimilar materials for the heat pipe 18 integrated with the host structure 16 in a manner that optimizes removal of unwanted heat generated by various devices on a space or terrestrial platform 14. A conventional heat pipe construction 18 mounted within a circular cross-section channel 28 formed in a retaining block 26 leaving an annular gap 30 between the outside surface wall 33 of the heat pipe and the inside surface wall 32 of the channel 28. A heat conductive fluid 40 is injected into the annular gap 30 permitting the dissimilar CTE materials to thermally expand and contract as the platform or structure 14 experiences extreme temperature changes.

Abstract: A laser-based tracking system for tracking the position of a targeted moving object. The tracking system includes two lasers: a reference laser and a slave laser. Each laser is a weapon, and when locked on a target, single laser effectiveness may be doubled without a thermal blooming performance loss associated with a single laser operating at twice the power. The slave laser beam is dithered relative to the reference laser beam in a direction along the longitudinal axis of the target. The system includes an optical receiver for repetitively scanning the irradiance profile reflected by the target. Since the slave laser beam is dithered relative to the reference laser beam, both laser beams will jitter and drift together providing a gain factor of two in average irradiance on the moving target.

Abstract: Apparatus, and a related method for its operation, for generating multiple parallel streams of data from a large solid-state mass storage device, under the individual control of multiple users requesting the data streams. The apparatus includes a hardware interface table containing a user command and current memory address for each active user requesting data from storage. Memory array addressing logic cycles through the hardware interface table and generates multiple streams of memory array addresses based on the user commands and the current memory addresses, but without using a processor to generate the addresses. The address streams are directed to a memory array, from which are output multiple streams of corresponding data. User commands for selective control of each data stream are converted to new memory addresses, which are stored in the hardware interface table and almost instantly result in performance of requested control functions with respect to the data streams.

Abstract: A digital processor with reconfigurable architecture includes a processor input and a processor output. A library stores a plurality of related function sequences for executing a processor operation. Memory stores data as required by the function sequences. A configurable device is connected to the library and the memory and between the processor input and the processor output. The configurable device sequentially stores the function sequences from the library in a plurality of programmable gate arrays configurable by the function sequences. The configurable device reconfigures the programmable gate arrays with another of the function sequences to complete the processor operation.

Abstract: The invention relates to high stiffness parabolic structures utilizing integral reinforced grids. The parabolic structures implement the use of isogrid structures which incorporate unique and efficient orthotropic patterns for efficient stiffness and structural stability.

Abstract: A method and apparatus for autonomous assignment of communications channels during call handoffs by a user terminal in a satellite-based telecommunications system. The method comprises the steps of transmitting a request for access from a user terminal to a control center via at least one satellite and selecting channel parameters and model assignment information for a first communications channel at the control center. The assignment information identifies predictable events which require the first user terminal to switch to a second communications channel. The channel parameters and model assignment information are transmitted from the control center to the first user terminal. A communications link is established over a first channel with the first user terminal.

Abstract: A technique for gathering, correlating, sorting and distributing usage data records in a satellite based telecommunications system having multiple orbiting satellites (10, 12), multiple earth stations (16, 18) and multiple gateways (29, 42) for connecting with conventional public switched telephone networks (28, 30). Calls originated by or destined to a satellite user terminal (20, 24) trigger the generation of usage data records of various types to record the times of usage and other data, for each call, pertaining to various system resources, such as the earth stations, satellites, and radio connections between them. The data records for each call are correlated (58) and linked together to define a service usage record for the call. The service usage records are periodically pooled (60) and sorted (62) by subscriber service provider at a central site (36) and then distributed (66) to service providers for billing purposes.

Abstract: A ranging device is disclosed that monitors for changes in a scene of interest. The ranging device includes a transmitter that sends pulses into the scene, a receiver that generates pulse samples in response to pulse returned from the scene, and a target discriminator that analyzes the pulse samples. The target discriminator detects targets entering the scene, targets leaving the scene, and targets moving in the scene through the use of at least one non-averaging statistical characteristic of the pulse samples. The target discriminator may generate short term and long term high order statistical samples in response to the pulse samples as well as detector samples consisting of the ratio of high order statistical samples. The detector samples are highly indicative of the presence or absence of a target in the scene.

Abstract: A satellite communications technique is disclosed that synchronizes the reception of numerous OFDM uplink signals (108, 110) at a satellite (106) receiver and bulk processes them in the satellite (106). In operation, the satellite (106) receives an OFDM uplink signal (110) transmitted by a CPE (104). The satellite 106 then compares the reception timing of the symbols in the received OFDM uplink signal (110) with a satellite timing reference, and generates a timing correction. The satellite (106) provides a downlink symbol clock as inherent structure in a downlink beam to the CPE (104) and also transmits the timing correction in the downlink beam. The CPE (104) uses the downlink symbol clock in conjunction with the timing correction to generate an uplink clock. The CPE (104) then transmits data in the OFDM uplink signal (110) synchronously with the uplink clock. Each CPE (102, 104) may be synchronized in this manner.

Abstract: A frequency modulation-based optical analog-to-digital converter utilizes a downward-folding, successive approximation approach. A series of stages is utilized to generate bits in the digital signal. In each stage, complementary low and high bandpass filters collectively cover a bandpass frequency range from a low frequency to a high frequency. The high frequency filtered signal from the high bandpass filter is observed to obtain a bit in the digital word. By performing the folding operations in the frequency domain, the converter avoids the difficult task of optical power subtraction, relying instead on frequency down-conversions. The high frequency filtered signal passed by the high bandpass filter is then downconverted and added to the low pass filter signal to generate a modulated signal for the next stage.

Abstract: A communication system 10 for providing uninterrupted radio operation, including: a pre-transmitter system 12 comprising: (i) a first buffer 14 for storing a sequence of digital audio samples from an audio source 16, the first buffer 30 having a beginning 18, an end 20 and a length 22; (ii) storing means 24 for storing the audio samples in the first buffer 14 in shift register configuration format; and (iii) frame construction means 26 for constructing a data frame including a first audio sample from the end 20 of the first buffer 14 and a second audio sample from the beginning 18 of the first buffer 14; wherein the data frame can be transmitted and received.