Abstract:
In an analog-to-digital converter (100), a method and apparatus compare (302) an analog input signal (102) with a reference signal (108) to generate a decision signal (110), and sum (304) the analog input signal with a control value (130) whose magnitude is determined by an accumulated value (126), and whose sign is determined by the decision signal, thereby generating an error signal (114). The method and apparatus further calculate (306) a correlation value (118) between the error signal and the decision signal, and accumulate (308) the correlation value to produce the accumulated value, thereby adaptively compensating for an inaccuracy in the A/D converter.
Abstract:
An optical device for use with an optical input beam comprising an optical thresholding device positioned along an optical path defined by the propagation direction of the optical input beam. If the combined intensity of the optical input beam and a control beam exceeds a threshold level, the optical beam passes through the thresholding device. Preferably, the optical thresholding device is a saturable absorber. When the device is configured as an optical comparator, the intensity of the optical input beam exceeds the threshold level and the thresholding device saturates and turns transparent so that the control beam passes through the thresholding device as an optical indicator beam. When the device is configured as an optical signal attenuator and the intensity of the optical input signal is negligible compared to that of the control beam, the combined intensity of the beams does not saturate the thresholding device.
Abstract:
An optical device for use with an optical input beam comprises and optical thresholding device having a predetermined threshold level, and is positioned along an optical path defined by the propagation direction of the optical input beam. A source generates a control beam through the optical thresholding device, wherein if the combined intensity of the optical input beam and the control beam is large enough to exceed the threshold level of the thresholding device, the optical beam passes through he thresholding device. The thresholding device attenuates the optical beam as it passes therethrough. In a preferred embodiment, the optical thresholding device is a saturable absorber. When the device is configured as an optical comparator, the intensity of the optical input beam is large enough to exceed the threshold level of the thresholding device, the thresholding device saturates and turns transparent so that the control beam passes through the thresholding device as an optical indicator beam and the optical input beam passes through the thresholding device. When configured as an optical signal attenuator and the intensity of the optical input signal is negligible compared to that of the control beam the combined intensity of the optical input signal and the control beam do not saturate the thresholding device.
Abstract:
An orthogonal pilot tone servo controller provides a servo control loop for each tap in a delay line processor where each servo acquires its independence from the other tap's servos utilizing an orthogonal code set modulated on top of the existing tap values. The orthogonal codes are attenuated in amplitude such that the code sets are transparent to the processed signals of interest, but the code's length enables each tap's servo controller to independently recover the tap's state from the aggregate of signals and codes through processing gain realized in each loop's recovery circuit. A plurality of taps can be thus be servo controlled simultaneously, providing for extremely wide bandwidth processes which can be performed accurately with digital controls.
Abstract:
An optical quantizer (10) that employs a chain of optical thresholding devices (16) positioned in the propagation path of an optical input beam (12) to be quantized. Each optical thresholding device (16) saturates and turns transparent if the intensity of the optical beam (12) that impinges it is above a predetermined threshold level designed into the device (16). If the input beam (12) saturates the optical thresholding device (16), the device (16) outputs an indicator signal (22) identifying the saturation. The input beam (12) propagates through the optical thresholding device (16) with some attenuation caused by the saturation, and impinges subsequent optical thresholding devices (16) in the chain. Eventually, the attenuation of the input beam (12) caused by the multiple saturations will decrease the beam intensity below the threshold level of the next optical thresholding device (16). The number of indicator signals (22) gives an indication of the intensity of the input beam (12). The optical thresholding devices (16) can provide optical or electrical indicator signals (22) depending on the type of thresholding device (16) used.
Abstract:
A transmitter-receiver includes a transmitting circuit for providing an output by converting the frequency of a transmission signal input thereto, a receiving circuit for providing an output by converting the frequency of a received signal input thereto, and a local oscillator which generates an oscillation signal having a local oscillating frequency based on a reference signal. A local oscillator signal splitter is connected to the local oscillator and splits the oscillation signal into substantially similar transmit and receive oscillation signals each at the local oscillating frequency. The local oscillator signal splitter supplies the transmit oscillation signal to the transmitting circuit and supplies the receive oscillation signal to the receiving circuit. The transmitting circuit converts the frequency of the transmission signal in accordance with said transmit oscillation signal, and the receiving circuit converts the frequency of the received signal in accordance with the receive oscillation signal.
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:
A method for determining the geolocation of a user terminal within a telecommunications system having a constellation of satellites which relay communications signals between earth stations and user terminals over preassigned channels. The method performs synchronization upon the telecommunications signals to calculate timing and frequency update information for the user terminals. The timing and frequency update information is also used within the earth station to calculate the geoposition of the user terminal. To do so, the earth station calculates a distance between the satellite and a user terminal based on the corresponding propagation time therebetween which is obtained from the timing information. Once the satellite to user terminal distance is obtained, a range solution line may be calculated therefrom. In addition, the frequency update information is used to calculate a Doppler solution line upon which the user terminal is positioned. Thereafter, the range and Doppler solution lines are combined to obtain points of intersection therebetween. These points of intersection represent potential geolocations of the user terminal. The earth station discriminates between these intersection points in one of several manners, such as the coverage beam spot or geographic cell assigned to the user terminal. Upon obtaining a single intersection point, the longitude and latitude of this point or output is the geolocation of the user terminal.
Abstract:
A correlative error detection system (60) for a signal equalizer (10) that corrects a distorted communications signal. The detection system (60) correlates a sequence of bits in a signal from an FFE and/or a DFE processor (12, 14) with a predetermined sequence of correlation values. The detection system (60) includes a summing network (66) that sums the correlated signals. If the sequence of signal bits matches the sequence of correlation values, then the summed correlated signal will include a signal maxima. A peak detector (76) detects and holds the signal maxima so that a slow speed weight computer (40) can process the signal values to set weight values in the processors (12, 14). By knowing how often the sequence of bits that match the correlative values should occur in a random bit stream for an undistorted signal, the weight computer (40) can set the weight values to provide that magnitude of the bit sequence.
Abstract:
An apparatus for positioning an end effector and associated position controller. The apparatus comprises a plurality of bimorph members, generally elongated in shape, that are coupled end-to-end. In one embodiment, each bimorph member includes a pair of elongated piezoelectric bimorph elements that cause a localized deformation in the bimorph member when driven with an input voltage. Accordingly, each bimorph member can be caused to bend in opposite directions, as well as twist, depending on its drive voltages. In one configuration, four bimorph members are connected end-to-end, with the last bimorph member operatively coupled to the end effector, providing a five-degree of freedom positioner. A multi-channel position controller that provides a pair of correlative feedback loops for each channel is used to generate appropriate drive voltages based on a global feedback signal and a local feedback signal corresponding to a measured position of each channel's corresponding piezoelectric bimorph element.