Abstract: A circular litter box having a scoop removal remounted in a scoop holder which is pushed around the sidewall of the box to scoop the box. The mounting mechanism for the scoop causes the scoop to assume a relatively vertical position during scooping, to minimize formation of a wave of litter in front of the scoop as it is rotated, but causes the scoop to assume a more horizontal position as the scoop is removed, so the collected waste will not spill from the scoop during removal.

Abstract: Methods and apparatus for accurately predicting a fuel injector tip temperature (FITT) are described. One technique for predicting the temperature of a fuel injector tip in an engine suitably includes the steps of estimating an initial temperature of the fuel injector tip and calculating a steady state temperature of the fuel injector tip. A filter coefficient is determined as a function of a rate of airflow into the engine, and the temperature of the fuel injector tip is predicted as a function of said initial temperature, the steady state temperature, and the filter coefficient. In a further embodiment, the steady state temperature is filtered into a feedback temperature at a rate that is determined by the filter coefficient.

Abstract: An approach for providing message synchronization in a communication system is disclosed. Using a selected channel coding method (e.g., Golay coding), an encoder encodes a message for transmission over a communication channel. An interleaver applies a predetermined interleaving pattern to the encoded message. A mask pattern with a prescribed sequence of bits is applied to the interleaved message; the prescribed sequence is ordered to eliminate an all zeros bit pattern and an all ones bit pattern. A multiplexer multiplexes the masked message with data traffic over the communication channel. The masked message is segmented into multiple blocks of a fixed length. At the receiver side, the mask pattern is applied to the demultiplexed message. The message is de-interleaved and decoded to restore the original message.

Abstract: The invention provides methods and compositions for increasing the delivery of nucleic acids into a host by administering a nucleic acid encoding a therapeutic nucleic acid along with an agent that modulates Kupffer cell function in the host.

Abstract: An approach for minimizing variation in transmit power of synchronized signals that are destined to a satellite is disclosed. A gateway station system for communicating with a communication satellite includes a multiple signal sources which generate the synchronized signals. The gateway station system utilizes a control logic that is coupled to the signal sources. The control logic operates to offset selectively transmission times of a portion of the synchronized signals according to a predetermined distribution and an offset period. The predetermined distribution specifies about half the number of the synchronized signals are to be offset. The offset period is half a symbol period. The terminals within the satellite communication system has a receiver that receives the synchronized signal from the communication satellite.

Abstract: A system (20) and method (30) for estimating the location of a terrestrial-based user terminal (23) is provided. The user terminal (23) is capable of measuring the relative signal strengths of a plurality of spot beams pilot signal emitted from a geostationary satellite (22). The user terminal (23) then estimates its position based on the measured relative signal strengths. Using this approach, the user terminal (23) can quickly determine its location without prior knowledge of its position or delay time.

Abstract: A system and method are provided for masking messages intended for a particular one of a plurality of receivers receiving messages on the same frequency in a satellite communication system. Each message contains a data portion and a parity portion. Before transmitting the message, the parity portion is masked by performing an exclusive-OR operation on the parity portion using a mask identified with the intended receiver. At the receiver, the parity portion of received messages are first unmasked by performing an exclusive-OR operation on the masked parity portion. The message is accepted by the receive only if the parity check is valid after the unmasking operation.

Abstract: Filtering loop and method for maintaining synchronization between a receiver and a transmitter reduces overhead and enables more robust operation. The method includes the step of receiving an error signal corresponding to a synchronization parameter. A first order filter is applied to the error signal such that a residual signal results. The method further provides for compensating the residual signal for drift such that the compensated residual signal estimates a rate of change in the residual signal. By compensating the residual signal for drift, difficulties associated with time lag and signal degradation are obviated.

Abstract: A waveform to be transmitted as a burst within a channel that is used for the synchronization of unsynchronized wireless communications terminals in a wireless communications system, and a method of synchronization involving the waveform, that consists of a composite waveform. The composite waveform comprises two or more component waveforms, wherein each of the two or more component waveforms has a known frequency variation throughout the burst. The composite waveform has a composite bandwidth on an order of an available channel bandwidth and each of said two or more component waveforms have a component bandwidth on the order of the available channel bandwidth. Furthermore, a range of values for the differences between the instantaneous frequencies of two of said two or more component waveforms is on an order of twice of said available channel bandwidth.

Abstract: A system and method employing an access terminal for maintaining discontinuous communications including a gateway receiver for receiving the discontinuous information, a radio frequency (RF) communication link via geosynchronous earth orbit satellite for conveying multiple communication channels using time division multiple access (TDMA), the access terminal initiating information communication with the receiver via at least one of the multiple communication channels. The access terminal further includes a memory for storing protocol processing information and a transmitter for establishing the radio frequency communication link to the receiver of the terrestrial gateway system. The access terminal memory provides for destroying of a signal pattern or protocol assigned to the access terminal by the gateway receiver or transmission of keep-alive bursts by the transmitter during periods of inactivity to maintain information communication with the receiver.

Abstract: A method, and related apparatus, for detecting interference at a first communications terminal comprising establishing a communications link between the first communications terminal and a second communications terminal. Then monitoring a noise floor of the communications link over time, the noise floor representing a base level of noise present in the communications link and calculating a long term noise floor power level without interference in response to the monitoring of the noise floor of the communications link over time. Then monitoring a noise floor of a current communication through the communications link, representing a current level of noise present on the communications link and calculating a short term noise floor power level in response to the monitoring of the noise floor of the current communication through the communications link. Finally, comparing the short-term noise floor power level with the long term noise floor power level without interference.

Abstract: A system for controlling/conserving signal transmission power in a communications system is disclosed. The system generally includes a first unit having a transmitter and a receiver, a second unit having a transmitter and a receiver, a forward communications channel between the first unit transmitter and the second unit receiver, and a reverse communications channel between the second unit transmitter and the first unit receiver. In operation, the system determines the received signal power needs of the second unit receiver. It then generates a reverse channel explicit-power-request command based on the determination of the received signal power needs of the second unit receiver. The reverse channel explicit-power-request command represents an absolute power level at which the first unit transmitter should transmit signals over the forward communications channel.

Abstract: An access terminal for initiating spot beam selection in a satellite communication system, in which the access terminal includes a receiver for measuring the received signal strength (RSS) of a multiplicity of radio frequency communication spot beam links. The access terminal is further provided with a microcontroller for comparing the received signal strengths from each of the multiplicity of spot beams to initiate information communication via a communication channel of the satellite communication system. In a described embodiment, the controller of the access terminal compares seven spot beam links to determine whether to initiate information communication with one of the seven spot beams received. Additionally, a memory coupled to the controller of the access terminal is used for storing spot beam identification information including the spot beam links assigned to the access terminal via the satellite communication system.

Abstract: A device and method of selecting and deselecting an equalizer in a digital communications receiver. The method includes receiving a receiver signal, estimating an estimated delay spread in the receiver signal, and determining a threshold delay spread. In the event the estimated delay spread exceeds the threshold delay spread, the method includes selecting the equalizer. In the event the estimated delay spread does not exceed the threshold delay spread, the method includes deselecting the equalizer. The method also includes generating a receiver output signal in response to an equalizer signal in the event the equalizer is selected, and generating the receiver output signal in response to the receiver signal in the event the delay spread does not exceed the threshold. The device includes a radio receiver that receives the receiver signal and an analysis circuit coupled to the radio receiver.

Abstract: A system for symbol timing maintenance in a communications receiver, in one embodiment, employs a receive channel, including a demodulator and an analog-to-digital converter for generating a plurality of samples; a symbol timing statistic generator for generating a symbol timing statistic in response to a portion of the plurality of samples; a noise estimator for generating an estimate of a noise level in response to the plurality of samples; a reception interval determiner for determining a reception interval; and a control loop for generating a signal indicative of symbol timing error. In an alternative embodiment, the system may, in addition to or instead of the noise estimator, and reception interval determiner, employ a bandwidth tuner for tuning a bandwidth of the control loop in response to the signal indicative of the symbol timing error having been generated.

Abstract: A system and method of blind channel estimation to receive a signal burst over a communications channel; divide the signal burst into a prescribed number of groups of symbols; hypothesize all possible transmitted data sequences or each group; generate a corresponding channel estimate for each possible data sequence; determine an error measurement for each corresponding channel estimate; select a number of the corresponding channel estimates for each group from amongst the corresponding channel estimates, the number of the corresponding channel estimates being selected for having smaller error measurements than remaining corresponding channel estimates not selected; identifying a best channel estimate for each group from amongst the number of the corresponding channel estimates having been selected for each group; and reviewing the best channel estimate having been identified for each group and reidentifying best channel estimates for some of the groups so as to increase smoothness of a curve in two-dimensiona

Abstract: The invention relates to a lens mounting suitable for use in a high performance optical instrument. The mounting (10) comprises a body or housing, a linear guide (16; 18; 36; 46; 64) mounted on the body, a lens carriage (14; 34; 44; 62) moveable along the linear guide, and a linear drive, which may be in the form of a ball-screw drive and comprising a ball-screw (20; 80) extending substantially parallel to the linear guide and a ball-screw follower (22; 68) linked to the lens carriage such that rotation of the ball-screw moves the carriage axially along the guide. One or more elements of the ball-screw drive are mounted relative to the linear guide to permit a degree of relative movement therebetween to accomodate misalignment between the linear guide and ball-screw.

Abstract: A device and method for receiving a radio signal transmitted over a channel, selecting and deselecting an equalizer, and balancing processing in response to such selection. A radio frequency signal is received from a transmission channel into a receive path, and delay spread in the radio frequency signal is estimated using an analysis circuit. The analysis circuit also determines a threshold delay spread. In the event the estimated delay spread exceeds the threshold delay spread, an equalizer is selected, otherwise the equalizer is deselected. Similarly, in the event the estimated delay spread does not exceed the threshold delay spread, a high complexity processor is selected, otherwise a low complexity processor is selected. If the low complexity processor is selected, an output signal is generated using the low complexity processor, and if the high complexity processor is selected, the output signal is generated using the high complexity processor.

Abstract: A system and method for determining a timing error of an incoming signal, in one embodiment, receives the incoming signal into a receiver, and locates a known portion within a time frame of the incoming signal. The known portion is compared with a stored representation of the known portion, and with a stored representation of a derivative of the known portion. The timing error of the incoming signal is determined with respect to the clock signal based on the comparing of the known portion with the stored representations, and a subsequent known portion is located within a subsequent time frame of the incoming signal based on the timing error.

Abstract: A digital filter includes a first memory device, a filter with at least one pole, i.e., a pole filter, coupled to the first memory device, and a second memory device coupled to the pole filter. The first memory device sequentially stores a digital signal in a forward sequence, and the pole filter sequentially reads the stored digital signal from the first memory device in a reverse sequence, thereby creating a time-reversed signal. The time-reversed signal is filtered by the pole filter, and is then stored as a filtered time-reversed signal in the second memory device in the forward sequence. A data signal is generated by the second memory device by reading the filtered time-reversed signal from the second memory device in the reverse sequence.