Abstract: The present invention discloses a microwave filter (10) for controlling the degenerate resonant modes of a spherical cavity resonator (12). The spherical cavity resonator (12) has an inner spherical surface (14) which defines a spherical cavity (16). A first and a second set of tuning elements (18) extend inward from the inner spherical surface (14) of the resonator (12) into the spherical cavity (16). One of the first set of tuning elements is located near an electromagnetic field peak, either a radial electric field peak or a surface magnetic field peak, of at least one of the degenerate modes for tuning a resonance thereof. One of the second set of tuning elements is located between electromagnetic field peaks, either radial electric or surface magnetic field peaks, of degenerate modes in at least one pair of the degenerate modes for intercoupling thereof.

Abstract: A retainer made from a shape memory alloy (SMA) is utilized in a separation device that is particularly useful for space applications. Upon being heated to a restoration temperature, the retainer changes from a constricted state to an expanded state. In its constricted state, the retainer surrounds and captures a plurality of securing segments to secure an object. To release the secured object, the retainer is heated to its restoration temperature with an electrical heater, causing the retainer to return to its expanded state and allow the securing segments to move apart and release the secured object.

Abstract: Methods and systems for encoding data representative of a sequence of video frames for transmission to a decoder. A motion compensated predictive coder (24) substantially losslessly compresses the data, computes a motion vector, and forms an intermediate coded representation which includes the compressed data and the motion vector. A frame detector (26), which detects frames having a prediction error which exceeds a predetermined threshold, is coupled to the motion compensated predictive coder (24). A digital storage device (22) is coupled to the motion compensated predictive coder (24) and the frame detector (26). The digital storage device (22) stores the intermediate coded representation and stores a representation of the frames having the prediction error which exceeds the predetermined threshold. A lossless decoder (29), coupled to the digital storage device (22), substantially losslessly decodes the intermediate coded representation to form a decoded representation.

Abstract: Operating on the principle of vector summation, a predistortion linearizer includes a signal divider on one side of a substrate plate that divides a microwave signal into a linear portion and a nonlinear portion. Signal energy on both the nonlinear and linear portions is coupled into two respective slotline transmission lines on the substrate by uniplanar Magic T hybrids. As the signals are transmitted along the slotlines, their relative amplitudes and phases are adjusted to introduce a distortion inverse to that expected in a subsequent amplification. The linear portion and nonlinear portion pass through another pair of baluns. The signals are then combined by an in-phase summation on the same side of the plate as the input signal divider.

Abstract: Methods and systems for encoding an audio signal into a bit stream, and for recreating the audio signal from the bit stream are disclosed. In an embodiment of an encoder, a first encoder (10) symbolically encodes a substantially vocal audio signal to form a first encoded signal. A second encoder (12) symbolically encodes a substantially nonvocal audio signal to form a second encoded signal. A multiplexer (14) multiplexes the first encoded signal and the second encoded signal to form the bit stream. In an embodiment of a decoder, a demultiplexer (80) extracts an encoded vocal signal and an encoded nonvocal signal from the bit stream. A first decoder (82) forms a decoded vocal signal based upon the encoded vocal signal. A second decoder (84) forms a decoded nonvocal signal based upon the encoded nonvocal signal. A mixer (86) combines the decoded vocal signal with the decoded nonvocal signal to form the audio signal.

Abstract: A method and system of displaying an image sequence containing a plurality of image frames to inhibit an unauthorized duplication thereof by a camera. The method includes steps of generating a pseudo-random noise sequence, and displaying the image sequence at a frame rate which is varied for successive pairs of the image frames in dependence upon the pseudo-random noise sequence. The frame rate is varied within a predetermined range about a nominal frame rate for the image sequence such that the variations are imperceptible by a human observer. The system includes a pseudo-random sequence generator (30) which generates the pseudo-random noise sequence, and a display device (36) to display the image sequence at a frame rate which is varied in dependence upon the pseudo-random noise sequence.

Abstract: A frequency synthesizer having two atomic frequency standard inputs that is adapted to provide seamless switching or transition between the atomic frequency standard inputs with no change in the synthesizer output phase and frequency. The synthesizer includes a multichannel phase comparison system, each channel adapted for handling an atomic frequency standard input, a digital phase lock loop, a digital to analog converter, and a voltage controlled crystal oscillator which provides the synthesizer output. The phase comparison system is adapted to continually monitor the integrity of the atomic frequency standard inputs and to continually estimate the phase differences between the two atomic frequency standard inputs. The phase difference is used to estimate the proper phase and frequency offset between the primary and secondary inputs.

Abstract: A plurality of biphase modulators (42) each modulate a sinusoidal radio frequency signal based upon a corresponding one of a plurality of bits contained in a time-dependent data word. The biphase modulators (42) form a plurality of biphase modulated signals which are communicated to a summing network (40). The summing network (40) contains a plurality of attenuators (44) which attenuate the modulated signals to form a plurality of attenuated signals. The summing network (40) combines the attenuated signals to form a radio frequency signal.