Abstract: A technique for reducing signal degradation and fading within a long optical transmission by utilizing a rotating waveplate arrangement to rotate the SOP of an optical signal launched into the transmission system, and thereby minimize polarization dependent hole-burning ("PDHB"). This effectively reduces the degree of polarization of the launched optical signal, without degrading the noise and dispersion characteristics of the signal. The rate of waveplate rotation is chosen to ensure that the SOP of the launched signal does not remain at a particular SOP long enough to anisotropically saturate any optical amplifier employed within the transmission system, and give rise to PDHB.

Abstract: A technique for reducing signal degradation and fading within a long optical transmission system by minimizing polarization dependent hole-burning ("PDHB") through the cyclic stressing of a birefringent optical fiber to modulate the SOP of an optical signal launched into the transmission system. This effectively reduces the degree of polarization of the launched optical signal, without degrading the noise and dispersion characteristics of the signal. The modulation frequency of the SOP is chosen to ensure that the launched signal does not remain at a particular SOP long enough to anisotropically saturate any optical amplifier employed within the transmission system, and give rise to PDHB.

Abstract: A performance monitoring technique which allows faults within an optical communication system to be detected and located. More specifically, a technique employing a signal generator to controllably insert maintenance signals at the input and output of each module within an optical communication system, and a single monitor to receive the inserted maintenance signals at a fixed point within the system, and, in response, determine the location of faulty modules. The monitor analyzes the received inserted maintenance signals, and locates faults by pinpointing modules from which a maintenance signal inserted at the module output is received uncorrupted by the monitor, but which return a corrupted maintenance signal when the insertion is made at the module input. A particular embodiment of the invention enables the maintenance signals to be inserted via pre-existing control drivers within system modules.

Abstract: A method is disclosed for transmitting information from a non-ISDN compatible communication device to an ISDN compatible receiving device via the D Channel of an Integrated Systems Digital Network. To facilitate this transmission, the information is reformatted, embedded in an ISDN signaling protocol message, and transmitted to an ISDN compatible recipient as Message Associated User-To-User Information.

Abstract: A method and apparatus are disclosed for the efficient generation of cyclic redundancy check (CRC) codes employing CRC generator polynomials of the form (1+x).multidot.f(x). The efficiency is achieved by independently and concurrently generating in parallel a preliminary CRC code word corresponding to f(x) and a term corresponding to (1+x) over a message M(x). The term corresponding to (1+x) is generated in a manner to have either a zero (0) state or a one (1) state. Then, the term corresponding to (1+x) is used to modify the preliminary CRC code word to obtain an overall CRC code word being generated over message M(x). If the term corresponding to (1+x) is a 0 state, then the overall CRC code word is obtained by shifting the bits of the preliminary CRC code word once to the left. If the term corresponding to (1+x) is a 1 state, then the overall CRC code word is obtained by shifting the bits of the preliminary CRC code word once to the left and adding f(x) to the shifted preliminary CRC code word.

Abstract: An improved technique for decoding wherein the number of coefficients to be included in each sub-block is selectable, and a code indicating the number of coefficients within each layer is inserted in the bitstream at the beginning of each encoded video sequence. This technique allows the original runs of zero coefficients in the highest resolution layer to remain intact by forming a sub-block for each scale from a selected number of coefficients along a continuous scan. These sub-blocks may be decoded in a standard fashion, with an inverse discrete cosine transform applied to square sub-blocks obtained by the appropriate zero padding of and/or discarding of excess coefficients from each of the scales. This technique further improves decoding efficiency by allowing an implicit end of block signal to separate blocks, making it unnecessary to decode an explicit end of block signal in most cases.

Abstract: A method of providing local autonomous control of channel allocation of a cellular telecommunications network. In one prior art method, which can be identified as the timid method, a channel is selected for use by an incoming user if it is not being used by any of the cells which surround it. Otherwise, another channel is selected according to the same rule. The channels are tested in random order and a call is blocked if all of the channels are in use. For heavy loading, because of the vagaries of the way the demand for channels occurs, this method can result in inefficient channel deployment. In another method, which can be identified as the aggressive method, a channel is selected for use by an incoming user even if that channel is currently being used in the surrounding cells. If the channel is in use, the incoming user "bumps" the current user off the channel in the timid mode. The "bumped" user is then forced to find and use another channel.

Abstract: A technique for interconnecting photonic circuits employing a fixed field of optical couplers situated between adjacent layers of photonic circuits. The coupler field facilitates the direct connection of optical fibers linked to components in one of the adjacent layers of photonic circuits with optical fibers linked to components in another adjacent layer. Each optical coupler within the field is a standard, commercially available optical fiber coupler which mates the optical fibers via a single low-loss connection. In addition, as each of these connectors allows easy connection/disconnection of optical fibers, reconfiguring previous interlayer connections is simplified. In a particular embodiment, the coupler field includes a plurality of individual couplers arranged in a regular geometric pattern upon a panel oriented at a 45.degree. angle with respect to the circuit packs of the adjacent layers. This provides easy access to the couplers, and allows for uncomplicated indexing of each connection.

Abstract: An adaptive technique for encoding and decoding which facilitates the transmission, reception, storage, or retrieval of a scalable video signal. The invention allows this scaling to be performed entirely in the spatial domain. In a specific embodiment of the invention this scaling is realized by adaptively encoding a video signal based upon a selection taken from among a multiplicity of predictions from previously decoded images, and a selection of compatible predictions obtained from up-sampling lower resolution decoded images of the current temporal reference. A technical advantage of the invention is that both the syntax and signal multiplexing structure of at least one encoded lower-resolution scale of video is compatible with the MPEG-1 standards.

Abstract: An improved technique for efficient frequency scaling wherein the number of coefficients to be included in each sub-block is selectable, and a code indicating the number of coefficients within each layer is inserted in the bitstream at the beginning of each encoded video sequence. This technique allows the original runs of zero coefficients in the highest resolution layer to remain intact by forming a sub-block for each scale from a selected number of coefficients along a continuous scan. These sub-blocks may be decoded in a standard fashion, with an inverse discrete cosine transform applied to square sub-blocks obtained by the appropriate zero padding of and/or discarding of excess coefficients from each of the scales. This technique further improves coding efficiency by allowing an implicit end of block signal to separate blocks, making it unnecessary to transmit an explicit end of block signal in most cases.

Abstract: An adaptive technique for video encoding and decoding which facilitates the transmission, reception, storage, or retrieval of a scalable video signal. The technique allows this scaling to be performed in both the spatial and frequency domains. In a specific embodiment, video encoding is adaptively performed based upon a selection from among a multiplicity of compatible spatial-domain predictions from previously decoded images, and a selection of compatible predictions obtained from up-sampling decoded lower resolution images. The decoded lower resolution images correspond to a current temporal reference, and at least one of these lower resolution images is encoded in more than one frequency domain scales. In yet another embodiment, one lower resolution signal is encoded (without reference to any other low resolution signal) by employing the MPEG-1 standard, with a modified partitioning of the resultant bitstream into two or more frequency scale bitstreams.

Abstract: A receiver system for measuring the bearing of a target having ambiguity correction. The receiver system includes a four element antenna array, three receivers and two phase detectors. The system further includes switching means for selectively connecting the antenna elements to the receivers and the receivers to the phase detectors to obtain two pairs of bearing components, from which the target bearing is computed.

Abstract: A sine wave synthesis controller circuit intended to be utilized in conjunction with a digitally-controlled neutral-point clamped inverter to produce a sinusoidal waveform from a direct current source. The controller circuit is configured so that it provides separate positive and negative control signals to the neutral-point clamped inverter's logic controller. These signals direct the modulation a sinusoidal waveform in response to a reference sine wave, the instantaneous voltage output by the neutral-point clamped inverter, as well as positive and negative reference voltages input to the controller.