Abstract: An optical receiver includes a first interferometer having a plurality of arms. The optical receiver further includes first tunable optical filters connected in series with the arms of the first interferometer, where each first tunable optical filter is tuned to filter a region of overlap in the optical frequency spectrum between adjacent optical channels.

Abstract: An optical receiver includes a first interferometer having a plurality of arms. The optical receiver further includes first tunable optical filters connected in series with the arms of the first interferometer, where each first tunable optical filter is tuned to filter a region of overlap in the optical frequency spectrum between adjacent optical channels.

Abstract: An optical receiver includes a first interferometer having a plurality of arms. The optical receiver further includes first tunable optical filters connected in series with the arms of the first interferometer, where each first tunable optical filter is tuned to filter a region of overlap in the optical frequency spectrum between adjacent optical channels.

Abstract: An optical receiver includes a first interferometer having a plurality of arms. The optical receiver further includes first tunable optical filters connected in series with the arms of the first interferometer, where each first tunable optical filter is tuned to filter a region of overlap in the optical frequency spectrum between adjacent optical channels.

Abstract: A system is provided including a first waveguide having an optical input and a first optical output. A second waveguide includes a second optical output. A coupling region is between the first waveguide and the second waveguide. The coupling region controllably couples the first waveguide and the second waveguide when a field is applied to the coupling region. The strength of the field is variable to control the coupling. Further, the first waveguide, the second waveguide, and the coupling region may be made of electro-optical material. In another example, a component is provided including a substrate and an electro-optical material formed on the substrate. A first and second waveguide are formed of said electro-optical material. An electrode structure is formed proximal to the first waveguide and the second waveguide. The electrode structure selectively provides an electric field in the electro-optical material when a voltage is applied to the electrode structure.

Abstract: A system is provided including a first waveguide having an optical input and a first optical output. A second waveguide includes a second optical output. A coupling region is between the first waveguide and the second waveguide. The coupling region controllably couples the first waveguide and the second waveguide when a field is applied to the coupling region. The strength of the field is variable to control the coupling. Further, the first waveguide, the second waveguide, and the coupling region may be made of electro-optical material. In another example, a component is provided including a substrate and an electro-optical material formed on the substrate. A first and second waveguide are formed of said electro-optical material. An electrode structure is formed proximal to the first waveguide and the second waveguide. The electrode structure selectively provides an electric field in the electro-optical material when a voltage is applied to the electrode structure.

Abstract: The present invention relates to an improved method of de-jittering MPEG-2 and MPEG-4 data that is transmitted over a network. First, a network system jitter associated with periodic reference data packets is estimated. Then, the estimated system jitter is used to adjust clock-stamped reference values in the data packets before they are provided to the PLL for clock synchronization. The invented de-jittering method improves the PLL's ability to synchronize the MPEG data and provides for a better quality playback.

Abstract: The present invention relates to a system and method for reliably transmitting data over wireless communication channels. The invented system 10 comprises a transmitting device 12 having an error control coding circuit 20 and an interleaver circuit 22 in communication with each other. The invented system 10 also includes a receiving device 14 having an error control decoding circuit 26 and a de-interleaver circuit 28 in communication with each other. The transmitting device 12 and the receiving device 14 communicate over a wireless communication channel 16. The error control coding circuit 20 applies an error control code to the data before it is transmitted over the communication channel 16. The data is also interleaved prior to being transmitted. After transmission over the communication channel 16, the data is de-interleaved and any transmission errors are detected and corrected.

Abstract: The invention is a system for digital watermarking that operates on a conventional digital video stream to etch, on hand, and read, on the other hand, digital watermarks in the stream that do not visibly interfere with the video content. A system according to the invention operates on digital data that has been transformed into the spatial-frequency domain, using inter-block differences between spatial-frequency coefficients to encode the bits of a digital watermark. Using the principles of the invention, it is possible to encode multiple watermark bits between two adjacent blocks, thus providing higher watermark data rates relative to underlying video content.

Abstract: A method of generating a authentication code (“MAC”) with improved error tolerance exhibits improved survivability against acceptable signal distortions such as recompression. A method of generating a message authentication code associated with an image includes receiving blocks of image coefficient data where each coefficient has an original value falling within a range of values. The range of values is divided into first and second regions both having allowed coefficient values, and an error tolerance buffer region formed between the first and second regions having disallowed coefficient values. The original values of DC coefficients from each block of the image coefficient data is mapped to a modified value contained in one of the first and second regions, but not contained in the error tolerance buffer region. A MAC is generated as a function of the most significant bits of the modified image coefficient values.

Abstract: According to the principles of the invention, there is provided a system for generating a message authentication code for a conventional digital video stream. The system operates on the rows and columns of block data for a video stream, and more specifically on histograms of DC coefficients from each row and column, to produce a compact code that is nonetheless descriptive of the underlying images in the video stream. The message authentication code can be reproduced from the images of a received video stream, and if desired, compared with a digital watermark embedded in the video stream in order to confirm the accuracy of the video content or identify the source of the video stream.

Abstract: The present invention relates to a system and method for reliably transmitting Internet Protocol (IP) data packets over fading Internet communication channels. The invented system 10 comprises a transmitting device 12 having an interleaver circuit 22. The invented system 10 also includes a receiving device 14 having a de-interleaver circuit 38. The transmitting device 12 and the receiving device 14 communicate over a fading Internet communication channel 16. The transmitting device 12 applies error control coding to the IP packets before they are transmitted over the fading Internet communication channel 16. The Interleaver circuit 22 interleaves the IP data packets before transmitting them over the fading Internet channel 16. The receiving device 14 receives the interleaved IP packets from the fading Internet channel 16. The de-interleaver circuit 38 de-interleaves the received IP data packets.

Abstract: A system (100) for watermarking digital data includes a watermark etching subsystem (105) and a watermark extraction subsystem (110). The watermark etching subsystem (105) obtains a matrix of digital data values, selects windows including a plurality of data values from the matrix, specifies a parameter that indicates an acceptable amount of variation in the data values, and etches watermark bits in each window of data values using the specified parameter. The watermark extraction subsystem (110) obtains a matrix of digital data values containing an etched watermark, selects windows comprising a plurality of data values from the matrix, and extracts watermark bits from each window of data values using the specified parameter.

Abstract: A system and method are provided for analyzing and transmitting video over a switched network. According to an aspect of the invention, two phases are generally provided: an analysis phase performed before transmission of the video; and a transmission phase performed after analyzing the video stream. During the pre-transmission video analysis phase, the video stream is analyzed in order to determine the needed traffic control parameters, such as the peak cell rate, the sustained cell rate, and the maximum burst size. The goal of the analysis phase is to select a transmission traffic contract for the encoded video stream that will minimize the utilization of network resources and permit the quality of the video to be maintained. After the analysis phase, the transmission phase is performed to transmit the video over the network in accordance with the selected traffic control parameters.

Abstract: A method and system for transmitting a video stream in an asynchronous transfer mode (ATM) network comprises steps of encoding the video into an MPEG-2 variable bit rate video stream, shaping the encoded variable bit rate video stream to conform to the traffic contract parameters for a Variable Bit Rate (VBR) connection in the network, and transmitting the shaped variable bit rate video stream on the VBR connection based on the traffic contract parameters. For a given network bandwidth, switch buffer space, and equivalent video quality, the network can statistically multiplex a larger number of variable bit rate video streams by maximizing the utilization of the network bandwidth and switch buffer space that the network allocates to each video stream.

Abstract: A fault locating system for optical telecommunications includes a central office and means associated therewith for generating a tone signal. Analog to digital conversion means convert the tone signal to a digital signal. Cable driving means, receiving the digital signal, provide a driving output to an optical cable. The optical cable output is coupled to an input of a repeater which reforms the received digital signal before retransmission thereof. The repeater is coupled to an input of a filter which passes signals at a frequency f.sub.1. The output of the first repeater is coupled to an input of a second optical cable. The output of the second optical cable is coupled to an input of a second repeater which reforms the received digital signal before retransmission thereof. The second repeater is coupled to an input of a second filter which passes signals at a frequency f.sub.2. The output of the (n-1)st repeater is coupled to the input of an nth optical cable.