Abstract: A noncooperative feedback system is provided for a compensation system associated with, for example, a transmitter or codec, for enabling the compensation system to improve the accuracy of digital signals transmitted to a digital network. The noncooperative feedback system is particularly suited for providing feedback to a compensation system for correcting distortion resulting from rob bit signaling (RBS), digital loss, or other types of digital signal degradation. The noncooperative feedback system includes a compensation selector in a transmitter (e.g., digital modem, analog modem, codec, etc.) that combines different compensations with frames of digital data by way of an addition mechanism to produce modified digital data frames. The transmitter is configured to transmit the modified digital data frames into the digital network. A receiver (e.g., digital modem, analog modem, etc.

Abstract: A rob bit compensation system improves the accuracy of digital signals received from and transmitted to a digital network, such as a telephone network, that employs rob bit signaling (RBS) wherein the network periodically robs a bit for its own use. The system can be employed within a digital modem or a coder/decoder (codec), each of which is interconnected with the digital network that periodically robs a bit every nth frame, where n is, for example, 6 or 24. The system can be implemented in association with the receive subsystem of the digital modem or in the communications paths within the codec associated with receiving data from the digital network. The system includes a compensation control utilized to detect when a least significant bit (LSB) of a particular frame of data consistently exhibits a certain logic state, either a mark (logical 1) or a space (logical 0). When an LSB of a particular frame does consistently exhibit the certain logic state, then the particular frame is considered an RBS frame.

Abstract: A cooperative feedback system is provided for a compensation system associated with, for example, a transmitter or codec, for enabling the compensation system to improve the accuracy of digital signals transmitted to a digital network. The cooperative feedback system is particularly suited for providing feedback to a compensation system for correcting distortion resulting from rob bit signaling (RBS), digital loss, or other types of digital signal degradation. The cooperative feedback system includes a compensation selector in a transmitter (e.g., digital modem, analog modem, codec, etc.) that combines compensations with frames of digital data by way of an addition mechanism to produce modified digital data frames. The transmitter is configured to transmit the modified digital data frames into the digital network. A receiver (e.g., digital modem, analog modem, etc.

Abstract: In a packet network, message packets (130) are comprised of vacant or unused bits for future system enhancements or for remedying unknown design oversights or utilizing vacant portions of fixed length data packets. Furthermore, message packets (130) comprise a message type identifier distinguishing message architecture. A transmit and receive packet network node (100) maintains an unused bit catalog (125) listing vacant or unused bits of particular message packet types. When a message packet type having vacant or unused bits is detected propagating through the packet network, background data is retrieved from a transmit background data queue (115) and interleaved into such message packets to form enriched message packets (130') for transportation through the packet network. Receiving packet network nodes (100) detect enriched message packets (130') and extract and buffer the background data.

Abstract: A method and system to ensure the confidentiality of a local area network when a first terminal of the local area network sends out a first and second plurality of voice messages which, respectively, may and may not be received by a second terminal, consists of providing a signature distributed over the first plurality of voice messages with a portion of the signature substituted for the least significant bit of the first plurality of voice messages. Filtering is provided in the second terminal which extracts the signature from the first plurality of voice messages arriving at the second terminal and which recognizes the signature. The filtering disconnects the second terminal from the network, for a given period of time, if the predetermined message has not been recognized. The method and system to ensure the confidentiality of a local area network is suited for integrated services digital networks (ISDN) applications.

Abstract: A rob bit compensation system improves the accuracy of digital signals transmitted to a digital network, such as a telephone network, that employs rob bit signaling (RBS) wherein the network periodically robs a bit for its own use. The rob bit compensation system can be employed within the transmit subsystem of a digital modem connected with the digital network that periodically robs a bit every nth frame, where n is, for example, 6, 12, or 24. The system may also be employed in association with the communications path within a coder/decoder (codec) that transmits data to the digital network. A feedback system advises the rob bit compensation system as to which frames of outgoing digital data are to have a bit robbed therefrom by the digital network. The feedback system causes a quantity to be mathematically combined with the digital data corresponding with each RBS frame in order to enhance accuracy of the RBS frames.

Abstract: A communication device (e.g., 106) having multiple transmission modes employs a method of transmitting user information (309, 310) and intermittent overhead data (307, 308). The communication device (106) selects from a first transmission technique and a second transmission technique. When the first transmission technique is selected and overhead data (307) is to be transmitted, the communication device (106) replaces a first predetermined amount of the user information (309) with the overhead data (307) to form a data unit. When the second transmission technique is selected and overhead data (308) is to be transmitted, the communication device (106) replaces a second predetermined amount of the user information (310) with the overhead data (308) to form the data unit, wherein the second predetermined amount is less than the first predetermined amount.

Abstract: A communication system includes a master station connected to a telephone line network and a plurality of remote stations for transmitting and receiving digital data to and from the master station through a radio transmission line. Among the master station and the remote stations, one channel is divided into a plurality of slots. One of the plurality of slots is assigned as a control slot to transmit and receive data in a time-division manner. The master station transmits control data to the remote stations by the control slot. The master station transmits control data by the control slot at every predetermined period and also transmits data concerning a communication by the control slot during a predetermined period.

Abstract: A high-speed signal input to and output from a high-speed optical interface part connected to an optical fiber transmission line is switched to different lines such that the switching is conducted by cross connect parts on an arbitrary basis. The high-speed signal is separated so as to obtain the low-speed signal. The low-speed signal output from the cross connect parts is separated so as to obtain the subscriber signal by signal terminal parts. Call connections are conducted for each subscriber by a time slot interchange part, whereupon a subscriber interface part performs analog-to-digital and digital-to-analog conversion so as to serve as an interface for a subscriber.