Abstract: A digital subscriber line (DSL) communication system that utilizes the high frequency band of a standard telephone line does not require the use of a plain old telephone service (POTS) splitter in the resident's home, which provided isolation between the POTS frequency band (0 to 4 kHz) and the DSL frequency band. A digital subscriber line modem utilizes either constant envelope modulation or quadrature amplitude modulation for outputting DSL signals upstream to a central office. When a telephone in the resident's home is detected as being off-hook, then the constant envelope modulation is used by the DSL modem in order to lessen the intermodulation product distortion that results in audible noise heard by a user of the telephone. When the telephone is on-hook, then another type of modulation, such as QAM, is used to maximize the upstream data rate capability in the DSL frequency band, since any noise generated by the QAM is not a problem due to the non-use of the POTS frequency band.

Abstract: A digital subscriber line communication system does not require the use of a plain old telephone service (POTS) splitter in the resident's home. Digital signal processing techniques are utilized to adapt to varying subscriber line conditions due to POTS telephone equipment. The digital signal processing techniques eliminate the need for a splitter by reducing susceptibility to distortion due to varying subscriber line characteristics. The digital subscriber line modem utilizes quadrature amplitude modulated (QAM) signals and frequency division multiplexing. The digital subscriber line modem includes a control circuit which includes a rapid retrain circuit. The rapid retrain circuit can retrain the digital subscriber line modem in less than 0.5 seconds.

Abstract: An adaptive gain algorithm allows the maximization of gain of an audio signal that is transmitted with a digital data signal by allowing a trellis decoder to compensate for occasional excursions of the audio and noise signal across a signal space boundary. By measuring the short term energy present in an audio signal, the algorithm of the present invention allows the maximum power to be used to transmit an analog signal without overloading the trellis decoder.

Abstract: In a simultaneous voice and data communications system, a voice signal is added to a data signal before transmission over the public switched telephone network (PSTN). In particular, in every signaling interval, a signal point is selected for transmission as a function of both the voice signal and the data signal. Since the voice signal is effectively offset by the data signal, compandors normally found in the PSTN are not effective in improving the signal to noise ratio of the transmitted voice and data signal. Therefore, the voice signal is additionally companded in the transmitter before transmission over the PSTN. This additional companding by the transmitter improves the signal to noise ratio of the combined voice and data signal.

Abstract: A simultaneous voice and data (SVD) communications system includes an SVD modem at either endpoint of the system. Each SVD modem provides an SVD signal to the opposite endpoint, where this SVD signal includes both a voice channel and a data channel. One, or both, of these SVD modems allows the respective user to alter either the voice signal that is provided to that user, or the voice signal that is transmitted from that user, via the voice channel of the SVD signal, to the opposite SVD endpoint.

Abstract: A method and apparatus for control of concurrent communication of analog information and digital information. In general terms, when the communication channel is viewed as a multi-dimensional space, the digital information signal is divided into symbols, and the symbols are mapped onto the signal space with a preset distance between them. The analog signal, generally limited in magnitude to less than half the distance separating the symbols, is converted to component signals and added (i.e., vector addition) to the symbols. The sum signal is then transmitted to the receiver where the symbols are detected and subtracted from the received signal to yield the analog signal components. The transmitted analog signal is recreated from those components. Both half-duplex and full-duplex operation is available in accordance with this invention. The illustrative embodiment includes a controller that is sensitive to input signals applied to the modem disclosed herein.

Abstract: A number of arrangements and methods that achieve concurrent communication of analog information and digital information. In general terms, when the communication channel is viewed as a multi-dimensional space, the digital information signal is divided into symbols, and the symbols are mapped onto the signal space with a preset distance between them. The analog signal, generally limited in magnitude to less than half the distance separating the symbols, is converted to component signals and added (i.e., vector addition) to the symbols. The sum signal is then transmitted to the receiver where the symbols are detected and subtracted from the received signal to yield the analog signal components. The transmitted analog signal is recreated from those components.

Abstract: In a simultaneous voice and data communication system, a stream of signal points is partitioned into a plurality of symbol blocks, each symbol block including a data segment and a control segment. The data segment carries information from a user, i.e., user data, while the control segment provides control information. A voice signal is then added to at least a portion, or all, of the signal points of each symbol block to provide for simultaneous voice and data transmission to an opposite endpoint. The control information may represent information from a secondary data source, and/or may include information about the characteristics of the succeeding block, e.g., the user data rate, and information pertaining to characteristics of the communications channel.

Abstract: In a simultaneous voice and data communications system, a voice signal is mapped into an N-dimensional signal space constellation as a vector, and added to a reference signal point, i.e., a data symbol, where the data symbol is selected from a constellation of data symbols every signaling interval as a function of a data signal. The constellation signal space is further divided into a number of shaped regions, where each region is associated with a different one of the data symbols. The shape of each region is selected as a function of the characteristics of the voice, or audio, signal. In particular, each region illustratively has a rectangular shape.

Abstract: A method and apparatus for concurrent communication of analog information and digital information. In general terms, when the communication channel is viewed as a multi-dimensional space, the digital information signal is divided into symbols, and the symbols are mapped onto the signal space with a preset distance between them. The analog signal, generally limited in magnitude to less than the distance separating the symbols, is converted to component signals and added (i.e., vector addition) to the symbols. The sum signal is then transmitted to the receiver where the symbols are detected and subtracted from the received signal to yield the analog signal components. The transmitted analog signal is recreated from those components. Both half-duplex and full-duplex operation is available in accordance with the disclosure.

Abstract: An analog signal is added to a data signal that specifies a symbol in a symbol constellation to produce a combined signal that is transmitted to a receiver. The symbol constellation is picked from a plurality of symbol constellations having differing symbol densities based on the amplitude of the analog signal.