Abstract: A system for bidirectional communication of digital data between a central unit and a remote unit wherein the need for tracking loops in the central unit has been eliminated. The central unit transmitter generates a master carrier and a master clock signal which are used to transmit downstream data to the remote units. The remote units recover the master carrier and master clock and synchronize local oscillators in each remote unit to these master carrier and master clock signals to generate reference carrier and clock signals for use by the remote unit receiver. These reference carrier and clock signals are also used by the remote unit transmitters to transmit upstream data to the central unit. The central unit receiver detects the phase difference between the reference carrier and clock signals from the remote units periodically and adjusts the phase of the master carrier and master clock signals for use by the central unit receiver to receive the upstream data.

Abstract: The invention provides a cost-effective system and method for testing telephone lines connected to transmission systems, such as Subscriber Line Multiplexer systems. The invention uses the same pair of wires for transmission and test. According to one embodiment of the invention, a system for allowing a test procedure to be performed on a communication system is provided. The communication system has a transmission line for connecting to telephone exchange and a subscriber line for connecting to a communication set. In the system of the invention, a detector is coupled to the transmission line for detecting test signals on the transmission line. A bypass circuit is coupled between the transmission and subscriber lines for allowing the test signals to bypass the communication system. Also, a discriminator is coupled to the subscriber line for discriminating a connection status of the communication set.

Abstract: A method and related apparatus for concurrent transmission and reception of at least one analog voice telephone signal and at least one ISDN service signal between a first location and a second location over a single twisted pair using a digitally encoded signal that is selected from the group consisting of 2B1Q and 4B3T signals. The method further includes the steps of sending line power over the single twisted pair, transferring the digitally encoded signal to the second location over the single twisted pair, and detecting non-operation of the digitally encoded signal between the first location and the second location to thereby impose a bypass lifeline and provide the analog telephone signal at the second location over the single twisted pair. The method also includes the step of providing the ISDN signal and the analog telephone signal at the second location over the single twisted pair when the non-operation is not detected.

Abstract: The present invention provides an effective way for Telecom operators to provide ADSL service to customers who are receiving POTS service over a pair gain system or who are connected to ISDN. According to one embodiment of the invention, an ADSLNDSL (Very High Speed DSL) splitter is integrated in the remote terminal of a pair gain system or in the NT1 (Network Termination 1) of an ISDN BA (Basic Access). Therefore, no extra box on the house and no extra truck roll is required when the customer orders ADSL service. Integrating the splitter makes the telephone line upwards compatible with UADSL since UADSL can be directly connected to an analog telephone line. According to another embodiment of the invention, both the splitter and ADSUUADSL modems are integrated in the remote terminal of a pair gain system or in the NT 1 of an ISDN BA. The splitter in the telephone company location may also be integrated in the central office terminal (COT) of the pair gain system.

Abstract: A bidirectional digital data communication system which generate phase coherent upstream clock and carrier signals from recovered downstream clock generated from a master clock in a central unit. The preferred species uses any downstream clock rate and generates a phase coherent upstream clock so long as the two clock rates can be related by the ratio M/N where M and N are integers. One embodiment uses an MCNS downstream and an SCDMA upstream and uses MNCN timestamp messages in the downstream to achieve an estimate of RU frame offset prior to establishing frame alignment using a ranging process. The use of timestamp messages to estimate the offset is aided by a low jitter method for inserting timestamp messages by avoiding straddling of MPEG packet headers with the sync message. Clock slip is detected by counting upstream clock cycles over a predetermined downstream clock interval and the RU transmitter is shut down if slip is detected to prevent ISI interference from misaligned codes.

Abstract: A method and apparatus for converting an analog voice channel signal and a 4-wire digital signal into a single 2-wire digital signal which can be transferred over a single twisted pair line. In one aspect, the method comprises the steps of converting the analog voice channel signal into a first binary signal, converting the 4-wire digital signal into a second binary signal, combining the first binary signal and the second binary signal into a higher rate binary signal, and converting the higher rate binary signal into a 2-wire digital signal which can be transmitted to another location over a single twisted pair line. In another aspect, the method comprises the steps of converting a 2-wire digital signal to a higher rate binary signal, separating a first binary signal and a second binary signal from the higher rate binary signal and converting the first binary signal into an analog voice channel signal, and converting the second binary signal into a 4-wire digital signal.

Abstract: The present invention provides an efficient way to implement ADSL over long distances by combining a repeater for ADSL with a pair gain system, whereby the pair gain system remotely provides DC power to the repeater over the same pair as that for transmission of DSL and ADSL signals. The invention allows telecom operators to save huge costs in implementing ADSL over long distances, without sacrificing the quality of signal transmission. According to an embodiment of the invention, a telecommunication system comprises a central office system, a customer premise system and a repeater unit. The central office system provides and receives digital subscriber line (DSL) and asymmetrical DSL (ADSL) signals over a first pair of wires. The central office system also provides DC power to the repeater unit via the first pair. The customer premise system receives and sends DSL and ADSL signals over a second pair of wires.

Abstract: A method and apparatus for carrying out synchronous co-division multiple access (SCDMA) communication of multiple channels of digital data over a shared transmission media such as a cable television system coaxial cable, a fiber optic or copper conductor telephone link, terrestial microwave, satellite link, local or wide area network, wireless including cellur network or some combination of these media using suitable interface circuitry. The system includes modems at remote units and a central unit to receive time division multiplexed digital data arranged into timeslots or channels and uses orthogonal codes to encode each channel of multiple data and spread the energy of each channel data over a frame of data transmitted in the code domain. Spreading the data this way makes the system less susceptible to impulse noise.

Abstract: A process for reducing the amount of overhead data in ATM cell headers prior to transmission both upstream and downstream on an HFC cable plant or other transmission media using SCDMA on at least the upstream path, without loss of either IP or Ethernet addressing information. A virtual link between each remote unit and a central unit is established using multiplexing to establish a virtual link to every remote unit. Downstream ATM cells are optimized by stripping off all but 2 bytes to leave a 50 byte cell. Incoming IP packets have their IP addressing information used to look up Ethernet domain address information for the RU and destination process to which this RU is coupled. An Ethernet header is appended to each IP packet as is RFC 1483 bytes to signal the start of the packet. The packet is parsed into 48 byte ATM cell payloads. VPI/VCI information for the virtual link of the remote unit to which the packet is bound is looked up using the Ethernet address information.

Abstract: A method and apparatus for carrying out synchronous co-division multiple access (SCDMA) communication of multiple channels of digital data over a shared transmission media such as a cable television system coaxial cable, a fiber optic or copper conductor telephone link, terrestial microwave, satellite link, local or wide area network, wireless including cellur network or some combination of these media using suitable interface circuitry. The system includes modems at remote units and a central unit to receive time division multiplexed digital data arranged into timeslots or channels and uses orthogonal codes to encode each channel of multiple data and spread the energy of each channel data over a frame of data transmitted in the code domain. Spreading the data this way makes the system less susceptible to impulse noise.