Abstract: A method and apparatus for controlling bit slips in a high-speed, two-way, communications channel. More particularly, the entire communications system, comprising, inter alia, a receiver, a transmitter and the physical communications channel is operated as a feedback loop. That is, the detection of bit slips is performed continuously in the receiver and a bit slip signal is generated that indicates the number of bit slips and the direction, i.e., forward or backward, of the bit slip. Thus, the bit slip signal is communicated to the transmitter and certain actions are performed to introduce bit adjustments in the bit stream to eliminate the effects of any future bit slips. The bit slip signal contains an indication of the number of bit slips which have occurred, the time between bit slips, and the direction of the slip. As a function of this information from the bit slip signal, bit adjustments are made in the communications stream to correct for the bit slips and mitigate any effect in future transmission.

Abstract: A method and apparatus for achieving maximum bandwidth reduction in communication networks. The invention provides a multisource coding scheme, implemented through an intersource coding block that provides maximum bandwidth reduction for transmissions from a plurality of time-correlated information sources over a single physical link. In one embodiment of the invention the intersource encoder uses run-length coding to compress the aggregate bit rate before the physical transmission. The intersource encoder provides data compression for both completely correlated and partially correlated sources. For completely correlated sources, the intersource encoder strips off the intersource redundancies and transmits only a single copy of the information over the physical link, wherein the single copy is a superpicture. For partially correlated sources, the intersource encoder compresses the aggregate signal through a predetermined coding scheme, including vector run-length coding.

Abstract: A method and apparatus for reducing bandwidth in an ATM network. The invention provides an ATM switch having a compression module for compressing ATM cell headers without affecting the virtual circuit established for the call. The compressed headers provide the ATM switch buffers with extra space to handle more cells for a given call. To realize the benefit of the extra space during transmission, the present invention provides a mapping interface between the PHY and ATM layers of the ATM communication. The mapping interface separates the compressed headers from the uncompressed headers into two different PHY payloads. The cells transmitted in the compressed payload are then expanded in an expansion module located in the call destination switch. The expansion module returns the compressed headers back to their original form.

Abstract: A digital communication system for transmitting and receiving a hybrid optical and RF communication signal. The system includes a hybrid transmitter that incorporates an optical transmitter, an RF transmitter, and a transmitter control unit that controls both transmitters. Similarly, a hybrid receiver includes an optical receiver and an RF receiver, both connected to a receiver control unit. When an optical carrier signal is transmitted to the optical receiver by the optical transmitter, the transmitter control unit causes the RF transmitter to transmit an RF synchronization signal along with the carrier to provide a timing base for the digital pulses carried by the optical signal. The receiver control unit uses the timing parameters from the RF signal to reconstruct the received optical carrier signal that may have deteriorated during the transmission due to ambient optical noise, attenuation or obstructing objects.

Abstract: A method and apparatus for implementation of a code division multiple access encoding scheme in a fiber-optic network. One preferred embodiment of the present invention provides an encoder and decoder for each terminal in the communications network, for example SONET OC-3, and allows each terminal to transmit their signals into the fiber-optic network at random. Because no time slot management is used, signals from all terminals interfere with one another. A coding technique is used by each decoder to sort its own signal out of this interference. The encoded data from each terminal is modulated with a technique known as MFSK (multiple frequency shift keying). The modulated signal is further used to intensity-modulate a semiconductor laser diode which may or may not be a single wavelength laser. At the receiver, the combined interference signal is first detected by a optical intensity detector and then sent to a frequency tone detectors which demodulate the MFSK signal.

Abstract: An optical communications system for transmission of optical signals using relaxation oscillation subcarrier, on-off keying modulation of the optical signals. Relaxation oscillation subcarrier on-off keying improves the signal-to-noise ratio of a receiver receiving the modulated optical signals and the data rate of the optical signal. A modulation device generates relaxation oscillations by pulsing a driving current for a transmitter between a first level below a threshold current and a second level above the threshold current. The optical communication system can further include a fiber optic link between the transmitter and the receiver. The optical communications system can further incorporate multiple frequency shift keying. The modulation device and modulation scheme can be used in all digital optical communications systems using a pulsed laser diode.

Abstract: Only one or only a few channels are sent at a time from curbside circuitry located in a curbside box, via a link such as either a coaxial or a fiber cable, into a customer's home TV set or personal computer. However, many more than a few channels are delivered to the curbside box from a central office or a central bank of paid video-movies to be selected by the customers. The curbside box serves a multitude of homes, a separate (narrow-band) cable running to each home from the (same) curbside switch. Each channel can be a free radio or free TV channel, a stored or an on-line newspaper pay channel, or a pay TV channel, or a pay-per-view channel. Requests from each TV set in each home (e.g., initiated by a hand-held remote control infra-red sending device) can be sent to the curbside circuitry from the home along a link such as a wire or along the same curbside-to-home cable itself. Storage of billing information with respect to each customer is accomplished by a billing recorder located in the curbside box.

Abstract: Only one or only a few channels are sent at a time from circuitry located in a curbside box, via a link such as either a coaxial or a fiber cable, into a customer's home TV set or personal computer. However, many more than a few channels are delivered to the curbside box, via a link such as a fiber or a coaxial cable, from a central office or a central bank of paid video-movies to be selected by the customers. Thus whereas the link from the central office or central bank is relatively broad-band (e.g. 500 MHz to 1,000 MHz), the cable from the curbside to the home (or any other kind of building) can be relatively narrow-band (e.g., 5 MHz to 50 MHz). The curbside box serves a multitude of homes--a separate (narrow-band) cable running to each home from the (same) curbside switch. Each channel can be a free radio or free TV channel, a stored or an on-line newspaper pay channel, or a pay TV channel, or a pay-per-view channel (i.e.