Abstract: A broadband fiber optic communication system conveys telecommunication messages over a fiber optic link between a master site and one or more remote sites. The remote sites are coupled over an unshielded twisted pair-configured, communication link to an optical network unit, which is ported to the fiber optic link. In order to convey broadband information signals that have been downlinked, from the master site to the optical network unit, to the remote sites, and to provide for return messages from the remote sites, a point-to-multi-point communication scheme is provided. Pursuant to this scheme, an upstream transceiver in the optical interface unit transmits STS-1 frames, which contain broadband information signals, such as asynchronous transfer mode (ATM) data cells, intended for one or more remote sites, and a return time slot-representative control code associated with each destination remote site, over the communication link to the remote sites.

Abstract: A two-stage cell routing filter mechanism employs a customer premises associated flag bit field in ATM data cells being serially transmitted from a host digital terminal's data transport path through an optical fiber to a downstream optical network unit associated with a plurality of customer premises equipments. The first stage of the cell routing filter is comprised of a look-up table (LUT) and an associated comparator mechanism. The state of each bit of the flag field of an ATM cell preamble will indicate whether or not the ATM cell is intended for the customer premises equipment associated with the bit. A downstream optical network unit contains an associated set of ATM cell filters associated with customer premises equipment. Each customer equipment cell filter examines a given bit position in the flag field portion of each received ATM cell preamble, to see whether the flag field bit of the preamble of the received ATM cell is set to prescribed bit value (e.g.

Abstract: A fiber optic telecommunication system has master site linked to a plurality of subscriber interface sites by a single pair of optical fibers. Downlink messages are transmitted in a continuous TDM format over a first optical fiber from the master site to subscriber interface sites, and in a burst mode TDMA format over a second optical fiber from the subscriber interface sites to the master site. Each subscriber interface site is coupled to the optical fiber link by way of a multiple fan-out fiber coupling pedestal at a common location on the fiber pair. To prevent collisions between successive uplink bursts from the subscriber interface sites, a guard band separates successive uplink messages from one another. The guard band duration accommodates optical fiber transmission distance between the common location on the uplink optical fiber and the subscriber interface site whose differential optical fiber transmission distance from the common location is greatest.

Abstract: A fiber optic telecommunication system has master site linked to a plurality of subscriber interface sites by a single pair of optical fibers. Downlink messages are transmitted in a continuous TDM format over a first optical fiber from the master site to subscriber interface sites, and in a burst mode TDMA format over a second optical fiber from the subscriber interface sites to the master site. Each subscriber interface site is coupled to the optical fiber link by way of a multiple fan-out fiber coupling pedestal at a common location on the fiber pair. To prevent collisions between successive uplink bursts from the subscriber interface sites, a guard band separates successive uplink messages from one another. The guard band duration accommodates optical fiber transmission distance between the common location on the uplink optical fiber and the subscriber interface site whose differential optical fiber transmission distance from the common location is greatest.

Abstract: A composite color television signal codec combines modified folded, hybrid differential pulse code modulation (H-DPCM) encoding and band-limiting decimation and interpolation filters to enhance encoding resolution without a reduction in signal quality of the reconstructed signal. The codec encodes, at five bits per sample, an NTSC 4.2 MHz composite color video signal for transmission over a 44.736 Mb/s communication channel. As in a conventional (H-DPCM) encoding scheme, a digital code value that is associated with a previous (quantized) jth sample of the signal and the difference between that digital code value and a digital code value of an ith sample are combined to produce an output code value for the ith sample.

Abstract: Apparatus and method for reducing the cost and complexity of equipment placed on subscribers' premises in a subscription communications system, such as a cable television system, while at the same time providing security against unauthorized system access includes a microprocessor controlled frequency converter in proximity to the subscriber's premises to convert information transmission signals to subscriber-receivable frequencies; a channel selection unit at the subscriber's premises for producing a command signal to initiate the transmission of information to the subscriber; and a verification circuit coupled to receive the command signals, to verify the same and electronically to instruct the microprocessor. The microprocessor may be provided with plural, plug-in converter modules for feeding signals to several subscribers and may be made responsive to subscriber generated auxiliary function signals from alarm detector units, utility meter reading devices, and the like.

Abstract: Apparatus and method for monitoring the quality and integrity of a communications system, such as a cable television system, which includes several monitoring circuits placed throughout the system to detect and amplify RF or audio frequency signals received at any number of selected points. The detected signals are used to amplitude modulate a continuous wave oscillator at a selected one of several discrete frequencies identifiable with the position of the monitoring circuits. The modulated CW signals are then fed upstream for processing at a central location. Each monitoring network includes a broadband detector so as to enable the detection of one or more discrete frequency signals or a band of signals. The use of several discrete frequency signals for normal monitoring purposes allows reliable monitoring to be carried out on a continuous basis without casing interference to the information signals being transmitted through the system.