Abstract: An encoding system encodes 8-bit data and control characters into 10-bit symbols. The 10-bit symbols have odd parity such that a single bit error results in an illegal code. Each 8-bit character maps either to a 10-bit symbol with balanced disparity or a pair of 10-bit symbols that collectively have balanced disparity. By periodically inserting an idle character that includes a run of seven consecutive like bits, a 1 MHz pilot tone is embedded in the data stream. The boundary of 10-bit symbols can be identified by locating a run of seven consecutive characters. 10-bit control symbols corresponding to 8-bit control characters are transmitted without reducing the bandwidth available for data transmission by replacing some or all of the preamble or idle portions of an Ethernet packet with the 10-bit control symbols.

Abstract: Methods and systems are described for determining and providing instructions for manual adjustment of a tilt angle of a radio frequency/free space optical transceiver system. Specifically, these instructions are provided for adjusting a tilt angle of a transceiver system using a tilt adjustment so that the transceiver system is approximately at a center of a range of motion of a gimbal assembly. A user interface in communication with a computing system of the local transceiver system provides instructions so that the above-described adjustments are implemented accurately and precisely. This tilt adjustment improves the reliability of the communication network because the gimbal assembly is able adjust the position of the transceiver system during relative movement between the transceivers system, thus maintaining the link despite the relative movement.

Abstract: A local communications apparatus is aligned with a remote apparatus, each apparatus comprising radio frequency (RF) and free space optical (FSO) transceivers with substantially parallel boresight. Coarse alignment is performed using the RF transceiver and fine alignment is performed using the FSO transceiver. A patterned search is performed to locate the RF signal from the remote apparatus and known features of the intensity profile are utilized to locate the global maximum, thus coarsely aligning the pair of apparatuses. A second patterned search is performed to locate the FSO signal from the remote apparatus and an iterative step-search is used to align the FSO signal centroid with the FSO transceiver, thus finely aligning the pair of apparatuses.

Abstract: Methods and systems are described for determining and providing instructions for manual adjustment of a tilt angle of a radio frequency/free space optical transceiver system. Specifically, these instructions are provided for adjusting a tilt angle of a transceiver system using a tilt adjustment so that the transceiver system is approximately at a center of a range of motion of a gimbal assembly. A user interface in communication with a computing system of the local transceiver system provides instructions so that the above-described adjustments are implemented accurately and precisely. This tilt adjustment improves the reliability of the communication network because the gimbal assembly is able adjust the position of the transceiver system during relative movement between the transceivers system, thus maintaining the link despite the relative movement.

Abstract: Methods and systems for improving the quality of transmitted data are described. Multiple distinct communication channels are used to transmit segments representing the same pre-transmission block of a data packet. Upon receipt of these segments, a system identifies differences between the segments for those segments that meet a quality threshold. The system selects one of segments for subsequent transmission or re-assembly into a data packet based on the prior performance of the communication channels used to transmit the segments.

Abstract: A communications networking having reduced transmission latency and improved reliability is described. To reduce signal transmission latency, network management data is removed from a data stream to prioritize the transmission of payload data at higher transmission rates. Management data is returned to the data stream in such a way that it minimizes an impact to payload transmission rates. To improve communications network reliability, the network is configured to form a primary communication path and a redundant communication path. Upon failure of a transceiver at one node, the network engages redundant transceivers on a per-node basis thereby using a segment of the redundant communication path. The data stream is returned to the primary communication path upon circumvention of the failed transceiver.

Abstract: A local communications apparatus is aligned with a remote apparatus, each apparatus comprising radio frequency (RF) and free space optical (FSO) transceivers with substantially parallel boresight. Coarse alignment is performed using the RF transceiver and fine alignment is performed using the FSO transceiver. A patterned search is performed to locate the RF signal from the remote apparatus and known features of the intensity profile are utilized to locate the global maximum, thus coarsely aligning the pair of apparatuses. A second patterned search is performed to locate the FSO signal from the remote apparatus and an iterative step-search is used to align the FSO signal centroid with the FSO transceiver, thus finely aligning the pair of apparatuses.

Abstract: A communications networking having reduced transmission latency and improved reliability is described. To reduce signal transmission latency, network management data is removed from a data stream to prioritize the transmission of payload data at higher transmission rates. Management data is returned to the data stream in such a way that it minimizes an impact to payload transmission rates. To improve communications network reliability, the network is configured to form a primary communication path and a redundant communication path. Upon failure of a transceiver at one node, the network engages redundant transceivers on a per-node basis thereby using a segment of the redundant communication path. The data stream is returned to the primary communication path upon circumvention of the failed transceiver.

Abstract: Methods and systems for improving the quality of transmitted data are described. Multiple distinct communication channels are used to transmit segments representing the same pre-transmission block of a data packet. Upon receipt of these segments, a system identifies differences between the segments for those segments that meet a quality threshold. The system selects one of segments for subsequent transmission or re-assembly into a data packet based on the prior performance of the communication channels used to transmit the segments.

Abstract: A pilot tone generator receives optical energy from an optical communication medium carrying a plurality of optical signals. Each optical signal carries data modulated at a unique wavelength and further modulated with a unique identification signal. The identification signal has an amplitude corresponding to an optical power of the associated optical signal. The pilot tone receiver detects each identification signal from the optical energy received and determines its corresponding amplitude. The pilot tone receiver calculates the optical power of each optical signal in the optical energy in response to the amplitude of the associated identification signal.

Abstract: In a data communication network, a system clock rate can be inferred at a receiver by measuring the data rate during successive periods. This information is used to adjust or adapt a receiver output clock to the inferred system clock. To adapt a receiver buffer output clock frequency to the buffer input clock frequency, the level of the buffer is periodically monitored. If the fill level is greater than an upper threshold, the output clock frequency is incremented. If the fill level is less than a lower threshold, the output clock frequency is decremented. A count is maintained of the number of successive adjustment operations performed while the fill level is outside the range bounded by the thresholds. When the fill level returns to the bounded range, a number of reverse frequency adjustments are performed. The number of reverse frequency adjustments are less than the number of earlier opposite frequency adjustments, preferably by a factor of two.

Abstract: A method and an apparatus to calculate in an intermediate node of a communication network, the new Frame Check Sequence (FCS) appended to a data bits message which has been modified in said intermediate network node. The invention is useful for high speed networks where the transit delay needs to be optimized in the network along with the computing resources in the intermediate network nodes in terms of computer cycles and memory size. The invention consists in calculating the difference between the FCS using the difference between the modified fields in the message and the distance in bits between the end of the modified field and the end of the message; the calculation consists in differentiating `short messages` in the data flow and to provide an optimized processing for the short messages, the processing for larger messages being based on this first optimized processing.

Abstract: A high performance data packet buffering method and a programmable data communication adapter for high speed packet transmission networks are disclosed. The line adapter includes programmable processing means, for receiving and transmitting data packets of fixed or variable length. This system is characterized in that it comprisesmeans for buffering (132) said data packets,means for identifying said buffering means and said data packets in said buffering means,means for queueing (FIG. 15) in storing means (131) said identifying means in a single instruction,means for dequeueing (FIG. 16) from said storing (131) means said identifying means in another single instruction,means for releasing said buffering means,Each instruction comprises up to three operations executed in parallel by said processing means:an arithmetical and logical (ALU) operation on said identifying means,memory operation on said storing means, anda sequence operation.

Abstract: In a communication node (10) which comprises switching device (24) operating under control of a clock signal of period T for exchanging information slots carried in external frames of period T' comprising n slots, with each slot comprising a x-bit data byte, between external Time Division Multiplex TDM links (12,14) attached to the communication node, a synchronization device prevents the slippage phenomena due to the asynchronies between T and T' from causing a loss of data slots by generating at the input of the switching means internal frames from the received external frames. These internal frames are synchronous with the clock signal of period T and have a format which allows the slippage to be compensated.

Abstract: The hybrid packet and circuit switching system allows merging of packet and circuit traffic from user interface modules on a TDM bus and transfer of packet information from one module to another module or the exchange circuit information between modules. Circuit exchanges or packet transfers are performed synchronously on the TDM busses in bursts of period T, with each burst comprising a fixed number of bytes. The bursts are switched by switch 1. A routing indication common to the packet and circuit bursts is used for controlling the switching of the bursts by the switch 1. The indication is performed by piggy backing the target module address for the circuit bursts, as well as for the packet burst, with the data bursts. Marking tables needed for the circuit burst allocation are located in the user interface modules.

Abstract: A distribution mechanism includes a scheduling device which partitions a common timing signal with a period T into n slots of t duration each, a configuration table having n addressable locations with each of the n locations storing communication control information and addressable by slot numbers generated by the scheduling device and a distribution buffer device (2) having at least a first and a second part, with each part having n addressable locations addressed by control information provided by the configuration table during each slot period to cause an interface involved in the to be established communications during a selected slot period, to write the information to be transmitted in one part of the distribution buffer and the information to be received by the interface to be read from the other part of the distribution buffer at addresses derived from the communication control information and the slot generated by the schedule means.

Abstract: The bit streams, transporting the frames, received from lines (6) are placed in register 12 in such a way that n bits are processed in parallel during a time interval T. Parallel processor 10 counts the consecutive logical "1" bits beginning at the low order (left most) bit of the n bits received in interval T and from the bits received in the previous interval T-1, to determine when this number is found equal to 5 which bits have to be deleted, and when this number is found equal to 6 whether a flag is received. As a result, it reassembles N-bit characters, with N<n, in register (16). The frame characters to be sent on lines (6) are stored into register (28), and processed in parallel in a time interval T by processor 10 which inserts 0 after five consecutive logical "1's" as a function of the value of the N bit and as a function of the bits of the previous character, to store into register (32), the bits which are sent on lines (6).