Abstract: A command synchronization establishment system using a network wherein data is transferred by an isochroous transfer, a command is transferred by an asynchronous transfer, and a synchronized clock is shared by apparatuses connected to the network, the system comprising a controller connected to the network, comprising a transmitter that transmits a command including a time-stamp to a target apparatus by using the asynchronous transfer, and the target apparatus connected to the network, comprising a receiver that receives the command, a storage device that temporally stores the received command in order not to execute the received command instantly, and a executing device that executes the received command in accordance with the time-stamp included in the command to be executed.

Abstract: A system and method for enabling an optical network unit (ONU) in a passive optical network to scramble data and send the scrambled data upstream to an optical line termination unit (OLT). In passive optical networks the clocks in the OLT and ONU are synchronized by recovering the clock from the data signal. However, the clocks may drift when no data transitions occur on a long string of data. In addition, the OLT may require data transitions to ensure proper adjusting of its receive threshold. In either circumstance, collectively called Loss of Synchronization, the data may not be received correctly by the receiver and the transmitter will need to resend the data. In the present invention, the transmitter will vary the seed used in the scrambling operation. The use of a different seed per each transmission significantly reduces the chances that a loss of synchronization will occur.

Abstract: Methods and apparatuses for synchronizing basestations in a cellular network. One exemplary method performs time synchronization between at least two basestations, a first basestation and a second basestation, of a cellular communication system. In this exemplary method, a first time-of-day and a first geographical location of a first mobile cellular receiver station (MS) are determined from a first satellite positioning system (SPS) receiver which is co-located with the first MS, and the first time-of-day and first location are transmitted by the first MS to a first basestation which determines a time-of-day of the first basestation from the first time-of-day and first location and from a known location of the first basestation.

Abstract: A communication system including a plurality of communication apparatuses connected via a data transmission line to execute data exchange between any of the communication apparatuses. The communication apparatuses include a transmitter/receiver configured to access said data transmission line at timing periods peculiar to respective communication apparatuses in synchronism with a common system clock among respective communication apparatuses. Further, the timing periods peculiar to respective communication apparatuses are set to be mutually shifted such that accesses to said data transmission line are not simultaneously generated from said plurality of communication apparatuses, and at least two communication apparatuses have communication speeds different from each other.

Abstract: A method and equipment for providing frequency synchronization in a telecommunications system, wherein time stamps providing timing information are transferred over a packet-switched network from a transmitter network element to a receiver network element having a receiver oscillator. The expected times for reception of time stamps are estimated (i), deviations from the estimated expected time for the time stamps are calculated (ii) and at least one time stamp deviating most from the estimated expected time is removed (iii). The steps (i)-(iii) are repeated until a pre-determined number of time stamps is removed. Frequency of the receiver oscillator is then estimated using the remaining time stamps and the frequency generation of the receiver oscillator is adjusted based on the estimated frequency.

Abstract: A distributed system with an architecture based on synchronized clocks that provides accurate coordination of control functions. The distributed system includes a set of nodes coupled to a communication link. Each node has a clock which holds a real-world time. The nodes participate in a synchronization protocol on the communication link for synchronizing the real-world time in each clock. The architecture of the distributed system is such that the synchronization of control functionality in the distributed system is based upon the real-world time in the clocks. A variety of examples of applications for this architecture are set forth.

Abstract: The invention relates to a method of synchronizing a reference clock of a first ground station and a local clock of a remote system, in particular a satellite. It includes: a) acquisition in a first loop of synchronization between reference bursts received by the remote system and generated bursts synchronized with the local clock, b) detection of the recognition word of the reference bursts received by the first remote system and generation of a time window containing N pulses of the reference clock, c) acquisition of the average phase of said pulses and comparison with the phase of the local clock, and d) in a second loop, synchronization of the phase of the local clock with said average phase. The method can be reiterated to synchronize a second ground station with the first one via the remote system.

Abstract: An apparatus which depends on one of a plurality of master clocks as a timing source includes a timing-dependency-direction-identifier-extraction unit which detects an identifier indicative of a direction of timing dependency from a received signal with respect to each of the master clocks, a timing-quality-information-extraction unit which detects a code indicative of a timing quality from the received signal with respect to each of the master clocks, and a synchronization unit which selects the timing source based on the code indicative of a timing quality, and identifies a direction of timing dependency of the timing source based on the identifier indicative of a direction of timing dependency.

Abstract: An integrated communication system includes a CDMA network and other network such as a private cordless phone network which operates under a communication protocol different from that of the CDMA network. The CDMA network receives a GPS time signal from a GPS satellite and transmits a GPS-synchronization signal in synchronism with the GPS time signal. When a cellular phone receives an output request signal such as a position registration request signal from the other network, it transmits an output signal such as a position registration signal to the other network at a time synchronized with the GPS-synchronization signal. The other communication network responsively corrects a time of synchronization of its operation time based on the received output signal.

Abstract: The invention relates to a wireless network which includes at least one base station (1 to 3) and a plurality of associated terminals (4 to 14) for the exchange of useful data and control data. According to the invention, the base station (1 to 3) is arranged to transmit the starting instant of a signaling sequence to at least one terminal (4 to 14). In order to evaluate the signaling sequences transmitted by the terminals, the base station (1 to 3) includes a device (21, 22) for correlating a received signaling sequence and for detecting the pulse arising from a received and correlated signaling sequence.

Abstract: An apparatus for testing the installation of Asymmetric Digital Subscriber Lines (ADSLs) that includes an ADSL Transceiver Unit - Central Office (ATU-C), an ADSL Transceiver Unit - Remote (ATU-R) and a load coil detector. The apparatus can test the operation of the Central Office ATU, the quality of the POTS cable pair connecting the end-user to the Central Office and the operation of the end-user's equipment. The tests can be carried out by using a standard main distribution frame test cord to connect the test apparatus to the existing test jacks and test shoes at the main distribution frame.

Abstract: A trigger node for a measurement and control system which enables relatively precise timing in the application of stimuli and/or measurement of responses without specialized adaptation of analog signaling to the measurement and control system. A trigger node according to the present teachings includes a synchronized clock that maintains a time using a synchronization scheme that provides the timing precision needed for the application of stimuli and/or measurement of responses. A trigger node according to the present teachings further includes mechanisms for asserting a trigger signal when the time from its synchronized clock matches a trigger time associated with the trigger signal. Multiple trigger nodes may be used to coordinate the timing of multiple measurement and control devices by appropriately setting the trigger times in the trigger nodes.

Abstract: The disclosure concerns an inter-base station frame synchronization system for use in a mobile communication system having at least one master base station and a plurality of slave base stations. The master base station is arranged to transmit a control channel signal to the slave base stations located around the master base station in synchronization with a reference frame timing. The slave base stations set a control channel signal observation period. The slave base stations are arranged to generate frame timing based on timings of a received control channel signal from the master base station or other slave base stations when the received control channel signal is received during the control channel signal observation period.

Abstract: In the Intelligent Networks environment, where multiple Service Providers and multi-Vendor equipment are involved in new service offering, the risk of overloading the network elements are real and managing the traffic is a challenge. Network traffic overloads could result from equipment failures, major equipment outages, or widespread loads above engineered levels. To solve the problem of network traffic overload, a direct link interconnect feature between the two SCPs that are deployed in load sharing mode in the network is provided. The communications link interconnects the two SCPs within the load sharing group, whereby the SCPs may exchange information on their congestion levels and controls as well as route queries to the SCP that is not overloaded.

Abstract: All mutual interference occurring between TCM-ISDN and ADSL that communicate by utilizing a line having the same properties and using the same reference signal, and all mutual interference occurring between ADSLs are rejected, by delaying the TTR in the own ATU-C by S1 and approximately adjusting the TTR transmitted to the ATU-R which is a device to be communicated by S2.

Abstract: Methods and an arrangement for synchronizing communication of framed data via asynchronous base stations (BS1, BS2) in a cellular communication system are presented. The synchronization methods are performed continuously by sending out certain system frame counter states from a central node in the system to all its connected base stations (BS1, BS2). Each base station (BS1, BS2) includes a local frame counter (LFCBS1, LFCBS2), which generates local frame counter states (t1(1)-t1(4), t2(1)-t2(4)) correlated to the system frame counter states. Transmission of information via the base stations (BS1, BS2) is synchronized by assigning each data frame (DR(1)-DR(4)) a particular frame number, which is given by the local frame counter states (t1(1)-t1(4), t2(1)-t2(4)), so that data framed (DF(1)-DF(4)) having identical numbers contain copies of a certain data packet.

Abstract: In a transmitter side of an image packet communications system, a transmission clock signal is generated subordinately synchronized to a reference clock signal. Based on the transmission clock signal, a transmission standard signal is generated as synchronous with the reference clock signal. Further, a packet generator generates image packets based on the timing of the transmission clock signal with reference to the transmission standard signal, with image packet headers attached thereto. In a receiver side of the image packet communications system, a reception clock signal is generated subordinately synchronized to the reference clock signal, so that the reception clock signal is synchronized with the transmission clock signal.

Abstract: Automatic switching between clock sources in synchronous networks is accomplished using Synchronous Status Message transmitted over the network and a control circuit positioned between SASE (Stand Alone Synchronization Equipment) and a network element (SDH-NE, Synchronous Digital Hierarchy Network Element).

Abstract: The network elements NE1, . . . , NE6 of a synchronous digital communications system must be synchronized with each other without the possibility of clock loops occurring. A network node NODE contains network elements NE1, . . . , NE6 and a central clock generator SASE. The network elements transmit clock signals 2M to the clock generator, which contain a clock of a message signal STM-N and a quality indicator (SSM) contained in the message signal which reflects the accuracy of the clock. The clock generator selects one of the clock signals 2M as the reference clock REF and informs the control installation STE which of the clock signals it has selected and the degree of accuracy of this clock signal. On the basis of this message STAT the control installation gives instructions ANW to the network elements with respect to the quality indicator which the network elements are to transmit to their outputs.

Abstract: A system and method for time division duplex communication over a single frequency band wherein guard time overhead is reduced by active adjustment of reverse link transmission timing as a function of round trip propagation time. A time frame is divided into a plurality of time slots, during each of which the base station transmits to a user station and the user station transmits to the base station. Communication is initiated by a round trip timing transaction. In response to a general polling message from the base station, a user station seeking to establish communication transmits a short reply message. The base station calculates the distance of the user station by measuring the propagation delay with respect to receipt of the reply message. The base station sends a timing adjustment command to the user station instructing the user station to advance or retard its timing according to the calculated distance, so as to minimize guard times between time slots.

Abstract: A microcontroller includes a direct memory access unit that compresses and decompresses data and transfers from one block of memory to another. Specifically, word size data can be read, one byte discarded, and stored as consecutive, byte size data. This can be used in conjunction with an extended read and extended write asynchronous serial port that stores status information along with data. Once the status information is processed, the status is stripped by performing the “compressive” DMA.

Abstract: A method and apparatus for accurately distributing traceable time values to a set of nodes in a system. Each node includes a slave clock that synchronizes a slave time value using a synchronization protocol. The system includes a traceable time source that generates a traceable time value and a master node having a master clock that synchronizes a master time value to the traceable time value and that distributes the master time value to the slave clocks via the communication link. The nodes may be distributed nodes or cards connected to a backplane.

Abstract: A device outputting a plurality of paths to a terminal after rearranging the plurality of paths when the paths are arranged in an order of free choice on a side of a communication line, the device having a counter which receives a path number of a path in response to first data about the path, and increments a count, starting from the path number, in response to additional data arriving and a storage unit, shared by the plurality of paths, which stores real data of the path at positions indicated by the count, and where the real data stored in the storage unit is output to the terminal.

Abstract: In a time divisional multiple access type mobile communication system including a plurality of base stations, each of the base stations receiving broadcast signals from the other base stations, and determining a broadcast transmission timing in synchronization with and different from timings of the received broadcast signals. Then, a broadcast signal is transmitted at the broadcast transmission timing.

Abstract: The units (CTR0, CTR1) are controlled by mutually independent clock pulses (SCLK, RXCK). In order to prevent the loss of microsynchronization when information is transferred from one clock system to the other and as a result of different error situations as regards the information received by the units, the information received is temporarily stored before being passed on for processing or the result information is temporarily stored before being transmitted. If reception is error free, the units are cross-synchronized. In the absence of a synchronization signal in one partner unit owing to faulty reception, this unit rejects the information received despite the fact that it is error free.

Abstract: A system for synchronizing data packet collection and transmission on multiple segments of a local area network (“LAN”) or a wide area network (“WAN”) using a common clock to generate time stamps placed on the data packets by all peripheral network devices. The common clock is located on a network analyzer device which acts as the “master” to other “slave” peripheral network devices which are driven by the common clock and coupled to the master device in a master-slave configuration. The system also synchronizes the initialization of data packet transmission and/or collection on multiple peripheral network devices by using a common industry standard architecture (“ISA”) address for all devices involved in the data transmission and/or collection.

Abstract: A method and apparatus for synchronizing to a time structure associated with base station transmissions in a radiocommunication system are described. A broadcast control channel can contain synchronization symbols within one or more of a plurality of timeslots. The symbols can be provided as periodic, e.g., exponential, signals which introduce a frequency deviation into the broadcast control channel. This frequency deviation can be recognized by the receiver to synchronize to the time structure of the base station transmissions. Moreover, the variation in the frequency deviation caused by phase rotation associated with local oscillator inaccuracy can also be compensated to achieve frequency synchronization.

Abstract: A method for synchronizing data between a mobile terminal and a computer is provided, in which schedule data can be synchronized between the mobile terminal and the computer using a radio network and Internet network. In this method, either a mobile terminal or a computer corresponding to a party for requesting data to synchronize transmits its head data to other party for synchronizing data through an Over-The-Air Function (OTAF) system. The party for synchronizing data compares the transmitted head data of the party requesting data to synchronize with its head data, and transmits its newest data and corresponding head data of the party for requesting data to synchronize to the party for requesting data to synchronize in accordance with the comparison result. The party for requesting data to synchronize stores the newest data from the party for requesting data, and transmits its newest data to the party for synchronizing data through the OTAF system.

Abstract: A method and system are provided for remultiplexing program bearing data. The remultiplexing method and system are applicable to MPEG-2 compliant transport streams carrying video programs. A descriptor based system is used for scheduling the timely output of transport packets wherein each descriptor records a dispatch time as well as a receipt time for each transport packet. The receipt time is used for estimating program clock reference adjustments, but final program clock reference adjustment is performed in hardware in relation to the precise output timing of each transport packets. A descriptor and transport packet caching technique is used for decoupling the synchronous receipt and transmission of transport packets from any asynchronous processing performed thereon. The descriptors can also be used for managing scrambling and descrambling control words (encryption and decryption keys). Remultiplexing functions may be distributed across a network.

Abstract: A system and method is disclosed for synchronizing clocks in a plurality of devices connected by a communication channel. A master control device is coupled to one or more slave control devices, e.g., event recorders, across a communication channel. Preferably, the communication channel is implemented according to an RS-485 interface. By periodically interrogating and monitoring the responses of each of the slave control devices, the master control device determines the transit time, i.e., communication, delays to each of the slave control devices. Operating in conjunction with this data, the master control device can then interpret and/or adjust any event times reported by the event recorders to improve the relative time accuracy of the event recorders as compared to a time maintained by the master control device. Consequently, the control system can achieve a relative time synchronization accuracy between the master and slave times to within 100 microseconds and preferably 100 nanoseconds or less.

Abstract: This invention discloses a transmission device used as a node device for a trunk network and a signal transmission method in a synchronous network.

Abstract: The network elements NE1, . . . , NE6 of a synchronous digital communications system must be synchronized with each other without the possibility of clock loops occurring. A network node NODE contains network elements NE1, . . . , NE6 and a central clock generator SASE. The network elements transmit clock signals 2M to the clock generator, which contain a clock of a message signal STM-N and a quality indicator (SSM) contained in the message signal which reflects the accuracy of the clock. The clock generator selects one of the clock signals 2M as the reference clock REF and informs the control installation STE which of the clock signals it has selected and the degree of accuracy of this clock signal. On the basis of this message STAT the control installation gives instructions ANW to the network elements with respect to the quality indicator which the network elements are to transmit to their outputs.

Abstract: A user headset is provided that is operable to contain an audio device (50) and a receiver (52). The receiver (52) is operable to receive both audio information on multiple channels and also data. The data is received in the form of pulse width modulated sync signals. The sync signals are operable to provide a synchronization signal for 3-D liquid crystal lenses (60). The data is encoded within the sync signal through pulse width modulation. The width of the pulse defines various commands. These various commands define the channel over which the audio is to be transmitted. These channels can either be user-defined or they can be a function of the transmitter. The transmitter includes an audio generator (42) for generating audio signals on multiple channels and also a data generator (40). These are modulated onto a broad band optical signal and transmitted via an IR data link.

Abstract: A method for synchronizing a cycle master node to a cycle slave node, including the steps of utilizing logic circuitry in the cycle slave node to determine a timer offset value, in response to the cycle slave node receiving synchronization information, transmitting the timer offset value to the cycle master node, and, utilizing logic circuitry in the cycle master node to adjust a value of a cycle master node cycle timer on the basis of the timer offset value. The synchronization information is preferably a cycle reset signal that is asserted at a prescribed rate which is a multiple of one cycle of the cycle slave node cycle timer. The cycle master node and the cycle slave node can advantageously be included in a first network or sub-network and the cycle reset signal can be supplied by a second network or sub-network which is external to the first network or sub-network.

Abstract: A synchronous bus system that enables the bus lengths between devices to be extended such that the timing budget is more than one clock cycle. A reset process resets the transmission and reception circuitry and both circuitry function according to prespecified parameters relative to the deassertion of the reset signal such that the amount of logic required to latch and sample the data is minimized. As the timing budget is not limited to one clock cycle, devices can be spaced further apart providing more physical space for devices. Furthermore, skew sensitivity is reduced as the skew is distributed over multiple clock periods.

Abstract: A baud rate generator in a data communication system comprises a first and second counter for counting clocks in a clock signal to generate a transmission and reception counts, first and second match detection circuits each for detecting a match between the transmission or reception count and a reference value to generate a transmission baud rate signal or reception baud rate signal, a third match detection circuit for detecting a match between the transmission baud rate signal and the reception baud rate signal, and a control section for controlling a transmission station and a receiving station for restart transmission if a mismatch is found in the third match detection section. A quick restart of data transmission can be obtained if a transmission error is found.

Abstract: A system and method for causal ordering in a distributed network with a minimum amount of delay. In a distributed network having three interconnected nodes, each having synchronized clocks, the second node sends a message to the first node. Before it sends the message, however, the second node attaches a time stamp t2 to the message. To determine when the first node can provide a causally ordered response, the method first determines a minimum message latency f from the third node to the second node. The method then adds the value of the time stamp t2 to the message latency f to calculate a minimum response time t1. On or after the time t1, the first node can provide the causally ordered response.

Abstract: A pulse code modulation modem system is configured to transmit data from a first modem to a second modem over the public switched telephone network (PSTN). The PSTN employs robbed bit signaling (RBS) such that symbols affected by RBS arrive at the second modem in a periodic manner based on a period of six symbols. The modem system is configured such that signal segments are formatted and transmitted with six symbols per segment. After obtaining symbol synchronization, the second modem initializes a modulo-6 symbol counter such that the zero count corresponds to the first symbol of each received signal segment. Those symbols affected by RBS are identified and analyzed to determine optimized signal point constellations that may be used to compensate for the RBS on a symbol-by-symbol basis during subsequent encoding and decoding. Upon a loss of synchronization, the second modem resets its modulo-6 counter in response to the detection of the first symbol in a subsequent signal segment.

Abstract: Synchronizing a local timing unit to a central timing unit in a first switching system to determine the difference in timing between a connected external link and the local timing unit. This timing difference is then transmitted to the central timing unit which utilizes this information to adjust a frequency synthesizer that outputs the frequency of the external link to a second switching system. The local timing units are synchronized to the central timing unit via multiple timing paths set up through switching units within a switching network of the first switching system. The timing difference transmitted from the local timing unit is transmitted over a plurality of control paths through the switching units. Each switching unit switches one bit of data for each group of data being received on each of the external links connected to the first switching system. Any of the external links connected to the first switching system can be utilized to provide timing information for the second switching system.

Abstract: In a digital communication system for voice signals, a system and method for recovering the timing of a pseudo-random noise (PN) sequence used for direct-sequence spreading and despreading of the communicated signals. In one embodiment, a received signal is a time-division duplexing (TDD) or time-division multiple access (TDMA) signal, and a receiver performs a complete "sliding correlator" examination of the received signal in a fixed time by using the timing of the TDMA or TDD frames. This examination allows a rapid initial acquisition of the PN synchronization. In another embodiment of the receiver, the initially acquired PN phase is verified by reading a SYNC field from the received signal and by checking that shifting the receiver's local PN phase results in a degraded correlation between the local PN sequence and the received signal.

Abstract: A system and method for time division duplex communication over a single frequency band wherein guard time overhead is reduced by active adjustment of reverse link transmission timing as a function of round trip propagation time. A time frame is divided into a plurality of time slots, during each of which the base station transmits to a user station and the user station transmits to the base station. Communication is initiated by a round trip timing transaction. In response to a general polling message from the base station, a user station seeking to establish communication transmits a short reply message. The base station calculates the distance of the user station by measuring the propagation delay with respect to receipt of the reply message. The base station sends a timing adjustment command to the user station instructing the user station to advance or retard its timing according to the calculated distance, so as to minimize guard times between time slots.

Abstract: A process for transmitting data selects sample values that represent data symbols and then converts the sample values to voltage levels in a transmitted PAM signal. A receiver samples the PAM signal and identifies the data symbols from the sampled voltage levels. At least some of the data symbols have multiple alternative representations; and for a data symbol having multiple alternatives, a sample value is selected to reduce low and high frequency components in the PAM signal. Accordingly, the PAM signal carries less information at low and high frequencies and is less disturbed by transformers, low pass filters, and local loop impairment in the transmission channel. The process for selecting sample values determines a weighted average of the lowest and highest frequency components. The weighting of the average can be selected according to a measured frequency response of the channel during initialization.

Abstract: A method for performing timer synchronization between a first processor having a first timer and a second processor having a second timer is presented. The first processor issues to the second processor a first timer value corresponding to the current value of the first timer and the second timer compares the first timer value with a second timer value corresponding to the current value of the second timer. If the second timer value is less than the first timer value, the second processor increments the second timer value to a new second timer value equal to the first timer value. If the second timer value is greater than the first timer value, the second processor issues to the first processors the second timer value and the first processor adjusts the first timer value to be equal to the second timer value.

Abstract: In synchronous digital communication systems using a synchronization quality marker (SSM), timing loops can be created. To avoid such timing loops, a synchronous digital communication system is provided having network elements (NE11, . . . , NE33) in which two classes (top, bottom) are defined for interface units (S.sub.1, . . . , S.sub.x, . . . , S.sub.X+i).

Abstract: Apparatus and methods for distributing synchronization throughout a network is disclosed. The distribution of the synchronization is through the use of generating a reference timing signal, and by counting the line clock pulses between the start of a frame and the timing reference signal pulse at a first office and that count is then encoded and transmitted to the next office. At the next office, the transmitted count is decoded and used for regenerating synchronization by counting a number of received line clock pulses from the start of the frame to regenerate the reference timing signal. Particular criteria for selecting the frequencies for the timing reference signal are disclosed.

Abstract: A time-division multiplexing synchronization mechanism employs a 1-bit/frame framing channel with a pattern that repeats every 2 frames. Acquisition and reacquisition of synchronization with such a framing pattern is enabled through the use of an explicit synchronization procedure. With this procedure, initial acquisition of frame synchronization as well as reframing after loss of synchronization are carried out while the transmission channel is carrying only a predefined bit pattern. When the receivers are in synchronization, synchronization is monitored and maintained using a 1-bit/frame framing channel, while the communications link is carrying multiplexed bit streams with the appropriate format.

Abstract: A method and an apparatus that improves a data transmission rate in a TCP connection having an asymmetrical path. An intermediate node transmits a predetermined number k of data packets to a destination node, and measures a time period A between transmitting the k data packets and receiving a receipt acknowledgment signal at the intermediate node indicating receipt of the k data packets at the destination node. The intermediate node then transmits to a source node k acknowledgement signals with a time interval of A/k between each acknowledgement signal.

Abstract: A system and method for frequency recovery that allows selection between either a synchronous recovery scheme or asynchronous recovery. A frequency recovery system for synchronizing a received data stream, comprising: a first timing signal generator configured to receive the data stream, extract any timing information included in the data stream, and output a first timing signal based on the extracted timing information;a clock source for providing a second timing signal; a data module for receiving the data stream and outputting the data stream at a desired rate, the data module utilizing either the first timing signal or the second timing signal to output the data at the desired rate; and a switch for selectively applying either the first timing signal or the second timing signal to the data module.

Abstract: Operation of a plurality of electronic devices is synchronized. The plurality of devices include a master unit and a plurality of other units, and the master unit transmits a synchronizing signal to at least one of the other units at predetermined intervals. Each of at least two of the other units detects whether a synchronizing signal is received at the respective unit within a predetermined period of time. If not, the respective unit changes from a slave mode of operation to a master mode of operation. Contention between the two or more potential back-up master units is resolved based on priority in a daisy-chain arrangement or by providing different time-out watch-dog periods for the potential back-up devices.

Abstract: A modem that operates reliably at a symbol rate that corresponds to twice its bandwidth even when it is coupled to a receiving A/D converter that operates under control of a clock is realized by synchronizing the modem's operation to the A/D's clock. The superior operation of this modem advantageously extends to A/D clock frequencies beyond the frequency of twice the modem's bandwidth. To minimize quantization noise, the modem's output is conditioned to minimize intersymbol interference by adjusting the modem's output to the A/D converter's sampling times and slicing levels. When the A/D's clock is higher than twice the bandwidth of the modem's output signal, some intersymbol interference cannot be avoided. In accordance with this invention, the position and value of this interference is computed at the receiver and subtracted from the received signal.