Abstract: A graphically configurable method and device for testing high-frequency (DS0, DS1, DS3, and SONET) communication networks is disclosed. The foregoing is accomplished by a microprocessor controlled test instrument configured through a graphical interface which selects signal paths and test parameters. The graphical interface intelligently presents the choices of paths and test parameters relevant for the current test configuration.

Abstract: This invention provides a cell switching apparatus having buffer memories in which accesses of a plurality off cells can be implemented in one-cell time. The cell switching apparatus arranges a plurality of buffer memories, in which accesses of a plurality of cells can be performed, in parallel, and schedules a score table so that the writing and reading out operations may not overlap. Accordingly, the incoming lines may be increased lip to (the number of incoming lines n)=(the number of buffer memories p-1).times.(the number of outgoing lines m) without increasing the access speed of the buffer memories.

Abstract: A method for adaptation to the time-variable channel impulse response during a burst in receivers for TDMA mobile radio systems, each burst including in the center a test sequence which is known to the receiver and by means of which an initial estimate of the channel impulse response is possible, whereinthe received signal of a burst is suitably sampled,the received burst is divided in 2N+1 sectors A.sub.-N, . . . , A.sub.+N, it being assumed that the channel impulse response can be regarded as being constant within a sector,a vector x of dimension (2N+1)L is defined, L being the number of channel impulse response coefficients and the (iL+l)-th component of x, -N.ltoreq.i.ltoreq.+N, 0.ltoreq.l.ltoreq.L-1 is initialized before the start of the detection using the l-th coefficient of the estimated value of the channel impulse response obtained from the test sequence, Matrices E, E.sub.i, E.sub.ii, S and vectors x.sub.i, d, r.sub.

Abstract: In current voice telephony, CATV, and wireless networks, traffic is channelized for both access and transport. This channelization is wasteful of resources where multiple services have varying demands for bandwidth and holding times, or a service generates traffic that is bursty in nature. The invention solves these problems by providing flexible and adapatable multiservice access to the networks. Customer requirements are checked by monitoring traffic on a local access at a connection request and/or during the established connection, and the local access is configured according to the transmission requirements. The local access can also be configured in response to the network information.

Abstract: A frequency-division multiplexer for carrying an OFDM signal on a large number of closely-spaced carriers receives the digital data at an input (12), applies coding such as convolutional coding (14), time interleaves (16) the signals, and assembles them frame-by-frame in a matrix (18). The data are converted to parallel form by a shift register (18), frequency interleaved (24), differentially encoded (26), and quadrature-phase-modulated (28) on several hundred or more closely-spaced carriers. A first inverse Fast Fourier Transform (FFT) circuit (30) transforms this information from the frequency domain into the time domain. Instead of being transmitted directly, the resultant signals are then amplitude-limited (42) and applied to an FFT (44) to reconvert them into the frequency domain. The phases of the wanted signals are then re-set, and the amplitudes of the signals near the edges of the band are reduced, in correction circuits (46).

Abstract: A method is disclosed for a user terminal (10) to obtain access to a DCCH transmitted on a TDM radio channel of a wireless communications system that also includes at least one TDM radio channel that transmits a DTC. The DCCH and DTC are each comprised of slots partitioned into fields. A first step (a) tunes a receiver (16) to a radio channel, receives a first slot, and decodes a predetermined first field from the first slot. The predetermined first field is a 12-bit CSFP field if the radio channel conveys a DCCH, or a 12-bit CDVCC if the radio channel conveys a DTC. A second step of the method calculates a CRC over the first field to determine if the first field is the CSFP field. If yes, the user terminal assumes that the radio channel conveys the DCCH and then uses information from the DCCH to access the wireless system.

Abstract: Disclosed is an apparatus for digitizing an electromagnetic input signal having frequency components within at least first and second segregated frequency bands, particularly useful in a wireless communications system. The apparatus includes a filtering circuit arrangement for passing only frequency components of the input signal substantially within the first and second frequency bands, to provide a filtered signal having a spectrum with spectral components below a predetermined power level within a frequency gap between the first and second frequency bands. An analog to digital (A/D) converter samples the filtered signal at a sampling rate sufficient to provide a digitized output signal with a frequency spectrum corresponding to that of the filtered signal and also with a replica of spectral components of one of the frequency bands appearing within the frequency gap.

Abstract: A method and structure for virtually eliminating any false detections of a synchronization code is described which creates a selectable window during which the synchronization code is expected to appear. A coincidental replication of the synchronization code outside the window does not trigger false synchronizations.

Abstract: In a base station which has a plurality of antennas, each of a plurality of comparison circuits operates to compare correlation levels, which are obtained by despreading received signals for a plurality of channels, with each other with respect to the antennas. Each of a plurality of transmission antenna selecting circuits operates to determine from which antenna a transmission signal is to be transmitted for every channel. Each of a plurality of multiplexing circuits operates to multiplex the transmission signals of the individual channels, which are spread, for every antenna. As a result, on the basis of the result of the comparison of the correlation levels with respect to the antennas, a transmission antenna is selected for every channel, and the signals of the channels that are to be transmitted by a given antenna are multiplexed, whereby the base station achieves transmission diversity.

Abstract: A central controller (101) in the TDM wireless communication system (100) transmits a data channel update message (600), including an allocation profile (603) and an update interval (605) to a second group of communication units (107-109). The allocation profile indicates time slots used to form a data channel and the update interval indicates a period of time until transmission of the next data channel update message. The data channel update message, transmitted via the data channel, is sent in response to a request from a first group of communication units (104-106) or upon expiration of a period of time based on a previous update interval. Repetition of this process allows time slots to be dynamically allocated in response to changing system requirements, while minimizing use of the data channel for data channel update messages.

Abstract: An apparatus continuously monitors the T1 output signal from a customer telecommunications equipment to a telecommunications network and provides a substitute input signal to the network whenever the T1 output signal from the customer equipment is interrupted. When the output signal from the customer equipment is present, the apparatus passes through the input and output signals between the customer equipment and the network. When the output signal from the customer equipment is interrupted, the apparatus loops back the output signal from the network into the input to the network, providing the network with a substitute signal. The monitor uses a high impedance, non-intrusive sensing circuit.

Abstract: To be able to operate base stations (FT) and mobile units (PT) of a cordless telephone system with the lowest possible use of energy, a processor (M-CT) of the base station (FT) and of the mobile unit (PT) contains a controlling program (CP) which is designed in such a way that the transmitting device (RE-T) of a transmitting unit (FT, PT) is activated essentially only at transmission times (SZ) and the receiving device (RE-R) of a receiving unit (PT, FT) is activated essentially only at reception times (EZ).

Abstract: A communication system (10), and a method executed by same, for allocating communications traffic through a plurality of satellites (12) of a constellation of low earth orbit satellites. Each of the plurality of satellites is oriented, at any given time when in view of a ground station (18), at a particular elevation angle. The method comprises the steps of: (a) providing each of the plurality of satellites with a receiver for receiving communication links from the ground station and a transmitter for transmitting communication links to user terminals; (b) in response to a request for service, determining if a highest elevation angle satellite can be assigned a new communications link; (c) if yes, assigning a new communication link to the highest elevation angle satellite; (d) if no, determining if a second highest elevation angle satellite can be assigned a new communications link; and (e) if yes, assigning a new communication link to the second highest elevation angle satellite.

Abstract: A finite impulse response (FIR) filter characterization is performed using a modified least means squares approach that updates values of FIR filter taps as groups of taps, periodically. For the taps updated for a current input signal sample, future convolution values for future input signal samples are computed and also a partial estimate of the signal response is computed. The expected response is then computed by summing the partial estimate signal response and other partial estimates of the signal response which are computed from future convolution, missed tap update convolution and normalizes error signal values which have been previously computed at past input signal samples and stored in memory.

Abstract: A crossbar switching fabric for routing data packets in an ATM switch. A logic unit associated with a reservation ring in an ATM switch intercepts data exiting a selected evaluator of the reservation ring, and processes this data to set-up a crossbar switching fabric for routing data packets of the ATM switch. The set-up data may be passed to the crossbar switching fabric upon each clock cycle thereby not incurring any pipeline processing delays. Alternatively, the set-up data is accumulated and stored in the logic unit until the completion of an arbitration session, whereafter it is sent to the crossbar. In place of the logic unit a plurality of registers may be added to each of the evaluators of the reservation ring. The registers in turn interconnected to each other in a shift register arrangement to provide the set-up data to the crossbar fabric.

Abstract: A method is described for rerouting a data stream previously routed via a route through a switching network which has now failed. The method includes the steps of detecting the failure on a link (L19) between first (SN1) and second (SN9) switching nodes in one of these switching nodes (SN1); transmitting from this one switching node (SN1) a request message (REQ) with first (IDA) and second (IDB) address fields containing addresses of the first (1) and second (9) switching nodes, respectively; in each switching node having received the request message (REQ) retransmitting it, until an alternative route for the data stream is found between two end switching nodes of said alternative route; and by one of these end switching nodes (SN1) chosen according to a predetermined rule after the alternative route has been found, allocating the data stream to this alternative route and transmitting it thereon.

Abstract: An oscilloscope preamplifier includes N inputs and Z outputs. A programmable cross-point multiplexer provides a first operating mode in which each of N inputs is connected to a different output thereby providing a preamplifier with Z channels, a second operating mode in which one input is multiplexed to all the outputs which are interleaved to maximize the sampling rate, and a range of operating modes in between. The programmable multiplexer includes a switching amplifier connected between each input and each output. Dials on the preamp select the mode by causing a microprocessor to program latches which activate or deactivate the switching amplifiers. A voltage divider is connected across inputs of the multiplexer to provide a programmable attenuator with selectable attenuation levels.

Abstract: There is disclosed a method for auditing routing information in a packet switching network. One method involves utilizing the telecommunications management network to sample through a general purpose management interface routing table information at live nodes in the operating network for a test message sent from a test initiator node to a final destination node through intermediate nodes. The telecommunications management network subsequently runs verification tests on the collected routing table information apart from the packet switching network. This method has the advantage that the verification test is not run on the network while still testing actual table routing information. Advantageously, this method tests actual routing information without overloading the network with additional routing requests provided by the test. Moreover, this method does not induce any load on the network. Further, this method uses data collected in real time from the network.

Abstract: A digital time-division duplex radio communication link is established or re-established between one of a plurality of portable units and one or more base units forming a cordless telephone system, so as to avoid potential interference created by the use of an unsynchronized call-up transmission in the presence of synchronized signals being exchanged by the rest of the system. The call-up transmission is pre-synchronized with the rest of the system so that switchovers between transmission bursts and reception windows occur at the same time as between the call-up signal and the rest of the system. This is achieved by deriving synchronization information from a synchronization signal which may, for example, be an existing signal on the system containing synchronization information (i.e., an existing call on the system) or may be a beacon signal which, in some systems, is transmitted by the fixed units for the purpose of range indication.

Abstract: A selective call receiver is provided that is capable of receiving a transmitted fragmented message and displaying the fragmented message in at least two scripts. The transmitted fragmented message includes a plurality of sequentially ordered message packets each comprising an address and message data, at least one of the message packets having a script select character within the message data. The fragmented message is received by a receiver and passed to a circuit for displaying the fragmented message in the scripts, such that a first portion of the fragmented message is displayed in one of the scripts and a second portion of the fragmented message subsequent to the script select character is displayed in another of the scripts. A retrieval circuit is capable of retrieving a garbled message fragment if a sequentially prior message fragment containing the script select character is missing from the fragmented message.