Abstract: A system for determining the rate at which data has been encoded in the receiver of a variable-rate communications system. The data is received in frames having a fixed number of symbols. Multiple copies of symbols fill the frame when data is encoded at less than the full rate. At an encoding rate of one fourth the full rate, for example, each symbol in the frame is repeated four times. The incoming symbols are provided to multiple paths for decoding. Each path decodes the symbols at one of the possible rates. Error metrics, which describe the quality of the decoded symbols, are extracted and provided to a processor. The error metrics may include Cyclic Redundancy Check (CRC) results, Yamamoto Quality Metrics, and Symbol Error Rates. The processor analyzes the error metrics and determines the most probable rate at which the incoming symbols were encoded.

Abstract: In an equalizer including a plurality of delay elements, a plurality of weighting elements and an adder, the impulse response of a signal transmission channel is estimated to selectively switch over a plurality of selector switches associated with the inputs and outputs of the respective delay elements, thereby selectively changing the combination of the delay elements and the weighting elements transmitting an input signal from the channel to the adder and also changing the combination of the adder and a delay element feeding back the output of the discriminator to the adder. Thus, the number of required taps of the equalizer can be reduced, so that the power consumption and size of the equalizer can be reduced.

Abstract: A system for communicating signals within a digital network without the aid of an array of separate signal lines or of the system data bus. The network communication system 10 of the present invention is operative in accordance with a time-sliced protocol to communicate signal information among a set of digital modules 1. The communication system 10 includes a driver network for transmitting signal information to a first interface circuit 14 in communication with a first 22 of said modules during a selected interval of an interval cycle. The first interface circuit 14 includes an input network 44 for receiving the transmitted information during the selected interval. The inventive network communication system 10 further includes a kickstart circuit 30 for initiating an interval cycle upon the transmission of signal information within the network 10, or upon the execution of a maximum (Nth) interval of a preceding interval cycle.

Abstract: A variable bandwidth filter device for use with a spread-spectrum transmitter including a chipping sequence generator, spread-spectrum processing means, an impulse generator, and a filter. The chipping-sequence generator generates a chipping sequence signal having a chipping-sequence-signal bandwidth. Using the chipping sequence signal, the spread-spectrum processing means processes a data signal to generate a spread-data signal having a spread bandwidth greater than the chipping-sequence-signal bandwidth. In response to each chip in the spread-data signal, the impulse generator generates an impulse signal. The filter filters the spectrum of each impulse signal with a bandpass equal to the spread bandwidth. The invention also comprises a method for generating a spread-spectrum signal using a chipping sequence having a rate less than the spread bandwidth.

Abstract: In a convolutional coding and Viterbi decoding system transparent to phase skips of .pi. and .pi./2 with applications in TDMA transmission, the transmitter 3 includes a demultiplexer receiving a digital bit stream and operating at the bit timing rate, a QPSK differential coder receiving the demultiplexed bit streams and supplying two coded bit streams, two convolutional coders each supplying one code word, and two multiplexers each receiving one code word from a respective convolutional coder and supplying one component of a symbol to be transmitted. The receiver generates two received symbol components which are applied to two demultiplexers each supplying one code word. Each bit of a code word is applied to a single Viterbi decoder. A QPSK type differential decoder supplies two decoded bit streams which are then multiplexed.

Abstract: A communication control system between parallel computers performs a broadcast communication in a network between parallel computer nodes. The communication control system includes a destination detecting unit for detecting the destination information designating the scope of the destination nodes from the data; a between-node distance processing unit for obtaining the distance between the particular computer node and the destination computer node, based on the destination information; and a destination judgment unit for judging whether the data should be obtained by the self node or whether the data should be further transmitted to the other node and for determining the direction of the transmission, based on the distance information.

Abstract: A demodulator responsive to a symbol containing analog signal includes a pair of relatively inexpensive analog-to-digital converters for sampling I and Q channels of the signal only once per symbol. A derotator responsive to outputs of the converters and a digital signal representing frequency and phase corrections for an input to the demodulator operates in accordance with a CORDIC function to derive I and Q channel digital signals that are compensated by the corrections. A digital phase shifter responsive to at least one of the digital I and Q signals controls when the input is sampled by the converter.

Abstract: The invention relates to a measuring device for measuring the phase deviation of at least a subordinate transport unit of a synchronous signal transmitted through a synchronous transmission system. The measuring device comprises a transmitter unit for forming the synchronous signal to be transmitted, a first desynchronizer for splitting up the synchronous signal and for detecting at least a given byte of the subordinate transport unit, a second desynchronizer for splitting up the received synchronous signal which has passed through the transmission system and for detecting at least the given byte in the received synchronous signal, and an evaluation unit for calculating the phase deviation from the moments of detection of at least the given byte in the transmitted and the received synchronous signals.

Abstract: A .pi./4 delay spread detection and compensation arrangement effectively detects distortion due to multipath delay spread in a digital channel and compensates for this distortion with minimum circuit complexity. An improvement in the bit error rate performance for a differential detector in the receiver is achieved through use of a detected direct current (DC) component, which is proportional to the amount of multipath delay spread on the digital channel. This DC component is used in the differential detector for compensating for this delay spread. In addition, the differential detector also provides a channel quality measure of the level of delay spread on the digital channel for use by the receiver in selecting either the differential detector or an equalizer for decoding of the data on the digital channel.

Abstract: In a radio receiver for receiving vestigial sideband (VSB) signals including symbol codes descriptive of digital signals, HDTV signals being exemplary of such VSB signals, a tuner provides for selecting one of channels at different locations in a frequency band used for transmitting such VSB signals. The tuner also includes mixers for performing plural conversion of the selected channel to a final intermediate-frequency signal, which is digitized by an analog-to-digital converter. A phase tracker, operative on narrow-bandpass filtered portions of the digitized final intermediate frequency signal centering on its carrier frequency, suppresses an imaginary portion of the final intermediate-frequency signal, arising from multipath distortion or from phase incoherency in local oscillations used during frequency conversion.

Abstract: A system for the transmission of information between elements of a data processing complex and a method for establishing such a system. Two elements of a data processing system are connected by a physical link comprising multiple conductors attached to transceivers at channels in each data processing element. Once the transceivers have been synchronized, commands and responses are exchanged which ensure that all of the transceivers in a channel are connected to the same channel on the other end of the conductor. If the transceivers are considered configured an entry is made in a Configured-Transceiver table. A search is made of an Allowed-Operational-Link table which contains sets of transceivers which are allowed to become operational links. The set of transceivers thus found, is compared against the Configured-Transceiver-Table to verify that all of the members of the set have been configured. If a match is found, this set of transceivers becomes an Intended-Operational-Link.

Abstract: This detector is for demodulating a received signal having been previously encoded by a trellis coded modulator and for producing an information data signal with reduced intersymbol interference. The detector comprises a predictor, a delay line, a feedforward filter, an adder, a subtracter, an updater and a trellis coded modulation estimator. The trellis coded modulation estimator has a feedback filter which is adjusted with respect to the feedforward filter to form a decision-feedback equalizer. Moreover, the delay line has a predetermined length which is adjusted according to an order of the feedforward filter and a depth of the trellis coded modulation estimator to achieve a zero relative delay between an output of the feedforward filter and outputs of the trellis coded modulation estimator.

Abstract: A signal suppressing apparatus for suppressing undesired signal components, in which a first filter electrically simulating a propagation system A of a physical phenomena such as a sound, vibration, electricity, etc. is mounted; a signal having a correlation to the signal to be input to the propagation system A is input to this first filter; and the output of the first filter exerts an influence upon the signal passing the propagation system A to make the passed signal approximate the intended value, wherein the first filter is split into a plurality of filters, each of which is composed by a discrete DSP, outputs are individually calculated in the split individual filters, and the individual calculation results are tabulated, whereby a value the same as the value obtained where the calculation is made without splitting of the first filter is obtained. This enables high speed signal processing even if a high speed DSP is not used.

Abstract: Digital signals, such as digitized television signals, are subjected to a source coding step followed by a channel mapping step. The source coding step causes the signal to be represented by first and second data streams. The first stream carries data regarded as more important and the second carries data regarded as less important. In the channel mapping step, the mapping is such that the data elements of the various data streams have differing probabilities of being erroneously detected at the receiver. The channel mapping step includes at least one multi-level coding step. The signal constellations used in the channel mapping step are partitioned into supersymbols, in which the distance between the symbols comprising at least ones of the supersymbols is less than a parameter referred to as the maximum intra-subset distance (MID).

Abstract: The method pertains to wireless transmission in the common-wave operation. For the operation of common-wave networks, it is required that the modulation contents of the transmission frequencies (1 . . . m) transmitted by the individual transmitting stations are identical. However, in order to enable a station or regional identification, one or more regionally differing additional carrier frequencies (n-3 . . . n) are transmitted, whose reception permits the selection of specific regionally related news or messages in the receiver. The demand of additional carrier frequencies may be reduced to four individual frequencies or frequency groups, if these additional carriers are modulated.

Abstract: A data-transmitting apparatus contains first and second transmitters, a transmit transformer, and a connecting unit for coupling the transformer to an outgoing twisted-pair cable. The first transmitter filters data to produce outgoing data transmitted to the transformer at a first data rate. The second transmitter transmits outgoing data to the transformer at a different, typically greater, second data rate. A data-receiving apparatus contains first and second receivers, a receive transformer, and a connecting unit for coupling an incoming twisted-pair cable to the receive transformer. The first and second receivers receive incoming data from the secondary winding respectively at the first and second data rates. Incoming data is typically provided along data transfer paths that extend from the receive transformer in a daisy chain manner to the receivers. Data moving at either data rate can be transmitted and received without the need for hot switching in the data paths.

Abstract: An apparatus for restoring a symbol timing of a signal received at a receiving side of a digital communication system.

Abstract: A method for signal equalization/ghost cancellation with an equalizing filter includes synthesizing a first equalizing filter function (LMS 1) with N (an integer) taps and associated coefficients. The respective coefficients are adjusted to minimize the error between a received reference signal output by the synthesized equalizing filter function and a non-distorted reference signal. The adjusted coefficients are evaluated to determine P (an integer) groups of M (an integer) taps and associated coefficients which contribute to said synthesized equalizing filter function according to a predetermined criterion and wherein P times M is less than N. A second equalizing filter function is synthesized corresponding to the first equalizing filter function with coefficients other than the P groups of M coefficients set to zero, and the P groups to M coefficients are adjusted to minimize the error.

Abstract: A number of arrangements and methods that achieve concurrent communication of analog information and digital information. In general terms, when the communication channel is viewed as a multi-dimensional space, the digital information signal is divided into symbols, and the symbols are mapped onto the signal space with a preset distance between them. The analog signal, generally limited in magnitude to less than half the distance separating the symbols, is converted to component signals and added (i.e., vector addition) to the symbols. The sum signal is then transmitted to the receiver where the symbols are detected and subtracted from the received signal to yield the analog signal components. The transmitted analog signal is recreated from those components.

Abstract: The present invention provides a transcoder for transcoding of digitally encoded bit streams produced by predictive encoders. The transcoder of this invention is less complex than previously known transcoders in terms of both computational and storage requirements. This efficiency is achieved by combining decoding and re-encoding steps into one step. This one-step transcoding is accomplished by modifying the originally quantized vectors and then requantizing and noiseless encoding these vectors into a bit stream in accordance with a predetermined objective.