Abstract: A method and means for for recovering data in a spread spectrum communications system. The present invention includes a method and means for providing a sync window time period. The sync window is set to encompass the correlation values which are generated one baud time from the previous recovered data bit. The present invention also determines the peak correlation value within the sync window and the location in time within the sync window that the peak correlation value occurs. The present invention also provides a polarity window time period. The polarity window occurs during the sync window. The present invention decodes the data according to the direction of the peak correlation and whether the peak occurred within the polarity window. The sync and polarity windows are then set to occur, such that the peak correlation of the next baud falls within the next instance of the sync window. In this way, data can be recovered continuously.

Abstract: A transceiver for transmitting and receiving spread spectrum signals having an adaptive threshold for distinguishing between valid receive data signals and noise. The transceiver includes a transmitter for transmitting spread spectrum signals and a receiver for receiving spread spectrum signals. A correlator correlates a received signal against an expected receive pattern. The correlation of the received signal is compared to a threshold value. If the correlation exceeds the threshold value, a carrier detect signal is generated. The number of false carrier detect signals occurring within a pre-determined period of time is determined. The threshold value is varied according to the number of false carrier detects.

Abstract: A power line communication amplifier circuit for providing a signal transmission across a power line medium when operating in a transmit mode, and for providing a relatively high input impedance to the power line when in a receive mode includes a unity gain buffer integrally coupled with a filter. The filter operates upon an input signal provided by a digital driver means. A control means is coupled to the digital driver means and to the buffer such that when said amplifier is switched to a receive mode, both the driver means and buffer provide a high input impedance.

Abstract: In a power line communications apparatus an improvement for blanking or snubbing impulse noise. The impulse noise is detected and used to snub the detected signal. The duration of the snubbing pulses is controlled to assure complete blanking of noise including the trailing noise signals following a main noise pulse which may not otherwise be detectable. Also, the number of snubbing pulses which can occur are limited to prevent too much energy from being snubbed during any given baud period.

Abstract: A collision detection circuit which indicates to a processing node, while the node is transmitting, that another transmission has, or is occurring, on the network comprises a means for directionally coupling a processing node to the network to discriminate between the outgoing power associated with a first message packet and the incoming power associated with a second message packet. A sensing means receives the incoming power from the directional coupling means during the transmission of the first message packet and indicates that a collision is occurring between the two transmissions. The directional coupling means comprises a cross-coupled voltage divider network configured such that a nulled voltage is generated at a pair of collision detection ports in response to the outgoing transmission, whereas a differential voltage is produced across the collision detection ports whenever an incoming colliding transmission appears.

Abstract: An error detection and correction method and apparatus is described which permits the correction of double errors using a (15,11) Hamming code and a parity bit. The Hamming code and parity bit allows the detection of double errors. A modulated waveform carrying the binary data is examined for anomalies such as noise pulses. A hint signal is generated based on the anomalies which points to a suspect bit. The state of this bit is changed to correct for double errors.

Abstract: A data communications network for delivering power and communications over the same cable bundle includes a plurality of communications nodes wherein associated with each of the nodes is a transformer having a core, a primary winding and a secondary winding. The secondary winding has a centertap connection which either splits or merges the current in the secondary winding to eliminate net DC flux within the transformer. A DC/DC converter is also included for transforming the relatively high DC voltage of the cable down to a regulated supply potential for use by that node. The converter is coupled between the centertap of the transformer and the cable bundle. A power source provides the DC voltage distributed across the network and is coupled to the cable bundle via a centertap connection of another winding.

Abstract: A high current CMOS circuit including a raised cosine signal generator for generating a raised cosine signal waveform and an input circuit arrangement for controlling the raised cosine signal generator is described. The raised cosine signal generator includes an output node to which a controlled chain of CMOS inverters are connected. The input circuit arrangement accepts an input signal, converts it into appropriate signals which drive respective inverters so that simultaneous conduction of inverter pairs is prevented. The off chip driver (OCD) minimizes ground bounce, electrical noise and radiation problems caused by large current transients or spikes (di/dt) that usually accompany such circuits.

Abstract: Described is an improved differential amplifier arrangement with a temperature compensated feedback circuit which sets and stabilizes the DC bias point of the amplifier. The circuit averages the two outputs of the amplifier and generates a DC voltage which is compared with a reference voltage to generate a control signal which is amplified and is used to control the bias point of the amplifier.

Abstract: Described is an improved electrical amplifier including a circuit arrangement which biases the amplifier so that current in an output stage of the amplifier is constant even though its load current varies. The circuit arrangement is configured so that the biasing current in the output stage is varied dynamically, thus compensating for changes in the current of the load which the amplifier drives.

Abstract: A pair of integrated circuits are described which provide a digital link between a branch exchange and a voice and data channel using an ordinary twisted pair. The downlink circuit permits coupling to a serial asynchronous port of different protocol than that used over the link and for instance, this port may be coupled to a keyboard, display or data terminal.

Abstract: A test control circuit includes a channel selector circuit and input and output buffers, which cooperate with input/output buses and respective latches of the multichannel apparatus, to allow an operator to select one or more input buses, and one or more output buses, of a respective channel or channels of the multichannel apparatus. Thus the circuit allows selectively applying an input test signal to one or more channels via the front of the apparatus, while selectively monitoring the resulting output signal from the channel or channels also via the front of the apparatus. An exemplary purpose of the test control system is to facilitate the channel alignment and head azimuth adjustment of, for example, a multichannel audio tape recorder.