Abstract: A device and method for detecting digital impairments affecting an upstream pulse code modulation (PCM) channel in a digital communication network, involves; receiving, by a digital PCM modem interconnected to the digital communication network, a random sequence of digital values selected from a constellation of digital values transmitted over the upstream PCM channel of the digital communication network; establishing distributions of the received digital values, each distribution corresponding to one of a plurality of time intervals; and deriving from the distributions the types of robbed bit signaling and digital loss affecting the upstream PCM channel of the digital communication network for each time interval.

Abstract: A device and method for preceding data signals for pulse code modulation (PCM) transmission includes a transmitter for transmitting a sequence of analog levels over an analog channel to a quantization device, wherein the analog channel modifies the transmitted analog levels, the transmitter comprising: a mapping device for mapping data bits to be transmitted to a sequence of equivalence classes, wherein each equivalence class contains one or more constellation points; and a constellation point selector interconnected to the mapping device which selects a constellation point in each equivalence class to represent the data bits to be transmitted and which transmits an analog level that produces the selected constellation point at an input to the quantization device.

Abstract: A device and method for precoding a sequence of analog levels transmitted over an analog channel to a quantization device, wherein the analog channel modifies the transmitted analog levels, including: a mapping device for mapping data bits to be transmitted to a sequence of equivalence classes, wherein each equivalence class contains one or more constellation points; a constellation point selector interconnected to the mapping device which selects a constellation point in each equivalence class to represent the data bits to be transmitted and which transmits a level that produces the selected constellation point at an input to the quantization device; and a filter device, operably coupled to the constellation point selector, which receives at its input previously transmitted levels and provides its output to the constellation point selector; wherein the filter device has a filter response which is based on the previously transmitted levels and a target response, and the target response is adapted using an ana

Abstract: In a digital communication device adapted to be coupled to a digital network and having an analog port adapted for interconnecting an analog device to the digital communication device, a device for generating and detecting tones, includes: a processor programmed to selectively generate one of a first set of digital tones in a generation mode and to detect one of a second set of digital tones in a detection mode; and a conversion circuit, operably coupled to the processor, adapted to convert the one of the first set of digital tones generated by the processor in the generation mode to an analog tone and transmit the analog tone to the analog device; the conversion circuit further being adapted to convert an analog tone received from the analog device to the one of the second set of digital tones and transmit the digital tone to the processor when the processor is in the detection mode.

Abstract: A method and apparatus for interfacing protocol application data frame operation requests with a data frame input/output device having a buffer structure containing data frames according to a buffer structure scheme, while maintaining isolation between the buffer structure and the protocol applications, including: receiving, with an interface, from a protocol application a data frame operation request for operation on a portion of an identified data frame within the buffer structure; linking, with the interface, the request to an appropriate data frame operation routine in the data frame input/output device; and the data frame operation routine executing the request, in conjunction with the protocol application, on the portion of the identified data frame without requiring that the protocol application have knowledge of the buffer structure scheme.

Abstract: The apparatus and method for high speed data and command transfer over an interface (202), such as an ISA or PCMCIA bus or interface, includes a transceiver (206) and a processor (210) having a direct memory access (DMA) controller (240), a memory (211) for storage of data, and a channel interface (218) for connection to a communications channel. The processor (210) is responsive through a set of program instructions, such as software or firmware, to receive an interrupt signal (310, 315) and, when the interrupt signal indicates a write command (320, 330), to transfer data via the transceiver from the interface to the memory for transmission over the communications channel (335), and when the interrupt signal indicates data received from the communications channel (350), the processor further responsive to generate a read command and transfer data from the memory to the interface via the transceiver (355).

Abstract: Architectures for a ferroelectric memory which avoids the half select phenomenon and the problems associated with destructive readout. Non-destructive readout is provided by measuring current through the ferroelectric memory as a measure of its resistance. Information is stored in the ferroelectric memory element by altering its resistance through a polarizing voltage. The half select phenomenon is avoided by using isolation techniques. In various embodiments, zener diodes or bipolar junction transistors are used for isolation.

Abstract: An apparatus, software modem, and method for a data communications device, such as a modem (100, 101), to determine a symbol rate and carrier frequency, from a received probe signal, for optimizing a bit rate for data transmission and reception. The various embodiments utilizing a processor (108) or a digital signal processor (106) receive a probe signal, which also typically contains noise and other distortions, particularly envelope delay distortion. The various method and apparatus embodiments then determine a variance of the envelope delay distortion, either directly or indirectly as a correlate of attenuation distortion or as a correlate of a selected transmit pre-emphasis filter specified under the ITU V.34 protocol. The variance of the envelope delay distortion is then utilized to eliminate or disable certain symbol rates and corresponding carrier frequencies in the determination of an optimal symbol rate and carrier frequency for data transmission and reception.

Abstract: A multiple terminal selector switch for use with millimeter-wave signals has a layout of components enabling the switch to be constructed on a monolithic microwave integrated circuit (MMIC) chip while maintaining adequately low cross talk among ports of the switch to retain isolation among its ports. The circuitry includes a transmission line having multiple taps spaced apart by an integral number of half wavelengths of the signal, wherein the taps connect to separate ports via arms of the circuit. Each arm has an electronically switchable element for producing open or short circuits for connection and disconnection of a switch port from the transmission line. One primary tap of the transmission line is unswitched and connects with a further port from which, or to which, signals of the other ports are selectively switched.

Abstract: A transmitter for transmitting a sequence of octets over a digital network which digital network converts the octets into a sequence of levels for transmission over an analog channel to a receiver, the levels producing an analog signal having a predefined spectral shape, the transmitter including: a mapping device which receives at its input groups of data bits to be transmitted and outputs for each group an equivalence class of one or more levels, wherein at least one equivalence class contains more than one level; a level selector, operably coupled to the mapping device, for selecting the level in the equivalence class to represent the group of data bits to be transmitted; a filter device, operably coupled to the level selector and having a filter response corresponding to the predefined spectral shape, which receives at its input previously selected levels and provides its output to the level selector, wherein the level selector selects the level to be transmitted based on the output of the filter device;

Abstract: System and Device for, and Method of, Communicating According to a Trellis Code of Baseband Signals Chosen from a Fixed Set of Baseband Signal Points. Signal points are chosen from a fixed set of signal points, such as exists in the baseband signal points found in PSTN companding algorithms. These signal points are assingned to subsets and transmitted according to a predefined transmitter state sequence, representable as a trellis diagram. The subsets may overlap by sharing signal points. The sharing of signal points improves the transmission performance of the arrangement in comparison to conventional disjoint sets. The signal points are selected and associated with subsets, such that the signal points transmittable from a given transmitter states maintain a minimum distance of d, even though the full combination of signal points of all subsets need not satisfy a minimum distance of d/2.

Abstract: An apparatus and method are provided for a data communications device, such as a modem (100, 101) or facsimile machine, to detect and discriminate various amplitude modulated signals, such as an ANS signal of the ITU V.25 protocol and an ANSam signal of the ITU V.8 protocol, which may be subject to impulse distortions (FIG. 5B). The apparatus and method embodiments band pass filter (204) an incoming signal at a first frequency, and dynamically limit (208) any impulse distortions of the incoming signal to a limit threshold (211). The limit thresholds may be dynamically determined by rectifying (209) and low pass filtering (210) the band pass filtered signal to determine a low frequency average magnitude level of the incoming signal, with the limit thresholds set as a predetermined variance from this low frequency average magnitude level.

Abstract: A data communications system (10) has a system management controller (100) and multiple data communications devices (21-1 through 21-n). The system management controller has a processor (110) and random access memory (115). The various data communications devices (21-1 through 21-n) are coupled to the system management controller (100) through a common address bus (12) and a common management bus (11). Through the processor (110), the system management controller (100) sequentially addresses each of the data communications devices (21-1 through 21-n) at a default data rate and determines a requested data rate for each device (FIG. 6, 305-333). The system management controller (100), through the processor (110), stores this requested data rate information, correlated with the address of each data communication device, in the random access memory (115) (FIG. 6, 305), and communicates with each such device at its requested data rate (FIG. 6, 335; FIG. 10, 500-545).

Abstract: Data communication stations 10, 12, 14 are connected by way of a shared bus 15 common to all the communication stations. When two stations attempt to access the shared bus simultaneously, a conflict resolution method if used to determine which of the two stations is allowed access to the bus 15. Each station seeking access to the bus 15 serially transmits its address. The priority of the stations is determined, and the station with priority is given access to the bus 15.

Abstract: A data communication system (100) has a table driven state machine (300) for communicating call establishment and call termination information with a network switch (200). The table driven state machine (300) has a processor (310) and a memory (320) which stores a set of vectors defining a state transition table for a predetermined signaling type of the switch (200), such as trunk signaling or wink start signaling. The set of vectors defines state transitions and output signals, such as transmit AB signaling bits and a ring flag, based upon input signals of the predetermined signaling type, such as receive AB signaling bits and an off hook flag. The set of vectors is utilized by the processor (310) to receive signaling information from the switch, and to generate signaling information to the switch and other output signals to the data communication system, all corresponding to the predetermined signaling type.

Abstract: An apparatus and method for a data communications device, such as a modem (100, 101), to determine a symbol rate and carrier frequency combination, from a received probe signal, for optimizing a bit rate for data transmission and reception. The various embodiments utilizing a processor (108) or a digital signal processor (106) receive a probe signal, which also typically contains noise and other distortions. The various method and apparatus embodiments then determine signal to distortion ratios for a plurality of symbol rate and carrier frequency combinations (820), and other optimization parameters, such as channel characteristics and attenuation distortion parameters (830). These optimization parameters are then utilized to determine an optimal symbol rate and carrier frequency (840).

Abstract: A system (10) and method for simultaneously enabling a voice and a data session has a voice data modem (200) coupleable to a data port (255), a voice jack (240), and a telco jack (280). The data port (255) is connected to data terminal equipment (100), the voice jack (240) is connected to a telephone, and the telco jack (280) is connected to a telephone network (120). The data ports for each of a plurality of voice data modems are connected to other data terminal equipment (180, 181, 182), the voice jacks are connected to first extensions of a net telco jacks are connected to different, second extensions of the network. The voice data modem (200) may receive multiplexed voice and data over a single, first extension of the network through the telco jack, (280), dumultiplex and decompress the voice and data, transmit or retransmit the voice separately from the data over a second network extension via the voice jack (240), and transmit the data to data terminal equipment through a data port or interface (255).