Abstract:
A method and device for transmitting a preamble sequence is disclosed. A transmitter according to an embodiment may extract a first sequence for a non-coherent receiver and a second sequence for a coherent receiver, from ternary preamble sequences including elements −1, 0 and 1, and map the first sequence and the second sequence to a preamble including a plurality of bits to generate a third sequence that the non-coherent receiver and coherent receiver support.
Abstract:
Line coding mismatches on a transmission channel in a telecommunications network will manifest a constant error signature having a certain number of errored seconds, severely errored seconds, unavailable time and lost sync. errors upon the application of a test pattern comprising a sequence of a first, second and third octet, each repeated a prescribed number of times. The first and second octets remain constant regardless of the nature of the transmission channel, while the nature of the third octet varies according to the transmission rate of the DS0 under test and associated DS1 under test. The test pattern will reveal a line coding mismatch. In a B8ZS environment (64 Kbps clear channel capability), the pattern may be run on any DS0 channel within the DS1. In an AMI-with-ZCS environment (56 Kbps or 64 Kbps restricted), the pattern must run on either channel 1 or 24.
Abstract:
A symbol detection and correction scheme for local area network modems, especially those which receive one of three symbols at any given time, such as those operating in accordance with the IEEE 802.4 standard. The invention significantly improves the bit error rate observed by the layer above the modem. The modem operates on a received signal with a pair of slicers. One slicer operating as a two-symbol detector, and a second slicer operates as a three-symbol detector. A receiver state machine is used to keep track of which portion of a frame is currently expected to be being received. Depending upon the particular context, one or both of the slicer outputs are used by the state machine to determine which of the three symbols was received. For example, when the receiver is in a state where only one of two data symbols are expected, and no control symbols are expected, only the two-symbol slicer output is used. The three-symbol slicer output, and logical combinations of the three-symbol slicer output and the two-symbol slicer output, are used as other times. The receiver state machine recognizes errors in pseduo-silence, start delimiter, and end-delimiter sequences without reporting such errors to the upper level, thereby greatly decreasing the error rate observed there.
Abstract:
An automatic selector for a data transmission line corrector selectively inserts a plurality of correctors in sequence in the line and measures the bipolarity errors associated with each corrector. The corrector which provides the least error is then connected to the line for purposes of that transmission.
Abstract:
PURPOSE:To detect an appropriate pulse trio with a simple circuit, by providing the circuit with a decoder circuit detecting that the counted value of a counter is ''2'' and a gate circuit detecting that the number of input pulses between violation pulses is ''2''. CONSTITUTION:When a trio string is inputted, the counted value of the counter 12 is ''2'' at the generation of violation error pulses. Namely, the number of unipolar pulses between violation error pulses is ''2''. When the counted value of the counter 12 is ''2'', outputs QA, QC, QD are turned to ''0'' and only an output QB is ''1''. Consequently, the output (d) of an AND gate 14 is turned to the high level and the output (e) of an AND gate 15 to which the output (d) and the output (b) of a violation error detector 11 are inputted is turned to ''1'', the high level, so that the pulse trio is detected.
Abstract:
System, methods and apparatus are described that facilitate tests and measurements related to multi-wire, multi-phase communications links. Information is transmitted in N-phase polarity encoded symbols and an eye pattern corresponding to the symbols is generated such that the symbols are aligned with a trigger for each symbol that corresponds to a clock edge used to sample the symbols. The eye pattern may be used to determine sufficiency of setup times in the communication links and other such characteristics defining a communications channel capabilities.
Abstract:
A HDB3 code violation detector includes a converting part (1) for receiving positive polarity data and negative polarity data from a PCM line and for converting a HDB3 code received via the PCM line into an NRZ signal, a first judging part (2) receiving the positive polarity data, the negative polarity data and the NRZ signal, for judging whether or not a pattern of the NRZ signal received from the converting part is possible when the NRZ signal is NRZ "1" and for outputting a judgement result, a second judging part (3) receiving the positive polarity data, the negative polarity data and the NRZ signal, for judging whether or not a pattern of the NRZ signal received from the converting part is possible when the NRZ signal has a maximum of three consecutive NRZ "0"s and for outputting a judgement result, a third judging part (4) receiving the positive polarity data, the negative polarity data and the NRZ signal, for judging whether or not a pattern of the NRZ signal received from the converting part is possible when the NRZ signal has at least four consecutive NRZ "0"s and for outputting a judgement result, and a detecting part (5) for detecting a code violation of the HDB3 code based on the judgement results of the first, second and third judging parts.
Abstract:
Zur Betriebsüberwachung in PCM-Strecken wird bei Verwendung eines redundanten Codes von der Möglichkeit Gebrauch gemacht, Fehler durch Verletzungen der Coderegel festzustellen. Bei Umcodierung der Übertragungssignale in den Zwischenregeneratoren der Ubertragungsstrecke ist es notwendig, für jeden einzelnen Regenerator einen Coderegel-Verletzungsprüfer vorzusehen, wodurch der Aufwand in den Regeneratoren ansteigt. Entsprechend der Erfindung ist der Coderegel-Verletzungsprüfer in den Impulsregenerator mit einbezogen, so daß dafür nur ein zusätzliches RS-Flipflop (RSFF), zwei Laufzeitglieder (τ1, τ2) und zwei Gatteranordnungen (NOR1,NOR2) notwendig sind. Die Anwendung der Erfindung erfolgt bei PCM-Strecken mit im AMI-Code vorliegenden Übertragungssignalen und insbesondere bei Übertragungsstrecken mit Schrittgeschwindigkeiten von einigen hundert Mbits.