US 5,970,051 AGranted

Reduction of errors in D4 channel bank by multiframe comparison of transmit enable lead to determine whether analog channel unit is installed in D4 channel bank slot

AssigneeAdtran, Inc.

InventorsDavid L. Mack, Michael W. Elliott, Clifford Hall

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Abstract

The problem of digital data corruption heat occurs when an analog card is inserted into a card/time slot of a D4 channel bank is effectively remedied by sampling and analyzing the channel bank's transmit enable (TNEN) lead for successive frames of time slots. Unless analyzed TNEN lead samples of a channel unit time slot of interest derived over successive frames have the same logic state associated with an analog channel unit, the PCM data lead remains default-coupled to a digital data transmission lead. This prevents PCM-encoded spurious noise on the analog PAM lead from being erroneously asserted in place of serialized digital data bits that should have been passed directly from the digital data bus to the PCM bus.

Claims23

Dependent claims

For use with a telephone communication network channel bank located at a first site and including a plurality of channel unit connector slots for installing one or more respective channel units, a respective channel unit communicating with a customer site over a communication path therebetween, and being operative, during a respective time slot, to transmit communication signals over an intra-channel bank communication link to a line interface unit, said intra-bank communication link including a lead, the state of which is asserted to a logic state representative of the type of said respective channel unit during said respective time slot, said line interface unit being operative to transmit digital communication signals over a time division multiplex communication link to a second site, a method of making a valid identification of the type of channel unit installed in said respective channel unit connector slot comprising the steps of:

(a) during respectively different time periods associated with said respective channel unit connector slot of said channel bank, sampling the state of said lead;
(b) determining the type of channel unit installed in said respective channel unit connector slot in accordance with a prescribed relationship between sampled states of said lead for said respectively different time periods associated with said respective channel unit connector slot;
and
wherein step (a) comprises sampling the state of said lead multiple times during each of said respectively different time periods associated with said respective channel unit connector slot of said channel bank and, for each of said respectively different time periods, defining the state of said lead in accordance with a majority decision of multiple samples of said lead.

1 more element

For use with a telephone communication network channel bank located at a first site and including a plurality of channel unit connector slots for installing a plurality of channel units, a respective channel unit communicating with a customer site over a communication path therebetween, and being operative, during a respective time slot, to transmit communication signals over an intra-channel bank communication link to a line interface unit, said intra-channel bank communication link including a digital data bus portion and an analog data bus portion, said intra-bank communication link further including a lead, the logic state of which is representative of the type of said respective channel unit during said respective time slot, said line interface unit being operative to transmit, over a time division multiplex communication link to a second site, communication signals that are provided on a selected one of said digital data bus portion and said analog data bus portion, in accordance with the logic state of said lead, a method of making a valid identification of the type of channel unit installed in said respective channel unit connector slot and thereby selecting said one of said digital data bus portion and said analog data bus portion of said intra-channel bank communication link for transmission of communication signals to said line interface unit, comprising the steps of:

(a) for successive frames of time slots, sampling the state of said lead during said respective time slot;
(b) determining the type of channel unit installed in said respective channel unit connector slot in accordance with a prescribed relationship between sampled states of said lead as sampled in step (a) during said respective time slot for said successive frames of time slots;
and
(c) selecting one of said digital data bus portion and said analog data bus portion of said intra-channel bank communication link for transmission of communication signals to said line interface unit, in accordance with the type of channel unit determined in step (b).

1 more element

For use with a telephone communication network channel bank located at a first site and including a plurality of channel unit connector slots for installing a plurality of channel units, a respective channel unit communicating with a customer site over a communication path therebetween, and being operative, during a respective time slot, to transmit communication signals over an intra-channel bank communication link to a line interface unit, said intra-channel bank communication link including a digital data bus portion and an analog data bus portion, said intra-bank communication link further including a lead, the logic state of which is representative of the type of said respective channel unit during said respective time slot, said line interface unit being operative to transmit, over a time division multiplex communication link to a second site, communication signals that are provided on a selected one of said digital data bus portion and said analog data bus portion, in accordance with the logic state of said lead, an arrangement for making a valid identification of the type of channel unit installed in said respective channel unit connector slot and selecting said one of said digital data bus portion and said analog data bus portion of said intra-channel bank communication link for transmission of communication signals to said line interface unit, comprising:

a sampling unit which is operative to sample the state of said lead during said respective time slot for successive frames of time slots;
a comparator which is operative to determine the type of channel unit installed in said respective channel unit connector slot in accordance with a prescribed relationship between sampled states of said lead as sampled by said sampling unit during said respective time slot for said successive frames of time slots;
and
a data bus portion selector which is operative to select one of said digital data bus portion and said analog data bus portion of said intra-channel bank communication link for transmission of communication signals to said line interface unit, in accordance with the type of channel unit determined by said comparator.

1 more element

Dependencies are inferred from the claim text.