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N/B Maintenance
N/B Maintenance
Data bits to be transmitted through the cable port are received from the LLC on two, four or eight parallel paths
(depending on the requested transmission speed) and are latched internally in the TSB41AB1 in
synchronization with the 49.152-MHz system clock. These bits are combined serially, encoded, and transmitted
at 98.304, 196.608, or 393.216Mbits/s (referred to as S100, S200, and S400 speeds, respectively) as the
outbound data-strobe information stream. During transmission, the encoded data information is transmitted
differentially on the TPB cable pair, and the encoded strobe information is transmitted differentially on the
TPA cable pair.
During packet reception the TPA and TPB transmitters of the receiving cable port are disabled, and the
receivers for that port are enabled. The encoded data information is received on the TPA cable pair, and the
encoded strobe information is received on the TPB cable pair. The received data-strobe information is decoded
to recover the receive clock signal and the serial data bits. The serial data bits are split into two-, four-, or eight-
bit parallel streams (depending upon the indicated receive speed), resynchronized to the local 49.152-MHz
system clock and sent to the associated LLC.
Both the TPA and TPB cable interfaces incorporate differential comparators to monitor the line states during
initialization and arbitration. The outputs of these comparators are used by the internal logic to determine the
arbitration status. The TPA channel monitors the incoming cable common-mode voltage. The value of this
common-mode voltage is used during arbitration to set the speed of the next packet transmission. In addition,
the TPB channel monitors the incoming cable common-mode voltage on the TPB pair for the presence of the
remotely supplied twisted-pair bias voltage.
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