Nortel Networks Circuit Card - Manual (Page 756)

Page 756 of 906 NTAK79 2.0 Mb PRI card
553-3001-211 Standard 3.00 August 2005
requirements of the CCITT recommendation G.742. This provides jitter
attenuation increasing from 0 dB to 60 dB over the frequency range from
about 6 Hz to 6 KHz.
Transmitter functions
The transmitter takes the binary (dual unipolar) data from the PCM
transceiver and produces bipolar pulses which conform to the CCITT
recommendation G.703 pulse shape.
Loopbacks
The remote loopback function causes the device to transmit the same data that
it receives, using the jitter attenuated receive clock. The data is also available
at the receive data outputs. Local loopback causes the transmit data and clock
to appear at the receive clock and data outputs. This data is also transmitted
on the line unless transmit AIS is selected.
CEPT transceiver
The transmitter and receiver functions are used for synchronization, channel,
and signal extraction. The functions meet applicable specifications of the
CCITT recommendation G.703 and G.732.
The transceiver provides transmit framing based on the 2.048 MHz clock
derived from the DS-30X system clock and 1 KHz framing pulse.
Slip control
Slip control provides organized recovery of PCM when the clock recovered
from the external facility is at a different frequency than the local clock.
D-channel support interface
The D-channel support interface is a 64 Kbps, full-duplex serial bit stream
configured as a DCE device. The data signals include:
• Receive data output
• transmit data input