Datasheet

DS26303: 3.3V, T1/E1/J1, Short-Haul, Octal Line Interface Unit
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6.8.4 Dual Loopback
A dual loopback is created by enabling both a remote loopback and a digital loopback. The transmit system data
TPOSn, TNEGn, and TCLKn are looped back to output on RCLKn, RPOSn, and RNEGn. The inputs at RTIPn and
RRINGn are looped back to TTIPn and TRINGn. This loopback is conceptually shown in
Figure 6-11.
Figure 6-11. Dual Loopback
Line
Driver
HDB3/
B8ZS
Encoder
Transmit
Digital
Transmit
Analog
TCLK
TPOS
TNEG
HDB3/
B8ZS
Decoder
RCLK
RPOS
RNEG
RTIP
RRING
TPOS
TNEG
Receive
Digital
Receive
Analog
Optional
Jitter
Attenuator
Optional
Jitter
Attenuator