XRT86L30
SINGLE T1/E1/J1 FRAMER/LIU COMBO
REV. 1.0.1
9.2
Receive Sensitivity
To meet Long Haul receive sensitivity requirements, the XRT86L30 can accept T1/E1/J1 signals that have
been attenuated by 43dB cable attenuation in E1 mode or 36dB cable attenuation in T1 mode without
experiencing bit errors, LOF, pattern synchronization, etc. Short haul specifications are for 12dB of flat loss in
E1 mode. T1 specifications are 655 feet of cable loss along with 6dB of flat loss in T1 mode. The XRT86L30
can tolerate cable loss and flat loss beyond the industry specifications. The receive sensitivity in the short haul
mode is approximately 4,000 feet without experiencing bit errors, LOF, pattern synchronization, etc. Although
data integrity is maintained, the RLOS function (if enabled) will report an RLOS condition according to the
receiver loss of signal section in this datasheet. The test configuration for measuring the receive sensitivity is
shown in Figure 61.
F
IGURE 61. TEST
C
ONFIGURATION FOR
M
EASURING
R
ECEIVE
S
ENSITIVITY
W&G ANT20
Rx
Tx
External Loopback
Tx
Rx
Flat Loss
Cable Loss
XRT86L30
1-Channel
Framer/LIU
Network
Analyzer
E1 = PRBS 215 - 1
T1 = PRBS 223 - 1
9.2.1
AIS (Alarm Indication Signal)
The XRT86L30 adheres to the ITU-T G.775 specification for an all ones pattern. The alarm indication signal is
set to "1" if an all ones pattern (at least 99.9% ones density) is present for T, where T is 3ms to 75ms in T1
mode. AIS will clear when the ones density is not met within the same time period T. In E1 mode, the AIS is
set to "1" if the incoming signal has 2 or less zeros in a 512-bit window. AIS will clear when the incoming signal
has 3 or more zeros in the 512-bit window.
9.2.2
NLCD (Network Loop Code Detection)
The Network Loop Code Detection can be programmed to detect a Loop-Up, Loop-Down, or Automatic Loop
Code. If the network loop code detection is programmed for Loop-Up, the NLCD will be set "High" if a
repeating pattern of "00001" occurs for more than 5 seconds. If the network loop code detection is
programmed for Loop-Down, the NLCD will be set "High" if a repeating pattern of "001" occurs for more than 5
seconds. If the network loop code detection is programmed for automatic loop code, the LIU is configured to
detect a Loop-Up code. If a Loop-Up code is detected for more than 5 seconds, the XRT86L30 will
automatically program the channel into a remote loopback mode. The LIU will remain in remote loopback even
if the Loop-Up code disappears. The channel will continue in remote loop back until a Loop-Down code is
detected for more than 5 seconds (or, if the automatic loop code is disabled) and then automatically return to
normal operation with no loop back. The process of the automatic loop code detection is shown in Figure 62.
191
EXAR [ EXAR CORPORATION ]
