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PRELIMINARY
XRT86VL38
REV. P1.0.6
OCTAL T1/E1/J1 FRAMER/LIU COMBO
346
7.1.4
Network Loop Down Code
By setting the LIU to generate a NLDC, the transmitters will send out a repeating "001" pattern. The output
waveform is shown in Figure 55.
7.1.5
QRSS Generation
The XRT86VL38 can transmit a QRSS random sequence to a remote location from TTIP/TRING. The
polynomial is shown in Table 183.
7.2
T1 Long Haul Line Build Out (LBO)
The long haul transmitter output pulses are generated using a 7-Bit internal DAC (6-Bits plus the MSB sign bit).
The line build out can be set to -7.5dB, -15dB, or -22dB cable attenuation by programming the appropriate
channel register. The long haul LBO consist of 32 discrete time segments extending over four consecutive
periods of TCLK. As the LBO attenuation is increased, the pulse amplitude is reduced so that the waveform
complies with ANSI T1.403 specifications. A long haul pulse with -7.5dB attenuation is shown in Figure 56, a
pulse with -15dB attenuation is shown in Figure 57, and a pulse with -22.5dB attenuation is shown in
Figure 58.
F
IGURE
55. N
ETWORK
L
OOP
D
OWN
C
ODE
G
ENERATION
T
ABLE
183: R
ANDOM
B
IT
S
EQUENCE
P
OLYNOMIALS
R
ANDOM
P
ATTERN
T1
E1
QRSS/PRBS
2
20
- 1
2
15
- 1
F
IGURE
56. L
ONG
H
AUL
L
INE
B
UILD
O
UT
WITH
-7.5
D
B A
TTENUATION
Network
Loop-Down
Code
1
1
1
1
0
0
0
0
0
0
0