XRT86L30
SINGLE T1/E1/J1 FRAMER/LIU COMBO
REV. 1.0.1
8.1.5
QRSS Generation
The XRT86L30 can transmit a QRSS random sequence to a remote location from TTIP/TRING. The
polynomial is shown in Table 170.
T
ABLE 170: RANDOM
B
IT
S
EQUENCE
P
OLYNOMIALS
E1
R
ANDOM
P
ATTERN
T1
20 - 1
2
215 - 1
QRSS/PRBS
8.2
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 52, a
pulse with -15dB attenuation is shown in Figure 53, and a pulse with -22.5dB attenuation is shown in
Figure 54.
F
IGURE 52. LONG HAUL LINE BUILD OUT WITH -7.5DB ATTENUATION
F
IGURE 53. LONG
H
AUL
L
INE
B
UILD
O
UT WITH -15
D
B ATTENUATION
185
EXAR [ EXAR CORPORATION ]
