
Data Sheet
75
Rev. 1.0, 2005-06-02
OctalLIU
TM
PEF 22508 E
Functional Description
By the registers XMP(2:0) compatible to the QuadLIU
XPM2.XPDIS is cleared, see XPM2 Or by the registers TXP(16:1), see TXP1, if the register bit XPM2.XPDIS is set, see Table 26 and Table 27.
For more details see chapter “Operational Description”
To reduce the crosstalk on the received signals in long haul applications the OctalLIU
TM offers the ability to place
a transmit attenuator (Line Build-Out, LBO) in the data path. This is used only in T1 mode. LBO attenuation is
selectable with the values 0, -7.5, -15 or -22.5 dB (register bits LIM2.LBO(2:1)). ANSI T1. 403 defines only 0 to -
15 dB.
Figure 32
Measurement Configuration for E1 Transmit Pulse Template
Figure 33
Measurement Configuration for T1/J1 Transmit Pulse Template
3.9.6.1
QuadLIU
TM Compatible Programming
After reset XPM2.XPDIS is zero so that programming with XPM(2:0) is selected. The default setting after reset for
the registers XMP(2:0) generates the E1 pulse shape, see Table 25, but with an unreduced amplitude. No reset
value for T1 mode exists. So after switching into T1 mode, an explicit new programming like described in Table 24 is necessary.
If LBO attenuation is selected, the programming of XPM(2:0) will be ignored. Instead the pulse shape
programming is handled internally: The generated pulse shape before LBO filtering is the same as for T1 0 to 40 m.
The given values are optimized for transformer ratio: 1 : 2.4 and cable type AWG24 using transmitter
load
= 120
load = 100 are used.
Table 24
Recommended Pulse Shaper Programming for T1/J1 with Registers XPM(2:0) (Compatible to
QuadLIU )
LBO
Range
XPM0
XPM1
XPM2
(dB)
(m)
(ft)
Hexadecimal
0
0 to 40
0 to 133
D7
22
11
0
40 to 81
133 to 266
FA
26
11
0
81 to 122
266 to 399
3D
37
11
OctalLIU_pulse_meas_temp_E1
OctalLIUTM
R
SER
R
load
U
PULSE
see chapter 3.6.1.
XL1
XL2
XL3
XL4
OctalLIU_pulse_meas_temp_T1
OctalLIUTM
R
SER
Cable, Z
0
R
load
0 to 200 m
U
PULSE
see chapter 3.6.1.
XL1
XL2
XL3
XL4
(0 to 655 ft)