1 liu operation, Liu operation – Rainbow Electronics DS26519 User Manual
Page 92
DS26519 16-Port T1/E1/J1 Transceiver
92 of 310
9.12.1 LIU Operation
The analog AMI/HDB3 waveforms off of the E1 lines or the AMI/B8ZS waveform off of the T1 lines are transformer
coupled into the RTIPn and RRINGn pins of the DS26519. The user has the option to use partially internal
termination, software selectable for 75
Ω/100Ω/110Ω/120Ω applications (in combination with an external 120Ω
resistor) or external termination. The LIU recovers clock and data from the analog signal and passes it through the
jitter attenuation mux. The DS26519 contains an active filter that reconstructs the analog received signal for the
nonlinear losses that occur in transmission. The receive circuitry also is configurable for various monitor
applications. The device has a usable receive sensitivity of 0dB to -43dB for E1 and 0dB to -36dB for T1, which
allows the device to operate on 0.63mm (22AWG) cables up to 2.5km (E1) and 6k feet (T1) in length. Data input to
the transmit side of the LIU is sent via the jitter attenuation mux to the wave shaping circuitry and line driver. The
DS26519 will drive the E1 or T1 line from the TTIPn and TRINGn pins via a coupling transformer. The line driver
can handle both CEPT 30/ISDN-PRI lines for E1 and long-haul (CSU) or short-haul (DSX-1) lines for T1. The
registers that control the LIU operation are shown in
Table 9-38. Registers Related to Control of the LIU
REGISTER
FRAMER
ADDRESSES
FUNCTION
Global Transceiver Clock Control Register 1
(
00F3h
MPS selections, backplane clock
selections.
Global LIU Software Reset Register 1 (
) 00F6h
Global LIU Software Reset Register 2 (
) 20F6h
Software reset control for the LIU.
Global LIU Interrupt Status Register 1 (
) 00FBh
Global LIU Interrupt Status Register 2 (
) 20FBh
Interrupt status bit for each of the 16 LIUs.
Global LIU Interrupt Mask Register 1 (
) 00FEh
Global LIU Interrupt Mask Register 2 (
) 20FEh
Interrupt mask register for the LIU.
LIU Transmit Receive Control Register (
) 1000h*
T1/J1/E1 selection, output tri-state, loss
criteria.
LIU Transmit Impedance and Pulse Shape
Selection Register (
1001h*
Transmit pulse shape and impedance
selection.
LIU Maintenance Control Register (
) 1002h*
Transmit maintenance and jitter
attenuation control register.
LIU Real Status Register (
1003h*
LIU real-time status register.
LIU Status Interrupt Mask Register (
) 1004h*
LIU mask registers based on latched
status bits.
LIU Latched Status Register (
) 1005h*
LIU latched status bits related to loss, open
circuit, etc.
LIU Receive Signal Level Register (
)
1006h*
LIU receive signal level indicator.
LIU Receive Impedance and Sensitivity Monitor
Register (
1007h*
LIU impedance match and sensitivity
monitor.
*The address shown is for LIU 1.