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XRT86VL38
PRELIMINARY
xr
OCTAL T1/E1/J1 FRAMER/LIU COMBO
REV. P1.0.6
309
4.2.5
Receive Interface with 1:1 and 1+1 Redundancy
The receivers on the backup card should be programmed for "High" impedance. Since there is no external
resistor in the circuit, the receivers on the backup card will not load down the line interface. This key design
feature eliminates the need for relays and provides one bill of materials for all interface modes of operation.
Select the impedance for the desired mode of operation, T1/E1/J1. To swap the primary card, set the backup
card to internal impedance, then the primary card to "High" impedance. See Figure 15. for a simplified block
diagram of the receive section for a 1:1 redundancy scheme.
F
IGURE
15. S
IMPLIFIED
B
LOCK
D
IAGRAM
OF
THE
R
ECEIVE
I
NTERFACE
FOR
1:1
AND
1+1 R
EDUNDANCY
"High" Impedence
Internal Impedence
Backplane Interface
Primary Card
Backup Card
XRT86VL38
Rx
T1/E1 Line
Rx
1:1
1:1
XRT86VL38