ADC and 3 Doubler - Manual (Page 29)

LTPH-UM-1234-01 Loopback Operation in HiGain Systems
HDU-409 Lists 1, 2, and 3 April 30, 2003 23
The SPLB generic command set for four-doubler loopbacks is listed in
Table 7 . The commands are specific combinations of either 6 or 7 bits that
continuously repeat. All NDUx loopbacks are towards the network. All
CDUx loopbacks are towards the customer.
Figure 6 on page 24 is a diagram
of the various HiGain loopbacks.
Table 7. SPLB Generic Command Set
Command Set Loopback
NDU1 1 1 0 0 0 0 (2-in-6)
NDU2 1 1 1 0 0 0 (3-in-6)
NDU3 1 0 1 0 0 0 1
NDU4 1 0 1 0 0 1 0
CDU1 1 1 1 1 0 0 (4-in-6)
CDU2 1 1 1 1 1 0 (5-in-6)
CDU3 1 0 1 1 0 0 1
CDU4 1 0 1 1 0 1 0