Comtech EF Data SDM-650B - Manual (Page 159)

SDM-650B Satellite Modem Maintenance
Rev. 6 6–15
6.3 Interface Fault Isolation
Stored faults for the interface are reported in the StFaults menu (refer to Chapter 4).
The following sections list the interface faults. All other faults are discussed in Section
6.2.
6.3.1 Transmit Faults (TX_INTF)
The faults listed below are only displayed when the ASYNC overhead channel unit is
installed.
Fault Possible Problem and Action
TX_PLL Indicates a loss of lock on the reference of the interface transmit clock recovery
oscillator.
Return the interface card for repair.
CLK_ACT Loss of activity on the selected transmit clock source.
The modem will fallback to the internal SCT clock source with an accuracy
of 10
-5 .