Comtech EF Data DMD2401/DMD2401L - Manual (Page 178)

DMD2401/DMD2401L/DMD2401 IBS/IDR Satellite Modem Maintenance
TM065 - Rev. 3.3 6-3
Table 6-2. DMD2401 RX Fault Matrix
Note: When EXT EXC is used as a reference for the Mod Clock, and activity on the EXT
EXC is lost, the modem switches Tx clock reference to SCTE if it exists, otherwise it
switches to SCT.
Table 6-3. DMD2401 TX Fault Matrix