Comtech EF Data SDM-309B - Manual (Page 124)

SDM-309B Satellite Modem M&C and Interfaces
MN/U-SDM309B Rev. # 4-4–47
an exact frame length, causing minimum loss of data. By using very high stability clocks,
the expected time between slips can be many days.
Loss of the buffer clock will mean the buffer will not be emptied and no data will be
available. The buffer clock will normally revert to the low stability internal reference
automatically.
4.3.2.1 Master/Master (Customer Clock)
Modem Settings (Master)
TX_CLOCK TX_TERR
BUFF_CLK TX_TERR
RX_CLK NORMAL
EXT_REF N/A
4.3.2.2 Master/Master (Station Clock)
Care should be taken when using this mode. Make sure that the station clock is also used
to synchronize the transmit data. Phasing problems may also occur between the transmit
data and the station clock input and for this reason, it is better to use the TERR clock on
transmit.
Modem Settings (Master)
SDM-309B
TX_CLOCK EXT_REF OR TX_TERR
BUFF_CLK EXT_REF OR TX_TERR
RX_CLOCK NORMAL
EXT_REF SET TO FREQUENCY OF STATION CLOCK.