Comtech EF Data SNM-1010L - Manual (Page 151)

Chapter 5. CLOCKING
OPTIONS
5.1 Clocking Options
Methods of clocking the data from the terrestrial equipment to the satellite (and vice
versa) will depend upon the application. The two most common options and
recommended configurations are described in the following paragraphs.
Notes:
1. The clocking options are available only when the modem is in the continuous
mode.
2. Clock settings in the SNM-1010L are set automatically when the operating mode
is selected.
5.1.1 Master/Master
This application is used when both earth stations incorporate high stability clocks and the
incoming data will be clocked to the local network. The disadvantage of the
master/master application is that the incoming data will slip, because the clocks will not
be synchronized.
However, if the buffer is properly set up, the slips will be an exact frame length, causing
minimum data loss. Use of very high stability clocks can result in several days between
the expected slips. Loss of the buffer clock means the buffer will not be emptied and data
will not be available.
The buffer clock will normally revert to the low stability internal reference automatically
when the selected clock is lost.
5–1