1-22. Hybrid Connectivity.
This form of connectivity is a combination of nodal/non-nodal and mesh connectivities (simplified sketch
shown above). It allows a nodal unit to communicate with up to four other units that may be any combination
of nodals and non-nodals.
1 - 2 3 . Timing Source Selection.
The TD-1337(V)/G is a synchronous multiplexer-demultiplexer. Therefore, all earth side interfacing equipments
and the TD-1337(V)/G must be synchronized. Interfacing earth side equipments are synchronized to the
TD-1337(V)/G by slaving their transmit timing to their receive timing or by being synchronized to the CNCE
or external standard source. A timing source selection is made as part of the TD-1337(V)/G configuration
routine. There are three possible timing source selections.
CNCE or External Standard. This timing source selection synchronizes the TD-1337(V)/G to a selected
group input. For this selection to be made, the group input must be in a balanced NRZ or conditioned
diphase format and at a rate of 72 kb/s or greater. To ensure proper operation, the group input
must have a timing stability of 1 part per million or better,
Master. This timing source selection causes the TD-1337(V)/G to operate from an internal timing
source. Normally, a nodal unit would be a master.
Slave. This timing source selection causes the TD-1337(V)/G to be synchronized to a remote TD-
1337(V)/G that is operating from a CNCE or external standard or as a master. Synchronization
is accomplished by means of control data that is automatically transmitted/received in the SG.
The facing page illustration shows typical examples of various timing source selections.