1-20. Nodal/Non-Nodal Connectivity.
This form of connectivity allows one nodal unit to communicate with up to four non-nodal units (simplified
sketch shown above).
The facing page illustration is a more detailed example of the above simplified sketch. In this example,
inputs from eight groups (users) identified as A through H are applied to input ports 1 through 8 of the
nodal unit. These eight inputs are multiplexed into a SG. The SG is processed through the terminal transmitting
equipment to produce a rf output designated F1. F1 is broadcast to the four non-nodal units via the
Each non-nodal unit demultiplexes received SG F1 to obtain desired group data. Data for each group
is then routed to its assigned output port.
In the return direction, each non-nodal unit multiplexes its group inputs into an output SG. These four
output SG'S (designated F2 through F5) are transmitted via the satellite to the nodal unit. At the nodal
unit, each incoming SG is demultiplexed by a separate demux. Data for each group is then routed to
its assigned output port.
For example, data from groups C and D enters ports 3 and 4 of the nodal unit mux and becomes part
of SG F1. In turn, non-nodal unit No. 2 receives and demultiplexes the groups C and D data from SG
F1. This group data is then routed to output ports 1 and 2 for users C' and D'. In the return direction
data from groups C' and D' are multiplexed by non-nodal unit No. 2 to form SG F3. Demux 2 in the
nodal unit demultiplexes received SG F3 and routes the demultiplexed data to output ports 3 and 4. Thus,
user C communicates with user C' and user D with user D'.
In summary, the following should be noted:
The same numbered port is used to input and output data for a given group. For example, if
data from a given group enters at mux input port 4, then return data for that group must exit
at output port 4.
Each demux has a port assignment capability controlled by operator entered configuration data.
That is, data for a given group is demultiplexed out of a received SG and routed to its assigned