User guide

Vipersat Configuration
3-10 Vipersat CDD-56X Series User Guide
STDMA Tx Rate
This menu item shows the STDMA Transmit Rate (in bps) of data that the
CDD-56X receives. This item is read-only and cannot be modified in this menu.
Hub Type
This menu item is only displayed if the CDD-56X is being used as a Hub in the
network, and provides the functionality for the STDMA Burst Controller.
Vipersat STDMA has five modes of operation:
•Fixed — all remotes get the same data slot time (slot size) in the cycle,
regardless of activity. Cycle time is fixed also.
• Dynamic Slot — data slot time of remotes vary according to activity,
cycle time does not.
• Dynamic Cycle — slot time and cycle time vary according to activity of
remotes.
•GIR (Guaranteed Information Rate) — each remote always has at least the
minimum data slot size when needed, and cycle time is variable up to a
maximum of one second.
• Entry Channel — remotes run in SCPC mode, but STDMA is used for
maintenance and control channel.
The Hub can be configured to operate as one of the five types by entering a T at
the command prompt to display the dialog shown in figure 3-9.
Figure 3-9 Hub Type prompt
This selection determines whether available bandwidth will be a static (fixed)
assignment, or whether bandwidth allocation will be dynamic with automatic
switching to dynamically optimize bandwidth utilization.