Slot Preamble Length; Slot Data Length; Figure 3-15 Slot Preamble Length Prompt - Comtech EF Data Vipersat CDM-570 User Manual

V i p e r s a t C o nf i g u r a t i o n
On Remote units, this menu item is an information-only display.
Note: The value entered at the command line in figure 3-14 is in milliseconds.
NOTE

Slot Preamble Length

This menu item, which appears in all Hub configurations, displays the current
Slot Preamble size in milliseconds and bytes for the remotes in the group. The
Slot Preamble is the period between when the remote begins to transmit (sends
an ACK) to the Hub and when the first data packet is sent. This allows time for
signal lock to occur before data is sent, thus preventing data loss. Higher data
rates allow for a shorter preamble, since it is easier to achieve signal lock. The
setting for this parameter should be obtained using the Vipersat STDMA Calcu-
lator.
Note: When the BFAT feature is enabled, the preamble length is set automati-
NOTE
On a Hub unit, entering P at the command prompt allows changing the pream-
ble duration in milliseconds.
On Remote units, this menu item is an information-only display.
Tip: Refer to the Viper Calculator for determining Slot Preamble Length values

Slot Data Length

This menu item displays the Slot Data Length in milli-seconds and bytes for the
remotes in the group, and represents the amount of data that can be transmitted
or received in one spin of the STDMA cycle by each of the Remotes belonging
to that group. This is the amount of time that the remote is provided to send data
in the cycle.
3-16
The corresponding value expressed in bytes is calculated by the
CDM-570/570L based on the STDMA transmit bit rate as shown in the
menu in figure 3-7.
cally for the unit.
Figure 3-15
to enter at the command prompt. For a copy of the latest Viper Calculator,
contact a Comtech Vipersat Networks representative.
Slot Preamble Length prompt
V i p e r s a t C D M - 5 7 0 / 5 7 0 L U s e r G u i d e