Comtech EF Data VMS v3.12.x Vipersat - Manual (Page 487)

Appendix E - Automatic Switching E-31
MN/22156, rev 12 Entry Channel Mode Switching
and not switch out to SCPC unless either an application switch occurs or a
manual switch is invoked.
5. In VMS, right-click on the Remote as shown in figure E-20, then select the
Revert Uplink Carrier command from the drop-down menu. The VMS will
send the revert command to the target modem, causing it to revert to its
STDMA home state.
Figure E-20 Revert Uplink Carrier Command, VMS modem
This completes resetting the Remote modem to operate in the STDMA mode.
Dynamic Entry Channel Mode
Dynamic ECM (ECMv2) utilizes a modified slotted Aloha method for Remotes
to establish registration in the network and obtain the means for switching into
SCPC mode. Rather than sharing an STDMA burst map, as is the method with
STDMA ECM, the Remotes rely on communicating with the Hub channel
controller through the use of a multicast Transmission Announcement Protocol
(TAP) message. This eliminates the restriction in the number of Remotes in an
Entry Channel group that is inherent with the burst map method.
The TAP, broadcast periodically, supplies the Remotes with the transmit param-
eters that are required for transmitting back to the Hub. In addition, the TAP
provides timing information in the form of slot parameters that define the