Using Stdma Ecm; Figure B-14 Ecm Switch Recovery: > 3 Minutes - Comtech EF Data Vipersat CDM-570 User Manual

State
Connected
State
Disconnected
Registration
Acknowledgment
Failure
Revert Switch
Command
Revert
Acknowledgment
Failure
Switch Command
ECM
State
Connected
Switch Command
ECM
Switch
Acknowledgment

Using STDMA ECM

Entry Channel mode operates slightly differently from other STDMA modes
due to the STDMA burst controller losing the ability to automatically control
the modem unit once it is operating in SCPC mode.
Once the switch from ECM to SCPC has occurred in the modem, the unit no
longer sends switch requests so VMS does not have a switch request to respond
to switch the modem back to STDMA from SCPC mode. The operator will have
to manually intervene to force a switch back into STDMA mode.
The following procedure illustrates this and demonstrates how to change the
operation of a modem operating in SCPC mode back to STDMA mode.
Figure B-15 shows the STDMA page for the CDM-570/570L set up to run in
Entry Channel mode.
A p p e n d i x B - A u t o m a t i c S w i t c h i n g
ECM Switch Recovery > 3min.
Burst
VMS
Demod
0
180
189
189.05
192
240.28
240.33
240.9
Figure B-14
E n t r y C h a n n e l M o d e S w i t c h in g
Switched
Demod
Satellite Delay
250 ms + 30ms E-E
ECM Switch Recovery: > 3 minutes
Remote
0
Unit Reboot
180.28
No Communications
189.35
No Communications
Home State - STDMA
> 240
TX Grant Burst ACK
Process Switch
240.61
Command
Switch
Acknowledgment &
PLDM
3/7/05
B-27