User guide

Entry Channel Mode (ECM)
G-4 VMS User Guide
Figure G-2 ECM switch recovery > 3 minutes
Using Entry Channel mode
Entry Channel mode operates slightly differently from other VMS modes due to
the STDMA burst controller losing the ability to automatically control once the
CDM-570/570L or SLM-5650A is operating SCPC in ECM mode.
The following procedure illustrates this and demonstrates how to change the
operation of a modem operating in SCPC ECM mode back to STDMA mode.
Figure G-3 shows the STDMA tab for the CDM-570/570L set up to run in Entry
Channel mode. Once a switch has occurred in an ECM enabled VMS controlled
modem the unit no longer sends switch requests so VMS does not have a switch
request to respond to switch the VMS controlled modem back to STDMA from
ECM mode.
The operator will have to manually intervene to switch the VMS controlled
modem back to STDMA mode when the VMS controlled modem is no longer
required to operate in ECM mode.
Unit Reboot
0
Burst
Demod
Switched
Demod
VMS Remote
State
Connected
0
Home State - STDMA
TX Grant Burst ACK
> 240
Satellite Delay
250 ms + 30ms E-E
State
Disconnected
180
F
a
i
l
u
r
e
No Communications
180.28
No Communications189.35
Switch Command
ECM
Registration
Acknowledgment
Failure
189
Revert Switch
Command
189.05
F
a
i
l
u
r
e
240.28
240.9
State
Connected
Switch Command
ECM
Switch
Acknowledgment
Process Switch
Command
240.61
Switch
Acknowledgment &
PLDM
2
4
0
.
6
2
240.33
ECM Switch Recovery > 3min.
3/7/05
Revert
Acknowledgment
Failure
192