Entry Channel Mode (ECM) Switching
1.If the outage was the result of power outage at the site, the remote CDM570(L) will reboot in its home state (STDMA), acknowledge the receipt of the first burst map causing it to rejoin the network through ECM. The VMS will park the demodulator previously in use and free the bandwidth slot.
2.If the outage was due to an extended rain fade or other communications blockage with no loss of power, the remote will rejoin the network via the previously assigned SCPC channel. When VMS receives a PLDM it will send a
Since it is not possible to know which of the above scenarios caused the communications outage the VMS will not free the bandwidth slot except through operator intervention.
Figure B-5 and figure B-5 diagram the time state differences and the process of recovery. Note that the times referenced in the diagrams are approximate.
Table
ECM Switch Recovery< 3min.
VMS | Burst | Switched | Remote |
| Demod | Demod |
|
State | 0 | |
Connected | ||
| ||
State | 180 | |
Disconnected | ||
| ||
Registration | 189 | |
Acknowledgment | ||
Failure |
| |
Revert Switch | 189.025 | |
Command | ||
| ||
Switch Command | 189.6 | |
ECM |
| |
No Switch wait ACK | ||
Switch | 191.59 | |
Acknowledgment | ||
Force Connected |
| |
State |
| |
Connected |
| |
Switch Command | 191.615 | |
ECM |
| |
Switch | 192.18 | |
Acknowledgment | ||
Satellite Delay |
|
|
| 0 |
|
|
|
| |||
|
|
|
|
| |
250ms + 30ms |
|
| 30 |
| |
|
|
|
| ||
|
|
|
| ||
|
|
|
|
|
|
|
|
|
|
|
|
|
| 180.28 |
| ||
|
|
| |||
|
|
|
|
|
|
189. 305
190.31
191.35
191. 895
191.9
Unit Reboot
Home State- STDMA Wait for TX Grant
State Unknown Force
Registration
Set ID
Process Switch
Command
STDMA TX Grant
Burst ACK
Switch
Acknowledgment&
PLDM
Process Switch
Command
Switch
Acknowledgment&
PLDM
3/7/05
Figure B-5 ECM switch recovery < 3 minutes
Appendix B - Automatic Switching |
