Figure B-5 Ecm Switch Recovery: < 3 Minutes - Comtech EF Data Vipersat CDD-562L User Manual

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 the VMS receives a PLDM it will
send a Revert-to-Home State command and free the bandwidth slot and burst
demodulator. The Remote will then rejoin the network through ECM.
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-6 diagram the time state differences and the process of
recovery. Note that the times referenced in the diagrams are approximate.
State
Connected
State
Disconnected
Registration
Acknowledgment
Failure
Revert Switch
Command
Switch Command
ECM
No Switch wait ACK
Switch
Acknowledgment
Force Connected
State
Connected
Switch Command
ECM
Switch
Acknowledgment
A p p e n d i x A u t o m a t i c S w i t c hi n g
B -
ECM Switch Recovery < 3min.
Burst
VMS
Demod
0
180
189
189.025
189.6
191.59
191.615
192.18
Figure B-5
E n t r y C h a n n e l M o d e ( E C M ) 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
Home State - STDMA
30
Wait for TX Grant
State Unknown Force
180.28
Registration
Set ID
Process Switch
189. 305
Command
STDMA TX Grant
190.31
Burst ACK
Switch
Acknowledgment &
PLDM
Process Switch
191. 895
Command
Switch
Acknowledgment &
PLDM
3/7/05
B-15