CDM-840 Remote Router MN-CDM840
Appendix M Revision 3
M–16
M.2.4 Roaming with DPC
The Roaming Oceanic Satellite Server (ROSS) is an integrated location server that works in
conjunction with Comtech EF Data’s Vipersat Management System (VMS) to facilitate on-the-
move satellite communications for oceanic vessels. With the support of ROSS, the modem
power margin is modified depending on the Effective Isotropic Radiated Power (EIRP) value.
ROSS stores multiple contours per service area, with each beam contour assigned a number (0
to 255) in order of power, high to lower gain.
Roaming DPC provides additional control within a service area with multiple beam contours. As
the vessel roams between beam contours, the power difference from beam-to-beam is applied
to the CDM-840 DPC beam offset control, adjusting the terminal’s power margin by adding or
subtracting the beam power differences. The net effect on power is that the maximum power
scale is increased or decreased, depending on the vessel’s location within that satellite service
area.
The beam offset plays a very important role in maintaining power during beam contour
transitioning. If the power control is operated without this additional adjustment, the uplink
power may exceed budget, or the vessel could drop communication all together because of
insufficient margins.
For more information about ROSS, please see adjunct Comtech EF Data publication
MN/13070 ROSS Roaming Oceanic Satellite Server Installation and Users Guide.
Figure M-8. Roaming DPC
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