Furuno FV-110, Operator'S Manual

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C-1
Appendix C
VMU settings
C
In this appendix you find detailed information how optimise performance in blockage
situations and how to set up supported VSAT modems. The appendix has the following
sections:
• Performance optimization for blockage
• OpenAMIP setup for iDirect iNFINITI & Evolution
• Serial setup for iDirect iNFINITI & Evolution
• COMTECH 570L and ROSS box
• COMTECH 570L
• STM SatLink 2900 VSAT modem
• Gilat SkyEdge II VSAT modem
• Inmarsat G5 modem
• Linkway S2 modem
C.1 Performance optimization for blockage
C.1.1 Performance of VSAT systems encountering blockage, configured
with multiple satellites
Blockage definition
In most VSAT installations the VSAT antenna is installed in a position with areas of
blockage. Blockage is often caused by the vessel's masts, stacks and other equipment
installed on board. During installation the blockage areas should be entered in the web
interface, see
To set up blocking zones (RX and TX) on page 5-27.
When blockage occurs, the ACU can inform the VSAT modem (if the blocking zones
have been typed correctly into the ACU web interface). It is often seen that by not
informing the VSAT modem of blockage the VSAT system gains a higher uptime,
although the quality of the extra gained uptime is not good enough to give the user a
stable data connection. Therefore it is not of any value to the user. Another disadvantage
of not informing the VSAT modem of blockage is that the VSAT modem does not have
the option to switch to a different satellite to avoid the blockage.
VSAT modems can typically
1
only receive one signal from the ACU, which is "TX-mute"
/ "modem must not transmit", they are therefore not able to perform fast switching, but are
limited to use a simple time-out, which is configured as a fixed value in the modem
configuration.
1. There are VSAT modems that can interpret more detailed information about blockage from
the ACU. This allows for increased performance in the event of blockage.