Pre-setup Preparation
NET-G3A Operator’s Manual
2-14
the power supplied by the external source and maintains the backup
batteries in a charged condition.
The Li-Ion batteries used in the iBEST system should run at no less
than 80 percent capacity after 500 charging cycles. These batteries do
not need to be drained before recharging.
Collecting Almanacs and
Ephemerides
Each satellite broadcasts a navigation message that includes the
ephemeris parameters of the satellite, the almanac, and various other
information. The ephemeris parameters describe the orbital motion of
the satellite and are used to predict its location/trajectory. The
almanac gives the approximate orbit (course) for the transmitting
satellite and all other satellites in the same system only.
• GPS and GLONASS satellites broadcast ephemeris data
cyclically within 30 seconds.
• GPS satellites broadcast almanac data cyclically within 12.5
minutes; GLONASS satellites broadcast almanac data cyclically
within 2.5 minutes.
When the receiver has an almanac, you can considerably reduce the
time needed to search for and lock onto satellite signals.
The receiver regularly updates the almanac and ephemerides and
stores the most recent versions in its Non-Volatile Random Access
Memory (NVRAM).
You need to collect or update the almanac and ephemerides under the
following circumstances:
• If the receiver has been off for a long time.
• If the last known receiver position, stored in the NVRAM, is
different from the present position by several hundred kilometers.
• After loading a new OAF.
• After loading new firmware.
• After clearing the NVRAM.
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