Pre-survey Preparation
GR-3 Operator’s Manual
2-26
8. Click the Serial Interface tab (Figure 2-23). Enable Echo to
display Bluetooth module replies and corresponding commands
on the computer terminal. Click Apply.
9. Click Disconnect then Exit to quit BTCONF.
Figure 2-23. BTCONF Serial Interface Tab
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.
• GPS and GLONASS satellites broadcast ephemeris data
cyclically, with a period of 30 seconds.
• GPS satellites broadcast almanac data cyclically with a period of
12.5 minutes; GLONASS satellites broadcast almanac data
cyclically with a period of 2.5 minutes.
If the receiver has an almanac, you can considerably reduce the time
needed to search for and lock onto satellite signals.
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