Meinberg IMS-GNS181, Руководство по установке

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4 GNSS Receiver
4.1.1.16 Receiver Information
This menu item lists all the important information and options of the reference clock.
Explanation of GPS Satellite Status "Satellites in View" and "Number of Good Satellites"
Satellites of the GPS and other GNSS systems are usually not stationary, but circle around the globe on
well-known tracks, so each individual satellite may be above or below the horizon at a given location and time.
Satellites that are below the horizon can’t be tracked anyway, so the receiver uses its last known position and
almanac data from the satellites to determine which satellites are currently expected to be above the horizon
at its geographic position, and can potentially be tracked. All these satellites are called to be
in view .
However, even some the satellites that are in view may be shielded by buildings, mountains, etc., so the
receiver may be unable to track these satellites. Also, individual satellites may be temporarily in maintenance
mode, so they must not be used even if they can be tracked. Only satellites that can be tracked and are not in
maintenance mode are considered
good and used to determine the current position and time.
So the number of good satellites can never exceed the number of satellites in view, but it can be signifi-
cantly less if the antenna has been installed in a location with limited view to the sky. In worst case this can
lead to limited accuracy, or only temporary synchronization.
IMS-GNS181 Setup Guide Date: 20th March 2020 25