Tasks
For more information about any of the options described above, please contact Microsemi
Customer Assistance (on page 3).
Configuring GPS for Various Conditions
This topic guides the user on how to configure the GPS receiver to operate under a variety of
conditions, including reduced GPS satellite availability and mobile applications.
In all cases, Microsemi recommends configuring the SyncServer with multiple references
and/or NTP server associations to provide synchronization if a single reference such as GPS
becomes unavailable.
To configure the mode and enter the position of the GPS receiver/antenna, use the
REFERENCES - GPS page.
To determine the number of "current" GPS satellites, use the STATUS - GPS page.
Stationary Applications
If the GPS antenna is in a location that provides 4 or more "current" GPS satellites on a con-
tinuous basis, Microsemi recommends letting the SyncServer operate in its factory con-
figuration. In that configuration, when the SyncServer starts, the GPS receiver comes up in
Survey mode. Upon locking to four or more GPS satellites the receiver determines and aver-
ages its position. After averaging the position it shifts to Position Hold mode. The user can
expect this type of operation when the GPS antenna is mounted outdoors in a high location
that provides good clear unobstructed views of the sky and horizon in all directions.
The lack of 4 "current" GPS satellites for sufficient durations may delay or prevent the GPS
receiver from determining its position and entering Position Hold. If the GPS antenna is in a
location that continuously provides 1 or more "current" GPS satellites, the SyncServer can
provide excellent synchronization to UTC once it has an accurate position and is in Position
Hold mode. Therefore, Microsemi recommends that the user perform the following actions
(in order of priority):
n Move the GPS antenna to a location that provides better visibility of GPS satellites and
improves the strength/quality of GPS signals reaching the GPS antenna input connector.
Consult the Selecting a Site for the Antenna (on page 100) topics.
n Determine and enter SyncServer's position, then put the GPS receiver in Position Hold
mode. Consult the Latitude and Longitude (see "Determining Latitude and Longitude"
on page 147) topic.
n Let the SyncServer operate for 24 hours to see if it can determine its position and trans-
ition into Position Hold unaided.
If the number of "current" GPS satellites drops to zero, and every effort has been made to
remedy this situation, the user may consider the following actions:
n Using a SyncServer equipped with a higher-stability oscillator, such as the OCXO or
Rubidium.
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