GPS7 GPS Synchronization and Timecode modu le
Table 3-19: Figures of merit for signal quality (cont.)
Figure
of merit
(FOM) Indicator Description
4 Acquire position This means t hat the instrument is acquiring
multiple fixes of the satellite position and
averaging this into a new position to store in
flash. This state will also be displayed if you
manually perform a new position acquisition.
This state normally lasts 60 seconds with good
GPS/GLONASS signal quality.
5
Adjust phase This means that the instrument is adjusting the
time base or frame timing to correctly line up
with the GPS/G LONASS signal.
6 Locked >
Signal quality is ≤ 16
7
Locked >>
Signal quality is > 16
8 Locked >>>
Signal quality is > 26
9 Locked >>>>
Signal quality is > 42
10 Locked >>>>>
Signal quality is > 68
11 Locked >>>>>>
Signal quality is > 110
These states indicate that the phase of
the frame signals is within 150 ns of the
GPS/GLONASS signal. The number of arrows
indicates the signal quality. It is normal for this
to vary with the time of day as the different
satellites move through their orbits, as well as
with changes in weather and other conditions.
NOTE. The duration of some states depends on the strength of the received
GPS/GLONASS signal. If the antenna only has access to part of the sky, or if the
cab
le loss between the antenna and the receiver is t oo large, then it may take
significantly longer to progress up to the higher entries in the FOM table.
Time flow block diagram
Th
e following time flow diagram shows time information is used at different
points in the system. In particular, it illustrates how the different user inputs and
configuration settings combine with the time base to create the timecode. An
asterisk (*) denotes points of possible user input.
3–106 TG8000 Multiformat Test Signal Generator User Manual
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