Tektronix TG700, Руководство пользователя

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GPS7 GPS Synchronization and Timecode Module
Blinks green to indicate an open circuit. This occurs if no antenna is
connected or if the current load is less than expected because a splitter or DC
block is being used.
Displays solid red if the connected antenna is shorted. A shorted antenna will
not damage the GPS7 module. If a splitter is used on the antenna, it may
appear as a short at DC but still pass through the RF signal, which would
allow the GPS to function.
Displays solid green if the current load of the antenna is within the nominal
range.
POSITION. Use the left ( ◄ ) or right ( ► ) arrow button to select Fixed or Mobile .
The Fixed and Mobile settings de fi ne how the GPS receiver calculates the time
and position information.
In fi xed mode, an averaged position is stored in fl ash memory, and only the
time is calculated each second. This provides greater stability of the time
information, and allows operation with fewer satellites. This mode is well suited
to broadcast-type installations where the antenna and mainframe do not move.
Mobile mode recalculates both the position and time each second. This allows
for compensation of velocity and acceleration, so the frequency and timing
information stay correct while moving, at the expense of some stability. This
mode is required if the antenna and mainframe are moving.
For applications where the position changes occasionally, but where the antenna
and unit are not moving, then either mode may be applicable. Mobile mode
may boot up faster since it does not need to average 60
fi xes to establish a fi xed
location. However, fi xed mode can run with fewer satellites once the position
is stored.
ACQUIRE POSITION.
Press the ENTER button to erase the saved position, and
then acquire and save a new averaged position. Note that the signal quality might
indicate low or no signal during this process.
NOTE.
The module must make 60, 1 second GPS readings with at least four
satellites to acquire the position. How long this takes depends on various
conditions. If there are less than four satellites, a reading cannot be taken.
SIGNAL WARNING. This function provides a warning that the antenna signal has
degraded. Set this level below the normal range experienced as a function of
time of day, weather, or other variables. To con
fi gure the output warning, see the
GPO submenu. (See page 3-136, GPO Submenu .) Use the left ( ◄ ) or right ( ► )
arrow button to select the FOM (quality of the GPS signal) value that will trigger
warning indicators. (See page 3-103,
Figures of Merit (FOM) .)
TG700 TV Signal Generator Platform User Manual 3–123