Tektronix TG700, Руководство пользователя

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GPS7 GPS Synchronization and Timecode Module
14. Press the ENTER button to return to the Gain Calibration menu.
15. Press the CANCEL button to exit the Gain Calibration menu.
16. Wait approximately two minutes for the GPS control loop to recover before
cycling the instrument power and putting the instrument back in service.
GPS Antenna
Requirements The GPS7 module requires an external antenna to receive signals from satellites.
You must set up an antenna system to provide the GPS signal as an input to the
module. You can con
fi gure the instrument to provide 3.3 V or 5 V DC power for
the antenna.
WARNING.
Prevent risk of shock or fi re by ensuring that the GPS antenna is
protected from lightning strikes when it is mounted outside a building or facility.
The GPS7 module and TG700 mainframe do not have isolation protection from
lightning, so the facility installation must provide suitable protection for the GPS
antenna external to the TG700 mainframe. Failure to use appropriate precautions
can result in injury or death.
CAUTION. To avoid antenna damage, do not turn on the DC antenna power until
you know that the antenna is designed to handle the selected voltage. Antenna
damage can occur if the antenna is not designed to handle the voltage you select.
When a GPS feed is fi rst connected to the antenna input on the module, it can take
several minutes for the signal quality to reach its nominal potential. How long that
takes depends on such things as antenna site, cable plant design, and available
satellites. Excluding those variables, the typical time to acquire satellites and
achieve speci
fi ed stability with a good satellite signal, known position, and a
warmed up instrument, is two minutes.
GPS Antenna System Antenna systems vary depending on the operating environment and on safety and
regulatory requirements. A simpli
fi ed typical system is shown in the following
fi gure to help you with planning and understanding the trade-offs of one set up
versus another. (See Figure 3-53.)
Figure 3-53: Simpli fi ed antenna system
TG700 TV Signal Generator Platform User Manual 3–101