Chapter 3
High Accuracy Timing
Qualifying GNSS antennas
T-BERD/MTS/SC Timing Expansion Module User Manual
Page 36
22112315, Rev. 004
July 2017
mode, or fine tune, which provides the best accuracy when testing for a prolonged
period of time.
To force the oscillator into holdover mode
•
Press the grey
Force Holdover
action button on the Timing Module tab of the
Main screen.
The button turns yellow, and the label changes to
Release Holdover
. If you determine
that the oscillator frequency has not been sufficiently stabilized, ensure that a valid
synchronization source is selected and connected, then press
Release Holdover
to
resume tuning.
Qualifying GNSS antennas
You can use the TEM Module (with a connected GNSS antenna) to determine the
quality of the signals received from selected GNSS satellites, and to verify that a
stationary antenna has been installed at the optimal location. You do not need to specify
GNSS as the synchronization source to qualify antennas; however, you do need to
connect a GNSS antenna to the TEM Module.
To qualify the location of a GNSS antenna
1
Connect the GNSS antenna that shipped with your TEM Module to the module
(see
“Connecting a GNSS antenna” on page 10
).
2
Specify the required GPS and location settings (see
). When specifying the settings, consider the following:
–
When specifying the GNSS system on the GPS tab, select the option for the
system
that includes SBAS
.
–
When specifying the timing mode on the Location tab, select
Survey
to indi-
cate that the
GPS receiver should survey the satellite constellation.
–
Specify
Manual
as the Survey Mode, then specify the Survey Position Accu-
racy (in meters), and the Survey Duration (in seconds, hours, or days).
3
Use the Results softkey to return to the Main screen, then press the grey
Start
Survey
action button to start the survey.
4
Wait for the period of time that you specified as the survey duration, then observe
the signal strength for the surveyed satellites in the Satellites Signal Strength
result category.
NOTE:
The oscillator should be placed into holdover mode before removing the
reference signal for a synchronization source. If you do not place the oscillator
into holdover mode before removing the signal, tuning may be adversely
impacted.
