Chapter 3
High Accuracy Timing
Surveying GNSS constellations
T-BERD/MTS/SC Timing Expansion Module User Manual
Page 34
22112315, Rev. 004
July 2017
Surveying GNSS constellations
After specifying survey settings (as described in
ready to start the survey.
To start the survey
1
Press the grey
Start Survey
action button on the Timing Module tab of the Main
screen.
The button turns yellow, and the survey runs for the duration specified or associ-
ated with the selected Survey Mode (see
).
2
To observe the surveyed constellation, do the following:
a
Press the View button (under the LED Panel) to set the results display to a
single pane.
b
Select the Satellite result group and the Sky Plot result category.
The surveyed constellation will appear in the Sky Plot. After the TEM Module’s GNSS
receiver receives valid GNSS time information from the surveyed satellites, the green
GNSS Time LED will illuminate, and the oscillator will begin to tune to the signal(s)
provided.
The constellation has been surveyed. When complete, the GNSS status on the LED
Panel will state “Fixed Position.”
Resetting the start location
If your survey does not appear to be progressing as expected, and the GNSS Location
Latitude, Longitude and Altitude coordinates are not correct, use the
Reset Start
Location
button (located on the right of the Survey Mode field). The button will turn
yellow, the GNSS receiver will be reset, and the current location and synchronization
information will be cleared.
Tuning the oscillator
The TEM Module’s rubidium oscillator can tune to the internal GNSS receiver, or to
reference signals provided by an external BITS/SETS clock, 1 Pulse Per Second (PPS
signal), or 10 MHz signal. Before tuning the oscillator to an internal or external synchro-
nization source, the oscillator must be warmed up (see
“Warming up the oscillator” on
), and you must specify the synchronization source to which the oscillator will
“Specifying oscillator and timing settings” on page 29
).
NOTE:
If you included SBAS when you selected the GNSS synchronization source
(before starting the survey), after the survey is complete, you should reset the
synchronization source
without SBAS
to ensure optimal timing performance.
