Spectracom VelaSync 1225, User Manual

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vey, the GNSS receiver must continue to track at least four satellites, otherwise the
GNSS survey will not complete.
Upon completion of the GNSS survey the GNSS receiver will lock-in the calculated
GNSS position and will enter
Standard Mode . Once in Standard Mode , the GNSS sur-
vey will only be performed again if:
the unit is halted or rebooted (see "Performing a GNSS Receiver Survey" on
page 133 ).
the equipment will be relocated to another location and the receiver detects this
(applies to most Trimble receivers)
you manually delete the GNSS position, see "Deleting the GNSS Receiver Pos-
ition" on page 136 .
In the event that VelaSync cannot complete a GNSS survey within 24 hours (e.g., the
survey progress does not go beyond 99%), see
"Single Satellite GNSS Receiver Mode"
below .
Single Satellite GNSS Receiver Mode
The Single Satellite Mode is designed for use cases in which it is
not
possible for the
GNSS receiver to track at least four GNSS satellites for at least 33 minutes con-
tinuously in a 12-hour time window so as to complete the GNSS survey, i.e. obtain a 3-D
fix. In such cases, VelaSync cannot operate in
Standard Mode . This occurs frequently in
areas with limited view of the sky (e.g., "urban canyons").
In Single Satellite Mode, the GNSS receiver will be considered a valid input reference as
long as:
a.
the receiver was able to complete a survey during a time window with good satel-
lite reception, OR you have manually entered a valid position for your antenna loc-
ation (instructions can be found under
"Manually Setting the GNSS Position" on
page 138 and "Determining Your Position" on page 139 .)
b.
the GNSS receiver continues to track at least one qualified satellite .
Note that VelaSync is designed to provide the most accurate time in Standard Mode ,
hence the Single Satellite Mode should only be used if the GNSS receiver could not com-
plete a survey. Note also that Single Satellite Mode can only be used if the VelaSync unit
remains stationary at all times.
Mobile GNSS Receiver Mode
In Mobile Mode
no surveys
will be carried out since the position status is updated in
near real-time. VelaSync will go into synchronization shortly after beginning to track
satellites.
3.3 Managing References
CHAPTER
3
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VelaSync User's Manual Rev. 3 131