Safran SecureSync 2400 - Page 249

In the Standard Mode the GNSS survey will initially be performed, once at least
four GNSS satellites become available. The GNSS survey is used to determine the
exact position and time; it takes 2000 seconds (33 minutes) to complete a sur-
vey. During the survey, 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 cal-
culated GNSS position and will enter Standard Mode. Once in Standard Mode,
the GNSS survey will only be performed again if:
the unit is halted or rebooted (see "Performing a GNSS Receiver Survey" on
page236).
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
Position" on page239.
In the event that SecureSync 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
continuously in a 12-hour time window so as to complete the GNSS survey, i.e.
obtain a 3-D fix. In such cases, SecureSync 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 ref-
erence as long as:
a. the receiver was able to complete a survey during a time window with
good satellite reception, OR you have manually entered a valid position for
your antenna location (instructions can be found under "Manually Setting
the GNSS Position" on page241 and "Determining Your Position" on
page242.)
b. the GNSS receiver continues to track at least one qualified satellite.
Note that SecureSync 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 complete a survey. Note also that Single Satellite Mode can only be
used if the SecureSync unit remains stationary at all times.
Mobile GNSS Receiver Mode
3.3 Managing References
CHAPTER 3 • SecureSync 2400 User Manual Rev. 5.2
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