Spectracom SecureSync User Reference Manual page 219

GNSS survey is performed, i.e. SecureSync will go into synchronization shortly after tracking
satellites.
3.6.14.3 Single Satellite GNSS Receiver Mode
This Single Satellite mode should only be used if SecureSync's built-in 1 GNSS receiver will
remain stationary at all times and it is impossible for the GNSS receiver to track at least four
GNSS satellites for at least 33 minutes continuously (in order to complete the GNSS survey), and
the current latitude and longitude is not known.
SecureSync's GNSS receiver is designed to provide the most accurate time in Stationary mode,
which can only be achieved if SecureSync completed a GNSS Survey,or SecureSync's location
has been entered manually, and while tracking at least four satellites. Hence, Single Satellite
mode should only be used if the GNSS survey cannot be completed, and the current latitude and
longitude are not known and therefore, cannot be entered manually.
In this mode, the GNSS receiver will be considered a valid input reference as long as a valid loc-
ation is entered (either automatically via the GNSS survey or manually entered by a user) and the
GNSS receiver continues to track at least one qualified satellite from that point forward.
The
account for antenna cable delays or other latencies (entered and displayed in nanoseconds).
By setting the correct Offset value, you can offset the system's
compensate for the antenna and in-line amplifier delays. Under typical conditions, the expected
cable and amplifier delays are negligible. You can calculate the delay based on the manufacture's
specifications.
The range of the cable delay is ±50,000,000 nanoseconds. The default value is 0 nanoseconds and
the resolution is 1 nanosecond.
The following formula is used to calculate the cable delay:
D = ( L * C ) / V
Where:
D = Cable delay in nanoseconds
L = Cable length in feet
1
Certain system configurations utilize a GNSS receiver installed in the GNSS antenna.
CHAPTER •
3 SecureSync User Reference Guide Rev. 18
NOTE – With SecureSync's GNSS Receiver configured in mobile mode, the spe-
cified accuracies of SecureSync will be degraded to less than three times that of sta-
tionary mode. Stationary mode accuracy of the receiver is less than 50 ns to
GPS/UTC (1 sigma), hence mobile mode is less accurate than 150 ns to GPS/UTC
time (1 sigma).
Offset option allows a user to enter an offset to the GNSS time and 1PPS reference to
3.6 OTHER Setup Pages
on-time point by the offset value to
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