password: ftp) to log in and retrieve the file. The file will be in the “rinex” subdirectory and will
have a “.[yy]o” extension where [yy] represents the last two digits of the current year. Many
online processing centers are available (e.g., http://www.ngs.noaa.gov/OPUS,
http://sopac.ucsd.edu/cgi-bin/SCOUT.cgi) and will process the observation file free of charge.
Doing this improves the position estimate of the antenna and is recommended for precise time
recovery. After this process is complete, it is possible to set the position mode to Manual using
the coordinates provided by those services.
The receiver has a countdown timer to show the amount of time left (position_period) while
in the auto positioning mode. Once this timer counts to zero, the RINEX file will be generated,
the receivers position (status gps:position:fixed) will be true, and the [time_remaining]
field will no longer be present in the status message.
4380A>status gps:auto_positioning
[time_remaining] 10 hours, 51 minutes
[OK] 2015-08-05T15:32:05Z
4380A>status gps:position
[alt] 1.965699000000000e+02
[fixed] false
lat] 3.992275579961000e+01
[lon] -7.758567122127999e+01
[OK] 2015-08-05T15:32:33Z
Q14: What are the benefits of surveying my GNSS antenna position?
A14: The primary benefit of surveying the position of the GNSS antenna is that the antenna
coordinates can be entered into the 4380A using the fix_position command to improve the
timing accuracy and stability of the unit. When observed over short timeframes, the GNSS
signals are noisy, so the instantaneous position solution for the antenna is less accurate and
stable than one that has been averaged over a longer time period. For a high performance
system like the 4380A, the improved accuracy and stability of a surveyed antenna position
translate directly into improvements in timing accuracy and stability.
Q15: How do I set the on-time-point (OTP) of the system?
A15: The OTP of a system is defined as the point at which the timing signals coincide with
UTC(USNO). Typical systems use distribution amplifiers and cabling to distribute timing signals
from a single source to multiple users. This distribution network will delay the timing signals
and affect their accuracy. For this reason, it is important to select an appropriate OTP so that
the desired timing signals are accurate when they reach the user.
As received, the OTP for the 4380A signal outputs is at the rear panel of the unit, at the plane of
the output module connectors. This is not generally a convenient location for the OTP of the
system because there will be a delay associated with the distribution of the signals to the user.
The figure below illustrates how to move the OTP of the system from the rear panel of the
© 2016 Microsemi Corporation. All rights reserved. SyncSystem 4380A FAQs Version 1.0 (22 Feb 2016)
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