DOC 4380A
4380A O & M Manual
11
098-00723-000– Jul 2017 Revision 4.0 SyncSystem 4380A O&M Manual
2.4.5.2 Auto Position Mode
The Auto mode is recommended for static locations where the antenna location has not been surveyed.
When using the Auto mode, the 4380A will automatically determine the location of its antenna. It does this
by averaging its calculated position solutions over a period specified by the auto_hours parameter. The
factory default for the position period is 12 hours. It is recommended that the auto positioning period
should be set to at least 4 hours. Once the position_period expires, the 4380A will enter the fixed position
mode (status gps:position:fixed). Fixing the antenna position reduces the noise of the GPS measurements
and increases the frequency stability of the timing outputs.
To set the positioning mode to auto, use the position_mode command on the command port.
4380A>position_mode auto
[OK] 2015-08-05T15:26:06Z
To set the positioning period, use the position_period command. If not specified, the value will be in
hours. Users can set this value to minutes using m after the value.
4380A>position_period 12
[OK] 2015-08-05T15:26:06Z
Select the proper datum, WGS84 (default) or NAD83, using the datum command.
4380A>datum wgs84
[OK] 2015-08-05T15:28:14Z
Use the settings gps command to verify the correct datum is being used.
4380A>settings gps
[antenna_delay] 2.650000000000000e-07
[antenna_voltage] 1.200000000000000e+01
[datum] wgs84
[mask_angle] 1.000000000000000e+01
[positioning]
[auto_hours] 1.200000000000000e+01
[manual_position]
[altitude] 1.963545000000000e+02
[latitude] 3.992275796000000e+01
[longitude] -7.758566956000000e+01
[mode] auto
[tracking_timeout] 1800
[OK] 2015-08-05T15:27:19Z
If these settings are correct, type save to save the current user default configuration on the system to ensure
the system uses the positioning mode and period after a reboot or power cycle.
Note: If the unit is rebooted, power cycled, or the application is restarted with the positioning mode set to
auto, the system will go through the process of determining its antenna position based on the position
period (auto_hours). Once that period expires, the system will again set itself fixed and use the new
determined solution as the fixed position. It will do this each time this occurs. The [ptd] or UTC offset
value reported by the system will be noisier during the auto position period and will become significantly
quieter when the antenna position is fixed.
In addition to automatically determining its antenna location, the 4380A generates a RINEX (Receiver
INdependent EXchange) format observation file. This file format is a standard used by the GPS
community and provides all the necessary GPS measurements for determining the antenna location. The
file can be retrieved from the system by using ftp (login: ftp, 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
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