OPUS Projects
User Instructions
and Technical Guide
NOAA | National Geodetic Survey
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values for new projects along with the recommended values are shown in Figure 1.19. The default
values are aggressive (tight), i.e. more likely to trigger a notification (flag) on the mark page and an
icon change. The manager has the option of replacing these values with ones better suited to a
particular project thereby shedding light on potential problems. It is recommended that you use
preferences that match those for "sharing" a solution with OPUS.
Under preferences if the "Precise" ephemeris is selected from the pull down rather than "Best Available"
but the user has not waited the ~13 days an warning message is generated. Every time a processing
request is
submitted, OP tries to "improve" the ephemeris.
These thresholds are also applied when data
files are uploaded to the project.
The
Data Processing Defaults (Figure 1.19) are just that - default values appearing in the project’s
processing forms. Like all defaults, they can be changed at the time of processing,
but selecting the
appropriate defaults for a project may simplify and help guide the processing. Nevertheless, the size,
location and type of survey project may dictate which selections you make. Always follow your project’s
specifications.
Figure 1.19 - Default Data and
solution quality thresholds.
Figure 1.20 - Data processing
suggested alternatives
Here are some recommended
values based on those for
sharing a mark via OPUS.
Consider your choices for these
defaults carefully.
User Instructions and Technical Guide
OPUS Projects
32 |
P a g e
NOAA |
National Geodetic Survey
Figure 1.29 - Session definition
1.3.5.2.4
Session Definition
The
Session Definition gives project managers some control over how data files are grouped together to
form sessions for processing. The
Minimum Data Duration (in seconds) sets a minimum data file
duration for use in OP processing. These values can only be changed before session processing has
begun. After processing has begun, this section is disabled (grayed out) and an
explanatory message
appears. If you want to go back and change the value after processing sessions you will need to delete
those sessions first.
If you have two or more sessions in one day then you may need to change this preference such that the
sessions appear in OP as a reflection of the way you planned the survey. For more information consult
Section 2 of this guide prior to making any changes.
The
Minimum Data Duration default
setting is 1800 seconds (30 minutes). This
means that in order for a RINEX file to be
considered for grouping to a session, it
must be at least 1800 seconds in
duration. Currently, the de facto
minimum duration for
ANY RINEX file to
exist in OPUS Projects is 7200 seconds
(two hours), which is the minimum
duration for an occupation that will
enable it to be loaded to OPUS and thereby into your project. So a default setting of 1800 seconds at
this time will force OP to consider any RINEX file that exists in your project. In the future, OP may allow
the processing of
shorter occupations, e.g., OPUS RS, thereby requiring the need to accept shorter
duration files. Changing the Minimum Data Duration to something larger than 7200 seconds will
instruct OP to filter your data to meet that requirement. For example, if you only wanted to consider
data files that were three-hours in length, then the Minimum Data Duration could be set at 10,800
seconds (three hours). This would exclude any file between two and three hours in duration.
The
Minimum Session Overlap Multiplier is a factor applied to the shorter occupation duration of
two (or more) data files being considered for inclusion in the same session. If the two (or
more) occupations overlap in time by at least the product of the multiplier and the duration of the
shorter occupation, then the marks are grouped in the session.
For instance, let's say that we have one
occupation that starts at 10:00 and goes until 12:00, and another that starts at 11:00 and goes
until 13:00. The shortest occupation is two hours, and if the Minimum Session Overlap Multiplier is 0.5,
then the minimum session overlap would be one hour. Both of these files include data from 11:00 to
12:00 so they would be grouped together in a session.
CAUTION - Changing these defaults may result in unintended consequences. Setting the Minimum
Session Overlap Multiplier too low or failure to closely adhere to a project's observation plan and
schedule could potentially cause data to be unintentionally grouped together within a session and/or
create sessions of very short duration.
The conditions set by both the
Minimum Data Duration and the
Minimum Session Overlap
Multiplier must be met in order for marks to be included in sessions.