User Instructions
and Technical Guide
OPUS Projects
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NOAA | National Geodetic Survey
tests performed with blocked data indicate that results from a Helmert blocked adjustment versus one
in which all data was processed through PAGES, so all correlations could be handled correctly, show
differences within the normal noise level of our GPS adjustments.
While the above discussion describes one short coming of the Helmert blocking system as incarnated in
this
software, the counter point is that it allows much larger problems to be solved than could otherwise
be handled and it allows inclusion of much larger amounts of real data in adjustments. While the
numerical tests done thus far do not prove that the technique will always provide good results they do
indicate that it is adequately working in all current applications provided the data are of reasonable
quality and the problem is structured correctly.
The nature of the network and the problem to be solved usually suggest an approach as to how the data
should be divided for this blocking strategy. The process of designing the groups of
data called blocks is
often thought of in terms of regions or geographical areas but there are other ways to think about how
to divide up the observational data. Time, for example, is another dimension which is a natural blocking
factor routinely employed in OP in the form of session processing.
Geographical Blocking - However, if geographical blocking is necessary, because of the size of the
project or available
resources, one concept would be to divide the marks in the network into logical
geographical regions, for example areas where marks are clustered such as in some urban areas. Each
block can then be processed independently with the PAGES program as is usually done for any network,
with one exception. In order to connect the regions into one complete network, marks common to all
blocks should be included. A natural choice would be one or more CORS or, perhaps,
dedicated marks
that are continuously occupied for the duration of the project. These serve to tie the individual blocks
together into a “whole” with the added potential benefit of improving tropo corrections because of
their longer data spans.
OPUS Projects
User Instructions and Technical Guide
NOAA |
National Geodetic Survey
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Appendix A.
FAQ – Troubleshooting Help
Q.
The Internet browser I am using fails to refresh my project map and it appears that my project
session or adjustment has not been processed by OP?
A.
Click the refresh button provided in the ‘Control’ menu within OP. This forces the Internet
browser to reload (submit) and update the map with the most recent project changes.
Q.
I submitted a session for processing and then realized a mark name was incorrect and changed
it. Will this confuse OP processing?
A.
Yes, most likely. Because OPUS Projects uses a web interface rather than a "true" GUI interface,
every action is distinct and separate from any other action. If you inadvertently create a
situation where
two actions may be trying to do the same thing a conflict can occur with only one action winning. For
example: I believe you said you were renaming marks while processing was on-going. Broadly, that is
OK, but if you happened to rename a mark in the project's information about itself at the same time that
the processing is trying to write its results to the project's information, then only one will "win" and get
written. This may cause your project to lock up or fail to write to completion or fail to refresh
information about itself.
Q.
I have seen a mark ID a001 in my project but I didn't upload a file with that mark ID. Where did
a001 come from?
A.
At least two of your uploaded
files have the same mark ID, but their OPUS solutions indicate
different locations so OP named it as a001 or where two files have different mark IDs, but the OPUS
solutions indicate they are the same mark. You may wish to change the mark name to the correct one
by going to the mark web page. This can be avoided at the outset by making sure you label the first four
characters of the RINEX (or receiver file) with the correct name of the mark. When you initially planned
your survey you should have identified what you will name each mark.
That four character name or
number should be perpetuated through the OP project starting with the uploading of the named files to
OPUS.
Q.
I uploaded a file, but the mark doesn't appear in the table at the bottom of the Manager's page.
Why doesn't the mark show up in the table?
A.
First refresh the Manager's web page. If the mark still doesn't appear, check the data file and its
OPUS results. In this case, the data span of the file is probably shorter than the minimum session length.
If you uploaded a file that is named exactly the same as a previously uploaded
file then the original will
be overwritten. Make sure each uploaded file contained the correct mark name.
Q.
I received a processing solution email, but it is (mostly) empty and has no attachments. What
should I do?
A.
The processing failed catastrophically. This is probably a problem in OPUS Projects that you can
help fix. Send an email to the OPUS Projects Team with the project ID, session ID and a short summary