Welcome to 'How to Submit an OPUS Share Observation'. I'm David Zenk, the National Geodetic Survey advisor for the Northern Plains region. I'll be your instructor for this lesson. The primary purpose of this lesson is to explain the steps needed to submit an OPUS Share observation in the context of supporting the GPS on Bench Marks campaign. There are many sources of information on the OPUS suite of tools. See the NGS website at www.geodesy.noaa.gov. 

The GPS on Bench Marks campaign has three goals, first to improve the NAVD 88 to NAPGD2022 transformation, second to pre-populate the NATRF 2022 control, and third to preserve the nation's valuable infrastructure network of legacy survey marks and update the information about those marks. All of which benefit each of us. 

OPUS is an acronym for online positioning user service. It started out as a service for static GPS users and has grown from there to serve other users. OPUS was designed to work with minimal data input from the user and be as fully automated as possible. Only a web browser and email are needed to use OPUS. OPUS is a fast, easy, and consistent way to access the National Spatial Reference System, or NSRS. OPUS has grown to be quite popular over time. OPUS now serves over half-a-million data submissions per year. OPUS Share has become quite popular too, driven by the GPS on Bench Marks campaign. Browsing the OPUS shared solutions map, shows exactly where users have shared valuable data on permanent marks of public interest. The blueprint for using OPUS Share is that the user will submit GPS data to OPUS website. OPUS will automatically process it on NGS computers with ties to three CORS. The solution will be returned via email in just a few minutes. In general, OPUS Share can be broken into four steps, upload, i entify, describe, and then finally share. The NGS sample field log sheet can be used to help organize the needed information. 

This is the OPUS submission page. It's the gateway for all types of OPUS submissions, including OPUS Share.  The OPUS screen shows the minimum six inputs. I'll describe each one on the next slides. The six required inputs are a GPS file, dual-frequency, RINEX version two or version three, or some proprietary types, and at least four hours in duration. OPUS will compute only the GPS observations that are above a 10 degree mask angle, and OPUS will decimate the logging interval to 30 seconds. The antenna type is also needed, you choose that from the list. The antenna height is the vertical height from the mark to the ARP measured in meters. You need to supply an email address, here you see mine, and then there are some options on the next slide. First click on the 'options' button. The screen will telescope open to show the options. The user can choose from the six options shown. 

Output format - most users will choose standard, but you could also try the extended output and examine the useful results found there. Users may choose to specifically include or exclude one or more specified CORS in their submission. Most users should leave the selections blank and allow OPUS to choose. Similarly, allow OPUS to choose the state plane coordinate system or SPCS. Leave the OPUS Projects identifier blank if the box is shown, and do not choose to set a user profile. Choose 'yes, share' - this option will enable the OPUS Share application, and finally press 'upload to static'. Be careful to measure the vertical antenna height from the mark to the antenna reference point.  OPUS Share expects that height to be entered in meters, and make sure that the antenna is carefully plumbed over the mark.  

Well exactly where is the ARP for antenna? NGS supplies antenna calibrations and diagrams for most popular GPS antennas on the ANTCAL page. In this example, the Trimble R10 diagram shows clearly that the ARP is the bottom of the antenna, which is also the top of the quick-release. Be sure to measure the height to the identified ARP. The tabulated NRP is the North reference point for the antenna and in the case of the Trimble R10 it's listed as MMI, meaning man-machine interface.   The NGS ANTCAL FAQ page lists the abbreviations and meanings for the ARP and NRP. Your field crew should be careful to point the antenna's NRP toward the north during observations. Once you've chosen 'yes, share' and click 'upload to static', you'll be given three options. You can choose the 'mark has a PID', the 'mark is new to NGS', or 'skip description'. Here are the three choices of how to identify your mark.  If you choose 'mark has a PID', you need to know the mark identity, the PID, and have two photos, small JPEG files 1024 by 768 are adequate. If you choose 'mark is new to NGS', you must fill in the required fields and have two photos. 'Skip description' is not an acceptable choice for OPUS Share. OPUS Share step three requires two photos, a close-up photo of the disc clearly showing the stamping, and a horizontal photo of the setup clearly showing the equipment. Again remember, JPEG format, 1024 by 768 is adequate. If you have an existing mark with a PID, you will need to supply the correct PID and then update each of the data fields shown. When finished, click 'upload description'. If you have a new mark, you'll need to fill in each of the data fields shown. Users who are not familiar with the contents of the field should consult an experienced user or ask their regional NGS advisor for assistance. When finished click 'upload description'. Having entered the required data for your mark, you may return to OPUS and submit an additional observation or close the OPUS tab. At this time your data file will be uploaded to OPUS Share and processed. You can expect emailed results usually within 5 minutes, possibly longer if the OPUS servers are busy. Note that you will also receive a second confirming email with a link to complete the process. In addition to the usual OPUS processing results, you will receive this second email containing notification that an OPUS contribution has been submitted. A hyperlink will be supplied to allow you to view a mock-up of the shared solution. Following the hyperlink will allow you to view a mock-up of the shared solution. Note that you now have three choices, approve the shared solution as shown by clicking 'share', edit the description that you've supplied by clicking 'edit', if the solution shown is not satisfactory or if you do not wish to continue for any reason, click 'discard'. 

Before we proceed to the QA and QC step, we need to discuss New User Registration. If you've never submitted an OPUS Share, then your email needs to be added to the OPUS registration list. This is a simple one-time process. If OPUS Share does not recognize your email, you will get a pop-up window that prompts for the necessary metadata. Pop-up blockers may prevent this window from appearing, so new users should be aware of this procedure. 

Let's return to the QA/QC steps. Once again following the hyperlink will bring you to an opportunity to choose from share, edit, or discard. OPUS Share, like all OPUS solutions, computes several baselines to surrounding CORS, evaluates their consistency, and then chooses the three best solutions. As the diagram shows, OPUS will compute an average of the three best solutions and then compute a peak-to-peak report. Here are the minimum standards for OPUS Share. Compare these to the OPUS report to verify that it meets the minimum standards and can be submitted to OPUS Share. 

Here's a typical OPUS report. Let's examine the minimum quality standards for OPUS Share submission and compare them to this OPUS report. There are five places to examine for quality acceptance. First, did the solution use the precise ephemeris or something else. NGS recommends that for best practice to wait 14 days for the final precise ephemeris to become available. Second, verify the antenna type and antenna height. Compare these to the field log sheet. Errors cannot be fixed, the file needs to be re-uploaded. Third, do the file start and stop time show at least four hours duration? Fourth, is the 'OBS USED' at least 70% and is the overall RMS 3 centimeters or less? Fifth, are the peak to peak values for latitude longitude four centimeters or less and is the peak to peak value for ellipsoid height 8 centimeters or less? In this example, all the standards are met. Remember that you must always follow best GPS practices and make sure your equipment is in good adjustment. GIGO means garbage in garbage out. 

If you need assistance, please contact me or your regional NGS advisor and good luck with your OPUS Share submissions. 

Thank you.