OPUS Processing with Emlid Reach

Here is a quick tutorial on using NGS's OPUS with the Emlid Reach RS2+, Emlid RS3, and Emlid RX. This workflow should be similar with any other GNSS receivers as well, visit https://www.ngs.noaa.gov/OPUS/about.jsp for more info. In this article, we take you through collecting data and processing it through the National Geodetic Survey’s Online Positioning User Service.  

First, we are going to prepare our base. Start by taking note of your pole height and then go into your logging settings. Emlid has a preset for OPUS which will provide us with the proper recording format. Enable AutoStart for your base logging so then you only have to power on the receiver and collect data on the point your submitting to OPUS. Also enable Backup data for RINEX, in case you want to use all the data available from this base in this time frame since the OPUS preset is only going to record data from the NAVSTAR GPS constellation. Now that your base is configured, head out to your point.  

We have a stake tack that will be a recurring point for our base in the future so that is what we are going to get an OPUS solution for. We are set up and collecting. OPUS can process in Static and Rapid Static based on how long your observation is. We recommend at least 90 minutes for Rapid Static and at least 4 hours for Static. Visit the OPUS website to learn about best practices and recommendations.  

OPUS File Requirements:  

Rapid- Static- 15 minutes to 2 hour collection 

Static- 2 hour to 48 hour collection  

GPS (L1/L2) only- Rinex 2, 3 , UBX & others 

With an RS2+ or RS3, if you’ve selected the OPUS preset, you’ll have the compatible file in the RINEX folder once you download your log. If you are unfamiliar with downloading logs from your Emlid Reach receiver, see this tutorial. Select your observation file with the extension .230 and Select Open. Then select your receiver in the drop down menu, input your pole height, and select the applicable processing method based on the length of your observation. You should then see a success message from the OPUS site letting you know that you have submitted the file. You will receive your solution via email. If everything goes according to plan, you will receive a solution page giving you information about your observations and a solved point in NAD_83 in the left column as well as information about the bases used to solve for your point. If there is some error with the file, you will receive an email from OPUS detailing it. Most commonly if you’ve submitted a file the same day that it is recorded the service may not have base information until 24 hours has elapsed.  

NOAA's OPUS provides free access to high-accuracy coordinates and uses the same software which computes for the CORS network. It is simple to upload your GPS data file collected with your RS3 or RS2+ receiver.