Setting a Repeatable Base Position in your Emlid Reach Base

This article will walk through setting an easily repeatable point for your base whether you have a known point, have corrections to set a point, or want to set an arbitrary point, while using your Emlid Reach RS2, RS2+, or RS3 as a base. Use Emlid Flow on your data collector to work with your base and rover. 

Setting a known point - Ideally, we have a known point that we can import before we even show up on site. If that's the case you can navigate to flow360.emlid.com and log in with your Emlid account to create the project you will be working on. Select New project, then name it. Select the correct coordinate system, vertical datum, and linear units. Then import the point file containing your known point. You can also manually enter the point if given the coordinates outside of an accepted file type. Now that the point is loaded into Flow 360, it will sync up with the Emlid Flow app on your data collector. Out in the field we set our base over the survey nail of our known point. Connect to the Base, then tap Base settings and Configure. Since we are using a 2 meter pole, we'll correct the Antenna height first. Emlid Flow will add the additional 134 mm antenna offset automatically. Then change the Coordinates entry method to Manual and tap Choose from project. Select the project containing the known point you set up earlier. Select that point, apply, and save. This is the best way to ensure our Base and therefore our Rover will have a high degree of absolute accuracy.  

Switching over to the Rover we can see we are receiving corrections from our Base and quickly have a Fix. The ‘move the receiver’ message is shown to initialize our imu and enable tilt compensation. Tapping the blue plus button will take you into the measurement view. Since we are using a 2 meter rod, we tap on the Pole height and adjust that for the correct height. We will also turn on Averaging for the points we collect and since we're not taking any shots that require tilt, turning off Tilt compensation and leveling our rod eliminates the need to wait for the imu to initialize as well as removing the error associated with tilt compensation.  

Setting without a known point – If we don’t have a known point hopefully the Base can receive corrections from an NTRIP network. We have Ohio’s DOT network so we will connect to that with NTRIP over Bluetooth. Now that we have a fix with our base, we can collect an average fixed point. And we can go back into our base settings as before and manually choose that point from our project to use as our base marker. Now switching over to our rover and collecting points will yield a high level of both absolute and relative accuracy.  

In the case that we don’t have a known point and there isn’t an NTRIP provider we can connect to, we will need to set our base marker a bit differently. Our suggestion is to collect a point using an average single solution and importing that in the same way we did with the known points. This way we can repeat this base position on this job site and maintain a high level of relative accuracy. So we will connect to the base, go into our project and tap the blue plus button and adjust our survey settings to allow us to collect a point without a fix. We can average that point for up to 59 minutes 59 seconds or collect one quickly since either way our absolute accuracy won’t be very good. Remember to turn FIX only back on for the rest of your survey. With that point collected we will go back into Base settings and import that point. We can also leave our base logging for OPUS in this configuration if we ultimately need absolute accuracy on this project. 

Using Emlid Flow on our data collector we set an easily repeatable point for our Emlid Reach RS2+ or RS3 base. We showed the process whether you have a known point, have corrections to set a point, or want to set an arbitrary point.