Setting a Repeatable Base Position in your Emlid Reach Base
This video clipped from our base and rover configuration video 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.
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 I set my base over the survey nail of my known point. Connect to the Base, then tap Base settings and Configure. Since I am using a 2 meter pole I’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 I am using a 2 meter rod, I tap on the Pole height and adjust that for the correct height. I will also turn on Averaging for the points I collect and since I’m not taking any shots that require tilt, turning off Tilt compensation and leveling my 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. I have Ohio’s DOT network so I will connect to that with NTRIP over Bluetooth. Now that I have a fix with my base, I can collect an average fixed point. And I can go back into my base settings as before and manually choose that point from my project to use as my base marker. Now switching over to my 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.