How to place the base, change its place and keep the same points?

Hello, in a very large field, about 200 rural hectares (500 acres) with some hills. I have staked out many points using an RTK Rover (RS+) where on occasions I have needed to move the base antenna (RS2) to different places since, as it is a very large place, the LoRa signal does not arrives to do FIX or because I had to continue working the next day.

I have realized that once I moved the base antenna, to validate that the previous work is correct, I have searched again for the point that I had already staked out previously but now it does not fall exactly in the same place as before, it tells me that it is at about 40 or 60 centimeters difference. So now I get confused because I don’t know which one is correct or why it doesn’t fall in the same place.

Surely I am doing something wrong and my lack of knowledge and experience or I am forgetting to do something before starting the day.

This is my Workflow step by step:

  1. I place the tripod in any part of the field where I can dominate as much as possible with the LoRa signal and get open sky.

  2. I perfect the level the antenna with tribrach

  3. I turn on the base antenna (RS2) and let it accumulate coordinates in “Average Simple” for 15 minutes (I attached a picture for further reference.)

  4. Once “Average Simple” is finished at the base, I turn on the RS+ rover and wait for FIX to start staking out and if I return to a previously point, it is where it gives me another place to stakeout with a difference of approximately 40 to 60 centimeters.

Maybe I should always need to put the base in already known points and type the coordinates manually or should I need to make the process for “shift” to a particular place?

If so, I don’t know how to create a known point or what or where point I should shift to.

To create a Known Point:

According to what I have studied, to create a known point I must do PPK. Cross the RINEX data with the data obtained from some CORS network antenna using Emlid Estudio and use the NASA ephemeris data. And with this I can manually put the coordinate in the base.

For shift:

To do a shift process I must have some known point within the same project and before doing stakeout I must go to that? I’m confused.

Could you help me to know what the workflow would be or what do I need to do?

I will really appreciate your help.

Thank you very much.

2 Likes

It sounds as if each session is disconnected from the previous one- in which case, each time the base is placed, it is done so using autonomously acquired coordinates. The difference of a few cm is quite impressive. With me, usually the difference is at least 1m.
Nonetheless, you are introducing a 40-60 cm error into your project with each set up.

You should be saving the fixed position of the staked out points in your RV3 project.
On each subsequent set up, the base should be placed on such a point- instead of using “single” to determine the coordinates of the base use “manual”- in the base configuration menu.
You should select the point recorded from your previous session.

1 Like

Hi, since you started your base in a Average Single location you only have a relative base position and not a absolute Base position. If you only need all of the 500 acre survey points tied to one network please follow Adrian’s advice above and that will tie all of the points to each other with multiple Base setups.
If you need a absolute position, you will need to start your Base with a known point, either through an active NTRIP/CORS correction service or through various PPK/PPP methods mentioned in Emlid’s Docs, after logging the Base position for 2hrs or more depending on the PPK/PPP method chosen. From there use Adrian’s advice to connect the different surveys together. Emlid has some excellent info on it at:

1 Like

You can use base shift to align two base setups. All you need to do is shoot a point that is in range of both the first base setup and the second setup. At the end of the day one mark a point and measure it in ReachView3. Next day, when you arrive on site, place your base station so that you can still reach that point with the rover. Average single your base and walk with the rover to the point. You will see a difference between the coordinates now and yesterday even though the rover is physically on the same spot. Now measure that point again and use the Base Shift function using these two measurements. Your second day survey data is now aligned with the first.

3 Likes