Placing the base or measuring a static point using antenna height records the measured height as the point instead of the ground

As the title says, I’ve recently realized about this since I’ve been having problems with inconsistent heights in my surveys. This is actually a big deal since I need to work with higher precision then usual for elevations in a current project.

I could just take out the measured height for every measured point according to each day, but it’s a huge hassle, and how am I supposed to work from here on out? I place the base on the same point each day, but since I’m using a tripod, the antenna height ends up varying a few centimeters each day. How am I supposed to account for that if not supposed to input the antenna height to get the proper ground height?

I hope I explained myself correctly. English is not my first language and although I’m proficient in it, I’m not very familiar with technical vocabulary regarding this field.

Rover rod with bipod or tripod attachment.

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Hi Rod,

If you place the base on the same known point, you can use the Manual base mode setup. It allows entering the antenna height. These coordinates will be there even after the reboot. You’ll just need to change the antenna height.

How do you set up the base currently? Maybe I’m missing something.

I know, this is what I do. What I’m getting at is that I first get the coordinates via averaging, then the next time I place the base there, I use the coordinates obtained from the day prior, and if I input the measured antenna height, it raises elevation of that point by that height amount, say I measured 1.6 m from the reference point to the RS2 Base, everything I survey from then on will be 1.6m higher, it adds the antenna height over elevation previously obtained, instead of calculating the current elevation based on the antenna height.

I think I understand your question. If you are acquiring position using the average method then whatever the ht value is you then deduct your HI. you then record this position for future use via the manual option which then has the HI option. you do not need to use average values every time you do a base setup. this will result in different daily values depending on satellite positions.

I only acquire position using the average method the first time, then on consecutive days I do use the manual option, and when I input the measured antenna height, it adds that value to the whole elevation.

What I ended up doing is measuring the antenna height any way and adding or subtracting the daily difference I get to the ellipsoidal height, but this is not a nice solution, is should always get the correct elevation of the reference point and calculate the surveyed points elevating taking the measured antenna height into consideration like regular systems do.

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I think that is the correct value of the base. The value of the ht of the base as reflected on the rover status page is the ht of the reference point of the GPS antenna and not the ground ht value. In order to get the correct ht value, deduct (1.6m +.134) from the average ht value when you enter it in manual mode.

Hi Rod,

I got you, and I agree with Juan in general. When you average the point for the first time, you need to do the following:

  1. Measure the tripod height
  2. Subtract the tripod height and 0.134m (the antenna height) from the elevation coordinate

After that, you can use these coordinates in Manual mode as now you have coordinates of the point on the ground.

I understand it would be much more convenient if ReachView 3 did that on its own. And we’re already working on that. I’ll remember this thread and post all the updates here.

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That’s good! The goal is to record the elevation of the point on the ground and not the APC .

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Dave,

Yep, that’s exactly what I meant!

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it is possible to do it differently:
perform measurements in survey mode. there you can record the name of the point and the height of the tripod. set the measurement time to 5 minutes. As a result, we get the coordinate and height of a point on the ground.
then it will be possible to enter the obtained coordinates and height when we install the instrument in base mode.
only you need to remember that in the base mode, when entering manually, you must also specify the height of the tripod above the point.

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