Difference in elevations in fix mode

Reach Module / M+ / M2 RTK / PPK configuration
1

Hello everyone,
I recently experienced something strange with Reach RS+. I’ ve made a stake out and have surveyed each point. The results were surprising because since point sovit11 elevations were rising and they should be decreasing.

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i have finished surveying the street and it crosses with recently surveyed street and elevations differ with about 80 cm.
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The elevations in second pictures are transformed with a licensed program from ellipsoidal to Baltic height system, and they also differ in ellipsoidal height.
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2

Do you have the raw ubx?

4

Yes, i am uploading all the ubx files for this date, i am not sure how to view them.
*.raw_201901230646_UBX.zip (8.0 MB)
raw_201901230744_UBX.zip (1.5 MB)
raw_201901230758_UBX.zip (726.2 KB)
raw_201901230807_UBX.zip (5.0 MB)

5

Any ideas?

6

Ill try take a look at the raw files later. Thanks for uploading.

7

Can you also provide the survey csv file?

8

Yes, here it is:
NoviPazar-CSV.zip (2.7 KB)

9

You were measuring each point only for 3-5 seconds. I would suggest measuring it for longer time (at least 10 seconds). Points are measured in Novi Pazar, Bulgaria?

10

Yes this is correct.

11

With the right (optimal) conditions, you dont need more than 2-3 secs.

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12

We can try to post process your data, but I can’t find any RINEX data from Bulgaria. Maybe you know any NTRIP caster? Which one were you using?

13

I was using 1Yocto network. The interesting thing is that all points are in straight line, meaning that X and Y are ok, even elevations collected by 2019-01-23 08:25:10 UTC are ok even with 2-3 sec. I have previous data collected by a surveying firm with gps, that matches elevations measured with emlid.

14

They have RINEX only for sale, unfortunately.

15

Hi @sdobrev85,

Can you share your RINEX base log here, please?

16

Hi,
I had the base corrections set for collecting RTCM data. I have attached them in case they can be in any use.
Can you share how to open these type of files?base_201901230646_RTCM3.zip (572.3 KB)
base_201901230807_RTCM3.zip (386.5 KB)

17

Do I understand right that you expect the height of the soviet17 and so10 to be the same?

18

Yes, it is one street, with 2% slope max, the difference should be about 6 cm. And i was on sight, there are no holes this deep.

19

The problem with the height starts with point: sovit11, it should be lower then sovit10.

20

I can assume, that the issue is related to the following factors:

  • As @jurijs.jeshkins mentioned, your point collecting time is a way to short. I’d recommend to increase it to a few minutes
  • Also, your NTRIP station is quite far from the rover. The distance is around 20km, however, the recommended baseline is 8-10km
  • Another reason is that you’ve got strange signal breaks on base logs

base1

base1
base1.png1919×1050 53.4 KB

base2
base3
base3.png1919×1050 46.5 KB

Do you have any plans to do more tests?

21

Thanks for the help. I am using Reach Rs+ in my practice, and if i encounter something else which is strange, i will let you know. I have made an initial test when i bought Reach and compared points measured with Trimble R4 and Reach RS, and results were satisfying, but i was using a pole holder and were gathering observations for longer periods (couple of minutes).

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