Base position logging

I am trying to log a known reference mark to confirm its accuracy for an upcoming job. I need to know what settings to put in the base so I collect independent point data for 8 hours and then PP. I think the setting was wrong yesterday. It just averaged 2 minutes of data and then kept logging the same coordinates all day.
Any help appreciated.

Did you enable the raw logging?

Yes, I logged for 8 hours. Is there a setting for the base that needs to be set. I don’t see anything that’s stands out. I used to have RINEX on my heads, but this has gone. Was this a result of an upgrade. I only have UBX now.

You can convert the ubx to rinex using Emlid RTKconv

Yes, done that. The results are a meter out in XY and.300+ in Z.

What coordinate system is the known point in?
XYZ from Reach are in ECEF
https://docs.emlid.com/reachrs/common/reachview/status/#position

You might need to convert into another format or use WGS84 from Reach

I guess you use RTKpost?
What settings are you running with ?

Yes I am using rtkconv and rtkpost for processing, using the settings given in the GPS Post Processing instructions. This is straight forward, unless things have changed.
What settings should the base be on. Obviously known point and height defeat the purpose of the check. I have to put something in there, so av.single,av.float or av.fix. I have not had one result even close to known point. I am using WGS84.

I would grab some same-day data from a close-by CORS station, use that as a base, and then have your 8 hour obs as the Rover.
Set it to static, and play around with the AR modes.
Also remember to use the Combine option, not only the forward/backwards. In my mind that there’s a huge difference just from that.
I have asked something similar a few weeks ago, maybe it could be useful for you as well: Using NTRIP station 178 km away?

I have taken a 30 day trial account with local caster, but are having problems connecting. This is probably due to my inexperience in casters, never having used one before. I have asked them for advice re the IP address because reach does not recognise it. Im not sure how things connect. I can use my android phone and IPad Mini
to connect to reach, but does there need to be a connection to the caster somehow?
I was intending to set the rover on the fixed point and use the CORS to correct the position. Is this the way to go?

If you want to post-process, there is no need to connect while collecting data. Your provider will have files available for download for that specific day, you can grab afterwards.
If you want to do it on-the-fly, you have to make a connection from the reach unit. You have to set that up in ReachView.

My knowledge base is non existent at this stage. I have entered the details in data correction field in my RS. User name,password,IP address, port and mount point, but it will not connect. Should the RS unit be able to connect to the caster without any other input, or is there more to do. The fine print is not always available on line and I need expert advice here.
Thanks

Hi Denis,

When you are going to post-process data, all settings you need to configure on the unit are:

  1. GNSS Select in RTK Settings Tab (I recommend selecting all systems)
  2. Enable UBX/RINEX logging in Logging Tab

You don’t need to configure anything in Base mode tab or Correction input tab.

Hi Dmitriy,
I have collected 8 hours of data and processed it. It shows that after a few seconds of recording it keeps saving the same XYZ for the entire period. This cannot be correct? I would have thought there would be variations in the readings with a result calculated from the entire data set. The result is significantly different each time I collect data. Whats happening?

Can you share your raw data?



I seem to consistently get Q=0 throughout all dataset, even if I just use Single and don’t use either sbs or nav files. Pretty wierd!

Disabling SBAS completely got me a Q=5 solution. However, the coordinates in the raw data is way off compared with the Single solution:
In the raw-log: -14.5103078, 13.362915936111111 (somewhere in Angola)
Single Solution: -14.51294136, 132.246236951 (somewhere in northern Australia)

Can that be your issue?

EDIT: Actually, it wasn’t disabling SBAS, but taking away the nav file, probably because it has the wrong coordinates nested in. Best RMS I was able to get was a combined 2,5 meters for the coordinates in Australia for a Single solution.

The purpose of the exercise is to prove the co-ordinates and height of a co-ordinated reference mark. There is a question mark over the correctness. The actual co-ordinates are -14.510304189, 132.246241452.elipsoid height 151.1039 (AHD 105.075)
To date the closest I have got is 80cm and mostly 120cm difference in location. Height difference ranges from 25 cm and 400 cm approx. I need to prove that this mark is correct or in error and I cannot go to the Govt Surveyor without good evidence if there is an error. On the other hand perhaps the equipment is not up to the job being only L1. I took to the site with a chain saw to make sure there was no foliage or obstructions, so the mark is in clear air.
I also need to get this sorted as I need the CRM for a major mapping project and i cant use it as it stands.

I will run another data collection overnight and post the raw data tomorrow.