Ntrip. +105km, reliable?

Hello.
I got a fixed solution with Ntrip at over 105 km baseline.

What do you think?

I was surprised!

2 Likes

Curious, which antenna(s) are you using with your M2(s)?

1 Like

Not surprising that it Fixed but it is surprising the PDOP and residuals you are getting. You can see the corrections are a little slower.

3 Likes

Hi @mauricioranzan,

Achieving a FIX solution is great, as it means the receiver has resolved all the ambiguities. However, achieving centimeter-level accuracy requires attention to other factors, such as the length of the baseline and a good satellite view.

For Reach M2, which is a multi-band receiver, we recommend a baseline of up to 60 km for RTK. Beyond that distance, atmospheric conditions can vary. This variation may introduce errors since the RTK algorithm assumes the atmospheric conditions are the same for the NTRIP base and the rover. So, the closer the base and the rover are located, the more similarly they experience signal distortion. This allows GNSS receivers to better compensate for the distortion.

8 Likes

Wow!

3 Likes

You might want to double triple check using a NTRIP closer or to another nearby known point just in case that is a FALSE FIX.

2 Likes

How about another base on the project site ?

https://www.javad.com/jgnss/javad/news/pr20151113.html

6 Likes

Please elaborate on your “Wow!”

2 Likes

Hello, I used the M2 and a BT-800 antenna

2 Likes

Just to follow up on this I did some testing yesterday just to see what I could get via NTRIP from my home station with a baseline of 100km. It was hanging out around 3 & 7cm horizontally & vertically but it wouldn’t fix. Corrections were in the 2-3sec range like we have discussed. The wow was confirmed. If it was that far out and not fixing at 100km then 60km would still be super sketchy for RTK. I PPK everything beyond 30km. Based on their spec 60km puts us outside of tolerances anyway.

6 Likes

Thank you for clarifying

2 Likes

On single baseline, if you want centimeter-repeatable results that are consistent from one day to another, stay under 10 km if the height important to you, 15 km if only the horizontal portion is important.

9 Likes

The key is the repeatability of the solution mentioned by the colleague wizprod, the GPS theory teaches that; Over 10km distance the tropospheric and ionospheric factors can induce errors by not being equal errors at both ends of the baseline. Finally everything will depend on the tolerance allowed by your project.

3 Likes

No. At 20km I can hold about 3cm total pretty well but I tried at 100km when I was in a different city just to see what would happen and it would not converge. I had a fix for about 2 seconds at a time and not reliable.

2 Likes