Pragmatic way to determine if cm level accuracy is reached

Q&A forumCategory: QuestionsPragmatic way to determine if cm level accuracy is reached
Alf Kuchenbuch asked 7 months ago

Dear All,
My base is running all the time. When I startup my rover, its accuracy is poor until it picks up the correction signal from base and its own satellites. After about 2min cm level accuracy is reached. What is a good indicator that my system has reached cm level accuracy? Is it PDOP<=1 or HDOP<= 0.6? Or is there a better way?
Thanks in advance,
Alf

Ardusimple Staff replied 7 months ago

Best is to use Fix Type indicator: when indicator is RTK FIXED this usually means you have sub 2-cm accuracy.
Alternatively you can read accuracy estimate value, available in GST message.

Alf Kuchenbuch replied 7 months ago

Great answer! That’s what I was looking for. Thanks!

2 Answers
django122 answered 7 months ago

Hello,
 
do you mean field 6,7,8 of the $GP message?
Matthias

Alf Kuchenbuch replied 7 months ago

Hi Matthias,
I use NMEA GxGST (GNSS Pseudorange Error Statistics) to see the standard deviations of latitude, longitude and altitude.
And I use NMEA GxGGA (Global Positioning System Fix Data) to see the field “Status”. If Status is 4, it’s Fixed RTK, which apparently is a good indicator to sub 2cm accuracy.
Regards,
Alf

django122 answered 7 months ago

Thanks. I use in the moment the status.  And i think it is ok.
Matthias