How to get the best raw data for post processing?

So I’m just messing around with the equipment I have access to, trying to make more accurate GCPs for drone mapping. A Spectra SP20 and the UK OSnet CORS.

I played around with it yesterday and once processed with my local CORS as the base, I had some fix positions, at seemingly random times, often just when walking between points. I went out again today with the goal of occupying each point for longer (3 mins, I know that’s not long but I only have a monopod so I have to stand there holding it) hoping to get at least a few fix positions on each GCP. But this time IT WAS WORSE! I only had a couple fix points, and this was in the same open field as yesterday.

I did each GCP as a individual static survey as well but only got fixes on 1 of the 7 GCPs

So is there a way to tell how good the data I’m logging is at the time? Or is it just a case of occupying each point for much longer (10-15mins)? And hoping to get some fixes?

If you do 180 epoch fixed control points with RTK GNSS from a CORS or base GNSS RTK under 10km it should give you residuals less than ±20mm horizontal and ±30mm vertical with a pole with bipods

If you need less than 10mm H and 15mmV then do 2 static sessions at least 6 hours long each on a tripod with tribrach and post process

Hi Sam,

Data quality may depend on many factors, but mostly on environmental conditions at your site. However, if you collect the same points at different times, it may change slightly. Satellite geometry alters due to their movement during the day and the result varies.

Typically, longer occupation on each point provides you with better data since the receiver has more time to resolve all ambiguities.

Some customers use specific applications and services that allow planning GNSS observation. For instance, something like this one.

On top of that, you can play with post-processing settings in Emlid Studio to obtain better results. You can also send me your datasets to I’ll try to process them with different settings and will post my conclusions here.

1 Like