UK GCP capture workflow with RS2+ & PPK solution help

Reach RS2 / RS2+ RTK / PPK configuration
1

Good Afternoon.

New to the Emlid Reach RS2+ world here and struggling with our ground control point workflow with PPK solution using OS RINEX data as we only have one receiver…however we’re struggling to obtain a fixed solution. Looking for some help/advise please.

Currently we are setting up over an unknown control point, powering on the unit, waiting a few minutes before starting a log file, conducting a 5-minute base configuration, then recording a point in Emlid Flow with SINGLE averaged observations over a 45 minute period. Wait another couple of minutes and then ending the log. All within an hour so we can utilise 1 hr RINEX file from the OS during processing. Move to new GCP, rinse and repeat. All GCP locations are in good positions and free of any obstructions.

Log files are downloaded along with the CSV file for the recorded points and run through Emlid Studio 1.9 via stop & go. Use Observation & position files from the receiver and the RINEX from the OS to generate new position file with the default settings other than a combined filter type. However we never get a solution so have to run either forward or reverse and then only a SINGLE solutions to the tracked positions is found, then run against the CSV returns SINGLE solutions for the recorded point(s).

The OS base we are using is in Shrewsbury (SHRE) and is never more than 40km away from anywhere we will be operating.

Help…

3

Sounds like you’re doing a couple of things wrong and using the wrong processing.

If you’re “averaging” each position for 45mins, then you don’t need to do the initial “Single” averaging for 5 minutes as it’s irrelevant (it does seem to let the RS unit “settle” though).

Simply set up the RS on the GCP, turn it on and start the logging. When you’ve been on point for your chosen time, then record your EmlidFlow point (Not needed, but take only as a backup), stop the logging and move to the next point and repeat.

When you’ve done all the GCP positions, then go back to the office and download all the logs, download the OS RINEX files and then process each separate GCP log point using the Static workflow instead of the Stop & Go.

You’ll need to process each individual log file along with the matching OSNet RINEX log separately. OSNet RINEX is used for the BASE data, with the Reach RS .25O in the Static Receiver and the corresponding .25P as the Navigation file. Then you can run the processing with default settings, although I’d run a Combined (Fwd & Back) solution. You can most likely disable the SBAS option too. Sometimes turning off the BeiDou processing can give a better result here in the UK too.

By the way, you don’t need worry about keeping everything inside the 1hr “window” of the OSNet RINEX file (actually a 90min log). EmlidStudio can use multiple Base RINEX files - instead of dragging & dropping a single file onto the region in EmlidStudio, click on the BASE region to bring up the file window, then add mutliple RINEX files before clicking “Open”.

Rinse & Repeat for each GCP Location and log file you recorded.

The Stop & Go Processing is more appropriate for when you use the RS unit with an external correction source - either another Reach Unit, or a 3rd party NTRIP provider.

You don’t need the EmlidFlow point data CSV - when using the STATIC processing the accurate point position is coming from processing the Reach’s log file, not the EmlidFlow point that you record.

I hope you don’t have a lot of GCP’s t do as that’ll take you a fair number of hours! You might want to think about finding an NTRIP correction source - either another Reach RS running as a Stationary Local Base & sending Local NTRIP, or a 3rd party NTRIP source. First way involves shelling out for another unit, second way involved coughing up for a subscription (the free NTRIP streams aren’t reliable enough).

Hope that lot helps…

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4

Hi @PSGSurvey,

Thanks for sharing your workflow in detail!

Could you share your RS2+ and OSnet logs with me? I’d like to take a closer look and see why the solution isn’t getting a FIX. You can either PM me or email them to support@emlid.com.

It seems like you’re on the right track with your workflow. However, just a couple of suggestions:

  • Using a PPK workflow, you don’t need to average the base position. You can start logging right away.

  • Since you’re working with multiple GCPs, processing each separately with static processing can be pretty time-consuming. I’d suggest using the Stop&Go workflow instead.

Start recording a raw data log and collect all the points in the Emlid Flow project. After that, post-process the logs and CSV file in Emlid Studio. You can use the OSnet log as your base, but make sure the log durations align. This way, you’ll get your corrected CSV. You can find more details on how to set it up in this guide.

As @ElectroNick suggested, if you’re looking for real-time results, the NTRIP service would be an alternative.

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