Novice question about PPK


I am using a Reach RS3 Base and Rover setup over Lora and connecting via bluetooth and I have a couple of questions.

If I am surveying a site and I am getting a FIX for most of my points but some of them are Single because I am either under dense forest, or I am in a sheltered corner of a building where the antennas can’t communicate, can I still use PPK if I am recording the raw logs? Is it possible to do this hybrid approach or is it only RTK vs. PPK?

My second question is related to just a surveying technique. I know the base is meant to stay in one place but is it possible to move the base to another known benchmark that I’ve shot on site in order to get points that might be hard to get with the base in the first location?


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Hi Jon,

Sure, you can use it as a backup for RTK. For this, both the base and the rover must record raw data logs. You can enable this in the Logging tab. Then you can post-process logs along with the CSV file from Emlid Flow in Emlid Studio. This is called Stop & Go mode, you can read this guide to learn more.

I should note that tilt compensation works only for RTK, not PPK. So hold the pole levelled above the points collected in this mode.

It’s also worth mentioning that the Stop & Go isn’t a remedy for such cases. If the receiver can’t resolve ambiguities to get FIX in RTK, it doesn’t guarantee that you’ll obtain FIX in Stop & Go. But post-processing settings are tuned, so at least you can play with them to get more accurate data.

Sure, it is. You can collect the point on the ground, fix it with a nail or whatever mark, and place the base over it. While configuring the base coordinates in the Manual mode, you need to choose the collected point from the project to keep the consistency of the dataset.


Hi Kirill,

Thanks so much for your reply! So I just finished a survey in the field this morning and had some trouble getting shots of the corners of the building and some areas that were under the overhang of the house or under a tree. The rover was unable to get a FIX. What is the best workflow for when this is happening? I don’t want to just give up and not be able to get the shot. I did attempt to turn of “fix only” and it turned off tilt correction and I am able to get the shot at least but probably at a high level of inaccuracy.

I’m just wondering what the best workflow is for when I’m unable to get a FIX on a point. If a FIX is unable to be achieved is this most likely due to lack of exposure to the sky for the satellites?

Thanks! Sorry if this is confusing, I’m still relatively new to the process.

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Hi Jon,

The surrounding objects interrupt signals, and it causes the multipath impact. When it happens, the receiver can’t resolve ambiguities and get the FIX solution. There’s no versatile cure for this because this is a standard limitation of GNSS. However, I can suggest the following workarounds:

  • Stop & Go technique as discussed above.

Pros: acts as a backup and doesn’t require additional costs and actions.
Cons: needs longer occupation of the points, helps not always.

  • Collecting points under a good sky view that can be used for drawing and geometric constructions of unachievable points
    For better visualization, you can check the image below:

Pros: variability, with proper skills you can survey even hard-to-reach spots.
Cons: requires the additional software to draw objects until the specific COGO tools are released in Emlid Flow. It may also complicate the sketching of the topographic outline.

  • Using classic geodetic instruments such as total station

Pros: acts wherever you work, high accuracy of measurements
Cons: need to own the total station and have enough skills to operate it

Hi Kirill,

Thanks again so much for your response. I think your second method you described will work best for my situation. I can always get offset points from the corner of the building and then measure back to the building and get elevation differences with our zip level. Luckily I can live with some slight inaccuracies. We also use a drone for our data gathering and I’ve been able to cross reference my survey data with that which has been extremely helpful. These woodsy sites in New Hampshire don’t make it easy!

Thanks again.