How to perform Stop & Go with Emlid Flow and avoid getting the “zero points found” issue

[natalia.botygina]

Today, we continue talking about PPK and want to share more details about the Stop & Go technique with Emlid Flow, along with tips on how to make the most of it.

What is Stop & Go with Emlid Flow?

Stop & Go with Emlid Flow lets you improve point positions collected without a real-time correction link between the base and rover. The workflow in the field involves using a base and a rover. The rover also visits each unknown point, briefly occupying it, and records the data in a CSV file in Emlid Flow. After that, you can upload all the data to Emlid Studio to calculate the precise positions.

You can learn more about the workflow in the following resources:

• How to record logs for Stop & Go with Emlid Flow
• Stop & Go with Emlid Flow
• Post-processing with Emlid Studio. Getting separate points from the track

What to consider when performing Stop & Go

Environmental conditions

Before recording logs, make sure you have the following conditions:

• Receivers are in an open area with a clear sky view 30 degrees above the horizon.
• There are no obstacles blocking the view, such as buildings, trees, cars, or humans.
• There are no interference sources. Electronic devices and power lines may produce RF noise that could affect the reception of the GNSS signal.
• You set up a minimum of 1 Hz update rate on the base and 5 Hz on the rover.

CSV file prerequisites

When collecting points with your Reach using Emlid Flow and exporting your project, ensure the following:

• You average the points. If you’re using Reach RS3, turn off tilt compensation while collecting points.
• You export your project in CSV format. CSV (PENZD) format is incompatible with the Stop & Go workflow.

Complete dataset

As a result of a survey, you should have the following files at hand:

• a RINEX observation file from the base
• a RINEX observation file from the rover
• a RINEX navigation file from the base or the rover
• a CSV file from Emlid Flow

What to do if you didn’t average points

If you didn’t average points when collecting the data, you still have a way out. Edit the CSV file by adding 1 s in the Averaging end field:

After that, post-process your dataset again.

Suppose you have processed your dataset and are not satisfied with the solution. In that case, you can double-check our previous post to learn more about evaluating your raw data and get an idea of whether you can fine-tune the solution.

Have you already performed Stop & Go with Emlid Flow? If you have questions or want to share your use cases, leave us a comment below or contact us directly at support@emlid.com.

[adnaanparker1 (Adnaan Parker)]

Good day

how long do you recommend averaging the points for?

[kornel.nemeti]

Hi Adnaan,

The main thing about averaging is that a longer averaging time doesn’t improve the accuracy. So, with an averaging of 1-2 minutes, you should be good to go.

In Stop&Go, you have a SINGLE solution while collecting the points, so the collected points will have an accuracy of several meters. Whether it’s possible to obtain a FIX solution after Stop&Go in Emlid Studio rather depends on the quality of the raw data logs.

[edgardoprado90 (Edgardo Prado)]

Hola.

De acuerdo a la publicación sobre stop and go, la precisión de los puntos recopilados en el csv, tendran un gran margen de error, y la única de manera de corregir a fix estos puntos levantados en campo, es postproceso en Emlid Studio?

De otro lado, podrías explicar a detalle lo siguiente: Si no calculaste el promedio de puntos al recopilar los datos, aún tienes una salida. Edita el archivo CSV agregando 1 en el campo Final del promedio

[kornel.nemeti]

Hi Edgardo,

You’re right. The points for Stop&Go are collected with a SINGLE solution, so they have only a meter-level accuracy. But if the raw data logs are of good quality, it’s possible to obtain a FIX solution for the points after the post-processing in Emlid Studio.

@edgardoprado90

De otro lado, podrías explicar a detalle lo siguiente: Si no calculaste el promedio de puntos al recopilar los datos, aún tienes una salida. Edita el archivo CSV agregando 1 en el campo Final del promedio

Instant collection and averaging are two different options to collect points, and the main thing is that for Stop&Go, they have to be averaged. If they’re not so, the columns of Averaging start and Averaging end in the CSV file will contain the same time.

Still, it’s possible to modify the data to make it work in the Stop&Go process. The solution is to open the CSV file and manually increase the Averaging end column by 1 second. This way, the data will be the same as it would have been averaged, and it’ll work properly with Stop&Go in Emlid Studio.