Utilizing SAPOS as a base for TrueView projects

1. Introduction

When a base station file is corrupt or incorrectly recorded (for example: the observation rate is not set correctly or the battery fails), a user may elect to use the efficient SMARTBase or PP-RTX for post processing the sensor trajectory solution for your TrueView or microdrones. Alternatively, with more effort and time required on a user's part, it is possible to use a VRS (Virtual Reference Station) or a Continuously Operating Reference Station (CORS).

In this article we will show how to get use base station file, either VRS or CORS, from SAPOS.

1.1. Pre-Requisites

This workflow only works for Germany, since SAPOS only works in Germany. Also, there are 16 states in Germany, this means that the user needs to know the state where the project was performed. Each state has a different website with a different login.
Each state has different rules on how to use their SAPOS services, the price per use also changes.

2. How to get the rinex file from their website

In this article we will describe how to get the base station file in rinex format for the state Hessen, the other states follow a similar pattern.

2.1. Virtual Reference Station (VRS)

VRS it is a great way to create a base station file close to your project area, however the quality may vary depending on the day. If the trajectory processing result is not the best, try with a CORS (explained in the next section).

1- Go to the SAPOS website of your state, for our case will be Hessen:
https://sapos.hvbg.hessen.de/
2- Login --> Go to "GPPS-Shop"--> Postprocessing-Daten--> Select "Virtuelle Referenzstation bestellen"

3- Select the day of the flight in GPS time, stating and ending time --> Select the Interval to be 1 sec (1hz), it is the recommended update rate for the TrueView sensors.
4- Select the approximate position of the flight.
5- Select Rinex 3 --> Press "Weiter"

6- Verify the information selected and press "Weiter" again
7- After that check out and press "berechnung starten", this will start the processing. After the processing is done, download the result.
8- Inside the results folder you will find:
a) The rinex file, with the attached ephemerides.
b) A txt file with the coordinates of the base station, the coordinates are in LLH and the datum is ETRS89

2.2. Continuously Operating Reference Station (CORS)

The CORS stations permanent base station that are continuously working. Before using a CORS, make sure to check the distance between the closes CORS to your project area. Depending on your TrueView sensor, there is a limitation from 10 to 30km maximum distance. If you find that your project is further than the recommended distance, then use VRS service.

1- Go to the SAPOS website of your state, for our case will be Hessen:
https://sapos.hvbg.hessen.de/
2- Login --> Go to "GPPS-Shop"--> Postprocessing-Daten--> Select "Referenzstation bestellen"

3- Select the closest CORS to your project area --> Press "Weiter"

4- Select the day of the flight in GPS time, stating and ending time --> Select the Interval to be 1 sec (1hz), it is the recommended update rate for the TrueView sensors.
5- Select Rinex 3 --> Press "Weiter"

6- Verify the information selected and press "Weiter" again
7- After that check out and press "berechnung starten", this will start the processing. After the processing is done, download the result.
8- Inside the results folder you will find:
a) The rinex file, with the attached ephemerides.
b) A txt file with the coordinates of the base station, the coordinates are in LLH and the datum is ETRS89