A strong and smooth GPS connection is the main prerequisite for executing a good measurement when land surveying. This connection needs to be made between your GNSS receiver and our land survey apps. Compatibility is key. We like to inform you about our steps for making our apps compatible with your hardware.
We have tested a lot of GNSS receivers since the release of our software. The most important test we performed was for making a GPS connection between GNSS receivers and our apps. We tested the following brands with success.
Our cm accurate GIS mapping and land surveying apps use Bluetooth to make a connection with a GNSS receiver. We considered this to be the best and most reliable method of connecting. It is well known, widely used, easy and fast. The distance between the GNSS receiver and the Android device is usually very small. It makes it an ideal situation for a Bluetooth connection.
When connecting the GNSS receiver to our software, you need to be aware of the different types of communication that will be exchanged between the two.
There are the messages going from the GNSS receiver to our GPS apps. These are send through the NMEA 0183-protocol. This particular protocol contains many different strings, each with their own information.
Our GPS apps needs the following NMEA 0183 strings to get all the information they need:
- GGA – Fix information
- GST – GPS Pseudorange Noise Statistics
Some of our land survey apps use some other NMEA 0183 strings as well, like GSA – Overall Satellite data.
There are also other, alternative, protocols to send information from the GNSS receiver to our land survey apps. If needed we can add this to our software.
Our GPS apps are like a ‘mailman’ for RTCM messages. Our land survey app connects as a NTRIP client to a certain NTRIP caster. Then our app will forward the RTCM messages, that are send from the NTRIP caster, to the GNSS receiver.
The messages that our land survey apps forward can vary. They can be RTCM 2.x or RTCM 3.x. Our apps do not convert messages that they forward. So if your GNSS receiver uses other messages from NTRIP, it should not be a problem for the working of the app.