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GNSS receiver modes

August 31 2022

There are many GNSS receiver models and they use standard protocols to communicate with the device that receives the coordinates. Use one of these modes to take full advantage of the capabilities of your receiver.

Internal receiver

Every android and iOS devices and most Windows tablets have an internal GNSS receiver that can establish the current position of the device. These receivers accuracy is typically between 3 and 5 meters. When installed on your device, OnPOZ Collect will automatically discover and use the internal receiver.

Android Mock location (external receiver acting as internal receiver)

This is a mode that takes over the internal receiver and makes the high-accuracy coordinates from an external receiver available for every application installed on the device. It is often used by RTK capable receivers. See an example of how to use this mode in the article Trimble Catalyst and OnPOZ Collect.

External receiver

External receivers are a more powerful version of the internal receiver of your smartphone or tablet. Depending on their specifications, they can provide very accurate coordinates – in many cases up to 1 or 2 centimeters

Bluetooth devices

External receivers are usually connected to the device via Bluetooth connection and are compatible with OnPOZ Collect. You can go to Settings > GNSS Device and choose your receiver from the list of Bluetooth devices. The next step would be to choose the model of the device from the list. If your specific receiver model is not listed, you can choose NMEA compatible. This standard protocol can be used with all GNSS receivers. The data collected in NMEA cannot be post processed. When properly configured, the receiver outputs the following basic NMEA logs:

GGA (Time, Coordinates)

RMC (Time, Coordinates, in addition to GGA)

GSA (DOPS factors and satellites in use)

GST (accuracy/sigmas)

GSV (sky plot)

Network (TCP/IP) device

If your receiver is not iOS BT ready or if the receiver is already BT connected with another application, then you can use an IP address and port to retrieve the NMEA information that is provided by your receiver or by a third party application. Moreover, some receiver can provide NMEA and raw data via TCP/IP, if raw data is available, post-processing can be achieved. See an example of how to use this mode in the articles EOS Arrow RTK and OnPOZ Collect and Septentrio and OnPOZ Collect.

Serial port device

If you are using OnPOZ Collect for Windows, you can select the serial port on which your GNSS receiver is connected. If you do not know which serial port to use, start Device Manager from the Control Panel and check Ports (COM & LPT) section. Selecting a serial port will also allow to select the model of GNSS receiver from a list. If your specific receiver model is not listed, you can choose NMEA compatible. This standard protocol can be used with all GNSS receivers. However, the data collected in NMEA cannot be post-processed.