The nRF9161 DK has a dedicated Global Navigation Satellite System (GNSS) port to support global navigation. GNSS functionality requires support in the onboard network protocol firmware.
The GNSS signal is received from the onboard or external active GNSS antenna. The onboard antenna (A2) is connected to the Low-Noise Amplifier (LNA) (U2).
The GNSS signal from the onboard antenna is amplified and filtered in the LNA (U2), which has an integrated prefilter and postfilter, before it is fed to the nRF9161 DK. This makes the GNSS receiver more sensitive to GNSS signals and less sensitive to interference from other sources on the Development Kit (DK) or nearby. The LNA is enabled by a GNSS-enable signal from the nRF9161 DK using the COEX0 pin.
An external active GNSS antenna can be connected to the U.FL connector J2. 3.0 V DC is fed through J2 to supply the LNA of the external antenna. When using an external GNSS antenna, the onboard GNSS LNA (U2) must be disabled to avoid interference. This is done by ensuring that the VEN signal is low and set by the %XCOEX0 AT command.
To optimize GNSS reception, do the following:
- GNSS signals do not usually penetrate ceilings or other structures that well. For best GNSS performance, the DK should be placed outside on a flat surface in an open space far from sources of interference and other structures that can block the satellite signals.
- The Molex patch antenna achieves the highest gain when placed horizontally on a surface (x-y) facing the z-axis since it can receive all propagated GNSS signals. A lower gain is experienced if the patch antenna is mounted at an angle.
The following figure shows the nRF9161 DK's GNSS circuitry.
