# CUAV C-RTK
The CUAV C-RTK GPS receiver (opens new window) is an RTK GPS module for the mass market. A complete RTK system consists of at least two C-RTK modules (one for the base station and the others for the aircraft). Using RTK, PX4 can get its position with centimetre-level accuracy, which is much more accurate than can be provided by a normal GPS.
RTK setup and use on PX4 via QGroundControl is largely plug and play (see RTK GPS for more information).
# Wiring and Connections
C-RTK GPS comes with a cable that terminates in a 6-pin connector and 4-pin connector that are compatible with Pixhack v3 (opens new window). The 6-pin connector provides the interface for RTK GPS, and should be connected to the flight controller's GPS port. The 4-pin connector is an m8n (standard) GPS interface that is intended for (optional) use as a second GPS.
At time of writing PX4 does not yet fully support a second GPS. The 4-pin port need not be connected.
The cables/connectors may need to be modified in order to connect to other flight controller boards. The pin mappings for Pixhawk 3 Pro and Pixracer are shown below.
The C-RTK GPS pinout is provided below. This can be used to help modify the connector for other autopilot boards.
|pin||C-RTK GPS 6P||pin||Pixhawk 3 Pro GPS||C-RTK GPS 4P|