# CUAV C-RTK

The [CUAV C-RTK GPS receiver](https://www.cuav.net/en/c_rtk_9ps/) is an [RTK GPS module](/px4-user-guide/drone_parts/peripherals/rtk_gps.md) 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.

![](/files/DMqUr4coX4pir9y0Az6t)

## Where to Buy

* [cuav taobao](https://item.taobao.com/item.htm?id=565380634341\&spm=2014.21600712.0.0)
* [cuav aliexpress](https://www.aliexpress.com/store/product/CUAV-NEW-Flight-Controller-GPS-C-RTK-differential-positioning-navigation-module-GPS-for-PIX4-Pixhawk-pixhack/3257035_32853894248.html?spm=2114.12010608.0.0.75592fadQKPPEn)

## Configuration

RTK setup and use on PX4 via *QGroundControl* is largely plug and play (see [RTK GPS](/px4-user-guide/drone_parts/peripherals/rtk_gps.md) 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](https://doc.cuav.net/flight-controller/pixhack/en/quick-start-pixhack-v3x.html#gps--compass). 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.

:::tip At time of writing PX4 does not yet fully support a second GPS. The 4-pin port need not be connected. :::

![](/files/pTxiGRv1eFGEbgahTduB)

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.

### Pinout

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 |
| --- | ------------ | --- | ----------------- | ------------ |
| 1   | SDA          | 1   | VCC               |              |
| 2   | SCL          | 2   | GPS\_TX           |              |
| 3   | GPS\_RX      | 3   | GPS\_RX           | GPS\_RX      |
| 4   | GPS\_TX      | 4   | SCL               | GPS\_TX      |
| 5   | VCC\_5V      | 5   | SDA               | VCC\_5v      |
| 6   | GND          | 6   | GND               | GND          |


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