GPS-RTK Board - NEO-M8P-2 (Qwiic)
With GPS you are able to achieve a theoretical accuracy of 3 meters. GPS-RTK has mastered dialing in the accuracy on their GPS modules to 2.5cm!
The SparkFun GPS-RTK Board is a powerful breakout board for the NEO-M8P-2 module from u-blox. The NEO-M8P-2 is a module for high accuracy GNSS and GPS location solutions including RTK. RTK is short for Real Time Kinematics. A GPS receiver capable of RTK takes in the normal signals from the Global Navigation Satellite Systems along with an RTCM correction stream and then calculates your location with 2.5cm accuracy in real time.
The NEO-M8P-2 is unique in that it is capable of both rover and base station operations. It features a survey-in mode allowing the module to become a base station and produce RTCM 3.x correction data.
The GPS-RTK even has four communications ports: USB (which enumerates as a COM port), UART (with 3.3V TTL), I2C (via the two Qwiic connnectors or broken out pins), and SPI. Sparkfun has also written an Arduino library for u-blox modules to make reading and controlling the GPS-RTK easy.
The NEO-M8P requires a good quality GPS/GNSS antenna and a 10cm metal disc is required to be placed under the antenna as a ground plane.
More information is available on the website of Sparkfun.