Adafruit Ultimate GPS HAT for Raspberry Pi A+/B+/Pi 2
Ultimate GPS HAT for Raspberry Pi Datasheet by Adafruit Industries LLC | Digi-Key Electronics
Using UART instead of USB – Adafruit Ultimate GPS on the Raspberry Pi @Raspberry_Pi #raspberrypi « Adafruit Industries – Makers, hackers, artists, designers and engineers!
Adafruit Ultimate GPS HAT for Raspberry Pi A+/B+/Pi 2/3/Pi 4 - Mini Ki
Microsecond accurate NTP with a Raspberry Pi and PPS GPS - Austin's Nerdy Things