DCF77 is a German time signal that can be decoded using an arduino
100 | GUDE DCF77 - Radio Time Receiver | Distrelec Export Shop
NTP Server via DCF77 on a Raspberry Pi | Weberblog.net
DCF77 Frankfurt Radio Controlled Atomic Time Signal LCD - YouTube
How to build a DCF77 HID USB real-time clock (dcf77-hid-usb-rtc) for usage with Linux systems « Adafruit Industries – Makers, hackers, artists, designers and engineers!
Synchronizing time with DCF77 and MSF60
FunkUsb – Funkuhr-Modul mit USB-Anschluss
CLOCK77/USB – DCF77 Clock Radio with USB port for Client and Server Systems: Amazon.co.uk: Computers & Accessories