DCF Timing advantages
The DCF time signal is broadcast from Frankfurt, central Germany, the coverage of the DCF signal is the whole of the Germany. However, the DCF time signal can also be received throughout much of Western and Central Europe, including the UK, France and the Nordic Countries.
The big advantage of DCF radio transmissions over GPS is that generally a good signal can be received by the ntp time server indoors close to the host computer or time server. GPS ideally requires a roof mounted antenna, with the associated inconvenience of installing it.