DCF77 signal emulator app actually works !!!
For most of Europe clocks can receive a radio signal from Germany on 77.5 Khz frequency. Now there's an app for Android that can emit 'sound' at 77.5 Khz through its speaker and when you hold a DCF77 clock's antenna near it it can convey the time. I used a fake time to show that it actually works and not just received the actual time over the air from Germany.