wwvbgps

Emulates WWVB longwave time broadcast using DAC harmonics to produce a very weak signal at the carrier frequency of 60KHz. This allows a radio-controlled clock (e.g. many Casio watches), to receive the signal when placed near the speaker of the iOS device. There are other apps that do this but they don't seem to use the GPS time signal, instead relying on the system clock which will drift when it doesn't have internet for a long time (e.g. at sea) because iOS does not appear to use GPS time for system clock updates. This app specifically avoids using the system clock and prefers GPS time. To force using GPS, try it in Airplane mode, with all the radios off. Tested with Casio GW M5610U.