AtomicClock vs wwvbgps

Check precise NTP reference time at a glance. AtomicClock helps you set watches, wall clocks, cameras, and other devices, compare local time with UTC, and follow moments when every second matters. Clear analog and digital time AtomicClock displays current time from NTP servers that reference atomic clocks. Choose a predefined server or add your own, then view local or UTC time in a clean analog or digital clock. Customize your reference clock • Switch between 12-hour and 24-hour time • Customize the time format • Choose from multiple clock faces and hands • Use a smooth, fluid second hand • Add acoustic ticking or the Greenwich Time Signal • Tap the screen to hide information and controls, freeze the display, or mute ticking Details for precise time checks View technical NTP information, including round-trip time and server stratum. Whether you are checking a timestamp, preparing a camera, aligning a wall clock, or setting a watch by hand, the seconds remain clear and easy to follow. AtomicClock is free to use. AtomicClock Pro is available as a one-time purchase with no subscription. It unlocks your preferred clock face, hands, and font, removes ads, and includes upcoming Pro features. AtomicClock displays NTP reference time for comparison and does not change your device’s system time. Results can vary with the selected server, network conditions, and device behavior.

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.