gourdo1/wwvb-emulator

WWVB Emulator is a small Python tool that tricks radio-controlled clocks and watches into setting their own time without needing the real WWVB radio broadcast from Fort Collins, Colorado. Those clocks normally listen for a low frequency radio signal to sync automatically, and this project fakes that signal using nothing more than a computer's headphone jack and a pair of ordinary wired earbuds. The trick works because playing a very loud 20 kHz tone through a sound card creates a small amount of natural distortion, and that distortion produces a faint extra tone at 60 kHz, the exact frequency WWVB uses. Coiling the headphone cable into a small loop and holding it close to the clock's antenna lets that faint signal reach the clock magnetically, in the same way a transformer passes current between two coils without touching. A clock or watch typically locks onto the fake signal within three to ten minutes once the loop is positioned correctly. To use it, someone installs the tool with Python's pip, plugs in wired headphones, turns the system volume up very high, and turns off any audio enhancement settings that could distort the tone in unwanted ways. The program offers several command line options, such as choosing a specific audio output device, shifting the encoded time to make up for lag, or rendering the signal to a WAV file instead of playing it live. It can also transmit a fixed test time or produce a true 60 kHz signal directly on audio hardware that supports very high sample rates. The README includes detailed troubleshooting notes, pointing out that some clean USB audio devices do not distort enough to work, while cheaper built in sound cards often perform better. It also explains that positioning and distance matter a lot, since the magnetic coupling weakens quickly as the loop moves away from the clock. The project can also be packaged into a standalone Windows executable using PyInstaller, so it runs on a computer with no Python installed. It is released under the MIT license.