Everybody Hertz

This page plays a long-wave time signal through your speaker. A radio-controlled watch or clock held next to it reads the signal and sets itself.

1. Check that this device shows the right time. The signal is built from its clock.
2. Pick the station your watch listens to.
3. Start a manual receive on the watch. Most radio watches have a button you hold for a couple of seconds until a receive indicator flashes. Your watch's manual says which one.
4. Press Transmit and hold the watch next to the speaker.
5. Wait. A receive takes 5 to 15 minutes.
6. Check the watch, then press Stop.

The page can't hear the watch, so it can't tell when the watch has locked on. It keeps sending until you stop it. Keep the page open and the screen on while it plays.

Lay the watch face near the speaker, a few centimetres away or touching. If you know which side holds the antenna, turn that side towards the speaker.

Headphones laid on the watch glass also work.

Turn the volume to maximum and switch silent mode off.

The tone is high-pitched. Don't wear headphones while it plays.

Pick a quiet spot away from chargers, monitors and other electronics. Once the receive starts, don't move the watch or the device.

A radio watch listens to the station that serves its home city. Pick the same one here. The key marked TZ is suggested from this device's time zone.

• WWVB 60 kHzNorth America. Sent from Fort Collins, Colorado.
• JJY40 40 kHzJapan. Sent from Fukushima.
• JJY60 60 kHzJapan. Sent from Saga. If one JJY station doesn't work, try the other.
• DCF77 77.5 kHzCentral Europe. Sent from Mainflingen, Germany.
• MSF 60 kHzThe United Kingdom. Sent from Anthorn.
• BPC 68.5 kHzChina. Sent from Shangqiu.

Advanced

Some watches set to a Japanese city can be synced anywhere with JJY. Set the home city to Tokyo, receive JJY, then set your own home city back. Not every watch keeps the right time through the switch, so check it afterwards.

No response

Check that the watch is in manual receive and the right station is picked. Turn the volume to maximum and switch silent mode off. Move the watch closer, or try a different spot along the speaker. Some speakers can't play a tone this high, so try another device.

Wrong time after sync

Off by seconds or minutes means this device's clock is wrong. Set it to update automatically, then receive again. Off by whole hours means the watch's home city or daylight saving setting is wrong.

Works only sometimes

Distance, volume and placement matter most. Keep the watch within a few centimetres, the volume at maximum and nothing moving. Chargers, monitors and other electronics add noise that can drown out the signal. Move away from them or unplug them.

Time stations broadcast on long wave, between 40 and 77.5 kHz, far above anything a speaker can play. So this page plays a tone shaped to carry odd harmonics, and picks it so one of them lands on the station's carrier. For a 60 kHz station that is a 20 kHz tone, whose third harmonic is 60 kHz. The speaker leaks that harmonic as a weak magnetic field, and the watch antenna picks it up from a few centimetres away.

Each second the page dips the tone and brings it back in the station's own pattern, the way the real transmitter keys its carrier. The pattern spells out the time and date. The page builds it from this device's clock, so that clock must be right. If it is a minute off, the watch will be a minute off too.