Time Station Emulator emulates radio time signal broadcasts from BPC, DCF77, JJY, MSF, and WWVB.

The vast majority of all radio-controlled clocks and watches (often marketed as “atomic clocks”) rely on one of these five stations. However, their broadcasts are limited in geographic range and notoriously prone to interference in urban areas, so many such clocks end up never actually using their self-setting functionality.

Time Station Emulator may allow setting such clocks when/where a suitable signal is not otherwise available.

Time Station Emulator works best with a built-in speaker of a phone or tablet.

• Choose emulator settings.

  The most important setting is which time station to emulate. Certain settings are only available for certain stations.

  Clocks (or watches) that support more than one station may prefer one of them over the others.

• Choose any clock settings and place the clock into sync mode.

  If your clock has them, try to choose station and/or time zone settings that make sense for your location.

  Most clocks provide a way to force a synchronization attempt. You will probably have to navigate menus and/or press physical buttons.

• Position the speaker as close as possible to the clock’s antenna.

  The transmission range is quite short, so positioning is crucial. Some experimentation will probably be required, especially if you’re unsure where the antenna is.

  The volume should be set so that the clock picks up the cleanest signal. Usually, this occurs at or near the maximum possible volume.

  DO NOT PLACE YOUR EARS NEAR THE SPEAKER TO DETERMINE VOLUME.

  Use a visual volume indicator instead.

  The generated waveform has full dynamic range, but is pitched high enough to be difficult to perceive.

  Even if you “can’t hear anything”, many common devices are capable of playing it back loud enough to potentially cause permanent hearing damage!

• Start transmitting and hold the speaker in position.

  If all goes well, the clock will set itself within three minutes.

Entering an offset changes the time encoded within the transmitted signal by up to one day in either direction. This is useful for correcting time zone differences as well as for setting a clock (or watch) a few minutes fast/slow.

You probably shouldn’t enter an offset when using this emulator to set your clock for the first time. Afterwards, the offset is easily calculated as the difference between the time that the clock should show and the time that the clock actually shows. If these are the same, no offset is needed.

Figuring out the offset in advance is often tricky:

• All five time stations broadcast the time relative to a different time zone.
• DCF77 and MSF change the transmitted hour value according to daylight saving time.
• Many clocks apply their own offset when displaying the received time, as with clocks for the North American market that allow selection of a US time zone (Pacific–Eastern).

Suppose you wish to set a watch from the UK that syncs to MSF during a visit to Sydney, NSW, Australia in the month of July:

• Sydney observes AEST (UTC+10:00).
• MSF in the UK transmits a BST (UTC+01:00) time.
• Sydney is 9 hours ahead of the UK, so the offset is +09:00.

However, if your visit were to occur in January:

• Sydney observes AEDT (UTC+11:00).
• MSF transmits a GMT (UTC+00:00) time.
• The offset is then +11:00!