SHAFAQNA (Shia International News Association) — NEED to set your smartphone's clock? Just switch on the lights - as long as they are fluorescent. They flicker in a way that is regular enough to keep clocks on track.
Most electronic devices use vibrating crystals to regulate their internal clocks, but the frequency of these crystals can vary with factors like temperature and humidity. That allows clocks to drift - by nearly 10 seconds per day in the case of some smartphones.
The usual way to reset a device's clock is by synchronising it with a master clock online. Now Zhenjiang Li, a computer scientist at the Hong Kong University of Science and Technology, and colleagues have come up with an alternative.
Mains electricity is alternating current supplied at a frequency of 50 or 60 cycles per second. The power delivered drops to zero twice per cycle, causing fluorescent lights to flicker. Li's team has shown that any device with a light sensor or camera can use this flicker to keep accurate time. By doing away with the need for a network connection, the method can also extend a device's battery life.
The researchers reckon that their scheme is accurate to better than a thousandth of a second per day. They will present their work at the MobiCom conference in Istanbul, Turkey, next month.—www.shafaqna.com/english
Source: New Scientist