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When people talk, they only make sound for 40 per cent of the time—a
fact that has led IBM to an idea for making batteries last longer when digital
cellphones communicate (GB 2 335 827). Switching the transmitter off during
silences saves power, but the lost synchronisation between the receiver and
transmitter means the message gets garbled. So IBM places the voice data in
packages, which are transmitted at constant speed. The transmitter switches into
a low power mode when an empty package arrives, so power is saved without loss
of synchronisation.