Mobile phone system uses data compression to reduce time during which transmitter is actually operating

摘要

The analog audio signal from the microphone (21) is converted (23, 24) to coded digital form. The coded signals are compressed (25 to 31) into regular short bursts of code which are transmitted (32) to the GSM cellular network. At the receiving end of the link, the pulse bursts are decoded and converted back to the audible analog signal. The relatively high level electromagnetic energy only occurs in short bursts, rather than continuously.