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Consumer Electronics by S. P. Bali

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DIGITAL CELLULAR PHONE BLOCK DIAGRAM

The voice to be transmitted enters the microphone and is input to the vocoder. This coder digitises the audio and then uses complex algorithms to minimise the amount of data needed to represent the information to be sent. This data stream is then input to a channel coder that adds additional bits needed for channel coding. This data stream is then sent to the Pi/4 DQPSK (Differential Quadrature Phase Shift Keying) modulator and up converted to the cellular frequency band. This RF carrier with modulation is then filtered and pulsed out at the appropriate time.

On the receiving side a transmitted carrier is received, filtered, and down-converted to an intermediate frequency which is again filtered. This is then ...

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