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GSM Transceiver

 Vector modulation is used to encode the chroma signal in NTSC analog broadcast video and data in digital telecom modems. It is also used in wireless applications such as GSM. SystemView can be used to model any of these applications.

The following discussion is based on the SystemView Application Note AN121B QPSK Transmitter and Receiver Simulation using Ideal Component. and the journal Communications Systems Design of July and August 1998.

A transceiver is simply a transmitter and receiver combined in a single unit. A full duplex connection therefore requires a pair of transceivers.

Transceiver Block Diagram

GSM Time Frame

GSM uses TDMA/FDMA. The 25 MHz bandwidth is divided into 124 carrier frequencies spaced 200 KHz apart. Each carrier is time division multiplexed into 26 slots containing 8 full duplex voice channels plus control channels.

The time-slot burst rate is 270.833 Kbps. This digital signal is modulated onto the analog carrier frequency using GMS.

The transmitter will be examined first.