Communications Blockset

Synchronization

In order to interpret information correctly, a communication receiver must be synchronized with the corresponding transmitter. A phase-locked loop, or PLL, can help accomplish this synchronization when used in conjunction with other components. A PLL is an automatic control system that adjusts the phase of a local signal to match the phase of the received signal. The PLL design works best for narrowband signals.

Synchronization Features of the Blockset

This blockset contains four phase-locked loop blocks in its Synchronization library. You can open the Synchronization library by double-clicking its icon in the main Communications Blockset library (commlib), or by typing

• commsync2
  

at the MATLAB prompt.

The following table indicates which block in the Synchronization library implements each supported type of PLL.

Table 1-2: Supported PLLs in Synchronization Library

Type of PLL	Block
Analog passband PLL	Phase-Locked Loop
Analog baseband PLL	Baseband PLL
Linearized analog baseband PLL	Linearized Baseband PLL
Digital PLL using a charge pump	Charge Pump PLL

This section discusses these topics:

• Overview of PLL Simulation
• Implementing an Analog Baseband PLL
• Implementing a Digital PLL

For details about phase-locked loops, see the works listed in Selected Bibliography for Synchronization.

Example Using the RF Impairments Library Blocks

Overview of PLL Simulation