Product manual
System description, Radio exchange boards
Technical Product Manual - DCT1800-GAP
TD 92093 (1/LZBNB 103 108 R4D) / 2006-03-09/ Ver.C
© 2006
15
Chapter 4 Radio exchange boards
4.1 General
The radio exchange can contain the following system boards (see figure 11):
• Central Processing Unit (CPU)
• Speech Processing Unit-S (SPU-S)
• Cell Link Unit (CLU)
• Cell Link Unit-S (CLU-S)
• Speech Link Unit (SLU)
• Digital Trunk Unit (DTU)
• Line Termination Unit (LTU)
The modular cabinet also contains the Modular Cabinet Connection Board (MCCB) (see figure 11).
4.2 Central Processing Unit – CPU
The central processing unit is responsible for overall control of the system. It contains two standard
I/O ports (RS232). One CPU board is required per system.
The CPU performs the following tasks:
• Initialization of the system
• Call processing
• Intra-system mobility management
• System testing and fault recovery
• System statistics information
4.3 Speech Processing Unit-S – SPU-S
The speech processing unit provides the communication interface between the LTU/DTU and the
CLU/CLU-S. Every SPU-S board contains 8 Speech Processing Circuits (SPC, see figure
5). Every
SPC handles the speech processing for one call. When a call is initiated, either by a cordless phone
or an incoming call is received via the LTU or DTU circuits, an SPC is assigned to the call.
The main functions of the board are:
• PCM to ADPCM transcoding and vice versa
• DTMF generation and dial tone detection
• Echo control