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IP LDK-20 Installation Manual Board Installation
21
3.2 MBUB (Main Board Unit)
Description
The MBUB controls communication between the peripheral interfaces, supervises all resources in the system,
controls the gain adjustment of the PCM signal, generates the system tones, and manages system call processing.
The MBUB (Figure 3.2a) incorporates the main control of the system, and is composed of the main microprocessor
(RAM and ROM), the PCM management (the CO/Extension interface circuits), and miscellaneous functional circuits.
Figure 3.2a MBUB
Figure 3.2a shows the MBUB, which provides Basic Rate Interface (BRI) circuits, Digital keyset and SLT interface
circuits, DTMF receivers, phase locked loop circuit (for 32Mhz clock synchronization), Ring Generation Unit, two
external relay contacts, one alarm detection circuit, one external PAGE port, internal/external MOH circuit, the
peripheral device decoding circuit, the master clock generation circuit, the RS-232C interface circuit, the system
battery backup circuit, as well as the system’s PCM voice processing circuit that has a flash memory for PCM tone
generation and PCM Gain control.