Mocomtech CIM-550 Manuel D’Utilisation

CiM-550 IP Enabled Satellite Modem

Rev. 2

Theory of Operation

CD/CIM550.IOM

86

6.3.4 T

RANSMIT AND

R

ECEIVE

C

LOCKING

EXTERNAL TX CLOCK MODE

TX DATA

TX CLOCK

(TT)

TRANSMIT

DATA

INTERFACE

TX

FIFO

PLL

CIRCUIT

CLOCK

VCXO

DATA TO

MODULATOR

CIRCUIT

THE MODEM LOCKS ITS CLOCK CIRCUITS

TO THIS CLOCK COMING FROM THE

EXTERNALLY CONNECTED EQUIPMENT

INTERNAL TX CLOCK MODE

TX DATA

TX C LO C K

(TT )

IN T ER N A L

C LO C K

(ST )

TRANSMIT

DATA

INTERFACE

TX

FIFO

PLL

CIRCUIT

CLOCK

VCXO

DIRECT

DIGITAL

SNTHESIZER

14.4 MHz

TCXO

DATA TO

MODULATOR

CIRCUIT

THIS CLOCK IS USED AS THE SYNCHRONIZATION

SOURCE FOR THE EQUIPMENT ATTACHED

TO THE MODEM

LOOP-TIMED TX CLOCK MODE

TX=RX OR TX<>RX

TX DATA

TX CLOCK

(TT)

INTERNAL

CLOCK

(ST)

TRANSMIT

DATA

INTERFACE

TX

FIFO

PLL

CIRCUIT

CLOCK

VCXO

DIRECT

DIGITAL

SNTHESIZER

DATA TO

MODULATOR

CIRCUIT

THIS CLOCK IS USED AS THE SYNCHRONIZATION

SOURCE FOR THE EQUIPMENT ATTACHED

TO THE MODEM

PLL

CIRCUIT

CLOCK

VCXO

RX SYMBOL

CLOCK FROM

DEMOD

Figure 6-1. Tx Clock Modes