Mocomtech CIM-550 manual 112

CiM-550 IP Enabled Satellite Modem	Rev. 2
Theory of Operation	CD/CIM550.IOM

6.3.4TRANSMIT AND RECEIVE CLOCKING

INTERNAL TX CLOCK MODE

DATA TO

MODULATOR

CIRCUIT

TX DATA

TX	PLL	CLOCK
FIFO	CIRCUIT	VCXO

TX CLOCK TRANSMIT

(TT)DATA

INTERFACE

		DIRECT	14.4 MHz
		DIGITAL
			TCXO
INTERNAL		SNTHESIZER
	CLOCK
	(ST)

THIS CLOCK IS USED AS THE SYNCHRONIZATION

SOURCE FOR THE EQUIPMENT ATTACHED

TO THE MODEM

EXTERNAL TX CLOCK MODE

					DATA TO
					MODULATOR
					CIRCUIT
	TX DATA
			TRANSMIT	TX	PLL	CLOCK
				FIFO	CIRCUIT	VCXO
			DATA
TX CLOCK
			INTERFACE
	(TT)
		THE MODEM LOCKS ITS CLOCK CIRCUITS
			TO THIS CLOCK COMING FROM THE
			EXTERNALLY CONNECTED EQUIPMENT

LOOP-TIMED TX CLOCK MODE

TX=RX OR TX<>RX

					DATA TO
					MODULATOR
					CIRCUIT
	TX DATA
				TX		PLL		CLOCK
			TRANSMIT	FIFO	CIRCUIT			VCXO
TX CLOCK
		(TT)	DATA
			INTERFACE
				DIRECT		CLOCK			PLL
				DIGITAL
							VCXO	CIRCUIT		RX SYMBOL
				SNTHESIZER
INTERNAL
										CLOCK FROM
	CLOCK									DEMOD
		(ST)

THIS CLOCK IS USED AS THE SYNCHRONIZATION

SOURCE FOR THE EQUIPMENT ATTACHED

TO THE MODEM

Figure 6-1. Tx Clock Modes

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