Patton electronic 1082/F user manual Second Modem

The first G.703 interface is in Network Timed mode. The second is in Recover Clock mode. See Figure 2.

G.703 INTF-	G.703 TX	HOST
	SMOOTHS	MODEM -
MODEM
	RX MODEM	RECOVERED
TIMED MODE
	CLOCK	TIMING

RX

TX

CSU

DTE

G.703

TX	FIFO	RX
RX	FIFO	TX

SECOND MODEM

RX

TX

G.703

TX FIFO

RX FIFO

SMOOTHED

RX

TX

2 or 4 Wire

NETWORK

FIRST MODEM

G.703 INTERFACE	HOST MODEM
NETWORK	INTERFACE
TIMED MODE	(EXTERNAL)
	TIMING

Figure 2. Network Loop Extension Configuration

Timing of Application 2: Network Replacement. The first modem uses an internal timing source and supplies the timing for the entire system. The first G.703 recovers the timing and clocks the data into the FIFO. The Tx of the first modem takes its internal clock and sends it (TXCLK1) to the G.703 FIFO for data (TXD1). The Rx of the second modem recovers the clock and presents a “jittery” clock and data to the second G.703’s trans- mitter. It has to smooth the clock before it uses the clock to transmit.

The Rx of the second G.703 recovers the timing and clocks the data into a FIFO. The Tx of the second modem sends the second modem’s recovered clock (TXCLK1) to the G.703 FIFO for data (TXD1). The Rx of the first modem uses its internal clock (RXCLK1) to send data (RXD1) into the FIFO. The Tx of the first G.703 smoothes the first modem’s recovered tim- ing and sends it to the FIFO for data.

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