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Timing Options
Slave Timing
With Slave Timing, illustrated in
the timing source (1). The SC 553 CSU/DSU recovers the receive T1 clock from the network
receive T1 data and uses it to clock T1 data into the receive buffer
source for T1 data output from the transmit buffer
(4)
the receive T1 clock to provide the channel transmit and receive clock signals on the appropriate
interface leads for each channel.
Select Slave Timing when using the SC 553 CSU/DSU in a network (or with a device at the remote
end) that supplies the clock, as in a DACS (Digital Access and Cross-Connect System) network.
Note
Select the appropriate timing option for the customer equipment: The CSU/DSU provides
transmit timing on the channel's Tx Clk lead.
Network Receive T1 Data
Timing
S1
Source
1
Network Send T1 Data
Figure D-1
076R155-000
Issue 7
Figure
SC553 CSU/DSU
2
Recovered
Receive
T1 Clock
3
Slave Timing
SpectraComm 553 Fractional T1 DSU
Installation and Operation Manual
Timing Option Descriptions
D-1, the network (or a device at the remote end) provides
(2)
(3)
to the network. The CSU/DSU also translates
Receive
Buffer
Clock
Translator
4
Transmit
(Send)
Buffer
and to provide the send timing
CH. Receive Data
CH. Rcv Clk
CH. Send Data
CH. Tx Clk
D-3
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