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Timing Options
Channel Timing (External/DTE Timing)
With Channel Timing, illustrated in
transmit clock signal
clock to provide the send timing source for T1 data output from the transmit buffer
network. The remote CSU/DSU uses this as its timing reference
CSU/DSU (5). The local CSU/DSU recovers the receive T1 clock from the network receive T1 data
and uses it to clock T1 data into the receive buffer (6). The CSU/DSU also translates
T1 clock to provide the receive clock signals for the channel, on the appropriate interface leads.
Select Channel Timing when using the SC 553 CSU/DSU in a private network with the customer
equipment on the channel supplying the clock.
Note
Select the appropriate timing option for the customer equipment: The SC 553 CSU/DSU expects
external timing on the channel's Ext Clk lead.
Network Receive T1 Data
5
4
Network Send T1 Data
Figure D-3
076R155-000
Issue 7
Figure
(1)
on the appropriate interface lead. The SC 553 CSU/DSU translates
SC553 CSU/DSU
6
Recovered
Receive
T1 Clock
3
Channel Timing
SpectraComm 553 Fractional T1 DSU
Installation and Operation Manual
Timing Option Descriptions
D-3, the customer equipment provides its own channel
(4)
and loops it back to the local
CH. Receive Data
Receive
Buffer
CH. Receive Data
Clock
Translator
7
2
Clock
Translator
CH. Send Data
Transmit
CH. Ext Clk
(Send)
Buffer
(2)
this
(3)
to the
(7)
the receive
CH. Rcv Clk
1
Timing
Source
S1
D-5
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