Timing Options
Timing Option Descriptions
076R155-000
SpectraComm 553 Fractional T1 DSU
D-3
Issue 7
Installation and Operation Manual
Slave Timing
With Slave Timing, illustrated in
, the network (or a device at the remote end) provides
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
(2)
and to provide the send timing
source for T1 data output from the transmit buffer
(3)
to the network. The CSU/DSU also translates
(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.
Figure D-1
Slave Timing
Note
Select the appropriate timing option for the customer equipment: The CSU/DSU provides
transmit timing on the channel's Tx Clk lead.
Receive
Buffer
Transmit
(Send)
Buffer
SC553 CSU/DSU
Network Receive T1 Data
Clock
Translator
CH. Receive Data
CH. Rcv Clk
Network Send T1 Data
Recovered
Receive
T1 Clock
CH. Send Data
CH. Tx Clk
S1
Timing
Source
1
2
3
4
