General DataComm DeskTop T1 Installation And Operation Instruction Manual page 82

C-8
DTE Split Timing
DTE Split Timing, illustrated in Figure C-4, is a combination of
Receive Timing and DTE Timing that utilizes two clock sources. As
in Receive Timing, the network (or a device at the remote end)
provides one timing source (1). The DeskTop T1 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 DeskTop T1 DSU also translates (4) the receive T1 clock to
provide the receive clock signal, on the appropriate interface lead. As
in DTE Timing, the customer equipment on the channel interface
provides the other timing source, its own channel transmit clock signal
(5) on the appropriate interface lead, but the DeskTop T1 DSU uses it
for nothing else.
Select DTE Split Timing when there are timing sources provided by
both the network and the customer equipment.
a. Select the appropriate timing option for the customer
equipment: The DeskTop T1 DSU expects external timing
on the DTE interface Ext Clk lead.
NOTE
b. All timing options that include split timing require every
timing source to be traceable to the same Stratum 1 clock.
GDC 048R154-000
Timing Options