CANOGA PERKINS 2370 High-Speed Universal Fiber Optic Modem - Manual (Page 17)

EdgeAccess Universal Chassis System
Model 2370 Model User Manual 3-3
3.2 P53 Interface for the L130
The L130 ELIM supports the P53 interface and external DCE/DTE adapter that converts the interface
to DTE with male DB-25 connector This interface supports FIFO buffers for received or transmitted
data and a programmable delay line to fine-tune the clock and data timing. The interface supports
these typical applications:
• With encryption devices on the BLACK side, where modems act as the network and supply the
synchronous clock, or on the RED (clear) side of data encryption (KG) equipment as the "tail-
circuit adapter" device. This allows the modem to accept two synchronous clocks, one for
transmitting (external clock) and one for receiving (FIFO input clock, SCT becomes an input).
• With systems that communicate over geosynchronous satellites, the FIFO can make up for clock
drift (Doppler shift) caused by the satellite's elliptical orbit around the earth.
Use the External Station configuration when an external station (slave) clock provides the timing (see
Figure 2). In this application, the modems act as the network, although the timing is from an outside
source. When connecting KG or KIV encryptors on the Black side with an external timing device, go
to the Functional Configuration screen and set the interface configuration values: set the modem with
the timing source to external; set the other modem to slave; for details, see Section 4.7.
FIFO
RX Data
RX Clock
Delay Line
Internal
Clock
TX Clock
TX Data
RXD
SCR
SCT
SCTE
TXD
J1, DB-25
Figure 2. P53 Interface for External Station Clock