10.4 Cdi-70 10/100/1000 Base-T Gigabit Ethernet (Gige) Interface - Comtech EF Data CDM-710G Installation And Operation Manual

CDM-710G High-Speed Satellite Modem
Clock Modes
When the Rx Buffer is enabled the Rx clock selections are as follows:
Rx-Sat (default)
Tx-Terr
Internal

10.4 CDI-70 10/100/1000 Base-T Gigabit Ethernet (GigE) Interface

There are no transmit or receive clocking options for the Gigabit Ethernet Interface:
•
The Tx or Rx data rate is programmed into the data interface and the established rate data
is passed between the interface and the modem.
•
Transmit data is accepted at the data interface at the native Ethernet rate and placed in a
buffer for transfer to the modulator at the programmed Tx data rate.
•
Rx data from the satellite is placed in a buffer and assembled into packets and sent to the
terrestrial interface at the Ethernet rate.
Effectively disables the Rx Buffer because the input and output clocks
are the same. Normally, the Rx Buffer is set for minimum when Rx-Sat
is selected. This is the selection usually used with routers.
Uses the clock from the Tx input (TT) to clock out the Rx Buffer. The Tx
and Rx data rates may differ on this interface, and asymmetric clocking
where data rate for Tx ≠ Rx is allowed.
The Internal Clock comes from the modem It is derived from either the
Ext Ref (J7) or Int Ref oscillator in the main part of the modem, not
from the data interface.
10–5
Revision 1
MN-CDM710G