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CDM-700 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
8.5
CDI-70 10/100/1000 Gigabit Ethernet 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.
8–6
Revision 5
MN/CDM700.IOM
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