7.1.2 Receive Clocking
There are four receive clocking modes that are used in the modem.
7.1.2.1 Satellite
When Satellite is selected, the modem disables the Rx Doppler buffer and derives a clock
from the incoming satellite signal. This means that the signal will be subject to
Doppler/plesiochronous offsets.
Modem Rx
Data Interface
Rx Buffer
DDS
VCXO
Rx Data Rx Clock (RT)
PLL
Rx Clk
Data from
decoder/deframer
Figure 7-4 Satellite Rx Clock Mode
7.1.2.2 Tx Clock In
When Tx Clock In is selected, the Rx clock and data are phase locked to the Tx data rate
frequency but at the Rx data rate. The clock and data appear on Receive Timing (RT)
and Receive Data (RD) respectively. The Rx Doppler buffer is enabled and the output
clock for the buffer is derived from either ST or TT.
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