Quantum and Evolution Series Installation and Operating Handbook
8-4
8.1.2 Receive
Clocking
There are four receive clocking modes that are used in the modem.
8.1.2.1 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
Satellite Rx Clock Mode
8.1.2.2 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 RT (Receive Timing)
and RD (Receive Data) respectively. The Rx Doppler buffer is enabled and the output
clock for the buffer is derived from either ST or TT.
