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SDM-300Ls Satellite Modem
Burst Mode Modulator Operation
B.2.2
Modulation and Encoding Types
QPSK modulation and 1/2 rate Viterbi forward error correction encoding is standard.
B.2.3
Scrambling Types
One of the following scrambling types can be selected by the operator.
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B.2.4
Differential Encoder
The differential encoder is not needed as the data inversion ambiguity is resolved during
acquisition.
B.2.5
Transmit Frequency (IF)
The range of the output IF spectrum can be selected by the operator from 50 to 180 MHz,
in 1 Hz steps.
B.2.6
Frequency Reference
SCT, RX Bit Clock, and IF output are locked to the Frequency Reference.
Internal (Standard
Internal High Stability
(Optional)
External Reference
Input (Standard)
Reference Frequency
Output (Optional)
Encoder
Viterbi, K7
A programmable seed 2^15 -1 Synchronous Scrambler.
None
Stability over the operating temperature range = ± 10 PPM.
Stability over the operating temperature range = ± 0.2 PPM.
The External frequency reference connector is located on the back panel. This
allows Frequency Reference to be locked to an external reference frequency
standard.
Impedance
75Ω
Frequency
1, 5, 10 or 20 MHz
≥ +0 dBm < +20 dBm
Amplitude
DC offset
Capacitively coupled
Connector
BNC
The External frequency reference connector can be used as an output when the
High Stability option is installed. When selected from the front panel, this output
can be used to lock other equipment to the Internal High Stability Reference of the
selected modem. The output is 10 MHz, the level is +10 dBm ± 5 dBm.
Code Rate
Modulation
1/2
QPSK
B–3
Revision 1
MN/SDM300L3.IOM
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