Comtech EF Data SDM-300L3 - Manual (Page 401)

SDM-300Ls Satellite Modem Revision 1
Burst Mode Modulator Operation MN/SDM300L3.IOM
B–3
B.2.2 Modulation and Encoding Types
QPSK modulation and 1/2 rate Viterbi forward error correction encoding is standard.
Encoder Code Rate Modulation
Viterbi, K7 1/2 QPSK
B.2.3 Scrambling Types
One of the following scrambling types can be selected by the operator.
• A programmable seed 2^15 -1 Synchronous Scrambler.
• None
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 Stability over the operating temperature range = ± 10 PPM.
Internal High Stability
(Optional)
Stability over the operating temperature range = ± 0.2 PPM.
External Reference
Input (Standard)
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 75
Ω
Frequency 1, 5, 10 or 20 MHz
Amplitude ≥ +0 dBm < +20 dBm
DC offset Capacitively coupled
Connector BNC
Reference Frequency
Output (Optional)
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.