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SDM-300L3 Satellite Modem
Specifications
14.9.1
Receive Carrier Acquisition Range
1. The modem will automatically lock to a correctly formatted carrier, which is
2. The operator can adjust the acquisition range from 0 to 1 MHz, in 1 Hz steps.
3. The operator can adjust the center of the acquisition range from -500 to +500 kHz,
14.9.2
Receive Carrier Reacquisition
1. The modem can be programmed to delay the acquisition process upon loss of
2. This delay can be programmed from 0 to 999 seconds in 1 second steps.
14.9.3
AGC Output
A programmable DC output, proportional to the receive signal level, is available at the
rear panel at 10 mA maximum, 0 to 10V. Default levels are 0V for minimum signal level
and 10V for maximum signal level. The low level (0V) can be programmed from 0 to 10V
in 0.5V increments. The high level can be programmed from 0 to 10V in 0.5V increments.
14.9.4
Doppler Tracking Performance
The modem will track the Doppler shown below with less than 0.5 dB degradation for
symbol rates ≥ 64 Ksym/s. The performance applies only to the QPSK rates 1/2, 3/4, and
7/8 with Viterbi decoding or Viterbi with Reed Solomon decoding.
•
•
•
The demodulator must lock to the carrier with Doppler applied. BER is measured after
demodulator is locked to the carrier.
E
/N
b
0
Error Criteria
-6
BER ≤ 10
7
4x10
Bits with no Errors
within Acquisition Range of the displayed RX frequency.
2
in 1 Hz steps.
lock. This will minimize the acquisition time for a brief loss of the carrier.
Doppler Offset
Doppler Rate
Doppler Acceleration
values in the table include the 0.5 dB added to account for degradation:
QPSK 1/2
6.5
6.5
15 Hz
20 Hz/sec
2
35 Hz/sec
QPSK 3/4
QPSK 7/8
7.7
8.8
7.7
8.8
14–26
Revision 0
MN/SDM300L3.IOM
Coding
Viterbi
Viterbi with Reed-Solomon
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