Comtech EF Data SNM-1001L - Manual (Page 261)

SNM-1001L Satellite Modem Revision 1
Specifications MN/SNM1001L.IOM
A–23
A.9.1 Receive Carrier Acquisition Range
1. The modem will automatically lock to a correctly formatted carrier, which is
within Acquisition Range of the displayed RX frequency.
2
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,
in 1 Hz steps.
A.9.2 Receive Carrier Reacquisition
1. The modem can be programmed to delay the acquisition process upon loss of
lock. This will minimize the acquisition time for a brief loss of the carrier.
2. This delay can be programmed from 0 to 999 seconds in 1 second steps.
A.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.
A.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.
• Doppler Offset 15 Hz
• Doppler Rate 20 Hz/sec
• Doppler Acceleration 35 Hz/sec 2
The demodulator must lock to the carrier with Doppler applied. BER is measured after
demodulator is locked to the carrier.
E
b
/N
0
values in the table include the 0.5 dB added to account for degradation:
Error Criteria QPSK 1/2 QPSK 3/4 QPSK 7/8 Coding
BER ≤ 10 -6 6.5 7.7 8.8 Viterbi
4x10 7 Bits with no Errors 6.5 7.7 8.8 Viterbi with Reed-Solomon