Operating instructions

DMD20/DMD20 LBST Universal Satellite Modem User Interfaces
TM103 – Rev. 2.8 4-17
Limitations of Fast Acquistion:
The maximum symbol rate for Fast Acquistion is 1028Ksps.
Fast Acquistion must be disabled for rates greater than 1028Ksps.
Only supports QPSK and 8PSK in a NON-DVB MODE.
Does not support spectral inversion applications.
INPUT THRESHOLD (dBm) {-30 to 90 dbm}
Allows the user to adjust the low level threshold limit for
input power. Input power level below the threshold limit
will trigger a major alarm on the demodulator.
EB/NO ALARM {0.0 to 9.90 db}
Allows the user to set the desired E
b
/N
o
for the local
receiver. This setting is compared against the receive
E
b
/N
o
and commands to the remote modem to increase
or decrease Transmit Power accordingly are sent.
DATA (menu)
DATA RATE (bps) {Refer to Technical Specs for Data Rates}
Allows the user to set the Data Rate in bps steps via the
Front Panel Arrows or Keypad.
SYMB RATE (sps) Allows the user to view the Symbol Rate.
INNER FEC Viterbi {1/2, 3/4, 7/8, None}
Optional FEC Rates:
Sequential {1/2, 3/4, 7/8}
Trellis 8PSK {2/3}
Turbo ≤ 5 Mbps {.793, .495}
Turbo ≤ 20Mbps {1/2, 3/4, 7/8}
Comstream Seq {3/4}
DVB VIT {1/2, 2/3, 3/4, 5/6, 7/8}
DVB Trellis {2/3, 5/6, 8/9}
Allows the user to select the Rx Code Rate and Type
TPC INTERLEAVER {DISABLED, ENABLED}
Allows the user to disable or enable TPC Interleaver.
Valid only for Radyne turbo codes TPC.495 and
TPC.793.
DIFF CODING {ENABLED, DISABLE}
Allows the user to enable or disable the Differential
Decoder. Having the decoder enabled ensures proper
phase lock. May not be adjustable in some modes.