VSATplus Product Website

Comtech EF Data DMD20 LBST L-Band Satellite Modem


  • DoubleTalk Carrier-in-Carrier bandwidth compression
  • Web browser interface
  • FSK M&C channel for smart BUCs
  • Integrated 10 MHz high-stability reference
  • Programmable 13, 15, 18, or 20 VDC for LNB
  • Optional 24 or 48 VDC for up to 10 W BUC
  • 950 to 2050 MHz L-Band TX/RX operation
  • BPSK/QPSK/OQPSK/8-PSK/8-QAM/16-QAM operation
  • 2.4 kbps to 20 Mbps, 1 bps steps
  • Configuration, monitor and control features full user-programmable
  • FEC – Viterbi, Reed-Solomon, Sequential, Trellis, TPC, Low Density Parity Check Code (LDPC)
  • Excellent spurious performance
  • Fully compliant with IESS-308/309/310/314/315
  • Optional DVB to EN301-210 and EN300-421
  • Industry-standard universal interface module
  • Standard features include: Reed-Solomon, Asynchronous Overhead, automatic uplink power control and CM701 compatible satellite control channel
ModulationBPSK, QPSK, and OQPSK (8PSK, 16QAM Optional)
L-Band Tuning Range950 to 2050 MHz in 1 Hz Steps
Impedance50 Ohm
ConnectorFemale Type N
Return Loss10 dB Minimum
Output Power0 to -25 dBm
Output Accuracy±1.0 dB Over Frequency and Temperature
Output SpectrumMeets IESS 308/309/310 Power Spectral Mask (DVB-S optional)

-55 dBc
-45 dBc
Harmonics-45 dBc
On/Off Power Ratio>60 dB
ScramblerCCITT V.35 or IBS (Others Optional)
Viterbi, K=7 at 1/2, 3/4 and 7/8
Trellis 2/3
Turbo Product Code (Optional) Per IESS 315
BPSK 21/44
QPSK/OQPSK 1/2, 3/4, 7/8
8PSK/16QAM 3/4, 7/8
Legacy Turbo Rates: 0.495, 0.793
Outer Encoder OptionsReed-Solomon INTELSAT (DVB Optional)
Custom (N,K) Reed-Solomon (Optional)
Data Clock SourceInternal, External, Rx Recovered
Internal Stability5 x 10-8
BUC DC VoltageBUC 24 V@4 A Maximum
BUC 48 V (Optional)
BUC Reference10 MHz, 3 dBm ± 3 dB
BUC FSK710/590 KHz Nominal (Optional)
DemodulationBPSK, QPSK, and OQPSK (8PSK, 16QAM Optional)
L-Band Tuning Range950 to 2050 MHz in 1 Hz Steps
Impedance50 Ohm
ConnectorType N Female
Return Loss10 dB Minimum
SpectrumINTELSAT IESS 308/309/310 Compliant (DVB-S optional)
Input Level10 x log (Symbol Rate) – 100, ±12dBm
Total Input Power-10 dBm or +40 dBc (the lesser) @ 64 Kbps, Symbol Rate Dependent
Viterbi, K=7 at 1/2, 3/4 and 7/8 Rate,
Rate Sequential 1/2, 3/4, 7/8 (Optional),
Trellis 2/3,
Turbo Product Code (Optional) Per IESS 315,
BPSK 21/44,
Custom (N,K) Reed-Solomon,
QPSK/OQPSK 1/2, 3/4, 7/8,
8PSK/16QAM 3/4, 7/8,
Legacy Turbo Rates: 0.495, 0.793,
Decoder OptionsReed-Solomon INTELSAT (DVB-S Optional)
DescramblerCCITT V.35 or IBS (Others Optional)
Acquisition RangeProgrammable ±1 kHz to ± 255 kHz
Sweep Delay Value100 msec to 6000 sec. in 100 msec Steps
LNB Reference10 MHz, 3 dBm ± 3 dB
LNB DC Voltage13, 15, 18, 20 VDC (750 mA Maximum), Programmable
Plesiochronous Buffer
Size0 ms to 64 msec
CenteringAutomatic on Underflow or Overflow
Centering ModesIBS: Integral Number of Frames
IDR: Integral Number of Multi Frames
ClockTransmit, External, Rx Recovered or SCT (Internal)
Monitor and Control
Remote RS-485/Terminal RS-232/Ethernet 10 Base-T, Web Browser
DMD20 LBST Drop and Insert (Optional)
Terrestrial Data1.544 Mbps or 2.048 Mbps, G.732/733
Line CodingAMI or B8ZS for T1 and HDB3 for E1
FramingD4, ESF and PCM30 (PCM 30C) or PCM31 (PCM 31C) for E1
Time Slot Selectionn x 64 Contiguous or Arbitrary Blocks for Drop or Insert
EFFICIENT D&I Closed Network, Satellite Overhead 0.4%
Time Slots1-31 Any Combination
Terrestrial Interfaces
DVB ASI/SPI, HSSI, Ethernet 4 Port 10/100 Base-T,
HSSI/Ethernet 4 Port 10/100 Base-T, HSSI/G703 T1/E1/T2/E2
DoubleTalk Carrier-in-Carrier
Delay Range0 to 300 ms
Power Spectral Density Ratio (Interferer to Desired)BSPK/OQPSK/QPSK/8-PSK/8-QAM: -7 dB to +10 dB 16-QAM: -7 dB to +7 dB
Maximum Symbol Rate Ratio3:1 (TX:RX or RX:TX)
Eb/No Degradation0 dB Power spectral density ratio
8-QAM: 0.7 dB
8-PSK: 0.8 dB
16-QAM: 0.9 dB
Satellite RestrictionsSatellite in “loop-back” mode (i.e., the transmit station can receive itself)
“Non-processing” satellite (i.e., does not demodulate or remodulate the signal)
IDR/ESC Interface (Optional)
G.703 T1 (DSX1)1.544 Mbps, 100 Ohm Balanced, AMI and B8ZS Line Codes
G.703 E12.048 Mbps, 75 Ohm Unbalanced and 120 Ohm Balanced, HDB3
G.703 T2 (DSX2)6.312 Mbps, 75 Ohm Unbalanced, B8ZS Line Code and 110 Ohm Balanced, B6ZS Line Code
G.703 E28.448 Mbps, 75 Ohm BNC, Unbalanced, HDB3 Line Code
IBS/Synchronous Interface (Standard)
RS-422/-530All Rates, Differential, Clock/Data, DCE
ITU V.35All Rates, Differential, Clock/Data, DCE
RS-232(DCE up to 200 Kbps)
Prime Power100 to 240 VAC, 50 to 60 Hz, 150 Watts Maximum with 10 W BUC
Operating Temperature0 to 50° C, 95% Humidity, Non-Condensing
Storage Temperature-20 to 70°C, 99% Humidity, Non-Condensing
Size19”W x 19.25”D x 1.75”H
(48.26 x 48.89 x 4.45 cm)
Weight8.5 pounds (3.83 kg)

Comtech EF Data DMD20 LBST L-Band Satellite Modem Datasheets

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