Comtech EF Data CDM-625A - Page 56

CDM-625A Advanced Satellite Modem MN-CDM625A
Introduction Revision 4
1–14
FEC (cont.)
Low Density Parity Check (LDPC) Codec (Optional plug-in card):
Rate 1/2 BPSK/QPSK/OQPSK
Rate 2/3 QPSK/OQPSK/8PSK/8-QAM
Rate 3/4 QPSK/OQPSK/8PSK/8-QAM/16-QAM
VersaFEC Codec (Optional plug-in card – short-block, low latency LDPC):
Rate 0.488 BPSK (also 0.493 BPSK Ultra-Low-Latency)
Rate 0.533, 0.631, 0.706, 0.803 QPSK (0.493, 0.654, 0.734 Ultra-Low-Latency)
Rate 0.642, 0.711, 0.780 8-QAM (also 0.576 8-QAM Extended CCM)
Rate 0.731, 0.780, 0.829, 0.853 16-QAM (also 0.644 16-QAM Extended CCM)
VersaFEC-2 Long-Block Codec (Optional plug-in card – low latency LDPC):
Rate 0.489 BPSK
Rate 0.489, 0.537, 0.586, 0.611, 0.635, 0.660, 0.684, 0.733 QPSK
Rate 0.521, 0.537, 0.562, 0.586, 0.611, 0.635, 0.660, 0.684, 0.708, 0.733 8-ARY
Rate 0.586, 0.611, 0.635, 0.660, 0.684, 0.708, 0.733, 0.757, 0.782 16-ARY
Rate 0.660, 0.684, 0.708, 0.733, 0.757, 0.782, 0.801, 0.831, 0.855, 0.879 32-ARY
VersaFEC-2 Short-Block Codec (Optional plug-in card – low latency LDPC):
Rate 0.489 BPSK
Rate 0.489, 0.537, 0.586, 0.611, 0.635, 0.660, 0.684, 0.733 QPSK
Rate 0.521, 0.537, 0.562, 0.586, 0.611, 0.635, 0.660, 0.684, 0.708, 0.733 8-ARY
Rate 0.586, 0.611, 0.635, 0.660, 0.684, 0.708, 0.733, 0.757, 0.782 16-ARY
Rate 0.660, 0.684, 0.708, 0.733, 0.757, 0.782, 0.801, 0.831 32-ARY
Transmit filtering
Root-Raised Cosine, alpha = 0.05, 0.10, 0.15, 0.20, 0.25, and 0.35 – front panel/software selectable
See graphs of output spectrum provided at the end of this section
Scrambling
IDR Mode, no RS, - per ITU V.35 (Intelsat variant)
IBS mode, no RS - per IESS-309, externally frame synchronized
Transparent Closed Network mode, no RS or Turbo coding - per ITU V.35 (Intelsat variant)
EDMAC mode, no RS coding - externally frame synchronized - proprietary
Turbo Product Code/LDPC/VersaFEC modes - externally frame synchronized - proprietary
All RS modes - externally frame synchronized per IESS-308/309/310
All VersaFEC
®
, VersaFEC-2
®
modes use IESS-315/V.35
All DoubleTalk® Carrier-in-Carrier® modes, regardless of FEC type, use IESS-315/V.35
External Reference
As an input: 1, 2, 5 or 10MHz -6dBm to +10dBm (nominal 50/75
Ω
, BNC female connector)
As an output: 10MHz, 2.7 volts peak-to-peak ±0.4 volts, low impedance output
(The Ext. reference phase locks Tx and Rx synthesizers, and all baseband clock generation)
Harmonics/spurious
Better than -60 dBC/4 kHz (typically <-65 dBC/4kHz)
950-2250 MHz band: measured F
0
±500 MHz
50-180 MHz band: measured from 1 to 500 MHz
Transmit on/off ratio
-60 dBC minimum
Output phase noise
< 0.48
0
rms double sided, 100 Hz to 1MHz (minimum of 16 dB better overall than the INTELSAT IESS-308/309
requirement)
dB/Hz
-63.0 100 Hz
Frequency Offset
-73.0 1 kHz
-83.0 10 kHz
-93.0 100 kHz
Fundamental AC line spurious is -42 dBc or lower
The sum of all other single sideband spurious, from 0 to 0.75 x symbol rate, is -48 dBc or lower
Output power
950-2250 MHz band: 0 to -40 dBm, 0.1 dB steps - manual mode. See AUPC section also
50-180 MHz band: 0 to -25 dBm, 0.1 dB steps - manual mode. See AUPC section also
Power accuracy
950-2250 MHz band:
±0.7 dB over frequency, data rate, modulation type and temperature range 15°to 35°C
±1.0 dB over frequency, data rate, modulation type and temperature range 0° to 50°C
‘ER’ Version:
±0.8 dB over frequency, data rate, modulation type and temperature range 15° to 35°C
±1.1 dB over frequency, data rate, modulation type and temperature range 0° to 50°C
50-180 MHz band:
±0.5 dB over frequency, data rate, modulation type and temperature range 15° to 35°C
±0.8 dB over frequency, data rate, modulation type and temperature range 0° to 50°C
‘ER’ Version:
±0.6 dB over frequency, data rate, modulation type and temperature range 15° to 35°C
±0.9 dB over frequency, data rate, modulation type and temperature range 0° to 50°C