Comtech EF Data CDM-550T - Manual (Page 112)

CDM-550T Satellite Modem Revision 3
Summary Of Specifications MN/CDM550T.IOM
FEC •
None: Uncoded BPSK/QPSK/OQPSK
•
Viterbi: k=7, per IESS 308/309
•
BPSK: Rate 1/2
•
QPSK/OQPSK: Rate 1/2, Rate 3/4 and Rate 7/8
• Sequential:
o k=36 (Rate 1/2) per IESS 309
o k= 63 (Rate 3/4) per IESS 309
o k= 87 (Rate 7/8)
•
Reed-Solomon (Optional plug-in card):
o 220,200 outer code (transparent modes)
o 200,180 outer code (EDMAC modes)
•
Interleaver depth = 4 (Viterbi)
•
Interleaver depth = 8 (Sequential)
•
Turbo Product Codec (Optional plug-in card):
o Rate 3/4 QPSK/OQPSK - 2 dimensional
o Rate 1/2 QPSK – 2 dimensional
o Rate 21/44 BPSK - 3 dimensional
o Rate 5/16 BPSK - 3 dimensional
Output frequency •
52 - 88 MHz, 100 Hz resolution (140 MHz band optional, 104 - 176 MHz)
•
Stability ±1.5 ppm, 0 to 50 o C (32 to 122 o F)
Harmonics and spurious Better than -55 dBC/4 kHz (typically <-60 dBC/4kHz)
Transmit on/off ratio 55 dB minimum
Output phase noise < 0.24
0
rms double sided, 100 Hz to 1MHz (minimum of 22 dB better overall than
the INTELSAT IESS 308/309 requirement)
Output power 0 to -20 dBm, 0.1 dB steps - manual mode. Refer to AUPC section.
Accuracy ±0.5 dB over frequency and temperature
Output impedance 50 and 75
Ω, front panel selectable
17 dB minimum return loss
O/P connector BNC female
Clocking options • Internal,
±1ppm
•
External, locking over a ±100 ppm range
•
Loop timing (Rx satellite clock) - supports asymmetric operation - Rx and
Tx data rates do not need to be identical
External TX Carrier Off By TTL 'low' signal or external contact closure - hardware function automatically
over-rides processor
14–2