Comtech EF Data MIDAS 4 System and Design - Manual (Page 65)

System and Design Manual, Revision 2
Network Management System 4–5
S S N N M M - - 1 1 0 0 0 0 1 1 N N e e t t w w o o r r k k
C C o o n n t t r r o o l l M M o o d d e e m m
The Comtech EF Data’s SNM-1001 Network Control Modem allows
communication with the traffic nodes over the control channels. It transmits on
the outbound control channel to the traffic nodes and receives the incoming
messages from the traffic nodes on the inbound control channel.
The outbound control channel is a continuous, Time Division Multiplexed
(TDM) channel transmitted by the MIDAS Controller to all the traffic nodes
in the network. The inbound control channel is a burst channel using Slotted
Aloha access protocol. The traffic nodes send requests and report status to the
MIDAS Controller and respond to MIDAS Controller commands.
System Specifications
Operating IF Range 50 to 180 MHz, in 100 Hz steps
Continuous Mode: TX only :
Digital
Data
QPSK, 1/2 rate, 19.2 kbps
Forward Error Correction Viterbi soft decision
Doppler Buffer 64 to 65536 bits, or 1 to 50 ms in total depth
Data Scrambling Intelsat V.35
Burst Mode: RX only
Digital
Data
QPSK, 1/2 rate, 19.2 kbps
Forward Error Correction Viterbi soft decision
Carrier Acquisition Range ± 4 kHz at Eb/N0 = 8 dB, > 99% probability
Acquisition Time:
19.2 kbps, QPSK, R=1/2
< 30 ms
Data Interfaces EIA-422/449
Phase Noise Per IESS-308
Modulator Specifications
Output Power
-5 to -30 dBm, adjustable in 0.1 dB steps
Spurious -55 dBc (4 kHz)
Data Clock Source Internal or External
Internal Clock Stability
± 1 x 10-5
Output Impedance 75 Ω
Output Return Loss ≥ 20 dB
Demodulator Specifications
Input Level (Desired Carrier)
-30 to -55 dBm
Maximum Composite Carrier -5 dBm or +30 dBc, within 2 MHz of desired carrier
Input Impedance 75 Ω
Input Return Loss ≥ 20 dB
Monitor & Control Specifications
Serial Interface Type
EIA-232
Data Rate 19.2 kbps
Commands ASCII