Comtech EF Data MIDAS 4 System and Design - Manual (Page 66)

System and Design Manual, Revision 2
4–6
Network Management System
S S N N M M - - 1 1 0 0 0 0 2 2
L L i i n n k k S S y y n n c c ™ ™ M M o o d d e e m m
The Comtech EF Data's SNM-1002 LinkSync™ Modem is responsible for
monitoring the receive frequency and the receive E
b
/N
o
of the outbound
control channel at the MIDAS Controller site.
The outbound control channel is used as the frequency and power reference
for LinkSync™ calculations. The modem also is used for transmitting the
interfering carrier to terminate circuits involving integrated traffic/control
modems and/or network terminals.
System Specifications
Operating IF Range
50 to 180 MHz, in 1 Hz steps
Digital Data Rate:
Receive 19.2 kbps
Transmit 2.4 kbps to 4.375 Mbit/s
Demodulation QPSK 1/2 rate
Modulation BPSK 1/2 rate
QPSK 1/2, 3/4, and 7/8 rates
Forward Error Correction Viterbi, K=7, 1/2, 3/4 and 7/8 rates
Data Scrambling Intelsat V.35
External Reference Input 1, 5, 10, 20 MHz
Modulator Specifications
Output Power
-5 to -30 dBm, adjustable in 0.1 dB steps
Output Spurious < -55 dBc, 0 to 500 MHz (4 kHz band)
Output Spectrum Meets IESS-308/309 power spectral mask
Output Return Loss > 20 dB
Output Impedance 75 Ω (Optional: 50Ω)
Data Clock Source Internal or External
Demodulator Specifications
Input Power
Desired Carrier -30 to -55 dBm
Maximum Composite -5 dBm or +40 dBc
Input Impedance 75 Ω (Optional: 50Ω)
Input Return Loss > 20 dB
Carrier Acquisition Range ± 35 kHz, from 100 Hz to 35 kHz in 1Hz steps
Acquisition Time
19.2 kbps, QPSK, R=1/2
< 2 second
Sweep Reacquisition 0 to 999 seconds, in 1 second steps
Data Clock Internal, External, TX, Recovered RX
Monitor & Control Specifications
Interface Type
EIA-232
Data Rate 19.2 kbps
Commands ASCII