Comtech EF Data SDM-2020 - Manual (Page 55)

SDM-2020 Satellite Demodulator Revision 4
Specification MN/SDM2020D.IOM
5–3
5.1.1 L-Band and 70/140 MHz Input Demodulator Charactistics
Table 5-2. L-Band and 70/140 MHz Input Demodulator Characteristics
Demodulator Specification
Parameter Single L-Band Input
(Older L-Band)
4 L-Band Inputs
(Newer L-Band)
Signal 70/140 MHz
Input (Optional)
RX IF Input 950 to 1750 MHz
in 2.5 kHz steps 950 to 1750 MHz
in 2.5 kHz steps 50 to 90 MHz and
100 to 180 MHz
in 2.5 kHz steps
Number of IF Inputs:
Standard
FAST Option
FAST Option
1 Physical Connector
4 Physical Connector
1 RF input connector
2 RF inputs enabled
4 RF inputs enabled 1 Physical Connector
Isolation, Unused Input to Tuner NA 50 dB minimum NA
Isolation, Between any Input NA 50 dB minimum NA
RX IF Impedance 75 Ω 75Ω 75Ω (50Ω Optional)
RX IF Return Loss (minimum) 10 dB 10 dB 18 dB
RX IF Connector Type F, Female Type F, Female BNC, Female
Minimum Input, Desired Carrier C.
(See Figure 5-1 and 5-2) C = –71 + 10 log
(Msym/s) dBm C = –65 + 10 log (Msym/s)
dBm C = –57 + 10 log
(Msym/s) dBm
Input AGC Range, minimum 40 dB 40 dB 30 dB
Input Level, Composite –5 dBm maximum, additive white Gaussian noise (AWGN)
Composite/Desired Carrier Ratio ≤ 17 +10 log [37.5/(Msym/s)]
LNB Power Supply Output
(Through Selected Input Only)
Selection 1
Selection 2
Selection 3 500 mA maximum, short circuit protected through
Type F connector feed:
20 to 24 VDC
12 to14 VDC, V-polarization per DiSEqC 4.2
16 to 20 VDC, H-polarization per DiSEqC 4.2 NA
RX Buffer None (Note: Some Data Interfaces contain a buffer.)
Acquisition Sweep Range/Increment 0 to ± 500 kHz/1Hz 0 to ± 60 kHz
Acquisition Time ≤ 5 seconds, typical at ± 50 kHz uncertainty
BER Performance See Tables.
Adjacent Carrier Performance QPSK and 8-PSK: Performance degradation will not be more than 0.5 dB in the
presence of two-like modulated carriers each spaced 1.3 x symbol rate on either side
of the desired carrier and each adjacent carrier 10 dB greater in power than the
desired carrier .
16-QAM: Performance degradation will not be more than 0.5 dB in the presence of
two-like modulated carriers each spaced 1.3 x symbol rate on either side of the
desired carrier and each adjacent carrier 10 dB greater in power than the desired
carrier for symbol rates < 10 Msys/s and 7 dB, each carrier for symbol rates over 10
Msym/s.
Spectral Inversion Automatic, detection with ambiguity resolution