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SDM-2020 Satellite Demodulator
A.8.3
Interface Specifications
A 75Ω coaxial cable (Belden 8281 or equivalent) is recommended for all ASI connectors.
Typical Coaxial cable length is up to 140 meters (460 feet) with good quality coaxial
cable. Typical attenuation of up to 18dB at 270 MHz is permitted.The following cables,
or an equivalent computer grade cable incorporating twisted, shielded pairs, are
recommended for the LVDS interface:
•
•
The Belden 8175 has a lower capacitance, however, it has a larger diameter and requires
theselection of an appropriate connector shell. The typical cable length for the
serial/parallel interfaces is ≤ 5 meters (16.405 feet).
Table A-38 describes the interface specifications.
Data Framing Formats
Hot Pluggable
Data Rate
Clock Rate Uncertainty
Transport Clock ASI
Impedance
Return Loss
Loop Functions
Connectors
Electrical Properties
Packet Types
Signal Types
Voltage Level
ASI Data Loop 3 dB
Frequency, TX Only
Jitter Tolerance
Jitter Transfer
Cable Length, Typical
Delay Variation Of
Interface And Modulator
Rev.3
Belden type LV Computer M9768
Belden 8175
Table A-38. ASI/LVDS Specifications
General Specifications
188, 204 byte packets per ETS 300 421, and None.
Not required. Unit power is turned off before removal or insertion of the
data interface.
ASI Specifications
1.5 to 100 Mbit/s ASI.
Programmed data rate ± 100 ppm.
The transport rate is 270 Mbit/s for all data rates.
75Ω
.
15 dB, frequencies, 5 to 270 MHz.
Loopback
(see text)
Loop Thru
BNC female, 75Ω.
Per EN 80053-9.
Burst or distributed.
Serial data.
800 mV ± 10% into 75Ω.
Wide: 2 Hz
Narrow: 0.3 Hz
Meets ITU-T G.823 (3/93) and ITU-T G.824 (3/93)
≤ 0.5 dB peaking up to cutoff frequency.
–20 dB per decade beyond cutoff.
100 meters (328 feet), RG59
140 meters (459 feet), Belden 8281
8 bits maximum, QPSK, and 8PSK only.
8PSK 2/3 and 5/6 all data rates. 8PSK 8/9 less than 80 Mbit/s.
Data Interfaces
A–67
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