Comtech EF Data SDM-2020 - Manual (Page 147)

SDM-2020 Satellite Demodulator Revision 4
ASI/RS-422Data Interface MN/SDM2020D.IOM
9–3
J3
J4
J5
J6
J7
ASI INPU
T
S
EIA-
42
2/
5
30
ASI O
U
TPUTS
Figure 9-2. ASI Module Assembly
A 75 Ω 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 18 dB at 270 MHz is permitted. The following cable,
or equivalent computer grade cables incorporating twisted, shielded pairs, are
recommended for the RS-422 interface:
• Belden type LV Computer M9768
• Belden 8175
The Belden 8175 has lower capacitance; however, it has a larger diameter and requires
the selection of an appropriate connector shell. The typical cable length for the
serial/parallel interfaces is
≤ 5 meters (16.405 feet). The interface operates to the
specifications described in Table 9-2.