Table A-11. Asi/Rs-422 Specifications - Comtech EF Data SDM-2020 Installation And Operation Manual

SDM-2020 Satellite Demodulator
A 75Ω coaxial cable (Belden 8281 or equivalent) is recommended for all ASI connectors.
Typical coaxial cable length is up to 70 meters (230 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:
•
•
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 A-11.
Data Framing Formats
Hot Pluggable
Data Rate
Clock Rate Uncertainty
Transport Clock ASI
Impedance
Return Loss
Connectors
Electrical Properties
Packet Types
Signal Types
Voltage Level
ASI Data Loop 3 dB
Cutoff Frequency
Jitter Tolerance
Jitter Transfer
Cable Length, Typical
Data Rate
Clock Rate Uncertainty
Connectors
Electrical Properties
Signal Types
Voltage Level
Rev.3
Belden type LV Computer M9768
Belden 8175

Table A-11. ASI/RS-422 Specifications

General Specifications
188, 204 byte packets per ETS 300 421, and None.
Not required. Unit power is turned off prior to 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.
BNC female, 75Ω.
Per TM 1449
Burst or distributed.
Serial data.
800 mV ± 10% into 75Ω.
2 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.
Rev. –
Rev. A
RS-422 Specifications
1.5 to 18 Mbit/s, serial RS-422.
Programmed data rate ± 100 ppm.
25-pin D female per EIA-530.
Per RS-422.
SD, TT, ST, RD, RT, RS, RR, CS, and DM.
Data synchronization is detected by correlating the data stream for the
MPEG2 sync pattern per ETS 300 421.
4 ± 2V differential into 100Ω.
(see Note 2)
RG59 Belden 8281
50 m 70 m
100 m 140 m
Data Interfaces
A–23