SDM-2020 Satellite Demodulator
Data Interfaces
Rev.3
A–35
A.5.4.4
Terrestrial Data Rate
The terrestrial interface supports synchronous data transfer rates from 1.5 to 70 Mbit/s.
Notes:
1.
EIA-612 (Electrical Characteristics for an Interface at Data Signaling Rates
up to 52 Mbits/s) defines the electrical characteristics required for data
transfers up to 52 Mbits/s utilizing ECL driver/receiver technology.
2.
The HSSI port will comply with EIA-612 for transfers less than 52 Mbits/s.
3.
For short distances, an SCSI-2 cable will work, although the impedance will be
wrong.
The recommended cable is a CISCO “CAB-HSI1 (DTE to DCE)” or “CAB-HNUL
(DCE to DCE)” incorporating twisted, shielded pairs. The maximum cable length should
be
≤
3 ft (7.62 cm) for the 70 Mbits/s transfer rates.
A.5.4.5
Terrestrial Electrical Characteristics
All signals are balanced, differentially driven, and received at standard 10K/100K ECL
levels. Table A-18 summarizes the electrical properties of the HSSI interface.
Table A-18. HSSI General Specifications
General Specifications
Connectors
50-pin mini-D female for EIA-613 (HSSI) data.
Electrical Properties
Per EIA-612 (10KH ECL).
TTL/TTL open-collector.
Typical Voltages Levels
Differential voltage:
≥
590 mV, 110
Ω
load
Input voltage range:
-0.5 to -2.0V
Referenced to receiver common.
A.5.4.6 Terrestrial
Timing
The nominal interface timing is as follows:
•
Clock is 50% duty cycle
•
Data/control signals transition on the rising (low to high) edge of the clock
•
Data/control signals are stable on the falling (high to low) edge of the clock
Summary of Contents for SDM-2020
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