Hssi Interface Specifications; Figure 3-3. Hssi Interface Example - Comtech EF Data CDM-Qx Installation And Operation Manual

CDM-Qx/QxL Multi-Channel Satellite Modem with DoubleTalk™ Carrier-in-Carrier®
Rear Panel Connectors
3.3.6.1

HSSI Interface Specifications

Item
Data Rate Range
Signals Supported
Connector
Electrical
Electrical Typical
Minimum Buffer Size
Tx
Impedance
Rx
Signal Characteristics
Clock / Data
Relationship
Tx Clock Modes
Rx Clock Modes
Tx / Rx Clock
Default
TA / CA
Selection CA is asserted when there is no modem fault
Operation
Signal Sense
Cable Length to 20
Mbps
Requirement
32 to 20 Mbps
ST, TT (or external) , SD, TA, CA, RT, RD, SG
DCE, 50-pin mini-D female per EIA-613 (HSSI)
Per EIA-612 (10KH ECL compatible).
Differential output voltage: > 590 mV pp into 110 load
Differential Input voltage: 150 to 1000 mV pp with 110 load
5.0 mS smallest buffer setting, 0.1 mS step size, 32 mS maximum size
110Ω for TT, SD, TA
ST, CA, RT, RD will drive 110Ω and meet HSSI voltage levels
The A terminal is negative with respect to the B terminal for a binary 0 (Space or OFF)
state.
The A terminal is positive with respect to the B Terminal for a binary 1 (Mark or ON)
state.
The data transitions occur during the OFF to ON transition of the clock. Data is stable
during the ON to Off transition of the clock.
TT (Input clock) continuous.
ST (output clock) is continuous output, programmable in 1 bps steps or phase locked
to satellite clock
RT (output clock) is continuous from satellite, ST (internal clock), continuous from TT
Asymmetrical clocking with Rx Doppler buffer disabled
CA looped to TA
Simplex (Tx only or Rx only) or full duplex
Programmable Normal or Inverted or TT and TD, RT and RD
2 M (6 ft) nominal, up to 15 M (49 ft) maximum – note higher data rates usually
require shorter cable lengths

Figure 3-3. HSSI Interface Example

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Revision 7
MN/CDMQX.IOM