Comtech EF Data CDM-700 - Manual (Page 240)

CDM-700 High Speed Satellite Modem Revision 5
HSSI Interface (CDI-60) MN/CDM700.IOM
D.3 General Specifications
Table D-1. Interface Specifications
Item Requirement
Data Rate Range 1 to 70 Mbps
Interfaces Per Module One HSSI
Signals Supported ST, TT (or external) , SD, TA, CA, RT, RD, SG
Connector DCE, 50-pin mini-D female per EIA-613 (HSSI)
Electrical Per EIA-612 (10KH ECL compatible).
Electrical Typical
Differential output voltage: > 590 mV pp into 110 load
Differential Input voltage: 150 to 1000 mV pp with 110 load
Minimum Buffer Size 5.0 mS smallest buffer setting, 0.1 mS step size, 32 mS maximum size
Impedance
Rx 110 for TT, SD, TA
Tx ST, CA, RT, RD will drive 110 and meet HSSI voltage levels
Signal Characteristics
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.
Clock / Data Relationship
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.
Tx Clock Modes
TT (Input clock) continuous.
ST (output clock) is continuous output, programmable in 1 bps steps
or phase locked to satellite clock
Rx Clock Modes
RT (output clock) is continuous from satellite, ST (internal clock),
continuous from TT
Gap Clock (See Figure D-3)
Not allowed – Send ST to external equipment so it will return a
continuous clock
Tx / Rx Clock Asymmetrical clocking with Rx Doppler buffer disabled
Acquisition Range Programmed Tx data rate ± 100 ppm
TA / CA
Default CA looped to TA
Selection: CA is asserted when there is no modem fault
Test
I/O Loopback per the Appendix
Interface Loopback per the Appendix
2047 test pattern generator
Operation Simplex (Tx only or Rx only) or full duplex
Signal Sense Programmable Normal or Inverted for TT and TD, RT and RD
Modules Per Modem The interface operates in Slot 1, Slot 2, or both slots.
Cable Length to 52 Mbps
2 m (6 ft) nominal, up to 15 m (49 ft) maximum – Note higher data
rates usually require shorter cable lengths.
LED Green LEDs indicate channel is enabled
Continuous Clock
Gap Clock
Figure D-3. Continuous and Gap Clock at TT
D–4