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4 general specifications, Continuous clock gap clock – Comtech EF Data CDM-710G User Manual

Page 178

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CDM-710G High-Speed Satellite Modem

Revision 1

HSSI Interface (CDI-60)

MN-CDM710G

13–4

Continuous Clock

Gap Clock

13.4

General Specifications

Item

Requirement

Data Rate Range

1 to 70 Mbps
Note: HSSI data rate limit of 70 Mbps may be reached before symbol rate limit is
reached.

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 13-4)

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

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 LED indicates channel is enabled




Figure 13-4. Continuous and Gap Clock at TT

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