Comtech EF Data SDM-2020 - Manual (Page 164)

SDM-2020 Satellite Demodulator Revision 4
ECL/HSSI Data Interface MN/SDM2020D.IOM
10–12
10.1.4.7 Terrestrial TX Clock Phase
The ECL/HSSI interface supports TX clock phase inversion. Terrestrial data is sampled
on the falling edge of TT clock in normal phase selection. In inverted phase selection, the
terrestrial data will be sampled on the rising edge of TT clock.
10.1.4.8 Terrestrial RX Clock Phase
The ECL/HSSI interface supports RX clock phase inversion. Terrestrial data (RD) is
synchronous to RT. In normal mode, the falling edge of the RT clock will be centered on
the RD signal. In inverted phase selection, the rising edge of RT clock will be centered on
the RD signal.
10.1.5 Monitor and Control Functions
10.1.5.1 System Implementation
Refer to Table 10-9 for signal definition.
Table 10-9. Signal Definition
Signal Definition
TA (Data Terminal Equipment Available)
LA (Loopback Circuit A)
LB (Loopback Circuit A) These signals are inputs from the HSSI interface. The state of these
inputs is read by the M&C from the ECL/HSSI interface status
register.
CA (Data Communication Equipment
Available)
LC (Loopback Circuit C)
TM (Test Mode) These signals are outputs from the HSSI interface. The state of these
outputs is controlled by the M&C writing the ECL/HSSI interface
control register.
TA This signal indicates the DTE is available for data transfers. When the
DTE is not available the RF output will be turned Off and the DTE
status menu shall reflect DTE unavailable.
LA and LB loopback input control signals These signals are available to the M&C, but no functional support is
required.
Upon Modem power-up the CA output is set UNAVAILABLE until all modem
initialization has been completed and no faults are detected. After completion of
initialization the CA line is set AVAILABLE. Any detectable faults that cause the
modem to be place in an non-operational mode shall set CA UNAVAILABLE.
TM output shall be set ACTIVE if the ECL/HSSI interface is commanded into Loopback
mode. TM shall be INACTIVE for all other modes.
LC output is not supported, and is set inactive for all modes.