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DMD15/DMD15L IBS/IDR Satellite Modem Operation
TM051 - Rev. 5.8 3-5
can be connected to the ‘Insert Data In’ Port where received data will overwrite ‘dropped on’ the
T1/E1 Data Stream. The modified T1/E1 Data Stream will then exit the modem out of the
‘Receive Data Out’ Port.
3.5 Earth Station to Earth Station (ES-ES) Communications Port
(Async Port J9)
The UIM contains a selectable RS-232, or RS-485 Asynchronous Communications Port for Earth-
Station-to-Earth-Station Communications. The data is routed from the 9-Pin “D” Connector J9 to
one of the M&C Processor UARTS on the Baseband Processor Card. The baud rate and protocol
can be selected from the Front Panel.
3.6 Terrestrial Loopback
The UIM also provides for terrestrial loopback. For Tx Terr Loopback, Tx Data, after passing
through the Line Interface is looped back to the Rx Data line drivers. For RX Terr Loopback, the
Receive Data from the satellite is looped back for retransmission to the satellite providing a far
end loopback. Tx/Rx Loopback provides both loopbacks simultaneously. Refer to Figures 3-4
through 3-6 for loopback functional block diagrams.
3.7 Modem Status
The UIM provides several status indications, which are controlled by the M&C Processor.
Form-C Contacts:
The UIM provides three Form-C Relays under processor control that appear at J11.
Mod Fault: De-energized when any transmit side fault is detected.
Demod Fault: De-energized when any receive side fault is detected.
Common Fault: De-energized when any fault that is not explicitly a Tx or
Rx Fault such as an M&C or Power Supply Fault.
Open Collector Faults:
The UIM provides two Open Collector Faults that appear at Pins 28 & 10 on J8.
Mod Fault: Will sink up to 20 ma (maximum) until a transmit or
common fault is detected. Will not sink current if a fault
is detected.
Demod Fault: Will sink up to 20 ma (maximum) until a receive or
common fault is detected. Will not sink current if a fault
is detected.
The open collector faults are intended for use in redundancy switch applications in order to
provide quick status indications.