Earth Station To Earth Station Communications Port; Terrestrial Loopback; Modem Status; Baseband Processor Card - Radyne DMD2050 Operation Manual

DMD2050 Universal Satellite Modem

3.2 Earth Station to Earth Station Communications Port

The modem contains a selectable RS-232, or RS-485 Asynchronous Communications Port for
Earth Station-to-Earth Station Communications. The baud rate and protocol can be selected from
the Front Panel.

3.3 Terrestrial Loopback

The modem provides for terrestrial loopback. For Tx Terr Loopback the Tx Data port is looped
back to the Rx Data port after the interface driver/receiver. 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 3-6
through 3-8 for loopback functional block diagrams.

3.4 Modem Status

The modems M&C system is connected to most of the circuitry on any board contained in the
chassis. These connections provide status on the working condition of the circuitry as well as
providing the data required for the various measurements the modem provides. The M&C
processes this information and generates status indications as well as alarms when necessary.
Detailed status information is available via the modems various user interfaces (front panel,
remote and terminal). A summary of this information can be connected to external equipment,
switches or alarms via the open collector and/or form-C fault connections.
Form-C Contacts:
The UIM provides three Form-C Relays under processor control that appear at J11.
Mod Fault:
Demod Fault:
Common Fault:
Open Collector Faults:
The UIM provides two Open Collector Faults that appear at Pins 28 & 10 on J8.
Mod Fault:
Demod Fault:
The open collector faults are intended for use in redundancy switch applications in order to
provide quick status indications.

3.5 Baseband Processor Card

The Baseband Processor Card (BB Card) contains two major subsystems – the Baseband
Processing System and the Monitor and Control Subsystem.
TM110 – Rev. 1.3
De-energized when any transmit side fault is detected.
De-energized when any receive side fault is detected.
De-energized when any fault that is not explicitly a Tx or
Rx Fault such as an M&C or Power Supply 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.
Will sink up to 20 ma (maximum) until a receive or
common fault is detected. Will not sink current if a fault
is detected.
Theory of Operation
3-7