Rx Baseband Processing; Monitor & Control (M&C) Subsystem; Remote/Terminal Port; Async Port - Radyne DMD2050 Operation Manual

Theory of Operation DMD2050 Universal Satellite Modem

3.1.4 Rx Baseband Processing

The Receive Processor performs the inverse function of the Tx Processor. Data received from
the satellite passes through the BB Loopback Circuit to the Reed-Solomon Decoder to the
Deframer. The Deframer acquires the IBS/IDR/DVB frame, synchronizes the Reed-Solomon
Decoder and extracts the received data and overhead from the frame structure, placing the data
into the PD Buffer, sending the overhead data to the UIM. In Closed-Net Mode, the data is
extracted from the buffer and is sent to the UIM. Backward Alarm indications are sent to the M&C
Subsystem. In Drop and Insert Mode, the Insert Processor synchronizes to the incoming
terrestrial T1/E1 Data Stream, extracts satellite channels from the PD Buffer, and then inserts
them into the desired terrestrial time slots in the T1/E1 Data Stream.
3.1.5 Monitor & Control (M&C) Subsystem
Also contained on the BB Card is the M&C Subsystem. The M&C contains a high-performance
microprocessor and is responsible for overall command and control of modem functions. The
M&C is constantly monitoring all subsystems of the modem by performing a periodic poll routine
and configures the modem by responding to commands input to the system. During each poll
cycle, the status of each of the subsystems is collected and reported to each of the external ports
and Front Panel. Performance statistics such as Eb/No, buffer fill %, etc. are compiled. If faults
are detected, the M&C will take appropriate actions to minimize the effect of such faults on the
system (refer to the Fault Matrices in Section 6).
The following sections describe the M&C Subsystem features:

3.1.5.1 Remote/Terminal Port

This port functions as the Modem Remote Port or Terminal Port. This port supports an
asynchronous control protocol as described in Section 4. It may be configured to support either
RS-232 or RS-485 signal levels. This port is intended for use in computer-based remote M&C.
All functions of the modem may be monitored and controlled from this port via a common terminal
connected to the Terminal Port. This function is front panel selectable.

3.1.5.2 Async Port

This port is dedicated for ES-ES Communications. The port may be configured for a number of
communications protocols. Overhead data to/from the UIM is routed to/from the framer/deframer.
This port may be configured to support either RS-232 or RS-485 signal levels. This port is also
used by SCC Framing for the in-band data.

3.1.5.3 Ethernet Port

This port is dedicated for Ethernet Communications. The port is configured for 10 Base-T
communications protocols.

3.1.5.4 Clock

The time and date is kept in order to 'time-tag' system events.
3-6 TM110 - Rev. 1.3